diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 3503bc852cdaf288e0756bba6799b3788d3fa61c..e5bef18d7d8f82768dec52f85a83293d5fb1a95c 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.221 2010/02/07 20:48:09 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.222 2010/02/16 22:34:41 tgl Exp $ -->
<!--
Documentation of the system catalogs, directed toward PostgreSQL developers
-->
@@ -168,11 +168,6 @@
<entry>metadata for large objects</entry>
</row>
- <row>
- <entry><link linkend="catalog-pg-listener"><structname>pg_listener</structname></link></entry>
- <entry>asynchronous notification support</entry>
- </row>
-
<row>
<entry><link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link></entry>
<entry>schemas</entry>
@@ -3253,68 +3248,6 @@
</table>
</sect1>
- <sect1 id="catalog-pg-listener">
- <title><structname>pg_listener</structname></title>
-
- <indexterm zone="catalog-pg-listener">
- <primary>pg_listener</primary>
- </indexterm>
-
- <para>
- The catalog <structname>pg_listener</structname> supports the
- <xref linkend="sql-listen" endterm="sql-listen-title"> and
- <xref linkend="sql-notify" endterm="sql-notify-title">
- commands. A listener creates an entry in
- <structname>pg_listener</structname> for each notification name
- it is listening for. A notifier scans <structname>pg_listener</structname>
- and updates each matching entry to show that a notification has occurred.
- The notifier also sends a signal (using the PID recorded in the table)
- to awaken the listener from sleep.
- </para>
-
- <table>
- <title><structname>pg_listener</> Columns</title>
-
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Name</entry>
- <entry>Type</entry>
- <entry>Description</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><structfield>relname</structfield></entry>
- <entry><type>name</type></entry>
- <entry>
- Notify condition name. (The name need not match any actual
- relation in the database; the name <structfield>relname</> is historical.)
- </entry>
- </row>
-
- <row>
- <entry><structfield>listenerpid</structfield></entry>
- <entry><type>int4</type></entry>
- <entry>PID of the server process that created this entry</entry>
- </row>
-
- <row>
- <entry><structfield>notification</structfield></entry>
- <entry><type>int4</type></entry>
- <entry>
- Zero if no event is pending for this listener. If an event is
- pending, the PID of the server process that sent the notification
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
-
- </sect1>
-
-
<sect1 id="catalog-pg-namespace">
<title><structname>pg_namespace</structname></title>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 71952ee1fc445510236ed000565a2e1edc2d7b66..5436971115564669376518f0cf43ff06f5a86699 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.503 2010/02/16 21:18:01 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.504 2010/02/16 22:34:42 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
@@ -11529,6 +11529,12 @@ postgres=# select * from unnest2(array[[1,2],[3,4]]);
</entry>
</row>
+ <row>
+ <entry><literal><function>pg_listening_channels</function>()</literal></entry>
+ <entry><type>setof text</type></entry>
+ <entry>channel names that the session is currently listening on</entry>
+ </row>
+
<row>
<entry><literal><function>inet_client_addr</function>()</literal></entry>
<entry><type>inet</type></entry>
@@ -11674,6 +11680,16 @@ SET search_path TO <replaceable>schema</> <optional>, <replaceable>schema</>, ..
</para>
</note>
+ <indexterm>
+ <primary>pg_listening_channels</primary>
+ </indexterm>
+
+ <para>
+ <function>pg_listening_channels</function> returns a set of names of
+ channels that the current session is listening to. See <xref
+ linkend="sql-listen" endterm="sql-listen-title"> for more information.
+ </para>
+
<indexterm>
<primary>inet_client_addr</primary>
</indexterm>
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 4972a8c2592184e95d5e3761c3cc2e4ce2eeb580..0bdb6401c34b5119e48d0367ba7bdd3b215ae748 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.298 2010/02/16 20:58:13 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.299 2010/02/16 22:34:42 tgl Exp $ -->
<chapter id="libpq">
<title><application>libpq</application> - C Library</title>
@@ -307,28 +307,28 @@
<entry>Description</entry>
</row>
</thead>
-
+
<tbody>
-
+
<row>
<entry><literal>disable</></entry>
<entry>only try a non-<acronym>SSL</> connection</entry>
</row>
-
+
<row>
<entry><literal>allow</></entry>
<entry>first try a non-<acronym>SSL</>
connection; if that fails, try an <acronym>SSL</>
connection</entry>
</row>
-
+
<row>
<entry><literal>prefer</> (default)</entry>
<entry>first try an <acronym>SSL</> connection; if
that fails, try a non-<acronym>SSL</>
connection</entry>
</row>
-
+
<row>
<entry><literal>require</></entry>
<entry>only try an <acronym>SSL</> connection</entry>
@@ -481,7 +481,7 @@
</para>
<para>
- If <literal>expand_dbname</literal> is non-zero and
+ If <literal>expand_dbname</literal> is non-zero and
<parameter>dbname</parameter> contains an <symbol>=</symbol> sign, it
is taken as a <parameter>conninfo</parameter> string in exactly the same way as
if it had been passed to <function>PQconnectdb</function>(see below). Previously
@@ -4111,50 +4111,48 @@ typedef struct {
<productname>PostgreSQL</productname> offers asynchronous notification
via the <command>LISTEN</command> and <command>NOTIFY</command>
commands. A client session registers its interest in a particular
- notification condition with the <command>LISTEN</command> command (and
+ notification channel with the <command>LISTEN</command> command (and
can stop listening with the <command>UNLISTEN</command> command). All
- sessions listening on a particular condition will be notified
+ sessions listening on a particular channel will be notified
asynchronously when a <command>NOTIFY</command> command with that
- condition name is executed by any session. No additional information
- is passed from the notifier to the listener. Thus, typically, any
- actual data that needs to be communicated is transferred through a
- database table. Commonly, the condition name is the same as the
- associated table, but it is not necessary for there to be any associated
- table.
+ channel name is executed by any session. A <quote>payload</> string can
+ be passed to communicate additional data to the listeners.
</para>
<para>
<application>libpq</application> applications submit
- <command>LISTEN</command> and <command>UNLISTEN</command> commands as
+ <command>LISTEN</command>, <command>UNLISTEN</command>,
+ and <command>NOTIFY</command> commands as
ordinary SQL commands. The arrival of <command>NOTIFY</command>
messages can subsequently be detected by calling
<function>PQnotifies</function>.<indexterm><primary>PQnotifies</></>
</para>
<para>
- The function <function>PQnotifies</function>
- returns the next notification from a list of unhandled
- notification messages received from the server. It returns a null pointer if
- there are no pending notifications. Once a notification is
- returned from <function>PQnotifies</>, it is considered handled and will be
- removed from the list of notifications.
+ The function <function>PQnotifies</function> returns the next notification
+ from a list of unhandled notification messages received from the server.
+ It returns a null pointer if there are no pending notifications. Once a
+ notification is returned from <function>PQnotifies</>, it is considered
+ handled and will be removed from the list of notifications.
+
<synopsis>
PGnotify *PQnotifies(PGconn *conn);
typedef struct pgNotify {
- char *relname; /* notification condition name */
+ char *relname; /* notification channel name */
int be_pid; /* process ID of notifying server process */
- char *extra; /* notification parameter */
+ char *extra; /* notification payload string */
} PGnotify;
</synopsis>
+
After processing a <structname>PGnotify</structname> object returned
by <function>PQnotifies</function>, be sure to free it with
<function>PQfreemem</function>. It is sufficient to free the
<structname>PGnotify</structname> pointer; the
<structfield>relname</structfield> and <structfield>extra</structfield>
- fields do not represent separate allocations. (At present, the
- <structfield>extra</structfield> field is unused and will always point
- to an empty string.)
+ fields do not represent separate allocations. (The names of these fields
+ are historical; in particular, channel names need not have anything to
+ do with relation names.)
</para>
<para>
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index e4364ec305f1c2dcadb9315650b070526950e989..f0a2aeba03ad70a8ece535d1146f8cba43b428fc 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.80 2010/02/16 20:58:14 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.81 2010/02/16 22:34:43 tgl Exp $ -->
<chapter id="protocol">
<title>Frontend/Backend Protocol</title>
@@ -354,7 +354,7 @@
<para>
This message contains the response data from the previous step
of GSSAPI or SSPI negotiation (AuthenticationGSS, AuthenticationSSPI
- or a previous AuthenticationGSSContinue). If the GSSAPI
+ or a previous AuthenticationGSSContinue). If the GSSAPI
or SSPI data in this message
indicates more data is needed to complete the authentication,
the frontend must send that data as another PasswordMessage. If
@@ -992,7 +992,7 @@
<para>
In the event of a backend-detected error during copy-in mode (including
- receipt of a CopyFail message), the backend will issue an ErrorResponse
+ receipt of a CopyFail message), the backend will issue an ErrorResponse
message. If the <command>COPY</> command was issued via an extended-query
message, the backend will now discard frontend messages until a Sync
message is received, then it will issue ReadyForQuery and return to normal
@@ -1117,7 +1117,7 @@
backend will send a NotificationResponse message (not to be
confused with NoticeResponse!) whenever a
<command>NOTIFY</command> command is executed for the same
- notification name.
+ channel name.
</para>
<note>
@@ -1340,7 +1340,7 @@ This section describes the base data types used in messages.
value that will appear, otherwise the value is variable.
Eg. String, String("user").
</para>
-
+
<note>
<para>
<emphasis>There is no predefined limit</emphasis> on the length of a string
@@ -1951,7 +1951,7 @@ Bind (F)
(denoted <replaceable>R</> below).
This can be zero to indicate that there are no result columns
or that the result columns should all use the default format
- (text);
+ (text);
or one, in which case the specified format code is applied
to all result columns (if any); or it can equal the actual
number of result columns of the query.
@@ -2500,7 +2500,7 @@ CopyOutResponse (B)
separated by separator characters, etc). 1 indicates
the overall copy format is binary (similar to DataRow
format). See <xref linkend="sql-copy"
- endterm="sql-copy-title"> for more information.
+ endterm="sql-copy-title"> for more information.
</para>
</listitem>
</varlistentry>
@@ -3187,7 +3187,7 @@ NotificationResponse (B)
</term>
<listitem>
<para>
- The name of the condition that the notify has been raised on.
+ The name of the channel that the notify has been raised on.
</para>
</listitem>
</varlistentry>
@@ -3197,9 +3197,7 @@ NotificationResponse (B)
</term>
<listitem>
<para>
- Additional information passed from the notifying process.
- (Currently, this feature is unimplemented so the field
- is always an empty string.)
+ The <quote>payload</> string passed from the notifying process.
</para>
</listitem>
</varlistentry>
@@ -4353,7 +4351,7 @@ the backend.
<para>
The NotificationResponse ('<literal>A</>') message has an additional string
-field, which is presently empty but might someday carry additional data passed
+field, which can carry a <quote>payload</> string passed
from the <command>NOTIFY</command> event sender.
</para>
@@ -4364,5 +4362,4 @@ string parameter; this has been removed.
</sect1>
-
</chapter>
diff --git a/doc/src/sgml/ref/listen.sgml b/doc/src/sgml/ref/listen.sgml
index 93ca74c57222ae9ab3157a9a61e38acb6064c998..57577c1f6aca31f2575e8a13a2fb536facd7203b 100644
--- a/doc/src/sgml/ref/listen.sgml
+++ b/doc/src/sgml/ref/listen.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/listen.sgml,v 1.23 2008/11/14 10:22:47 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/listen.sgml,v 1.24 2010/02/16 22:34:43 tgl Exp $
PostgreSQL documentation
-->
@@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
-LISTEN <replaceable class="PARAMETER">name</replaceable>
+LISTEN <replaceable class="PARAMETER">channel</replaceable>
</synopsis>
</refsynopsisdiv>
@@ -30,24 +30,23 @@ LISTEN <replaceable class="PARAMETER">name</replaceable>
<para>
<command>LISTEN</command> registers the current session as a
- listener on the notification condition <replaceable
- class="PARAMETER">name</replaceable>.
+ listener on the notification channel named <replaceable
+ class="PARAMETER">channel</replaceable>.
If the current session is already registered as a listener for
- this notification condition, nothing is done.
+ this notification channel, nothing is done.
</para>
<para>
Whenever the command <command>NOTIFY <replaceable
- class="PARAMETER">name</replaceable></command> is invoked, either
+ class="PARAMETER">channel</replaceable></command> is invoked, either
by this session or another one connected to the same database, all
- the sessions currently listening on that notification condition are
+ the sessions currently listening on that notification channel are
notified, and each will in turn notify its connected client
- application. See the discussion of <command>NOTIFY</command> for
- more information.
+ application.
</para>
<para>
- A session can be unregistered for a given notify condition with the
+ A session can be unregistered for a given notification channel with the
<command>UNLISTEN</command> command. A session's listen
registrations are automatically cleared when the session ends.
</para>
@@ -78,16 +77,31 @@ LISTEN <replaceable class="PARAMETER">name</replaceable>
<variablelist>
<varlistentry>
- <term><replaceable class="PARAMETER">name</replaceable></term>
+ <term><replaceable class="PARAMETER">channel</replaceable></term>
<listitem>
<para>
- Name of a notify condition (any identifier).
+ Name of a notification channel (any identifier).
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Notes</title>
+
+ <para>
+ <command>LISTEN</command> takes effect at transaction commit.
+ If <command>LISTEN</command> or <command>UNLISTEN</command> is executed
+ within a transaction that later rolls back, the set of notification
+ channels being listened to is unchanged.
+ </para>
+ <para>
+ A transaction that has executed <command>LISTEN</command> cannot be
+ prepared for two-phase commit.
+ </para>
+ </refsect1>
+
<refsect1>
<title>Examples</title>
diff --git a/doc/src/sgml/ref/notify.sgml b/doc/src/sgml/ref/notify.sgml
index 563fbbe9638b94733327197aa324a919938c53e0..b612bb4cb2a9884684bd6135b36882755f71c604 100644
--- a/doc/src/sgml/ref/notify.sgml
+++ b/doc/src/sgml/ref/notify.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/notify.sgml,v 1.31 2008/11/14 10:22:47 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/notify.sgml,v 1.32 2010/02/16 22:34:43 tgl Exp $
PostgreSQL documentation
-->
@@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
-NOTIFY <replaceable class="PARAMETER">name</replaceable>
+NOTIFY <replaceable class="PARAMETER">channel</replaceable> [ , <replaceable class="PARAMETER">payload</replaceable> ]
</synopsis>
</refsynopsisdiv>
@@ -29,35 +29,39 @@ NOTIFY <replaceable class="PARAMETER">name</replaceable>
<title>Description</title>
<para>
- The <command>NOTIFY</command> command sends a notification event to each
- client application that has previously executed
- <command>LISTEN <replaceable class="parameter">name</replaceable></command>
- for the specified notification name in the current database.
+ The <command>NOTIFY</command> command sends a notification event together
+ with an optional <quote>payload</> string to each client application that
+ has previously executed
+ <command>LISTEN <replaceable class="parameter">channel</></command>
+ for the specified channel name in the current database.
</para>
<para>
- <command>NOTIFY</command> provides a simple form of signal or
+ <command>NOTIFY</command> provides a simple
interprocess communication mechanism for a collection of processes
accessing the same <productname>PostgreSQL</productname> database.
- Higher-level mechanisms can be built by using tables in the database to
- pass additional data (beyond a mere notification name) from notifier to
- listener(s).
+ A payload string can be sent along with the notification, and
+ higher-level mechanisms for passing structured data can be built by using
+ tables in the database to pass additional data from notifier to listener(s).
</para>
<para>
- The information passed to the client for a notification event includes the notification
- name and the notifying session's server process <acronym>PID</>. It is up to the
- database designer to define the notification names that will be used in a given
- database and what each one means.
+ The information passed to the client for a notification event includes the
+ notification channel
+ name, the notifying session's server process <acronym>PID</>, and the
+ payload string, which is an empty string if it has not been specified.
</para>
<para>
- Commonly, the notification name is the same as the name of some table in
+ It is up to the database designer to define the channel names that will
+ be used in a given database and what each one means.
+ Commonly, the channel name is the same as the name of some table in
the database, and the notify event essentially means, <quote>I changed this table,
take a look at it to see what's new</quote>. But no such association is enforced by
the <command>NOTIFY</command> and <command>LISTEN</command> commands. For
- example, a database designer could use several different notification names
- to signal different sorts of changes to a single table.
+ example, a database designer could use several different channel names
+ to signal different sorts of changes to a single table. Alternatively,
+ the payload string could be used to differentiate various cases.
</para>
<para>
@@ -89,19 +93,22 @@ NOTIFY <replaceable class="PARAMETER">name</replaceable>
</para>
<para>
- <command>NOTIFY</command> behaves like Unix signals in one important
- respect: if the same notification name is signaled multiple times in quick
- succession, recipients might get only one notification event for several executions
- of <command>NOTIFY</command>. So it is a bad idea to depend on the number
- of notifications received. Instead, use <command>NOTIFY</command> to wake up
- applications that need to pay attention to something, and use a database
- object (such as a sequence) to keep track of what happened or how many times
- it happened.
+ If the same channel name is signaled multiple times from the same
+ transaction with identical payload strings, the
+ database server can decide to deliver a single notification only.
+ On the other hand, notifications with distinct payload strings will
+ always be delivered as distinct notifications. Similarly, notifications from
+ different transactions will never get folded into one notification.
+ Except for dropping later instances of duplicate notifications,
+ <command>NOTIFY</command> guarantees that notifications from the same
+ transaction get delivered in the order they were sent. It is also
+ guaranteed that messages from different transactions are delivered in
+ the order in which the transactions committed.
</para>
<para>
It is common for a client that executes <command>NOTIFY</command>
- to be listening on the same notification name itself. In that case
+ to be listening on the same notification channel itself. In that case
it will get back a notification event, just like all the other
listening sessions. Depending on the application logic, this could
result in useless work, for example, reading a database table to
@@ -111,12 +118,7 @@ NOTIFY <replaceable class="PARAMETER">name</replaceable>
notification event message) is the same as one's own session's
<acronym>PID</> (available from <application>libpq</>). When they
are the same, the notification event is one's own work bouncing
- back, and can be ignored. (Despite what was said in the preceding
- paragraph, this is a safe technique.
- <productname>PostgreSQL</productname> keeps self-notifications
- separate from notifications arriving from other sessions, so you
- cannot miss an outside notification by ignoring your own
- notifications.)
+ back, and can be ignored.
</para>
</refsect1>
@@ -125,16 +127,61 @@ NOTIFY <replaceable class="PARAMETER">name</replaceable>
<variablelist>
<varlistentry>
- <term><replaceable class="PARAMETER">name</replaceable></term>
+ <term><replaceable class="PARAMETER">channel</replaceable></term>
<listitem>
<para>
- Name of the notification to be signaled (any identifier).
+ Name of the notification channel to be signaled (any identifier).
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><replaceable class="PARAMETER">payload</replaceable></term>
+ <listitem>
+ <para>
+ The <quote>payload</> string to be communicated along with the
+ notification. This string must be shorter than 8000 bytes, and
+ is treated as text.
+ (If binary data or large amounts of information need to be communicated,
+ it's best to put it in a database table and send the key of the record.)
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Notes</title>
+
+ <indexterm>
+ <primary>pg_notify</primary>
+ </indexterm>
+
+ <para>
+ To send a notification you can also use the function
+ <literal><function>pg_notify</function>(<type>text</type>,
+ <type>text</type>)</literal>. The function takes the channel name as the
+ first argument and the payload as the second. The function is much easier
+ to use than the <command>NOTIFY</command> command if you need to work with
+ non-constant channel names and payloads.
+ </para>
+ <para>
+ There is a queue that holds notifications that have been sent but not
+ yet processed by all listening sessions. If this queue becomes full,
+ transactions calling <command>NOTIFY</command> will fail at commit.
+ The queue is quite large (8GB in a standard installation) and should be
+ sufficiently sized for almost every use case. However, no cleanup can take
+ place if a session executes <command>LISTEN</command> and then enters a
+ transaction for a very long time. Once the queue is half full you will see
+ warnings in the log file pointing you to the session that is preventing
+ cleanup. In this case you should make sure that this session ends its
+ current transaction so that cleanup can proceed.
+ </para>
+ <para>
+ A transaction that has executed <command>NOTIFY</command> cannot be
+ prepared for two-phase commit.
+ </para>
+ </refsect1>
+
<refsect1>
<title>Examples</title>
@@ -146,6 +193,12 @@ NOTIFY <replaceable class="PARAMETER">name</replaceable>
LISTEN virtual;
NOTIFY virtual;
Asynchronous notification "virtual" received from server process with PID 8448.
+NOTIFY virtual, 'This is the payload';
+Asynchronous notification "virtual" with payload "This is the payload" received from server process with PID 8448.
+
+LISTEN foo;
+SELECT pg_notify('fo' || 'o', 'pay' || 'load');
+Asynchronous notification "foo" with payload "payload" received from server process with PID 14728.
</programlisting>
</para>
</refsect1>
diff --git a/doc/src/sgml/ref/unlisten.sgml b/doc/src/sgml/ref/unlisten.sgml
index 7cdd7394cb99fd6ce8823efa394c284fc545ab05..9e22ea4edc4050c9f083bbe69bd23fe204fba5f8 100644
--- a/doc/src/sgml/ref/unlisten.sgml
+++ b/doc/src/sgml/ref/unlisten.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/unlisten.sgml,v 1.30 2008/11/14 10:22:47 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/unlisten.sgml,v 1.31 2010/02/16 22:34:43 tgl Exp $
PostgreSQL documentation
-->
@@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
-UNLISTEN { <replaceable class="PARAMETER">name</replaceable> | * }
+UNLISTEN { <replaceable class="PARAMETER">channel</replaceable> | * }
</synopsis>
</refsynopsisdiv>
@@ -33,8 +33,8 @@ UNLISTEN { <replaceable class="PARAMETER">name</replaceable> | * }
registration for <command>NOTIFY</command> events.
<command>UNLISTEN</command> cancels any existing registration of
the current <productname>PostgreSQL</productname> session as a
- listener on the notification <replaceable
- class="PARAMETER">name</replaceable>. The special wildcard
+ listener on the notification channel named <replaceable
+ class="PARAMETER">channel</replaceable>. The special wildcard
<literal>*</literal> cancels all listener registrations for the
current session.
</para>
@@ -52,10 +52,10 @@ UNLISTEN { <replaceable class="PARAMETER">name</replaceable> | * }
<variablelist>
<varlistentry>
- <term><replaceable class="PARAMETER">name</replaceable></term>
+ <term><replaceable class="PARAMETER">channel</replaceable></term>
<listitem>
<para>
- Name of a notification (any identifier).
+ Name of a notification channel (any identifier).
</para>
</listitem>
</varlistentry>
@@ -83,6 +83,11 @@ UNLISTEN { <replaceable class="PARAMETER">name</replaceable> | * }
At the end of each session, <command>UNLISTEN *</command> is
automatically executed.
</para>
+
+ <para>
+ A transaction that has executed <command>UNLISTEN</command> cannot be
+ prepared for two-phase commit.
+ </para>
</refsect1>
<refsect1>
@@ -100,7 +105,7 @@ Asynchronous notification "virtual" received from server process with PID 8448.
<para>
Once <command>UNLISTEN</> has been executed, further <command>NOTIFY</>
- commands will be ignored:
+ messages will be ignored:
<programlisting>
UNLISTEN virtual;
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index e0cef7dd7b0b133dbc53ad92c6e2d16443986bfa..c4b38ddb6c8c2392c4968e4c8705716f4c08f936 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.31 2010/02/07 20:48:09 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.32 2010/02/16 22:34:43 tgl Exp $ -->
<chapter id="storage">
@@ -77,6 +77,11 @@ Item
(used for shared row locks)</entry>
</row>
+<row>
+ <entry><filename>pg_notify</></entry>
+ <entry>Subdirectory containing LISTEN/NOTIFY status data</entry>
+</row>
+
<row>
<entry><filename>pg_stat_tmp</></entry>
<entry>Subdirectory containing temporary files for the statistics
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index d5f999f494b028de9a141d89f0b3853415d01aa6..6226acc9283921ff4e4abe49cb5def1629370e39 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -41,7 +41,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.48 2010/01/02 16:57:35 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.49 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -59,25 +59,6 @@
#include "miscadmin.h"
-/*
- * Define segment size. A page is the same BLCKSZ as is used everywhere
- * else in Postgres. The segment size can be chosen somewhat arbitrarily;
- * we make it 32 pages by default, or 256Kb, i.e. 1M transactions for CLOG
- * or 64K transactions for SUBTRANS.
- *
- * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF,
- * page numbering also wraps around at 0xFFFFFFFF/xxxx_XACTS_PER_PAGE (where
- * xxxx is CLOG or SUBTRANS, respectively), and segment numbering at
- * 0xFFFFFFFF/xxxx_XACTS_PER_PAGE/SLRU_PAGES_PER_SEGMENT. We need
- * take no explicit notice of that fact in this module, except when comparing
- * segment and page numbers in SimpleLruTruncate (see PagePrecedes()).
- *
- * Note: this file currently assumes that segment file names will be four
- * hex digits. This sets a lower bound on the segment size (64K transactions
- * for 32-bit TransactionIds).
- */
-#define SLRU_PAGES_PER_SEGMENT 32
-
#define SlruFileName(ctl, path, seg) \
snprintf(path, MAXPGPATH, "%s/%04X", (ctl)->Dir, seg)
@@ -183,6 +164,8 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
shared = (SlruShared) ShmemInitStruct(name,
SimpleLruShmemSize(nslots, nlsns),
&found);
+ if (!shared)
+ elog(ERROR, "out of shared memory");
if (!IsUnderPostmaster)
{
diff --git a/src/backend/access/transam/twophase_rmgr.c b/src/backend/access/transam/twophase_rmgr.c
index 0ea8e42ca567c9bb1469104c0f421de3b4cf586c..86a1d12f93d302d126917a2162da0cd130498993 100644
--- a/src/backend/access/transam/twophase_rmgr.c
+++ b/src/backend/access/transam/twophase_rmgr.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.12 2010/01/02 16:57:35 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/twophase_rmgr.c,v 1.13 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,7 +16,6 @@
#include "access/multixact.h"
#include "access/twophase_rmgr.h"
-#include "commands/async.h"
#include "pgstat.h"
#include "storage/lock.h"
@@ -25,7 +24,6 @@ const TwoPhaseCallback twophase_recover_callbacks[TWOPHASE_RM_MAX_ID + 1] =
{
NULL, /* END ID */
lock_twophase_recover, /* Lock */
- NULL, /* notify/listen */
NULL, /* pgstat */
multixact_twophase_recover /* MultiXact */
};
@@ -34,7 +32,6 @@ const TwoPhaseCallback twophase_postcommit_callbacks[TWOPHASE_RM_MAX_ID + 1] =
{
NULL, /* END ID */
lock_twophase_postcommit, /* Lock */
- notify_twophase_postcommit, /* notify/listen */
pgstat_twophase_postcommit, /* pgstat */
multixact_twophase_postcommit /* MultiXact */
};
@@ -43,7 +40,6 @@ const TwoPhaseCallback twophase_postabort_callbacks[TWOPHASE_RM_MAX_ID + 1] =
{
NULL, /* END ID */
lock_twophase_postabort, /* Lock */
- NULL, /* notify/listen */
pgstat_twophase_postabort, /* pgstat */
multixact_twophase_postabort /* MultiXact */
};
@@ -52,7 +48,6 @@ const TwoPhaseCallback twophase_standby_recover_callbacks[TWOPHASE_RM_MAX_ID + 1
{
NULL, /* END ID */
lock_twophase_standby_recover, /* Lock */
- NULL, /* notify/listen */
NULL, /* pgstat */
NULL /* MultiXact */
};
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index c239c098fd6f865ea2e759664a77c6f308cbceb4..46a842bb9a8e708f17d02d9abc47a91a845d0e1c 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.285 2010/02/13 16:15:46 sriggs Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.286 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1736,8 +1736,12 @@ CommitTransaction(void)
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
- /* NOTIFY commit must come before lower-level cleanup */
- AtCommit_Notify();
+ /*
+ * Insert notifications sent by NOTIFY commands into the queue. This
+ * should be late in the pre-commit sequence to minimize time spent
+ * holding the notify-insertion lock.
+ */
+ PreCommit_Notify();
/* Prevent cancel/die interrupt while cleaning up */
HOLD_INTERRUPTS();
@@ -1825,6 +1829,7 @@ CommitTransaction(void)
/* Check we've released all catcache entries */
AtEOXact_CatCache(true);
+ AtCommit_Notify();
AtEOXact_GUC(true, 1);
AtEOXact_SPI(true);
AtEOXact_on_commit_actions(true);
diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile
index 837865efbe5f048ba440bd00aa61769c0a9fa212..a73971d162771240d9c713dc1f58582699d19e2a 100644
--- a/src/backend/catalog/Makefile
+++ b/src/backend/catalog/Makefile
@@ -2,7 +2,7 @@
#
# Makefile for backend/catalog
#
-# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.76 2010/01/06 19:56:29 tgl Exp $
+# $PostgreSQL: pgsql/src/backend/catalog/Makefile,v 1.77 2010/02/16 22:34:43 tgl Exp $
#
#-------------------------------------------------------------------------
@@ -30,7 +30,7 @@ POSTGRES_BKI_SRCS = $(addprefix $(top_srcdir)/src/include/catalog/,\
pg_attrdef.h pg_constraint.h pg_inherits.h pg_index.h pg_operator.h \
pg_opfamily.h pg_opclass.h pg_am.h pg_amop.h pg_amproc.h \
pg_language.h pg_largeobject_metadata.h pg_largeobject.h pg_aggregate.h \
- pg_statistic.h pg_rewrite.h pg_trigger.h pg_listener.h pg_description.h \
+ pg_statistic.h pg_rewrite.h pg_trigger.h pg_description.h \
pg_cast.h pg_enum.h pg_namespace.h pg_conversion.h pg_depend.h \
pg_database.h pg_db_role_setting.h pg_tablespace.h pg_pltemplate.h \
pg_authid.h pg_auth_members.h pg_shdepend.h pg_shdescription.h \
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index afc5e5fabc133ed7f1f94d43df68f30a97a79d19..f5863480f5e0b4a6877efd3cf0f5272ee7edf077 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -7,109 +7,280 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.150 2010/01/02 16:57:36 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/async.c,v 1.151 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*-------------------------------------------------------------------------
- * New Async Notification Model:
- * 1. Multiple backends on same machine. Multiple backends listening on
- * one relation. (Note: "listening on a relation" is not really the
- * right way to think about it, since the notify names need not have
- * anything to do with the names of relations actually in the database.
- * But this terminology is all over the code and docs, and I don't feel
- * like trying to replace it.)
- *
- * 2. There is a tuple in relation "pg_listener" for each active LISTEN,
- * ie, each relname/listenerPID pair. The "notification" field of the
- * tuple is zero when no NOTIFY is pending for that listener, or the PID
- * of the originating backend when a cross-backend NOTIFY is pending.
- * (We skip writing to pg_listener when doing a self-NOTIFY, so the
- * notification field should never be equal to the listenerPID field.)
- *
- * 3. The NOTIFY statement itself (routine Async_Notify) just adds the target
- * relname to a list of outstanding NOTIFY requests. Actual processing
- * happens if and only if we reach transaction commit. At that time (in
- * routine AtCommit_Notify) we scan pg_listener for matching relnames.
- * If the listenerPID in a matching tuple is ours, we just send a notify
- * message to our own front end. If it is not ours, and "notification"
- * is not already nonzero, we set notification to our own PID and send a
- * PROCSIG_NOTIFY_INTERRUPT signal to the receiving process (indicated by
- * listenerPID).
- * BTW: if the signal operation fails, we presume that the listener backend
- * crashed without removing this tuple, and remove the tuple for it.
- *
- * 4. Upon receipt of a PROCSIG_NOTIFY_INTERRUPT signal, the signal handler
+ * Async Notification Model as of 9.0:
+ *
+ * 1. Multiple backends on same machine. Multiple backends listening on
+ * several channels. (Channels are also called "conditions" in other
+ * parts of the code.)
+ *
+ * 2. There is one central queue in disk-based storage (directory pg_notify/),
+ * with actively-used pages mapped into shared memory by the slru.c module.
+ * All notification messages are placed in the queue and later read out
+ * by listening backends.
+ *
+ * There is no central knowledge of which backend listens on which channel;
+ * every backend has its own list of interesting channels.
+ *
+ * Although there is only one queue, notifications are treated as being
+ * database-local; this is done by including the sender's database OID
+ * in each notification message. Listening backends ignore messages
+ * that don't match their database OID. This is important because it
+ * ensures senders and receivers have the same database encoding and won't
+ * misinterpret non-ASCII text in the channel name or payload string.
+ *
+ * Since notifications are not expected to survive database crashes,
+ * we can simply clean out the pg_notify data at any reboot, and there
+ * is no need for WAL support or fsync'ing.
+ *
+ * 3. Every backend that is listening on at least one channel registers by
+ * entering its PID into the array in AsyncQueueControl. It then scans all
+ * incoming notifications in the central queue and first compares the
+ * database OID of the notification with its own database OID and then
+ * compares the notified channel with the list of channels that it listens
+ * to. In case there is a match it delivers the notification event to its
+ * frontend. Non-matching events are simply skipped.
+ *
+ * 4. The NOTIFY statement (routine Async_Notify) stores the notification in
+ * a backend-local list which will not be processed until transaction end.
+ *
+ * Duplicate notifications from the same transaction are sent out as one
+ * notification only. This is done to save work when for example a trigger
+ * on a 2 million row table fires a notification for each row that has been
+ * changed. If the application needs to receive every single notification
+ * that has been sent, it can easily add some unique string into the extra
+ * payload parameter.
+ *
+ * When the transaction is ready to commit, PreCommit_Notify() adds the
+ * pending notifications to the head of the queue. The head pointer of the
+ * queue always points to the next free position and a position is just a
+ * page number and the offset in that page. This is done before marking the
+ * transaction as committed in clog. If we run into problems writing the
+ * notifications, we can still call elog(ERROR, ...) and the transaction
+ * will roll back.
+ *
+ * Once we have put all of the notifications into the queue, we return to
+ * CommitTransaction() which will then do the actual transaction commit.
+ *
+ * After commit we are called another time (AtCommit_Notify()). Here we
+ * make the actual updates to the effective listen state (listenChannels).
+ *
+ * Finally, after we are out of the transaction altogether, we check if
+ * we need to signal listening backends. In SignalBackends() we scan the
+ * list of listening backends and send a PROCSIG_NOTIFY_INTERRUPT signal
+ * to every listening backend (we don't know which backend is listening on
+ * which channel so we must signal them all). We can exclude backends that
+ * are already up to date, though. We don't bother with a self-signal
+ * either, but just process the queue directly.
+ *
+ * 5. Upon receipt of a PROCSIG_NOTIFY_INTERRUPT signal, the signal handler
* can call inbound-notify processing immediately if this backend is idle
* (ie, it is waiting for a frontend command and is not within a transaction
* block). Otherwise the handler may only set a flag, which will cause the
* processing to occur just before we next go idle.
*
- * 5. Inbound-notify processing consists of scanning pg_listener for tuples
- * matching our own listenerPID and having nonzero notification fields.
- * For each such tuple, we send a message to our frontend and clear the
- * notification field. BTW: this routine has to start/commit its own
- * transaction, since by assumption it is only called from outside any
- * transaction.
- *
- * Like NOTIFY, LISTEN and UNLISTEN just add the desired action to a list
- * of pending actions. If we reach transaction commit, the changes are
- * applied to pg_listener just before executing any pending NOTIFYs. This
- * method is necessary because to avoid race conditions, we must hold lock
- * on pg_listener from when we insert a new listener tuple until we commit.
- * To do that and not create undue hazard of deadlock, we don't want to
- * touch pg_listener until we are otherwise done with the transaction;
- * in particular it'd be uncool to still be taking user-commanded locks
- * while holding the pg_listener lock.
- *
- * Although we grab ExclusiveLock on pg_listener for any operation,
- * the lock is never held very long, so it shouldn't cause too much of
- * a performance problem. (Previously we used AccessExclusiveLock, but
- * there's no real reason to forbid concurrent reads.)
- *
- * An application that listens on the same relname it notifies will get
+ * Inbound-notify processing consists of reading all of the notifications
+ * that have arrived since scanning last time. We read every notification
+ * until we reach either a notification from an uncommitted transaction or
+ * the head pointer's position. Then we check if we were the laziest
+ * backend: if our pointer is set to the same position as the global tail
+ * pointer is set, then we move the global tail pointer ahead to where the
+ * second-laziest backend is (in general, we take the MIN of the current
+ * head position and all active backends' new tail pointers). Whenever we
+ * move the global tail pointer we also truncate now-unused pages (i.e.,
+ * delete files in pg_notify/ that are no longer used).
+ *
+ * An application that listens on the same channel it notifies will get
* NOTIFY messages for its own NOTIFYs. These can be ignored, if not useful,
* by comparing be_pid in the NOTIFY message to the application's own backend's
* PID. (As of FE/BE protocol 2.0, the backend's PID is provided to the
* frontend during startup.) The above design guarantees that notifies from
- * other backends will never be missed by ignoring self-notifies. Note,
- * however, that we do *not* guarantee that a separate frontend message will
- * be sent for every outside NOTIFY. Since there is only room for one
- * originating PID in pg_listener, outside notifies occurring at about the
- * same time may be collapsed into a single message bearing the PID of the
- * first outside backend to perform the NOTIFY.
+ * other backends will never be missed by ignoring self-notifies.
+ *
+ * The amount of shared memory used for notify management (NUM_ASYNC_BUFFERS)
+ * can be varied without affecting anything but performance. The maximum
+ * amount of notification data that can be queued at one time is determined
+ * by slru.c's wraparound limit; see QUEUE_MAX_PAGE below.
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include <limits.h>
#include <unistd.h>
#include <signal.h>
-#include "access/heapam.h"
-#include "access/twophase_rmgr.h"
+#include "access/slru.h"
+#include "access/transam.h"
#include "access/xact.h"
-#include "catalog/pg_listener.h"
+#include "catalog/pg_database.h"
#include "commands/async.h"
+#include "funcapi.h"
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "storage/ipc.h"
+#include "storage/lmgr.h"
#include "storage/procsignal.h"
#include "storage/sinval.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
-#include "utils/fmgroids.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
-#include "utils/tqual.h"
+/*
+ * Maximum size of a NOTIFY payload, including terminating NULL. This
+ * must be kept small enough so that a notification message fits on one
+ * SLRU page.
+ */
+#define NOTIFY_PAYLOAD_MAX_LENGTH 8000
+
+/*
+ * Struct representing an entry in the global notify queue
+ *
+ * This struct declaration has the maximal length, but in a real queue entry
+ * the data area is only big enough for the actual channel and payload strings
+ * (each null-terminated). AsyncQueueEntryEmptySize is the minimum possible
+ * entry size, if both channel and payload strings are empty (but note it
+ * doesn't include alignment padding).
+ *
+ * The "length" field should always be rounded up to the next QUEUEALIGN
+ * multiple so that all fields are properly aligned.
+ */
+typedef struct AsyncQueueEntry
+{
+ int length; /* total allocated length of entry */
+ Oid dboid; /* sender's database OID */
+ TransactionId xid; /* sender's XID */
+ int32 srcPid; /* sender's PID */
+ char data[NAMEDATALEN + NOTIFY_PAYLOAD_MAX_LENGTH];
+} AsyncQueueEntry;
+
+/* Currently, no field of AsyncQueueEntry requires more than int alignment */
+#define QUEUEALIGN(len) INTALIGN(len)
+
+#define AsyncQueueEntryEmptySize (offsetof(AsyncQueueEntry, data) + 2)
+
+/*
+ * Struct describing a queue position, and assorted macros for working with it
+ */
+typedef struct QueuePosition
+{
+ int page; /* SLRU page number */
+ int offset; /* byte offset within page */
+} QueuePosition;
+
+#define QUEUE_POS_PAGE(x) ((x).page)
+#define QUEUE_POS_OFFSET(x) ((x).offset)
+
+#define SET_QUEUE_POS(x,y,z) \
+ do { \
+ (x).page = (y); \
+ (x).offset = (z); \
+ } while (0)
+
+#define QUEUE_POS_EQUAL(x,y) \
+ ((x).page == (y).page && (x).offset == (y).offset)
+
+/* choose logically smaller QueuePosition */
+#define QUEUE_POS_MIN(x,y) \
+ (asyncQueuePagePrecedesLogically((x).page, (y).page) ? (x) : \
+ (x).page != (y).page ? (y) : \
+ (x).offset < (y).offset ? (x) : (y))
+
+/*
+ * Struct describing a listening backend's status
+ */
+typedef struct QueueBackendStatus
+{
+ int32 pid; /* either a PID or InvalidPid */
+ QueuePosition pos; /* backend has read queue up to here */
+} QueueBackendStatus;
+
+#define InvalidPid (-1)
+
+/*
+ * Shared memory state for LISTEN/NOTIFY (excluding its SLRU stuff)
+ *
+ * The AsyncQueueControl structure is protected by the AsyncQueueLock.
+ *
+ * When holding the lock in SHARED mode, backends may only inspect their own
+ * entries as well as the head and tail pointers. Consequently we can allow a
+ * backend to update its own record while holding only SHARED lock (since no
+ * other backend will inspect it).
+ *
+ * When holding the lock in EXCLUSIVE mode, backends can inspect the entries
+ * of other backends and also change the head and tail pointers.
+ *
+ * In order to avoid deadlocks, whenever we need both locks, we always first
+ * get AsyncQueueLock and then AsyncCtlLock.
+ *
+ * Each backend uses the backend[] array entry with index equal to its
+ * BackendId (which can range from 1 to MaxBackends). We rely on this to make
+ * SendProcSignal fast.
+ */
+typedef struct AsyncQueueControl
+{
+ QueuePosition head; /* head points to the next free location */
+ QueuePosition tail; /* the global tail is equivalent to the
+ tail of the "slowest" backend */
+ TimestampTz lastQueueFillWarn; /* time of last queue-full msg */
+ QueueBackendStatus backend[1]; /* actually of length MaxBackends+1 */
+ /* DO NOT ADD FURTHER STRUCT MEMBERS HERE */
+} AsyncQueueControl;
+
+static AsyncQueueControl *asyncQueueControl;
+
+#define QUEUE_HEAD (asyncQueueControl->head)
+#define QUEUE_TAIL (asyncQueueControl->tail)
+#define QUEUE_BACKEND_PID(i) (asyncQueueControl->backend[i].pid)
+#define QUEUE_BACKEND_POS(i) (asyncQueueControl->backend[i].pos)
+
+/*
+ * The SLRU buffer area through which we access the notification queue
+ */
+static SlruCtlData AsyncCtlData;
+
+#define AsyncCtl (&AsyncCtlData)
+#define QUEUE_PAGESIZE BLCKSZ
+#define QUEUE_FULL_WARN_INTERVAL 5000 /* warn at most once every 5s */
+
+/*
+ * slru.c currently assumes that all filenames are four characters of hex
+ * digits. That means that we can use segments 0000 through FFFF.
+ * Each segment contains SLRU_PAGES_PER_SEGMENT pages which gives us
+ * the pages from 0 to SLRU_PAGES_PER_SEGMENT * 0x10000 - 1.
+ *
+ * It's of course possible to enhance slru.c, but this gives us so much
+ * space already that it doesn't seem worth the trouble.
+ *
+ * The most data we can have in the queue at a time is QUEUE_MAX_PAGE/2
+ * pages, because more than that would confuse slru.c into thinking there
+ * was a wraparound condition. With the default BLCKSZ this means there
+ * can be up to 8GB of queued-and-not-read data.
+ *
+ * Note: it's possible to redefine QUEUE_MAX_PAGE with a smaller multiple of
+ * SLRU_PAGES_PER_SEGMENT, for easier testing of queue-full behaviour.
+ */
+#define QUEUE_MAX_PAGE (SLRU_PAGES_PER_SEGMENT * 0x10000 - 1)
+
+/*
+ * listenChannels identifies the channels we are actually listening to
+ * (ie, have committed a LISTEN on). It is a simple list of channel names,
+ * allocated in TopMemoryContext.
+ */
+static List *listenChannels = NIL; /* list of C strings */
+
/*
* State for pending LISTEN/UNLISTEN actions consists of an ordered list of
* all actions requested in the current transaction. As explained above,
- * we don't actually modify pg_listener until we reach transaction commit.
+ * we don't actually change listenChannels until we reach transaction commit.
*
* The list is kept in CurTransactionContext. In subtransactions, each
* subtransaction has its own list in its own CurTransactionContext, but
@@ -126,7 +297,7 @@ typedef enum
typedef struct
{
ListenActionKind action;
- char condname[1]; /* actually, as long as needed */
+ char channel[1]; /* actually, as long as needed */
} ListenAction;
static List *pendingActions = NIL; /* list of ListenAction */
@@ -134,9 +305,9 @@ static List *pendingActions = NIL; /* list of ListenAction */
static List *upperPendingActions = NIL; /* list of upper-xact lists */
/*
- * State for outbound notifies consists of a list of all relnames NOTIFYed
- * in the current transaction. We do not actually perform a NOTIFY until
- * and unless the transaction commits. pendingNotifies is NIL if no
+ * State for outbound notifies consists of a list of all channels+payloads
+ * NOTIFYed in the current transaction. We do not actually perform a NOTIFY
+ * until and unless the transaction commits. pendingNotifies is NIL if no
* NOTIFYs have been done in the current transaction.
*
* The list is kept in CurTransactionContext. In subtransactions, each
@@ -149,12 +320,18 @@ static List *upperPendingActions = NIL; /* list of upper-xact lists */
* condition name, it will get a self-notify at commit. This is a bit odd
* but is consistent with our historical behavior.
*/
-static List *pendingNotifies = NIL; /* list of C strings */
+typedef struct Notification
+{
+ char *channel; /* channel name */
+ char *payload; /* payload string (can be empty) */
+} Notification;
+
+static List *pendingNotifies = NIL; /* list of Notifications */
static List *upperPendingNotifies = NIL; /* list of upper-xact lists */
/*
- * State for inbound notifies consists of two flags: one saying whether
+ * State for inbound notifications consists of two flags: one saying whether
* the signal handler is currently allowed to call ProcessIncomingNotify
* directly, and one saying whether the signal has occurred but the handler
* was not allowed to call ProcessIncomingNotify at the time.
@@ -168,57 +345,259 @@ static volatile sig_atomic_t notifyInterruptOccurred = 0;
/* True if we've registered an on_shmem_exit cleanup */
static bool unlistenExitRegistered = false;
+/* has this backend sent notifications in the current transaction? */
+static bool backendHasSentNotifications = false;
+/* has this backend executed its first LISTEN in the current transaction? */
+static bool backendHasExecutedInitialListen = false;
+/* GUC parameter */
bool Trace_notify = false;
-
-static void queue_listen(ListenActionKind action, const char *condname);
+/* local function prototypes */
+static bool asyncQueuePagePrecedesPhysically(int p, int q);
+static bool asyncQueuePagePrecedesLogically(int p, int q);
+static void queue_listen(ListenActionKind action, const char *channel);
static void Async_UnlistenOnExit(int code, Datum arg);
-static void Exec_Listen(Relation lRel, const char *relname);
-static void Exec_Unlisten(Relation lRel, const char *relname);
-static void Exec_UnlistenAll(Relation lRel);
-static void Send_Notify(Relation lRel);
+static void Exec_ListenPreCommit(void);
+static void Exec_ListenCommit(const char *channel);
+static void Exec_UnlistenCommit(const char *channel);
+static void Exec_UnlistenAllCommit(void);
+static bool IsListeningOn(const char *channel);
+static void asyncQueueUnregister(void);
+static bool asyncQueueIsFull(void);
+static bool asyncQueueAdvance(QueuePosition *position, int entryLength);
+static void asyncQueueNotificationToEntry(Notification *n, AsyncQueueEntry *qe);
+static ListCell *asyncQueueAddEntries(ListCell *nextNotify);
+static void asyncQueueFillWarning(void);
+static bool SignalBackends(void);
+static void asyncQueueReadAllNotifications(void);
+static bool asyncQueueProcessPageEntries(QueuePosition *current,
+ QueuePosition stop,
+ char *page_buffer);
+static void asyncQueueAdvanceTail(void);
static void ProcessIncomingNotify(void);
-static void NotifyMyFrontEnd(char *relname, int32 listenerPID);
-static bool AsyncExistsPendingNotify(const char *relname);
+static void NotifyMyFrontEnd(const char *channel,
+ const char *payload,
+ int32 srcPid);
+static bool AsyncExistsPendingNotify(const char *channel, const char *payload);
static void ClearPendingActionsAndNotifies(void);
+/*
+ * We will work on the page range of 0..QUEUE_MAX_PAGE.
+ *
+ * asyncQueuePagePrecedesPhysically just checks numerically without any magic
+ * if one page precedes another one. This is wrong for normal operation but
+ * is helpful when clearing pg_notify/ during startup.
+ *
+ * asyncQueuePagePrecedesLogically compares using wraparound logic, as is
+ * required by slru.c.
+ */
+static bool
+asyncQueuePagePrecedesPhysically(int p, int q)
+{
+ return p < q;
+}
+
+static bool
+asyncQueuePagePrecedesLogically(int p, int q)
+{
+ int diff;
+
+ /*
+ * We have to compare modulo (QUEUE_MAX_PAGE+1)/2. Both inputs should
+ * be in the range 0..QUEUE_MAX_PAGE.
+ */
+ Assert(p >= 0 && p <= QUEUE_MAX_PAGE);
+ Assert(q >= 0 && q <= QUEUE_MAX_PAGE);
+
+ diff = p - q;
+ if (diff >= ((QUEUE_MAX_PAGE+1)/2))
+ diff -= QUEUE_MAX_PAGE+1;
+ else if (diff < -((QUEUE_MAX_PAGE+1)/2))
+ diff += QUEUE_MAX_PAGE+1;
+ return diff < 0;
+}
+
+/*
+ * Report space needed for our shared memory area
+ */
+Size
+AsyncShmemSize(void)
+{
+ Size size;
+
+ /* This had better match AsyncShmemInit */
+ size = mul_size(MaxBackends, sizeof(QueueBackendStatus));
+ size = add_size(size, sizeof(AsyncQueueControl));
+
+ size = add_size(size, SimpleLruShmemSize(NUM_ASYNC_BUFFERS, 0));
+
+ return size;
+}
+
+/*
+ * Initialize our shared memory area
+ */
+void
+AsyncShmemInit(void)
+{
+ bool found;
+ int slotno;
+ Size size;
+
+ /*
+ * Create or attach to the AsyncQueueControl structure.
+ *
+ * The used entries in the backend[] array run from 1 to MaxBackends.
+ * sizeof(AsyncQueueControl) already includes space for the unused zero'th
+ * entry, but we need to add on space for the used entries.
+ */
+ size = mul_size(MaxBackends, sizeof(QueueBackendStatus));
+ size = add_size(size, sizeof(AsyncQueueControl));
+
+ asyncQueueControl = (AsyncQueueControl *)
+ ShmemInitStruct("Async Queue Control", size, &found);
+
+ if (!asyncQueueControl)
+ elog(ERROR, "out of shared memory");
+
+ if (!found)
+ {
+ /* First time through, so initialize it */
+ int i;
+
+ SET_QUEUE_POS(QUEUE_HEAD, 0, 0);
+ SET_QUEUE_POS(QUEUE_TAIL, 0, 0);
+ asyncQueueControl->lastQueueFillWarn = 0;
+ /* zero'th entry won't be used, but let's initialize it anyway */
+ for (i = 0; i <= MaxBackends; i++)
+ {
+ QUEUE_BACKEND_PID(i) = InvalidPid;
+ SET_QUEUE_POS(QUEUE_BACKEND_POS(i), 0, 0);
+ }
+ }
+
+ /*
+ * Set up SLRU management of the pg_notify data.
+ */
+ AsyncCtl->PagePrecedes = asyncQueuePagePrecedesLogically;
+ SimpleLruInit(AsyncCtl, "Async Ctl", NUM_ASYNC_BUFFERS, 0,
+ AsyncCtlLock, "pg_notify");
+ /* Override default assumption that writes should be fsync'd */
+ AsyncCtl->do_fsync = false;
+
+ if (!found)
+ {
+ /*
+ * During start or reboot, clean out the pg_notify directory.
+ *
+ * Since we want to remove every file, we temporarily use
+ * asyncQueuePagePrecedesPhysically() and pass INT_MAX as the
+ * comparison value; every file in the directory should therefore
+ * appear to be less than that.
+ */
+ AsyncCtl->PagePrecedes = asyncQueuePagePrecedesPhysically;
+ (void) SlruScanDirectory(AsyncCtl, INT_MAX, true);
+ AsyncCtl->PagePrecedes = asyncQueuePagePrecedesLogically;
+
+ /* Now initialize page zero to empty */
+ LWLockAcquire(AsyncCtlLock, LW_EXCLUSIVE);
+ slotno = SimpleLruZeroPage(AsyncCtl, QUEUE_POS_PAGE(QUEUE_HEAD));
+ /* This write is just to verify that pg_notify/ is writable */
+ SimpleLruWritePage(AsyncCtl, slotno, NULL);
+ LWLockRelease(AsyncCtlLock);
+ }
+}
+
+
+/*
+ * pg_notify -
+ * SQL function to send a notification event
+ */
+Datum
+pg_notify(PG_FUNCTION_ARGS)
+{
+ const char *channel;
+ const char *payload;
+
+ if (PG_ARGISNULL(0))
+ channel = "";
+ else
+ channel = text_to_cstring(PG_GETARG_TEXT_PP(0));
+
+ if (PG_ARGISNULL(1))
+ payload = "";
+ else
+ payload = text_to_cstring(PG_GETARG_TEXT_PP(1));
+
+ Async_Notify(channel, payload);
+
+ PG_RETURN_VOID();
+}
+
+
/*
* Async_Notify
*
* This is executed by the SQL notify command.
*
- * Adds the relation to the list of pending notifies.
+ * Adds the message to the list of pending notifies.
* Actual notification happens during transaction commit.
* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
*/
void
-Async_Notify(const char *relname)
+Async_Notify(const char *channel, const char *payload)
{
+ Notification *n;
+ MemoryContext oldcontext;
+
if (Trace_notify)
- elog(DEBUG1, "Async_Notify(%s)", relname);
+ elog(DEBUG1, "Async_Notify(%s)", channel);
- /* no point in making duplicate entries in the list ... */
- if (!AsyncExistsPendingNotify(relname))
+ /* a channel name must be specified */
+ if (!channel || !strlen(channel))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("channel name cannot be empty")));
+
+ if (strlen(channel) >= NAMEDATALEN)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("channel name too long")));
+
+ if (payload)
{
- /*
- * The name list needs to live until end of transaction, so store it
- * in the transaction context.
- */
- MemoryContext oldcontext;
+ if (strlen(payload) >= NOTIFY_PAYLOAD_MAX_LENGTH)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("payload string too long")));
+ }
- oldcontext = MemoryContextSwitchTo(CurTransactionContext);
+ /* no point in making duplicate entries in the list ... */
+ if (AsyncExistsPendingNotify(channel, payload))
+ return;
- /*
- * Ordering of the list isn't important. We choose to put new entries
- * on the front, as this might make duplicate-elimination a tad faster
- * when the same condition is signaled many times in a row.
- */
- pendingNotifies = lcons(pstrdup(relname), pendingNotifies);
+ /*
+ * The notification list needs to live until end of transaction, so store
+ * it in the transaction context.
+ */
+ oldcontext = MemoryContextSwitchTo(CurTransactionContext);
- MemoryContextSwitchTo(oldcontext);
- }
+ n = (Notification *) palloc(sizeof(Notification));
+ n->channel = pstrdup(channel);
+ if (payload)
+ n->payload = pstrdup(payload);
+ else
+ n->payload = "";
+
+ /*
+ * We want to preserve the order so we need to append every
+ * notification. See comments at AsyncExistsPendingNotify().
+ */
+ pendingNotifies = lappend(pendingNotifies, n);
+
+ MemoryContextSwitchTo(oldcontext);
}
/*
@@ -226,11 +605,11 @@ Async_Notify(const char *relname)
* Common code for listen, unlisten, unlisten all commands.
*
* Adds the request to the list of pending actions.
- * Actual update of pg_listener happens during transaction commit.
- * ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ * Actual update of the listenChannels list happens during transaction
+ * commit.
*/
static void
-queue_listen(ListenActionKind action, const char *condname)
+queue_listen(ListenActionKind action, const char *channel)
{
MemoryContext oldcontext;
ListenAction *actrec;
@@ -244,9 +623,9 @@ queue_listen(ListenActionKind action, const char *condname)
oldcontext = MemoryContextSwitchTo(CurTransactionContext);
/* space for terminating null is included in sizeof(ListenAction) */
- actrec = (ListenAction *) palloc(sizeof(ListenAction) + strlen(condname));
+ actrec = (ListenAction *) palloc(sizeof(ListenAction) + strlen(channel));
actrec->action = action;
- strcpy(actrec->condname, condname);
+ strcpy(actrec->channel, channel);
pendingActions = lappend(pendingActions, actrec);
@@ -259,12 +638,12 @@ queue_listen(ListenActionKind action, const char *condname)
* This is executed by the SQL listen command.
*/
void
-Async_Listen(const char *relname)
+Async_Listen(const char *channel)
{
if (Trace_notify)
- elog(DEBUG1, "Async_Listen(%s,%d)", relname, MyProcPid);
+ elog(DEBUG1, "Async_Listen(%s,%d)", channel, MyProcPid);
- queue_listen(LISTEN_LISTEN, relname);
+ queue_listen(LISTEN_LISTEN, channel);
}
/*
@@ -273,16 +652,16 @@ Async_Listen(const char *relname)
* This is executed by the SQL unlisten command.
*/
void
-Async_Unlisten(const char *relname)
+Async_Unlisten(const char *channel)
{
if (Trace_notify)
- elog(DEBUG1, "Async_Unlisten(%s,%d)", relname, MyProcPid);
+ elog(DEBUG1, "Async_Unlisten(%s,%d)", channel, MyProcPid);
/* If we couldn't possibly be listening, no need to queue anything */
if (pendingActions == NIL && !unlistenExitRegistered)
return;
- queue_listen(LISTEN_UNLISTEN, relname);
+ queue_listen(LISTEN_UNLISTEN, channel);
}
/*
@@ -304,28 +683,63 @@ Async_UnlistenAll(void)
}
/*
- * Async_UnlistenOnExit
+ * SQL function: return a set of the channel names this backend is actively
+ * listening to.
*
- * Clean up the pg_listener table at backend exit.
+ * Note: this coding relies on the fact that the listenChannels list cannot
+ * change within a transaction.
+ */
+Datum
+pg_listening_channels(PG_FUNCTION_ARGS)
+{
+ FuncCallContext *funcctx;
+ ListCell **lcp;
+
+ /* stuff done only on the first call of the function */
+ if (SRF_IS_FIRSTCALL())
+ {
+ MemoryContext oldcontext;
+
+ /* create a function context for cross-call persistence */
+ funcctx = SRF_FIRSTCALL_INIT();
+
+ /* switch to memory context appropriate for multiple function calls */
+ oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+ /* allocate memory for user context */
+ lcp = (ListCell **) palloc(sizeof(ListCell *));
+ *lcp = list_head(listenChannels);
+ funcctx->user_fctx = (void *) lcp;
+
+ MemoryContextSwitchTo(oldcontext);
+ }
+
+ /* stuff done on every call of the function */
+ funcctx = SRF_PERCALL_SETUP();
+ lcp = (ListCell **) funcctx->user_fctx;
+
+ while (*lcp != NULL)
+ {
+ char *channel = (char *) lfirst(*lcp);
+
+ *lcp = lnext(*lcp);
+ SRF_RETURN_NEXT(funcctx, CStringGetTextDatum(channel));
+ }
+
+ SRF_RETURN_DONE(funcctx);
+}
+
+/*
+ * Async_UnlistenOnExit
*
- * This is executed if we have done any LISTENs in this backend.
- * It might not be necessary anymore, if the user UNLISTENed everything,
- * but we don't try to detect that case.
+ * This is executed at backend exit if we have done any LISTENs in this
+ * backend. It might not be necessary anymore, if the user UNLISTENed
+ * everything, but we don't try to detect that case.
*/
static void
Async_UnlistenOnExit(int code, Datum arg)
{
- /*
- * We need to start/commit a transaction for the unlisten, but if there is
- * already an active transaction we had better abort that one first.
- * Otherwise we'd end up committing changes that probably ought to be
- * discarded.
- */
- AbortOutOfAnyTransaction();
- /* Now we can do the unlisten */
- StartTransactionCommand();
- Async_UnlistenAll();
- CommitTransactionCommand();
+ Exec_UnlistenAllCommit();
}
/*
@@ -337,71 +751,144 @@ Async_UnlistenOnExit(int code, Datum arg)
void
AtPrepare_Notify(void)
{
- ListCell *p;
-
- /* It's not sensible to have any pending LISTEN/UNLISTEN actions */
- if (pendingActions)
+ /* It's not allowed to have any pending LISTEN/UNLISTEN/NOTIFY actions */
+ if (pendingActions || pendingNotifies)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot PREPARE a transaction that has executed LISTEN or UNLISTEN")));
+ errmsg("cannot PREPARE a transaction that has executed LISTEN, UNLISTEN or NOTIFY")));
+}
- /* We can deal with pending NOTIFY though */
- foreach(p, pendingNotifies)
+/*
+ * PreCommit_Notify
+ *
+ * This is called at transaction commit, before actually committing to
+ * clog.
+ *
+ * If there are pending LISTEN actions, make sure we are listed in the
+ * shared-memory listener array. This must happen before commit to
+ * ensure we don't miss any notifies from transactions that commit
+ * just after ours.
+ *
+ * If there are outbound notify requests in the pendingNotifies list,
+ * add them to the global queue. We do that before commit so that
+ * we can still throw error if we run out of queue space.
+ */
+void
+PreCommit_Notify(void)
+{
+ ListCell *p;
+
+ if (pendingActions == NIL && pendingNotifies == NIL)
+ return; /* no relevant statements in this xact */
+
+ if (Trace_notify)
+ elog(DEBUG1, "PreCommit_Notify");
+
+ Assert(backendHasExecutedInitialListen == false);
+
+ /* Preflight for any pending listen/unlisten actions */
+ foreach(p, pendingActions)
{
- const char *relname = (const char *) lfirst(p);
+ ListenAction *actrec = (ListenAction *) lfirst(p);
- RegisterTwoPhaseRecord(TWOPHASE_RM_NOTIFY_ID, 0,
- relname, strlen(relname) + 1);
+ switch (actrec->action)
+ {
+ case LISTEN_LISTEN:
+ Exec_ListenPreCommit();
+ break;
+ case LISTEN_UNLISTEN:
+ /* there is no Exec_UnlistenPreCommit() */
+ break;
+ case LISTEN_UNLISTEN_ALL:
+ /* there is no Exec_UnlistenAllPreCommit() */
+ break;
+ }
}
- /*
- * We can clear the state immediately, rather than needing a separate
- * PostPrepare call, because if the transaction fails we'd just discard
- * the state anyway.
- */
- ClearPendingActionsAndNotifies();
+ /* Queue any pending notifies */
+ if (pendingNotifies)
+ {
+ ListCell *nextNotify;
+
+ /*
+ * Make sure that we have an XID assigned to the current transaction.
+ * GetCurrentTransactionId is cheap if we already have an XID, but
+ * not so cheap if we don't, and we'd prefer not to do that work
+ * while holding AsyncQueueLock.
+ */
+ (void) GetCurrentTransactionId();
+
+ /*
+ * Serialize writers by acquiring a special lock that we hold till
+ * after commit. This ensures that queue entries appear in commit
+ * order, and in particular that there are never uncommitted queue
+ * entries ahead of committed ones, so an uncommitted transaction
+ * can't block delivery of deliverable notifications.
+ *
+ * We use a heavyweight lock so that it'll automatically be released
+ * after either commit or abort. This also allows deadlocks to be
+ * detected, though really a deadlock shouldn't be possible here.
+ *
+ * The lock is on "database 0", which is pretty ugly but it doesn't
+ * seem worth inventing a special locktag category just for this.
+ * (Historical note: before PG 9.0, a similar lock on "database 0" was
+ * used by the flatfiles mechanism.)
+ */
+ LockSharedObject(DatabaseRelationId, InvalidOid, 0,
+ AccessExclusiveLock);
+
+ /* Now push the notifications into the queue */
+ backendHasSentNotifications = true;
+
+ nextNotify = list_head(pendingNotifies);
+ while (nextNotify != NULL)
+ {
+ /*
+ * Add the pending notifications to the queue. We acquire and
+ * release AsyncQueueLock once per page, which might be overkill
+ * but it does allow readers to get in while we're doing this.
+ *
+ * A full queue is very uncommon and should really not happen,
+ * given that we have so much space available in the SLRU pages.
+ * Nevertheless we need to deal with this possibility. Note that
+ * when we get here we are in the process of committing our
+ * transaction, but we have not yet committed to clog, so at this
+ * point in time we can still roll the transaction back.
+ */
+ LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE);
+ asyncQueueFillWarning();
+ if (asyncQueueIsFull())
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("too many notifications in the NOTIFY queue")));
+ nextNotify = asyncQueueAddEntries(nextNotify);
+ LWLockRelease(AsyncQueueLock);
+ }
+ }
}
/*
* AtCommit_Notify
*
- * This is called at transaction commit.
- *
- * If there are pending LISTEN/UNLISTEN actions, insert or delete
- * tuples in pg_listener accordingly.
- *
- * If there are outbound notify requests in the pendingNotifies list,
- * scan pg_listener for matching tuples, and either signal the other
- * backend or send a message to our own frontend.
+ * This is called at transaction commit, after committing to clog.
*
- * NOTE: we are still inside the current transaction, therefore can
- * piggyback on its committing of changes.
+ * Update listenChannels and clear transaction-local state.
*/
void
AtCommit_Notify(void)
{
- Relation lRel;
ListCell *p;
- if (pendingActions == NIL && pendingNotifies == NIL)
- return; /* no relevant statements in this xact */
-
/*
- * NOTIFY is disabled if not normal processing mode. This test used to be
- * in xact.c, but it seems cleaner to do it here.
+ * Allow transactions that have not executed LISTEN/UNLISTEN/NOTIFY to
+ * return as soon as possible
*/
- if (!IsNormalProcessingMode())
- {
- ClearPendingActionsAndNotifies();
+ if (!pendingActions && !pendingNotifies)
return;
- }
if (Trace_notify)
elog(DEBUG1, "AtCommit_Notify");
- /* Acquire ExclusiveLock on pg_listener */
- lRel = heap_open(ListenerRelationId, ExclusiveLock);
-
/* Perform any pending listen/unlisten actions */
foreach(p, pendingActions)
{
@@ -410,281 +897,640 @@ AtCommit_Notify(void)
switch (actrec->action)
{
case LISTEN_LISTEN:
- Exec_Listen(lRel, actrec->condname);
+ Exec_ListenCommit(actrec->channel);
break;
case LISTEN_UNLISTEN:
- Exec_Unlisten(lRel, actrec->condname);
+ Exec_UnlistenCommit(actrec->channel);
break;
case LISTEN_UNLISTEN_ALL:
- Exec_UnlistenAll(lRel);
+ Exec_UnlistenAllCommit();
break;
}
+ }
+
+ /*
+ * If we did an initial LISTEN, listenChannels now has the entry, so
+ * we no longer need or want the flag to be set.
+ */
+ backendHasExecutedInitialListen = false;
+
+ /* And clean up */
+ ClearPendingActionsAndNotifies();
+}
+
+/*
+ * Exec_ListenPreCommit --- subroutine for PreCommit_Notify
+ *
+ * This function must make sure we are ready to catch any incoming messages.
+ */
+static void
+Exec_ListenPreCommit(void)
+{
+ /*
+ * Nothing to do if we are already listening to something, nor if we
+ * already ran this routine in this transaction.
+ */
+ if (listenChannels != NIL || backendHasExecutedInitialListen)
+ return;
+
+ if (Trace_notify)
+ elog(DEBUG1, "Exec_ListenPreCommit(%d)", MyProcPid);
+
+ /*
+ * We need this variable to detect an aborted initial LISTEN.
+ * In that case we would set up our pointer but not listen on any channel.
+ * This flag gets cleared in AtCommit_Notify or AtAbort_Notify().
+ */
+ backendHasExecutedInitialListen = true;
+
+ /*
+ * Before registering, make sure we will unlisten before dying.
+ * (Note: this action does not get undone if we abort later.)
+ */
+ if (!unlistenExitRegistered)
+ {
+ on_shmem_exit(Async_UnlistenOnExit, 0);
+ unlistenExitRegistered = true;
+ }
+
+ /*
+ * This is our first LISTEN, so establish our pointer.
+ *
+ * We set our pointer to the global tail pointer and then move it forward
+ * over already-committed notifications. This ensures we cannot miss any
+ * not-yet-committed notifications. We might get a few more but that
+ * doesn't hurt.
+ */
+ LWLockAcquire(AsyncQueueLock, LW_SHARED);
+ QUEUE_BACKEND_POS(MyBackendId) = QUEUE_TAIL;
+ QUEUE_BACKEND_PID(MyBackendId) = MyProcPid;
+ LWLockRelease(AsyncQueueLock);
+
+ /*
+ * Try to move our pointer forward as far as possible. This will skip over
+ * already-committed notifications. Still, we could get notifications that
+ * have already committed before we started to LISTEN.
+ *
+ * Note that we are not yet listening on anything, so we won't deliver
+ * any notification to the frontend.
+ *
+ * This will also advance the global tail pointer if possible.
+ */
+ asyncQueueReadAllNotifications();
+}
+
+/*
+ * Exec_ListenCommit --- subroutine for AtCommit_Notify
+ *
+ * Add the channel to the list of channels we are listening on.
+ */
+static void
+Exec_ListenCommit(const char *channel)
+{
+ MemoryContext oldcontext;
+
+ /* Do nothing if we are already listening on this channel */
+ if (IsListeningOn(channel))
+ return;
+
+ /*
+ * Add the new channel name to listenChannels.
+ *
+ * XXX It is theoretically possible to get an out-of-memory failure here,
+ * which would be bad because we already committed. For the moment it
+ * doesn't seem worth trying to guard against that, but maybe improve this
+ * later.
+ */
+ oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+ listenChannels = lappend(listenChannels, pstrdup(channel));
+ MemoryContextSwitchTo(oldcontext);
+}
+
+/*
+ * Exec_UnlistenCommit --- subroutine for AtCommit_Notify
+ *
+ * Remove the specified channel name from listenChannels.
+ */
+static void
+Exec_UnlistenCommit(const char *channel)
+{
+ ListCell *q;
+ ListCell *prev;
+
+ if (Trace_notify)
+ elog(DEBUG1, "Exec_UnlistenCommit(%s,%d)", channel, MyProcPid);
+
+ prev = NULL;
+ foreach(q, listenChannels)
+ {
+ char *lchan = (char *) lfirst(q);
+
+ if (strcmp(lchan, channel) == 0)
+ {
+ listenChannels = list_delete_cell(listenChannels, q, prev);
+ pfree(lchan);
+ break;
+ }
+ prev = q;
+ }
- /* We must CCI after each action in case of conflicting actions */
- CommandCounterIncrement();
+ /*
+ * We do not complain about unlistening something not being listened;
+ * should we?
+ */
+
+ /* If no longer listening to anything, get out of listener array */
+ if (listenChannels == NIL)
+ asyncQueueUnregister();
+}
+
+/*
+ * Exec_UnlistenAllCommit --- subroutine for AtCommit_Notify
+ *
+ * Unlisten on all channels for this backend.
+ */
+static void
+Exec_UnlistenAllCommit(void)
+{
+ if (Trace_notify)
+ elog(DEBUG1, "Exec_UnlistenAllCommit(%d)", MyProcPid);
+
+ list_free_deep(listenChannels);
+ listenChannels = NIL;
+
+ asyncQueueUnregister();
+}
+
+/*
+ * ProcessCompletedNotifies --- send out signals and self-notifies
+ *
+ * This is called from postgres.c just before going idle at the completion
+ * of a transaction. If we issued any notifications in the just-completed
+ * transaction, send signals to other backends to process them, and also
+ * process the queue ourselves to send messages to our own frontend.
+ *
+ * The reason that this is not done in AtCommit_Notify is that there is
+ * a nonzero chance of errors here (for example, encoding conversion errors
+ * while trying to format messages to our frontend). An error during
+ * AtCommit_Notify would be a PANIC condition. The timing is also arranged
+ * to ensure that a transaction's self-notifies are delivered to the frontend
+ * before it gets the terminating ReadyForQuery message.
+ *
+ * Note that we send signals and process the queue even if the transaction
+ * eventually aborted. This is because we need to clean out whatever got
+ * added to the queue.
+ *
+ * NOTE: we are outside of any transaction here.
+ */
+void
+ProcessCompletedNotifies(void)
+{
+ bool signalled;
+
+ /* Nothing to do if we didn't send any notifications */
+ if (!backendHasSentNotifications)
+ return;
+
+ /*
+ * We reset the flag immediately; otherwise, if any sort of error
+ * occurs below, we'd be locked up in an infinite loop, because
+ * control will come right back here after error cleanup.
+ */
+ backendHasSentNotifications = false;
+
+ if (Trace_notify)
+ elog(DEBUG1, "ProcessCompletedNotifies");
+
+ /*
+ * We must run asyncQueueReadAllNotifications inside a transaction,
+ * else bad things happen if it gets an error.
+ */
+ StartTransactionCommand();
+
+ /* Send signals to other backends */
+ signalled = SignalBackends();
+
+ if (listenChannels != NIL)
+ {
+ /* Read the queue ourselves, and send relevant stuff to the frontend */
+ asyncQueueReadAllNotifications();
+ }
+ else if (!signalled)
+ {
+ /*
+ * If we found no other listening backends, and we aren't listening
+ * ourselves, then we must execute asyncQueueAdvanceTail to flush
+ * the queue, because ain't nobody else gonna do it. This prevents
+ * queue overflow when we're sending useless notifies to nobody.
+ * (A new listener could have joined since we looked, but if so this
+ * is harmless.)
+ */
+ asyncQueueAdvanceTail();
}
- /* Perform any pending notifies */
- if (pendingNotifies)
- Send_Notify(lRel);
-
- /*
- * We do NOT release the lock on pg_listener here; we need to hold it
- * until end of transaction (which is about to happen, anyway) to ensure
- * that notified backends see our tuple updates when they look. Else they
- * might disregard the signal, which would make the application programmer
- * very unhappy. Also, this prevents race conditions when we have just
- * inserted a listening tuple.
- */
- heap_close(lRel, NoLock);
-
- ClearPendingActionsAndNotifies();
+ CommitTransactionCommand();
- if (Trace_notify)
- elog(DEBUG1, "AtCommit_Notify: done");
+ /* We don't need pq_flush() here since postgres.c will do one shortly */
}
/*
- * Exec_Listen --- subroutine for AtCommit_Notify
+ * Test whether we are actively listening on the given channel name.
*
- * Register the current backend as listening on the specified relation.
+ * Note: this function is executed for every notification found in the queue.
+ * Perhaps it is worth further optimization, eg convert the list to a sorted
+ * array so we can binary-search it. In practice the list is likely to be
+ * fairly short, though.
*/
-static void
-Exec_Listen(Relation lRel, const char *relname)
+static bool
+IsListeningOn(const char *channel)
{
- HeapScanDesc scan;
- HeapTuple tuple;
- Datum values[Natts_pg_listener];
- bool nulls[Natts_pg_listener];
- NameData condname;
- bool alreadyListener = false;
-
- if (Trace_notify)
- elog(DEBUG1, "Exec_Listen(%s,%d)", relname, MyProcPid);
+ ListCell *p;
- /* Detect whether we are already listening on this relname */
- scan = heap_beginscan(lRel, SnapshotNow, 0, NULL);
- while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+ foreach(p, listenChannels)
{
- Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple);
+ char *lchan = (char *) lfirst(p);
- if (listener->listenerpid == MyProcPid &&
- strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0)
- {
- alreadyListener = true;
- /* No need to scan the rest of the table */
- break;
- }
+ if (strcmp(lchan, channel) == 0)
+ return true;
}
- heap_endscan(scan);
+ return false;
+}
- if (alreadyListener)
- return;
+/*
+ * Remove our entry from the listeners array when we are no longer listening
+ * on any channel. NB: must not fail if we're already not listening.
+ */
+static void
+asyncQueueUnregister(void)
+{
+ bool advanceTail;
- /*
- * OK to insert a new tuple
- */
- memset(nulls, false, sizeof(nulls));
+ Assert(listenChannels == NIL); /* else caller error */
- namestrcpy(&condname, relname);
- values[Anum_pg_listener_relname - 1] = NameGetDatum(&condname);
- values[Anum_pg_listener_listenerpid - 1] = Int32GetDatum(MyProcPid);
- values[Anum_pg_listener_notification - 1] = Int32GetDatum(0); /* no notifies pending */
+ LWLockAcquire(AsyncQueueLock, LW_SHARED);
+ /* check if entry is valid and oldest ... */
+ advanceTail = (MyProcPid == QUEUE_BACKEND_PID(MyBackendId)) &&
+ QUEUE_POS_EQUAL(QUEUE_BACKEND_POS(MyBackendId), QUEUE_TAIL);
+ /* ... then mark it invalid */
+ QUEUE_BACKEND_PID(MyBackendId) = InvalidPid;
+ LWLockRelease(AsyncQueueLock);
+
+ /* If we were the laziest backend, try to advance the tail pointer */
+ if (advanceTail)
+ asyncQueueAdvanceTail();
+}
- tuple = heap_form_tuple(RelationGetDescr(lRel), values, nulls);
+/*
+ * Test whether there is room to insert more notification messages.
+ *
+ * Caller must hold at least shared AsyncQueueLock.
+ */
+static bool
+asyncQueueIsFull(void)
+{
+ int nexthead;
+ int boundary;
- simple_heap_insert(lRel, tuple);
+ /*
+ * The queue is full if creating a new head page would create a page that
+ * logically precedes the current global tail pointer, ie, the head
+ * pointer would wrap around compared to the tail. We cannot create such
+ * a head page for fear of confusing slru.c. For safety we round the tail
+ * pointer back to a segment boundary (compare the truncation logic in
+ * asyncQueueAdvanceTail).
+ *
+ * Note that this test is *not* dependent on how much space there is on
+ * the current head page. This is necessary because asyncQueueAddEntries
+ * might try to create the next head page in any case.
+ */
+ nexthead = QUEUE_POS_PAGE(QUEUE_HEAD) + 1;
+ if (nexthead > QUEUE_MAX_PAGE)
+ nexthead = 0; /* wrap around */
+ boundary = QUEUE_POS_PAGE(QUEUE_TAIL);
+ boundary -= boundary % SLRU_PAGES_PER_SEGMENT;
+ return asyncQueuePagePrecedesLogically(nexthead, boundary);
+}
-#ifdef NOT_USED /* currently there are no indexes */
- CatalogUpdateIndexes(lRel, tuple);
-#endif
+/*
+ * Advance the QueuePosition to the next entry, assuming that the current
+ * entry is of length entryLength. If we jump to a new page the function
+ * returns true, else false.
+ */
+static bool
+asyncQueueAdvance(QueuePosition *position, int entryLength)
+{
+ int pageno = QUEUE_POS_PAGE(*position);
+ int offset = QUEUE_POS_OFFSET(*position);
+ bool pageJump = false;
- heap_freetuple(tuple);
+ /*
+ * Move to the next writing position: First jump over what we have just
+ * written or read.
+ */
+ offset += entryLength;
+ Assert(offset <= QUEUE_PAGESIZE);
/*
- * now that we are listening, make sure we will unlisten before dying.
+ * In a second step check if another entry can possibly be written to the
+ * page. If so, stay here, we have reached the next position. If not, then
+ * we need to move on to the next page.
*/
- if (!unlistenExitRegistered)
+ if (offset + QUEUEALIGN(AsyncQueueEntryEmptySize) > QUEUE_PAGESIZE)
{
- on_shmem_exit(Async_UnlistenOnExit, 0);
- unlistenExitRegistered = true;
+ pageno++;
+ if (pageno > QUEUE_MAX_PAGE)
+ pageno = 0; /* wrap around */
+ offset = 0;
+ pageJump = true;
}
+
+ SET_QUEUE_POS(*position, pageno, offset);
+ return pageJump;
}
/*
- * Exec_Unlisten --- subroutine for AtCommit_Notify
- *
- * Remove the current backend from the list of listening backends
- * for the specified relation.
+ * Fill the AsyncQueueEntry at *qe with an outbound notification message.
*/
static void
-Exec_Unlisten(Relation lRel, const char *relname)
+asyncQueueNotificationToEntry(Notification *n, AsyncQueueEntry *qe)
{
- HeapScanDesc scan;
- HeapTuple tuple;
+ size_t channellen = strlen(n->channel);
+ size_t payloadlen = strlen(n->payload);
+ int entryLength;
+
+ Assert(channellen < NAMEDATALEN);
+ Assert(payloadlen < NOTIFY_PAYLOAD_MAX_LENGTH);
+
+ /* The terminators are already included in AsyncQueueEntryEmptySize */
+ entryLength = AsyncQueueEntryEmptySize + payloadlen + channellen;
+ entryLength = QUEUEALIGN(entryLength);
+ qe->length = entryLength;
+ qe->dboid = MyDatabaseId;
+ qe->xid = GetCurrentTransactionId();
+ qe->srcPid = MyProcPid;
+ memcpy(qe->data, n->channel, channellen + 1);
+ memcpy(qe->data + channellen + 1, n->payload, payloadlen + 1);
+}
- if (Trace_notify)
- elog(DEBUG1, "Exec_Unlisten(%s,%d)", relname, MyProcPid);
+/*
+ * Add pending notifications to the queue.
+ *
+ * We go page by page here, i.e. we stop once we have to go to a new page but
+ * we will be called again and then fill that next page. If an entry does not
+ * fit into the current page, we write a dummy entry with an InvalidOid as the
+ * database OID in order to fill the page. So every page is always used up to
+ * the last byte which simplifies reading the page later.
+ *
+ * We are passed the list cell containing the next notification to write
+ * and return the first still-unwritten cell back. Eventually we will return
+ * NULL indicating all is done.
+ *
+ * We are holding AsyncQueueLock already from the caller and grab AsyncCtlLock
+ * locally in this function.
+ */
+static ListCell *
+asyncQueueAddEntries(ListCell *nextNotify)
+{
+ AsyncQueueEntry qe;
+ int pageno;
+ int offset;
+ int slotno;
- scan = heap_beginscan(lRel, SnapshotNow, 0, NULL);
- while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
+ /* We hold both AsyncQueueLock and AsyncCtlLock during this operation */
+ LWLockAcquire(AsyncCtlLock, LW_EXCLUSIVE);
+
+ /* Fetch the current page */
+ pageno = QUEUE_POS_PAGE(QUEUE_HEAD);
+ slotno = SimpleLruReadPage(AsyncCtl, pageno, true, InvalidTransactionId);
+ /* Note we mark the page dirty before writing in it */
+ AsyncCtl->shared->page_dirty[slotno] = true;
+
+ while (nextNotify != NULL)
{
- Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(tuple);
+ Notification *n = (Notification *) lfirst(nextNotify);
+
+ /* Construct a valid queue entry in local variable qe */
+ asyncQueueNotificationToEntry(n, &qe);
+
+ offset = QUEUE_POS_OFFSET(QUEUE_HEAD);
- if (listener->listenerpid == MyProcPid &&
- strncmp(NameStr(listener->relname), relname, NAMEDATALEN) == 0)
+ /* Check whether the entry really fits on the current page */
+ if (offset + qe.length <= QUEUE_PAGESIZE)
{
- /* Found the matching tuple, delete it */
- simple_heap_delete(lRel, &tuple->t_self);
+ /* OK, so advance nextNotify past this item */
+ nextNotify = lnext(nextNotify);
+ }
+ else
+ {
+ /*
+ * Write a dummy entry to fill up the page. Actually readers will
+ * only check dboid and since it won't match any reader's database
+ * OID, they will ignore this entry and move on.
+ */
+ qe.length = QUEUE_PAGESIZE - offset;
+ qe.dboid = InvalidOid;
+ qe.data[0] = '\0'; /* empty channel */
+ qe.data[1] = '\0'; /* empty payload */
+ }
+ /* Now copy qe into the shared buffer page */
+ memcpy(AsyncCtl->shared->page_buffer[slotno] + offset,
+ &qe,
+ qe.length);
+
+ /* Advance QUEUE_HEAD appropriately, and note if page is full */
+ if (asyncQueueAdvance(&(QUEUE_HEAD), qe.length))
+ {
/*
- * We assume there can be only one match, so no need to scan the
- * rest of the table
+ * Page is full, so we're done here, but first fill the next
+ * page with zeroes. The reason to do this is to ensure that
+ * slru.c's idea of the head page is always the same as ours,
+ * which avoids boundary problems in SimpleLruTruncate. The
+ * test in asyncQueueIsFull() ensured that there is room to
+ * create this page without overrunning the queue.
*/
+ slotno = SimpleLruZeroPage(AsyncCtl, QUEUE_POS_PAGE(QUEUE_HEAD));
+ /* And exit the loop */
break;
}
}
- heap_endscan(scan);
- /*
- * We do not complain about unlistening something not being listened;
- * should we?
- */
+ LWLockRelease(AsyncCtlLock);
+
+ return nextNotify;
}
/*
- * Exec_UnlistenAll --- subroutine for AtCommit_Notify
+ * Check whether the queue is at least half full, and emit a warning if so.
+ *
+ * This is unlikely given the size of the queue, but possible.
+ * The warnings show up at most once every QUEUE_FULL_WARN_INTERVAL.
*
- * Update pg_listener to unlisten all relations for this backend.
+ * Caller must hold exclusive AsyncQueueLock.
*/
static void
-Exec_UnlistenAll(Relation lRel)
+asyncQueueFillWarning(void)
{
- HeapScanDesc scan;
- HeapTuple lTuple;
- ScanKeyData key[1];
+ int headPage = QUEUE_POS_PAGE(QUEUE_HEAD);
+ int tailPage = QUEUE_POS_PAGE(QUEUE_TAIL);
+ int occupied;
+ double fillDegree;
+ TimestampTz t;
+
+ occupied = headPage - tailPage;
+
+ if (occupied == 0)
+ return; /* fast exit for common case */
+
+ if (occupied < 0)
+ {
+ /* head has wrapped around, tail not yet */
+ occupied += QUEUE_MAX_PAGE+1;
+ }
- if (Trace_notify)
- elog(DEBUG1, "Exec_UnlistenAll");
+ fillDegree = (double) occupied / (double) ((QUEUE_MAX_PAGE+1)/2);
+
+ if (fillDegree < 0.5)
+ return;
+
+ t = GetCurrentTimestamp();
- /* Find and delete all entries with my listenerPID */
- ScanKeyInit(&key[0],
- Anum_pg_listener_listenerpid,
- BTEqualStrategyNumber, F_INT4EQ,
- Int32GetDatum(MyProcPid));
- scan = heap_beginscan(lRel, SnapshotNow, 1, key);
+ if (TimestampDifferenceExceeds(asyncQueueControl->lastQueueFillWarn,
+ t, QUEUE_FULL_WARN_INTERVAL))
+ {
+ QueuePosition min = QUEUE_HEAD;
+ int32 minPid = InvalidPid;
+ int i;
+
+ for (i = 1; i <= MaxBackends; i++)
+ {
+ if (QUEUE_BACKEND_PID(i) != InvalidPid)
+ {
+ min = QUEUE_POS_MIN(min, QUEUE_BACKEND_POS(i));
+ if (QUEUE_POS_EQUAL(min, QUEUE_BACKEND_POS(i)))
+ minPid = QUEUE_BACKEND_PID(i);
+ }
+ }
- while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
- simple_heap_delete(lRel, &lTuple->t_self);
+ ereport(WARNING,
+ (errmsg("pg_notify queue is %.0f%% full", fillDegree * 100),
+ (minPid != InvalidPid ?
+ errdetail("PID %d is among the slowest backends.", minPid)
+ : 0),
+ (minPid != InvalidPid ?
+ errhint("Cleanup can only proceed if this backend ends its current transaction.")
+ : 0)));
- heap_endscan(scan);
+ asyncQueueControl->lastQueueFillWarn = t;
+ }
}
/*
- * Send_Notify --- subroutine for AtCommit_Notify
+ * Send signals to all listening backends (except our own).
+ *
+ * Returns true if we sent at least one signal.
*
- * Scan pg_listener for tuples matching our pending notifies, and
- * either signal the other backend or send a message to our own frontend.
+ * Since we need EXCLUSIVE lock anyway we also check the position of the other
+ * backends and in case one is already up-to-date we don't signal it.
+ * This can happen if concurrent notifying transactions have sent a signal and
+ * the signaled backend has read the other notifications and ours in the same
+ * step.
+ *
+ * Since we know the BackendId and the Pid the signalling is quite cheap.
*/
-static void
-Send_Notify(Relation lRel)
+static bool
+SignalBackends(void)
{
- TupleDesc tdesc = RelationGetDescr(lRel);
- HeapScanDesc scan;
- HeapTuple lTuple,
- rTuple;
- Datum value[Natts_pg_listener];
- bool repl[Natts_pg_listener],
- nulls[Natts_pg_listener];
-
- /* preset data to update notify column to MyProcPid */
- memset(nulls, false, sizeof(nulls));
- memset(repl, false, sizeof(repl));
- repl[Anum_pg_listener_notification - 1] = true;
- memset(value, 0, sizeof(value));
- value[Anum_pg_listener_notification - 1] = Int32GetDatum(MyProcPid);
-
- scan = heap_beginscan(lRel, SnapshotNow, 0, NULL);
-
- while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
- {
- Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple);
- char *relname = NameStr(listener->relname);
- int32 listenerPID = listener->listenerpid;
+ bool signalled = false;
+ int32 *pids;
+ BackendId *ids;
+ int count;
+ int i;
+ int32 pid;
- if (!AsyncExistsPendingNotify(relname))
- continue;
-
- if (listenerPID == MyProcPid)
- {
- /*
- * Self-notify: no need to bother with table update. Indeed, we
- * *must not* clear the notification field in this path, or we
- * could lose an outside notify, which'd be bad for applications
- * that ignore self-notify messages.
- */
- if (Trace_notify)
- elog(DEBUG1, "AtCommit_Notify: notifying self");
+ /*
+ * Identify all backends that are listening and not already up-to-date.
+ * We don't want to send signals while holding the AsyncQueueLock, so
+ * we just build a list of target PIDs.
+ *
+ * XXX in principle these pallocs could fail, which would be bad.
+ * Maybe preallocate the arrays? But in practice this is only run
+ * in trivial transactions, so there should surely be space available.
+ */
+ pids = (int32 *) palloc(MaxBackends * sizeof(int32));
+ ids = (BackendId *) palloc(MaxBackends * sizeof(BackendId));
+ count = 0;
- NotifyMyFrontEnd(relname, listenerPID);
- }
- else
+ LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE);
+ for (i = 1; i <= MaxBackends; i++)
+ {
+ pid = QUEUE_BACKEND_PID(i);
+ if (pid != InvalidPid && pid != MyProcPid)
{
- if (Trace_notify)
- elog(DEBUG1, "AtCommit_Notify: notifying pid %d",
- listenerPID);
+ QueuePosition pos = QUEUE_BACKEND_POS(i);
- /*
- * If someone has already notified this listener, we don't bother
- * modifying the table, but we do still send a NOTIFY_INTERRUPT
- * signal, just in case that backend missed the earlier signal for
- * some reason. It's OK to send the signal first, because the
- * other guy can't read pg_listener until we unlock it.
- *
- * Note: we don't have the other guy's BackendId available, so
- * this will incur a search of the ProcSignal table. That's
- * probably not worth worrying about.
- */
- if (SendProcSignal(listenerPID, PROCSIG_NOTIFY_INTERRUPT,
- InvalidBackendId) < 0)
- {
- /*
- * Get rid of pg_listener entry if it refers to a PID that no
- * longer exists. Presumably, that backend crashed without
- * deleting its pg_listener entries. This code used to only
- * delete the entry if errno==ESRCH, but as far as I can see
- * we should just do it for any failure (certainly at least
- * for EPERM too...)
- */
- simple_heap_delete(lRel, &lTuple->t_self);
- }
- else if (listener->notification == 0)
+ if (!QUEUE_POS_EQUAL(pos, QUEUE_HEAD))
{
- /* Rewrite the tuple with my PID in notification column */
- rTuple = heap_modify_tuple(lTuple, tdesc, value, nulls, repl);
- simple_heap_update(lRel, &lTuple->t_self, rTuple);
-
-#ifdef NOT_USED /* currently there are no indexes */
- CatalogUpdateIndexes(lRel, rTuple);
-#endif
+ pids[count] = pid;
+ ids[count] = i;
+ count++;
}
}
}
+ LWLockRelease(AsyncQueueLock);
- heap_endscan(scan);
+ /* Now send signals */
+ for (i = 0; i < count; i++)
+ {
+ pid = pids[i];
+
+ /*
+ * Note: assuming things aren't broken, a signal failure here could
+ * only occur if the target backend exited since we released
+ * AsyncQueueLock; which is unlikely but certainly possible.
+ * So we just log a low-level debug message if it happens.
+ */
+ if (SendProcSignal(pid, PROCSIG_NOTIFY_INTERRUPT, ids[i]) < 0)
+ elog(DEBUG3, "could not signal backend with PID %d: %m", pid);
+ else
+ signalled = true;
+ }
+
+ pfree(pids);
+ pfree(ids);
+
+ return signalled;
}
/*
* AtAbort_Notify
*
- * This is called at transaction abort.
+ * This is called at transaction abort.
*
- * Gets rid of pending actions and outbound notifies that we would have
- * executed if the transaction got committed.
+ * Gets rid of pending actions and outbound notifies that we would have
+ * executed if the transaction got committed.
*/
void
AtAbort_Notify(void)
{
+ /*
+ * If we LISTEN but then roll back the transaction we have set our pointer
+ * but have not made any entry in listenChannels. In that case, remove
+ * our pointer again.
+ */
+ if (backendHasExecutedInitialListen)
+ {
+ /*
+ * Checking listenChannels should be redundant but it can't hurt doing
+ * it for safety reasons.
+ */
+ if (listenChannels == NIL)
+ asyncQueueUnregister();
+
+ backendHasExecutedInitialListen = false;
+ }
+
+ /* And clean up */
ClearPendingActionsAndNotifies();
}
@@ -939,31 +1785,299 @@ DisableNotifyInterrupt(void)
return result;
}
+/*
+ * Read all pending notifications from the queue, and deliver appropriate
+ * ones to my frontend. Stop when we reach queue head or an uncommitted
+ * notification.
+ */
+static void
+asyncQueueReadAllNotifications(void)
+{
+ QueuePosition pos;
+ QueuePosition oldpos;
+ QueuePosition head;
+ bool advanceTail;
+ /* page_buffer must be adequately aligned, so use a union */
+ union {
+ char buf[QUEUE_PAGESIZE];
+ AsyncQueueEntry align;
+ } page_buffer;
+
+ /* Fetch current state */
+ LWLockAcquire(AsyncQueueLock, LW_SHARED);
+ /* Assert checks that we have a valid state entry */
+ Assert(MyProcPid == QUEUE_BACKEND_PID(MyBackendId));
+ pos = oldpos = QUEUE_BACKEND_POS(MyBackendId);
+ head = QUEUE_HEAD;
+ LWLockRelease(AsyncQueueLock);
+
+ if (QUEUE_POS_EQUAL(pos, head))
+ {
+ /* Nothing to do, we have read all notifications already. */
+ return;
+ }
+
+ /*----------
+ * Note that we deliver everything that we see in the queue and that
+ * matches our _current_ listening state.
+ * Especially we do not take into account different commit times.
+ * Consider the following example:
+ *
+ * Backend 1: Backend 2:
+ *
+ * transaction starts
+ * NOTIFY foo;
+ * commit starts
+ * transaction starts
+ * LISTEN foo;
+ * commit starts
+ * commit to clog
+ * commit to clog
+ *
+ * It could happen that backend 2 sees the notification from backend 1 in
+ * the queue. Even though the notifying transaction committed before
+ * the listening transaction, we still deliver the notification.
+ *
+ * The idea is that an additional notification does not do any harm, we
+ * just need to make sure that we do not miss a notification.
+ *
+ * It is possible that we fail while trying to send a message to our
+ * frontend (for example, because of encoding conversion failure).
+ * If that happens it is critical that we not try to send the same
+ * message over and over again. Therefore, we place a PG_TRY block
+ * here that will forcibly advance our backend position before we lose
+ * control to an error. (We could alternatively retake AsyncQueueLock
+ * and move the position before handling each individual message, but
+ * that seems like too much lock traffic.)
+ *----------
+ */
+ PG_TRY();
+ {
+ bool reachedStop;
+
+ do
+ {
+ int curpage = QUEUE_POS_PAGE(pos);
+ int curoffset = QUEUE_POS_OFFSET(pos);
+ int slotno;
+ int copysize;
+
+ /*
+ * We copy the data from SLRU into a local buffer, so as to avoid
+ * holding the AsyncCtlLock while we are examining the entries and
+ * possibly transmitting them to our frontend. Copy only the part
+ * of the page we will actually inspect.
+ */
+ slotno = SimpleLruReadPage_ReadOnly(AsyncCtl, curpage,
+ InvalidTransactionId);
+ if (curpage == QUEUE_POS_PAGE(head))
+ {
+ /* we only want to read as far as head */
+ copysize = QUEUE_POS_OFFSET(head) - curoffset;
+ if (copysize < 0)
+ copysize = 0; /* just for safety */
+ }
+ else
+ {
+ /* fetch all the rest of the page */
+ copysize = QUEUE_PAGESIZE - curoffset;
+ }
+ memcpy(page_buffer.buf + curoffset,
+ AsyncCtl->shared->page_buffer[slotno] + curoffset,
+ copysize);
+ /* Release lock that we got from SimpleLruReadPage_ReadOnly() */
+ LWLockRelease(AsyncCtlLock);
+
+ /*
+ * Process messages up to the stop position, end of page, or an
+ * uncommitted message.
+ *
+ * Our stop position is what we found to be the head's position
+ * when we entered this function. It might have changed
+ * already. But if it has, we will receive (or have already
+ * received and queued) another signal and come here again.
+ *
+ * We are not holding AsyncQueueLock here! The queue can only
+ * extend beyond the head pointer (see above) and we leave our
+ * backend's pointer where it is so nobody will truncate or
+ * rewrite pages under us. Especially we don't want to hold a lock
+ * while sending the notifications to the frontend.
+ */
+ reachedStop = asyncQueueProcessPageEntries(&pos, head,
+ page_buffer.buf);
+ } while (!reachedStop);
+ }
+ PG_CATCH();
+ {
+ /* Update shared state */
+ LWLockAcquire(AsyncQueueLock, LW_SHARED);
+ QUEUE_BACKEND_POS(MyBackendId) = pos;
+ advanceTail = QUEUE_POS_EQUAL(oldpos, QUEUE_TAIL);
+ LWLockRelease(AsyncQueueLock);
+
+ /* If we were the laziest backend, try to advance the tail pointer */
+ if (advanceTail)
+ asyncQueueAdvanceTail();
+
+ PG_RE_THROW();
+ }
+ PG_END_TRY();
+
+ /* Update shared state */
+ LWLockAcquire(AsyncQueueLock, LW_SHARED);
+ QUEUE_BACKEND_POS(MyBackendId) = pos;
+ advanceTail = QUEUE_POS_EQUAL(oldpos, QUEUE_TAIL);
+ LWLockRelease(AsyncQueueLock);
+
+ /* If we were the laziest backend, try to advance the tail pointer */
+ if (advanceTail)
+ asyncQueueAdvanceTail();
+}
+
+/*
+ * Fetch notifications from the shared queue, beginning at position current,
+ * and deliver relevant ones to my frontend.
+ *
+ * The current page must have been fetched into page_buffer from shared
+ * memory. (We could access the page right in shared memory, but that
+ * would imply holding the AsyncCtlLock throughout this routine.)
+ *
+ * We stop if we reach the "stop" position, or reach a notification from an
+ * uncommitted transaction, or reach the end of the page.
+ *
+ * The function returns true once we have reached the stop position or an
+ * uncommitted notification, and false if we have finished with the page.
+ * In other words: once it returns true there is no need to look further.
+ */
+static bool
+asyncQueueProcessPageEntries(QueuePosition *current,
+ QueuePosition stop,
+ char *page_buffer)
+{
+ bool reachedStop = false;
+ bool reachedEndOfPage;
+ AsyncQueueEntry *qe;
+
+ do
+ {
+ if (QUEUE_POS_EQUAL(*current, stop))
+ break;
+
+ qe = (AsyncQueueEntry *) (page_buffer + QUEUE_POS_OFFSET(*current));
+
+ /*
+ * Advance *current over this message, possibly to the next page.
+ * As noted in the comments for asyncQueueReadAllNotifications, we
+ * must do this before possibly failing while processing the message.
+ */
+ reachedEndOfPage = asyncQueueAdvance(current, qe->length);
+
+ /* Ignore messages destined for other databases */
+ if (qe->dboid == MyDatabaseId)
+ {
+ if (TransactionIdDidCommit(qe->xid))
+ {
+ /* qe->data is the null-terminated channel name */
+ char *channel = qe->data;
+
+ if (IsListeningOn(channel))
+ {
+ /* payload follows channel name */
+ char *payload = qe->data + strlen(channel) + 1;
+
+ NotifyMyFrontEnd(channel, payload, qe->srcPid);
+ }
+ }
+ else if (TransactionIdDidAbort(qe->xid))
+ {
+ /*
+ * If the source transaction aborted, we just ignore its
+ * notifications.
+ */
+ }
+ else
+ {
+ /*
+ * The transaction has neither committed nor aborted so far,
+ * so we can't process its message yet. Break out of the loop.
+ */
+ reachedStop = true;
+ break;
+ }
+ }
+
+ /* Loop back if we're not at end of page */
+ } while (!reachedEndOfPage);
+
+ if (QUEUE_POS_EQUAL(*current, stop))
+ reachedStop = true;
+
+ return reachedStop;
+}
+
+/*
+ * Advance the shared queue tail variable to the minimum of all the
+ * per-backend tail pointers. Truncate pg_notify space if possible.
+ */
+static void
+asyncQueueAdvanceTail(void)
+{
+ QueuePosition min;
+ int i;
+ int oldtailpage;
+ int newtailpage;
+ int boundary;
+
+ LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE);
+ min = QUEUE_HEAD;
+ for (i = 1; i <= MaxBackends; i++)
+ {
+ if (QUEUE_BACKEND_PID(i) != InvalidPid)
+ min = QUEUE_POS_MIN(min, QUEUE_BACKEND_POS(i));
+ }
+ oldtailpage = QUEUE_POS_PAGE(QUEUE_TAIL);
+ QUEUE_TAIL = min;
+ LWLockRelease(AsyncQueueLock);
+
+ /*
+ * We can truncate something if the global tail advanced across an SLRU
+ * segment boundary.
+ *
+ * XXX it might be better to truncate only once every several segments,
+ * to reduce the number of directory scans.
+ */
+ newtailpage = QUEUE_POS_PAGE(min);
+ boundary = newtailpage - (newtailpage % SLRU_PAGES_PER_SEGMENT);
+ if (asyncQueuePagePrecedesLogically(oldtailpage, boundary))
+ {
+ /*
+ * SimpleLruTruncate() will ask for AsyncCtlLock but will also
+ * release the lock again.
+ */
+ SimpleLruTruncate(AsyncCtl, newtailpage);
+ }
+}
+
/*
* ProcessIncomingNotify
*
* Deal with arriving NOTIFYs from other backends.
* This is called either directly from the PROCSIG_NOTIFY_INTERRUPT
* signal handler, or the next time control reaches the outer idle loop.
- * Scan pg_listener for arriving notifies, report them to my front end,
- * and clear the notification field in pg_listener until next time.
+ * Scan the queue for arriving notifications and report them to my front
+ * end.
*
* NOTE: since we are outside any transaction, we must create our own.
*/
static void
ProcessIncomingNotify(void)
{
- Relation lRel;
- TupleDesc tdesc;
- ScanKeyData key[1];
- HeapScanDesc scan;
- HeapTuple lTuple,
- rTuple;
- Datum value[Natts_pg_listener];
- bool repl[Natts_pg_listener],
- nulls[Natts_pg_listener];
bool catchup_enabled;
+ /* Do nothing if we aren't actively listening */
+ if (listenChannels == NIL)
+ return;
+
/* Must prevent catchup interrupt while I am running */
catchup_enabled = DisableCatchupInterrupt();
@@ -974,62 +2088,13 @@ ProcessIncomingNotify(void)
notifyInterruptOccurred = 0;
- StartTransactionCommand();
-
- lRel = heap_open(ListenerRelationId, ExclusiveLock);
- tdesc = RelationGetDescr(lRel);
-
- /* Scan only entries with my listenerPID */
- ScanKeyInit(&key[0],
- Anum_pg_listener_listenerpid,
- BTEqualStrategyNumber, F_INT4EQ,
- Int32GetDatum(MyProcPid));
- scan = heap_beginscan(lRel, SnapshotNow, 1, key);
-
- /* Prepare data for rewriting 0 into notification field */
- memset(nulls, false, sizeof(nulls));
- memset(repl, false, sizeof(repl));
- repl[Anum_pg_listener_notification - 1] = true;
- memset(value, 0, sizeof(value));
- value[Anum_pg_listener_notification - 1] = Int32GetDatum(0);
-
- while ((lTuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
- {
- Form_pg_listener listener = (Form_pg_listener) GETSTRUCT(lTuple);
- char *relname = NameStr(listener->relname);
- int32 sourcePID = listener->notification;
-
- if (sourcePID != 0)
- {
- /* Notify the frontend */
-
- if (Trace_notify)
- elog(DEBUG1, "ProcessIncomingNotify: received %s from %d",
- relname, (int) sourcePID);
-
- NotifyMyFrontEnd(relname, sourcePID);
-
- /*
- * Rewrite the tuple with 0 in notification column.
- */
- rTuple = heap_modify_tuple(lTuple, tdesc, value, nulls, repl);
- simple_heap_update(lRel, &lTuple->t_self, rTuple);
-
-#ifdef NOT_USED /* currently there are no indexes */
- CatalogUpdateIndexes(lRel, rTuple);
-#endif
- }
- }
- heap_endscan(scan);
-
/*
- * We do NOT release the lock on pg_listener here; we need to hold it
- * until end of transaction (which is about to happen, anyway) to ensure
- * that other backends see our tuple updates when they look. Otherwise, a
- * transaction started after this one might mistakenly think it doesn't
- * need to send this backend a new NOTIFY.
+ * We must run asyncQueueReadAllNotifications inside a transaction,
+ * else bad things happen if it gets an error.
*/
- heap_close(lRel, NoLock);
+ StartTransactionCommand();
+
+ asyncQueueReadAllNotifications();
CommitTransactionCommand();
@@ -1051,20 +2116,17 @@ ProcessIncomingNotify(void)
* Send NOTIFY message to my front end.
*/
static void
-NotifyMyFrontEnd(char *relname, int32 listenerPID)
+NotifyMyFrontEnd(const char *channel, const char *payload, int32 srcPid)
{
if (whereToSendOutput == DestRemote)
{
StringInfoData buf;
pq_beginmessage(&buf, 'A');
- pq_sendint(&buf, listenerPID, sizeof(int32));
- pq_sendstring(&buf, relname);
+ pq_sendint(&buf, srcPid, sizeof(int32));
+ pq_sendstring(&buf, channel);
if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
- {
- /* XXX Add parameter string here later */
- pq_sendstring(&buf, "");
- }
+ pq_sendstring(&buf, payload);
pq_endmessage(&buf);
/*
@@ -1074,20 +2136,51 @@ NotifyMyFrontEnd(char *relname, int32 listenerPID)
*/
}
else
- elog(INFO, "NOTIFY for %s", relname);
+ elog(INFO, "NOTIFY for \"%s\" payload \"%s\"", channel, payload);
}
-/* Does pendingNotifies include the given relname? */
+/* Does pendingNotifies include the given channel/payload? */
static bool
-AsyncExistsPendingNotify(const char *relname)
+AsyncExistsPendingNotify(const char *channel, const char *payload)
{
ListCell *p;
+ Notification *n;
+
+ if (pendingNotifies == NIL)
+ return false;
+
+ if (payload == NULL)
+ payload = "";
+
+ /*----------
+ * We need to append new elements to the end of the list in order to keep
+ * the order. However, on the other hand we'd like to check the list
+ * backwards in order to make duplicate-elimination a tad faster when the
+ * same condition is signaled many times in a row. So as a compromise we
+ * check the tail element first which we can access directly. If this
+ * doesn't match, we check the whole list.
+ *
+ * As we are not checking our parents' lists, we can still get duplicates
+ * in combination with subtransactions, like in:
+ *
+ * begin;
+ * notify foo '1';
+ * savepoint foo;
+ * notify foo '1';
+ * commit;
+ *----------
+ */
+ n = (Notification *) llast(pendingNotifies);
+ if (strcmp(n->channel, channel) == 0 &&
+ strcmp(n->payload, payload) == 0)
+ return true;
foreach(p, pendingNotifies)
{
- const char *prelname = (const char *) lfirst(p);
+ n = (Notification *) lfirst(p);
- if (strcmp(prelname, relname) == 0)
+ if (strcmp(n->channel, channel) == 0 &&
+ strcmp(n->payload, payload) == 0)
return true;
}
@@ -1108,21 +2201,3 @@ ClearPendingActionsAndNotifies(void)
pendingActions = NIL;
pendingNotifies = NIL;
}
-
-/*
- * 2PC processing routine for COMMIT PREPARED case.
- *
- * (We don't have to do anything for ROLLBACK PREPARED.)
- */
-void
-notify_twophase_postcommit(TransactionId xid, uint16 info,
- void *recdata, uint32 len)
-{
- /*
- * Set up to issue the NOTIFY at the end of my own current transaction.
- * (XXX this has some issues if my own transaction later rolls back, or if
- * there is any significant delay before I commit. OK for now because we
- * disallow COMMIT PREPARED inside a transaction block.)
- */
- Async_Notify((char *) recdata);
-}
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 271a7a2129b826d2c88f4ac04db7dc94c140bc61..371d1f245eb4a3a7a8a3ea4ffe182c5629e8909a 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.461 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.462 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2777,6 +2777,7 @@ _copyNotifyStmt(NotifyStmt *from)
NotifyStmt *newnode = makeNode(NotifyStmt);
COPY_STRING_FIELD(conditionname);
+ COPY_STRING_FIELD(payload);
return newnode;
}
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 001c2096b4e5f33dee7c02e7e4b1effb6ce3807b..7dfc1969f5da87184b358046c4d9c36c964447eb 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -22,7 +22,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1325,6 +1325,7 @@ static bool
_equalNotifyStmt(NotifyStmt *a, NotifyStmt *b)
{
COMPARE_STRING_FIELD(conditionname);
+ COMPARE_STRING_FIELD(payload);
return true;
}
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 593fe397d3f18d23285cc050c3ae1c9da644a169..878e4b3b94c550c8b00d75769401d084c0df1bbc 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.382 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.383 2010/02/16 22:34:43 tgl Exp $
*
* NOTES
* Every node type that can appear in stored rules' parsetrees *must*
@@ -1820,6 +1820,7 @@ _outNotifyStmt(StringInfo str, NotifyStmt *node)
WRITE_NODE_TYPE("NOTIFY");
WRITE_STRING_FIELD(conditionname);
+ WRITE_STRING_FIELD(payload);
}
static void
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 35ba22203fe85da1acd6b7cd0a5654c267e3d7ae..f28191d2d00a1b12b69be87bce9824d6ec792e2f 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.231 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.232 2010/02/16 22:34:43 tgl Exp $
*
* NOTES
* Path and Plan nodes do not have any readfuncs support, because we
@@ -231,6 +231,7 @@ _readNotifyStmt(void)
READ_LOCALS(NotifyStmt);
READ_STRING_FIELD(conditionname);
+ READ_STRING_FIELD(payload);
READ_DONE();
}
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index da70ee089c5cdad99f74a1cb6246ec501982d12f..235a7001adf3b240f6de6445bbf8c026b0211bc9 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.708 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.709 2010/02/16 22:34:49 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -400,7 +400,7 @@ static TypeName *TableFuncTypeName(List *columns);
%type <ival> Iconst SignedIconst
%type <list> Iconst_list
-%type <str> Sconst comment_text
+%type <str> Sconst comment_text notify_payload
%type <str> RoleId opt_granted_by opt_boolean ColId_or_Sconst
%type <list> var_list
%type <str> ColId ColLabel var_name type_function_name param_name
@@ -6123,14 +6123,20 @@ DropRuleStmt:
*
*****************************************************************************/
-NotifyStmt: NOTIFY ColId
+NotifyStmt: NOTIFY ColId notify_payload
{
NotifyStmt *n = makeNode(NotifyStmt);
n->conditionname = $2;
+ n->payload = $3;
$$ = (Node *)n;
}
;
+notify_payload:
+ ',' Sconst { $$ = $2; }
+ | /*EMPTY*/ { $$ = NULL; }
+ ;
+
ListenStmt: LISTEN ColId
{
ListenStmt *n = makeNode(ListenStmt);
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 01a9fabc8c9eddf00ebedf23f46cafd41e1feeed..b4923d278a71230e856b270a867b11964989c327 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.103 2010/01/15 09:19:03 heikki Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.104 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -20,6 +20,7 @@
#include "access/nbtree.h"
#include "access/subtrans.h"
#include "access/twophase.h"
+#include "commands/async.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
@@ -122,6 +123,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
size = add_size(size, WalRcvShmemSize());
size = add_size(size, BTreeShmemSize());
size = add_size(size, SyncScanShmemSize());
+ size = add_size(size, AsyncShmemSize());
#ifdef EXEC_BACKEND
size = add_size(size, ShmemBackendArraySize());
#endif
@@ -225,6 +227,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
*/
BTreeShmemInit();
SyncScanShmemInit();
+ AsyncShmemInit();
#ifdef EXEC_BACKEND
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 4e635d1e8aa0590e85abc3a2e334e8c2045e5672..7a6cab968bbad60e85d386d6c60045d1fef72476 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.55 2010/01/02 16:57:52 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/lmgr/lwlock.c,v 1.56 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -24,6 +24,7 @@
#include "access/clog.h"
#include "access/multixact.h"
#include "access/subtrans.h"
+#include "commands/async.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "storage/ipc.h"
@@ -174,6 +175,9 @@ NumLWLocks(void)
/* multixact.c needs two SLRU areas */
numLocks += NUM_MXACTOFFSET_BUFFERS + NUM_MXACTMEMBER_BUFFERS;
+ /* async.c needs one per Async buffer */
+ numLocks += NUM_ASYNC_BUFFERS;
+
/*
* Add any requested by loadable modules; for backwards-compatibility
* reasons, allocate at least NUM_USER_DEFINED_LWLOCKS of them even if
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 15d0808ad24b9f20eb560362975d96f906313513..2ae15d5ce029714188dd4a9411aadb74f65f6b65 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.589 2010/02/16 20:15:14 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.590 2010/02/16 22:34:50 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@@ -3779,7 +3779,8 @@ PostgresMain(int argc, char *argv[], const char *username)
* collector, and to update the PS stats display. We avoid doing
* those every time through the message loop because it'd slow down
* processing of batched messages, and because we don't want to report
- * uncommitted updates (that confuses autovacuum).
+ * uncommitted updates (that confuses autovacuum). The notification
+ * processor wants a call too, if we are not in a transaction block.
*/
if (send_ready_for_query)
{
@@ -3795,6 +3796,7 @@ PostgresMain(int argc, char *argv[], const char *username)
}
else
{
+ ProcessCompletedNotifies();
pgstat_report_stat(false);
set_ps_display("idle", false);
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 4879970632a000113567a6426fbba6b38814ba32..07f4d0c57adb23f3bfc843ef6561ac2dc8b140be 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.332 2010/02/14 18:42:15 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.333 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -926,17 +926,17 @@ standard_ProcessUtility(Node *parsetree,
case T_NotifyStmt:
{
NotifyStmt *stmt = (NotifyStmt *) parsetree;
- PreventCommandDuringRecovery();
- Async_Notify(stmt->conditionname);
+ PreventCommandDuringRecovery();
+ Async_Notify(stmt->conditionname, stmt->payload);
}
break;
case T_ListenStmt:
{
ListenStmt *stmt = (ListenStmt *) parsetree;
- PreventCommandDuringRecovery();
+ PreventCommandDuringRecovery();
CheckRestrictedOperation("LISTEN");
Async_Listen(stmt->conditionname);
}
@@ -945,8 +945,8 @@ standard_ProcessUtility(Node *parsetree,
case T_UnlistenStmt:
{
UnlistenStmt *stmt = (UnlistenStmt *) parsetree;
- PreventCommandDuringRecovery();
+ PreventCommandDuringRecovery();
CheckRestrictedOperation("UNLISTEN");
if (stmt->conditionname)
Async_Unlisten(stmt->conditionname);
@@ -1105,8 +1105,8 @@ standard_ProcessUtility(Node *parsetree,
case T_ReindexStmt:
{
ReindexStmt *stmt = (ReindexStmt *) parsetree;
- PreventCommandDuringRecovery();
+ PreventCommandDuringRecovery();
switch (stmt->kind)
{
case OBJECT_INDEX:
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index b2127a3129a0dbd94181d9b5f2e32a3a615dc74d..294c7c904bb56efd439fc16b5016991be3ef4ab0 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.322 2010/02/14 18:42:16 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.323 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -3465,6 +3465,11 @@ get_utility_query_def(Query *query, deparse_context *context)
0, PRETTYINDENT_STD, 1);
appendStringInfo(buf, "NOTIFY %s",
quote_identifier(stmt->conditionname));
+ if (stmt->payload)
+ {
+ appendStringInfoString(buf, ", ");
+ simple_quote_literal(buf, stmt->payload);
+ }
}
else
{
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 06df8f6af8d4c5248e05f3359e19fd3c0d6dbe87..733d8ef74d2088f8d7b04c68d224a11a493b9ed0 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -42,7 +42,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
* Portions taken from FreeBSD.
*
- * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.184 2010/01/26 16:18:12 tgl Exp $
+ * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.185 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2458,6 +2458,7 @@ main(int argc, char *argv[])
"pg_xlog",
"pg_xlog/archive_status",
"pg_clog",
+ "pg_notify",
"pg_subtrans",
"pg_twophase",
"pg_multixact/members",
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 8422bb76ab5885195cc2aa109e21bd549898ef6c..9661f0cd803ea4c40e971994495762db95109c87 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2010, PostgreSQL Global Development Group
*
- * $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.143 2010/01/02 16:57:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.144 2010/02/16 22:34:50 tgl Exp $
*/
#include "postgres_fe.h"
#include "common.h"
@@ -555,8 +555,13 @@ PrintNotifications(void)
while ((notify = PQnotifies(pset.db)))
{
- fprintf(pset.queryFout, _("Asynchronous notification \"%s\" received from server process with PID %d.\n"),
- notify->relname, notify->be_pid);
+ /* for backward compatibility, only show payload if nonempty */
+ if (notify->extra[0])
+ fprintf(pset.queryFout, _("Asynchronous notification \"%s\" with payload \"%s\" received from server process with PID %d.\n"),
+ notify->relname, notify->extra, notify->be_pid);
+ else
+ fprintf(pset.queryFout, _("Asynchronous notification \"%s\" received from server process with PID %d.\n"),
+ notify->relname, notify->be_pid);
fflush(pset.queryFout);
PQfreemem(notify);
}
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 19b9b1f3ef5b82f81bb69a2a423fc23d8eba859e..0b10472c12e2fa76e8df10dde751e0c3db6acb2b 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2010, PostgreSQL Global Development Group
*
- * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.193 2010/02/15 02:55:01 itagaki Exp $
+ * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.194 2010/02/16 22:34:50 tgl Exp $
*/
/*----------------------------------------------------------------------
@@ -1864,7 +1864,7 @@ psql_completion(char *text, int start, int end)
/* NOTIFY */
else if (pg_strcasecmp(prev_wd, "NOTIFY") == 0)
- COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s'");
+ COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(channel) FROM pg_catalog.pg_listening_channels() AS channel WHERE substring(pg_catalog.quote_ident(channel),1,%d)='%s'");
/* OPTIONS */
else if (pg_strcasecmp(prev_wd, "OPTIONS") == 0)
@@ -2105,7 +2105,7 @@ psql_completion(char *text, int start, int end)
/* UNLISTEN */
else if (pg_strcasecmp(prev_wd, "UNLISTEN") == 0)
- COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(relname) FROM pg_catalog.pg_listener WHERE substring(pg_catalog.quote_ident(relname),1,%d)='%s' UNION SELECT '*'");
+ COMPLETE_WITH_QUERY("SELECT pg_catalog.quote_ident(channel) FROM pg_catalog.pg_listening_channels() AS channel WHERE substring(pg_catalog.quote_ident(channel),1,%d)='%s' UNION SELECT '*'");
/* UPDATE */
/* If prev. word is UPDATE suggest a list of tables */
diff --git a/src/include/access/slru.h b/src/include/access/slru.h
index 8e820ae72dd09c054e228e10d8b490c0b4b3abbb..4cc40ba5f7087153773ea75cd1db8168212e7cbe 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.25 2010/01/02 16:58:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.26 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -17,6 +17,25 @@
#include "storage/lwlock.h"
+/*
+ * Define SLRU segment size. A page is the same BLCKSZ as is used everywhere
+ * else in Postgres. The segment size can be chosen somewhat arbitrarily;
+ * we make it 32 pages by default, or 256Kb, i.e. 1M transactions for CLOG
+ * or 64K transactions for SUBTRANS.
+ *
+ * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF,
+ * page numbering also wraps around at 0xFFFFFFFF/xxxx_XACTS_PER_PAGE (where
+ * xxxx is CLOG or SUBTRANS, respectively), and segment numbering at
+ * 0xFFFFFFFF/xxxx_XACTS_PER_PAGE/SLRU_PAGES_PER_SEGMENT. We need
+ * take no explicit notice of that fact in slru.c, except when comparing
+ * segment and page numbers in SimpleLruTruncate (see PagePrecedes()).
+ *
+ * Note: slru.c currently assumes that segment file names will be four hex
+ * digits. This sets a lower bound on the segment size (64K transactions
+ * for 32-bit TransactionIds).
+ */
+#define SLRU_PAGES_PER_SEGMENT 32
+
/*
* Page status codes. Note that these do not include the "dirty" bit.
* page_dirty can be TRUE only in the VALID or WRITE_IN_PROGRESS states;
@@ -55,8 +74,8 @@ typedef struct SlruSharedData
/*
* Optional array of WAL flush LSNs associated with entries in the SLRU
* pages. If not zero/NULL, we must flush WAL before writing pages (true
- * for pg_clog, false for multixact and pg_subtrans). group_lsn[] has
- * lsn_groups_per_page entries per buffer slot, each containing the
+ * for pg_clog, false for multixact, pg_subtrans, pg_notify). group_lsn[]
+ * has lsn_groups_per_page entries per buffer slot, each containing the
* highest LSN known for a contiguous group of SLRU entries on that slot's
* page.
*/
@@ -94,7 +113,7 @@ typedef struct SlruCtlData
/*
* This flag tells whether to fsync writes (true for pg_clog and multixact
- * stuff, false for pg_subtrans).
+ * stuff, false for pg_subtrans and pg_notify).
*/
bool do_fsync;
diff --git a/src/include/access/twophase_rmgr.h b/src/include/access/twophase_rmgr.h
index a42d77452055fc2a285c4770acf11ab3526f079f..1d4d1cb2217b5d84910db92cbdec43cb0f43f772 100644
--- a/src/include/access/twophase_rmgr.h
+++ b/src/include/access/twophase_rmgr.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.11 2010/01/02 16:58:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/twophase_rmgr.h,v 1.12 2010/02/16 22:34:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -23,9 +23,8 @@ typedef uint8 TwoPhaseRmgrId;
*/
#define TWOPHASE_RM_END_ID 0
#define TWOPHASE_RM_LOCK_ID 1
-#define TWOPHASE_RM_NOTIFY_ID 2
-#define TWOPHASE_RM_PGSTAT_ID 3
-#define TWOPHASE_RM_MULTIXACT_ID 4
+#define TWOPHASE_RM_PGSTAT_ID 2
+#define TWOPHASE_RM_MULTIXACT_ID 3
#define TWOPHASE_RM_MAX_ID TWOPHASE_RM_MULTIXACT_ID
extern const TwoPhaseCallback twophase_recover_callbacks[];
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 9a1d19380c7f45ed9451928f34995b54fb6c7782..2d63232b9b587404bccf75f5d18de8fce5ee50a2 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.584 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.585 2010/02/16 22:34:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -53,6 +53,6 @@
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 201002121
+#define CATALOG_VERSION_NO 201002161
#endif
diff --git a/src/include/catalog/pg_listener.h b/src/include/catalog/pg_listener.h
deleted file mode 100644
index 4d1a77d6602c0dbbee3d40122e1c9b8a7946be94..0000000000000000000000000000000000000000
--- a/src/include/catalog/pg_listener.h
+++ /dev/null
@@ -1,59 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * pg_listener.h
- * Asynchronous notification
- *
- *
- * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * $PostgreSQL: pgsql/src/include/catalog/pg_listener.h,v 1.28 2010/01/05 01:06:56 tgl Exp $
- *
- * NOTES
- * the genbki.pl script reads this file and generates .bki
- * information from the DATA() statements.
- *
- *-------------------------------------------------------------------------
- */
-#ifndef PG_LISTENER_H
-#define PG_LISTENER_H
-
-#include "catalog/genbki.h"
-
-/* ----------------------------------------------------------------
- * pg_listener definition.
- *
- * cpp turns this into typedef struct FormData_pg_listener
- * ----------------------------------------------------------------
- */
-#define ListenerRelationId 2614
-
-CATALOG(pg_listener,2614) BKI_WITHOUT_OIDS
-{
- NameData relname;
- int4 listenerpid;
- int4 notification;
-} FormData_pg_listener;
-
-/* ----------------
- * Form_pg_listener corresponds to a pointer to a tuple with
- * the format of pg_listener relation.
- * ----------------
- */
-typedef FormData_pg_listener *Form_pg_listener;
-
-/* ----------------
- * compiler constants for pg_listener
- * ----------------
- */
-#define Natts_pg_listener 3
-#define Anum_pg_listener_relname 1
-#define Anum_pg_listener_listenerpid 2
-#define Anum_pg_listener_notification 3
-
-/* ----------------
- * initial contents of pg_listener are NOTHING.
- * ----------------
- */
-
-#endif /* PG_LISTENER_H */
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 727b13e264ced924765b807de73f3bda6c9f4c61..1c87a94a0de0a7b8f9562d122ed1daedd0ad5080 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.568 2010/02/07 20:48:11 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.569 2010/02/16 22:34:56 tgl Exp $
*
* NOTES
* The script catalog/genbki.pl reads this file and generates .bki
@@ -4131,8 +4131,12 @@ DATA(insert OID = 2599 ( pg_timezone_abbrevs PGNSP PGUID 12 1 1000 0 f f f t t
DESCR("get the available time zone abbreviations");
DATA(insert OID = 2856 ( pg_timezone_names PGNSP PGUID 12 1 1000 0 f f f t t s 0 0 2249 "" "{25,25,1186,16}" "{o,o,o,o}" "{name,abbrev,utc_offset,is_dst}" _null_ pg_timezone_names _null_ _null_ _null_ ));
DESCR("get the available time zone names");
-DATA(insert OID = 2730 ( pg_get_triggerdef PGNSP PGUID 12 1 0 0 f f f t f s 2 0 25 "26 16" _null_ _null_ _null_ _null_ pg_get_triggerdef_ext _null_ _null_ _null_ ));
+DATA(insert OID = 2730 ( pg_get_triggerdef PGNSP PGUID 12 1 0 0 f f f t f s 2 0 25 "26 16" _null_ _null_ _null_ _null_ pg_get_triggerdef_ext _null_ _null_ _null_ ));
DESCR("trigger description with pretty-print option");
+DATA(insert OID = 3035 ( pg_listening_channels PGNSP PGUID 12 1 10 0 f f f t t s 0 0 25 "" _null_ _null_ _null_ _null_ pg_listening_channels _null_ _null_ _null_ ));
+DESCR("get the channels that the current backend listens to");
+DATA(insert OID = 3036 ( pg_notify PGNSP PGUID 12 1 0 0 f f f f f v 2 0 2278 "25 25" _null_ _null_ _null_ _null_ pg_notify _null_ _null_ _null_ ));
+DESCR("send a notification event");
/* non-persistent series generator */
DATA(insert OID = 1066 ( generate_series PGNSP PGUID 12 1 1000 0 f f f t t i 3 0 23 "23 23 23" _null_ _null_ _null_ _null_ generate_series_step_int4 _null_ _null_ _null_ ));
diff --git a/src/include/commands/async.h b/src/include/commands/async.h
index 5c9e8ab8906bc023a3f00888e221ed9576412a13..a9e4d42853d4f051287c938864c5fa0270a672cd 100644
--- a/src/include/commands/async.h
+++ b/src/include/commands/async.h
@@ -6,28 +6,44 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/commands/async.h,v 1.39 2010/01/02 16:58:03 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/commands/async.h,v 1.40 2010/02/16 22:34:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef ASYNC_H
#define ASYNC_H
+#include "fmgr.h"
+
+/*
+ * The number of SLRU page buffers we use for the notification queue.
+ */
+#define NUM_ASYNC_BUFFERS 8
+
extern bool Trace_notify;
+extern Size AsyncShmemSize(void);
+extern void AsyncShmemInit(void);
+
/* notify-related SQL statements */
-extern void Async_Notify(const char *relname);
-extern void Async_Listen(const char *relname);
-extern void Async_Unlisten(const char *relname);
+extern void Async_Notify(const char *channel, const char *payload);
+extern void Async_Listen(const char *channel);
+extern void Async_Unlisten(const char *channel);
extern void Async_UnlistenAll(void);
+/* notify-related SQL functions */
+extern Datum pg_listening_channels(PG_FUNCTION_ARGS);
+extern Datum pg_notify(PG_FUNCTION_ARGS);
+
/* perform (or cancel) outbound notify processing at transaction commit */
+extern void PreCommit_Notify(void);
extern void AtCommit_Notify(void);
extern void AtAbort_Notify(void);
extern void AtSubStart_Notify(void);
extern void AtSubCommit_Notify(void);
extern void AtSubAbort_Notify(void);
extern void AtPrepare_Notify(void);
+extern void ProcessCompletedNotifies(void);
/* signal handler for inbound notifies (PROCSIG_NOTIFY_INTERRUPT) */
extern void HandleNotifyInterrupt(void);
@@ -40,7 +56,4 @@ extern void HandleNotifyInterrupt(void);
extern void EnableNotifyInterrupt(void);
extern bool DisableNotifyInterrupt(void);
-extern void notify_twophase_postcommit(TransactionId xid, uint16 info,
- void *recdata, uint32 len);
-
#endif /* ASYNC_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 0c3aecfa6e636f122e06140b4a9dbef39dd9ee94..ca229c8e23d79155a58dfb079f7a8438963e0d50 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -13,7 +13,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.429 2010/02/12 17:33:20 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.430 2010/02/16 22:34:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2097,6 +2097,7 @@ typedef struct NotifyStmt
{
NodeTag type;
char *conditionname; /* condition name to notify */
+ char *payload; /* the payload string, or NULL if none */
} NotifyStmt;
/* ----------------------
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
index f0beb20a24b87cba9fe3406e417980e9f163eb29..2ace9585009c06e1a469fc127d2ae91bb279f271 100644
--- a/src/include/storage/lwlock.h
+++ b/src/include/storage/lwlock.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.44 2010/02/07 20:48:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/storage/lwlock.h,v 1.45 2010/02/16 22:34:57 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -68,6 +68,8 @@ typedef enum LWLockId
AutovacuumScheduleLock,
SyncScanLock,
RelationMappingLock,
+ AsyncCtlLock,
+ AsyncQueueLock,
/* Individual lock IDs end here */
FirstBufMappingLock,
FirstLockMgrLock = FirstBufMappingLock + NUM_BUFFER_PARTITIONS,
diff --git a/src/test/regress/expected/guc.out b/src/test/regress/expected/guc.out
index 83cacbdd2092b197b213552974e9578c0e1157c3..59c120c99a3b90079970a86a5acbf738b1735f7f 100644
--- a/src/test/regress/expected/guc.out
+++ b/src/test/regress/expected/guc.out
@@ -532,9 +532,9 @@ CREATE TEMP TABLE tmp_foo (data text) ON COMMIT DELETE ROWS;
CREATE ROLE temp_reset_user;
SET SESSION AUTHORIZATION temp_reset_user;
-- look changes
-SELECT relname FROM pg_listener;
- relname
------------
+SELECT pg_listening_channels();
+ pg_listening_channels
+-----------------------
foo_event
(1 row)
@@ -571,9 +571,9 @@ SELECT current_user = 'temp_reset_user';
-- discard everything
DISCARD ALL;
-- look again
-SELECT relname FROM pg_listener;
- relname
----------
+SELECT pg_listening_channels();
+ pg_listening_channels
+-----------------------
(0 rows)
SELECT name FROM pg_prepared_statements;
diff --git a/src/test/regress/expected/sanity_check.out b/src/test/regress/expected/sanity_check.out
index 4dc59d9b5def23c6031a1a983d9a0b94bf69d232..1d9e11004489b35ec9e791d28c323eb814262f0b 100644
--- a/src/test/regress/expected/sanity_check.out
+++ b/src/test/regress/expected/sanity_check.out
@@ -107,7 +107,6 @@ SELECT relname, relhasindex
pg_language | t
pg_largeobject | t
pg_largeobject_metadata | t
- pg_listener | f
pg_namespace | t
pg_opclass | t
pg_operator | t
@@ -154,7 +153,7 @@ SELECT relname, relhasindex
timetz_tbl | f
tinterval_tbl | f
varchar_tbl | f
-(143 rows)
+(142 rows)
--
-- another sanity check: every system catalog that has OIDs should have
diff --git a/src/test/regress/sql/guc.sql b/src/test/regress/sql/guc.sql
index a7b795af47d6660c405093b5a61d42808ee054b9..21ed86f26ba259e7258e6b69afa8f8e80e2a2442 100644
--- a/src/test/regress/sql/guc.sql
+++ b/src/test/regress/sql/guc.sql
@@ -165,7 +165,7 @@ CREATE TEMP TABLE tmp_foo (data text) ON COMMIT DELETE ROWS;
CREATE ROLE temp_reset_user;
SET SESSION AUTHORIZATION temp_reset_user;
-- look changes
-SELECT relname FROM pg_listener;
+SELECT pg_listening_channels();
SELECT name FROM pg_prepared_statements;
SELECT name FROM pg_cursors;
SHOW vacuum_cost_delay;
@@ -174,7 +174,7 @@ SELECT current_user = 'temp_reset_user';
-- discard everything
DISCARD ALL;
-- look again
-SELECT relname FROM pg_listener;
+SELECT pg_listening_channels();
SELECT name FROM pg_prepared_statements;
SELECT name FROM pg_cursors;
SHOW vacuum_cost_delay;