From 48f8eadffb0a0c6274d0f9d58d5f73166c1f2fc5 Mon Sep 17 00:00:00 2001
From: Neil Conway <neilc@samurai.com>
Date: Wed, 11 May 2005 01:41:41 +0000
Subject: [PATCH] This patch reduces the size of the message header used by
statistics collector messages, per recent discussion on pgsql-patches. This
actually required quite a few changes -- for example, "databaseid !=
InvalidOid" was used to check whether a slot in the backend entry table was
initialized, but that no longer works since the slot might be initialized
prior to receiving the BESTART message which contains the database id. We now
use procpid > 0 to indicate that a slot is non-empty.
Other changes:
- various comment improvements and cleanups
- there's no need to zero-out the entire activity buffer in
pgstat_add_backend(), we can just set activity[0] to '\0'.
- remove the counting of the # of connections to a database; this
was not used anywhere
One change in behavior I wasn't sure about: previously, the code
would create a hash table entry for a database as soon as any message
was received whose header referenced that database. Now, we only
create hash table entries as needed (so for example BESTART won't
create a database hash table entry, since it doesn't need to
access anything in the per-db hash table). It would be easy enough
to retain the old behavior, but AFAICS it is not required.
---
src/backend/postmaster/pgstat.c | 187 ++++++++++++++--------------
src/backend/utils/adt/pgstatfuncs.c | 20 ++-
src/include/pgstat.h | 29 +++--
3 files changed, 129 insertions(+), 107 deletions(-)
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index a2196373191..3d2244b0d81 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2005, PostgreSQL Global Development Group
*
- * $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.93 2005/05/09 11:31:33 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.94 2005/05/11 01:41:40 neilc Exp $
* ----------
*/
#include "postgres.h"
@@ -162,6 +162,7 @@ static void pgstat_exit(SIGNAL_ARGS);
static void pgstat_die(SIGNAL_ARGS);
static void pgstat_beshutdown_hook(int code, Datum arg);
+static PgStat_StatDBEntry *pgstat_get_db_entry(int databaseid);
static int pgstat_add_backend(PgStat_MsgHdr *msg);
static void pgstat_sub_backend(int procpid);
static void pgstat_drop_database(Oid databaseid);
@@ -653,6 +654,9 @@ pgstat_bestart(void)
return;
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_BESTART);
+ msg.m_databaseid = MyDatabaseId;
+ msg.m_userid = GetSessionUserId();
+ memcpy(&msg.m_clientaddr, &MyProcPort->raddr, sizeof(msg.m_clientaddr));
pgstat_send(&msg, sizeof(msg));
/*
@@ -748,6 +752,7 @@ pgstat_report_tabstat(void)
pgStatXactRollback = 0;
pgstat_setheader(&tsmsg->m_hdr, PGSTAT_MTYPE_TABSTAT);
+ tsmsg->m_databaseid = MyDatabaseId;
pgstat_send(tsmsg, len);
}
@@ -825,7 +830,7 @@ pgstat_vacuum_tabstat(void)
}
/*
- * Add this tables Oid to the message
+ * Add this table's Oid to the message
*/
msg.m_tableid[msg.m_nentries++] = tabentry->tableid;
nobjects++;
@@ -854,6 +859,7 @@ pgstat_vacuum_tabstat(void)
+msg.m_nentries * sizeof(Oid);
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
+ msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, len);
}
@@ -933,9 +939,8 @@ pgstat_drop_database(Oid databaseid)
if (pgStatSock < 0)
return;
- msg.m_databaseid = databaseid;
-
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DROPDB);
+ msg.m_databaseid = databaseid;
pgstat_send(&msg, sizeof(msg));
}
@@ -960,6 +965,7 @@ pgstat_reset_counters(void)
errmsg("must be superuser to reset statistics counters")));
pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETCOUNTER);
+ msg.m_databaseid = MyDatabaseId;
pgstat_send(&msg, sizeof(msg));
}
@@ -1176,8 +1182,6 @@ pgstat_count_xact_rollback(void)
PgStat_StatDBEntry *
pgstat_fetch_stat_dbentry(Oid dbid)
{
- PgStat_StatDBEntry *dbentry;
-
/*
* If not done for this transaction, read the statistics collector
* stats file into some hash tables.
@@ -1185,15 +1189,11 @@ pgstat_fetch_stat_dbentry(Oid dbid)
backend_read_statsfile();
/*
- * Lookup the requested database
+ * Lookup the requested database; return NULL if not found
*/
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &dbid,
- HASH_FIND, NULL);
- if (dbentry == NULL)
- return NULL;
-
- return dbentry;
+ return (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
+ (void *) &dbid,
+ HASH_FIND, NULL);
}
@@ -1298,9 +1298,6 @@ pgstat_setheader(PgStat_MsgHdr *hdr, int mtype)
hdr->m_type = mtype;
hdr->m_backendid = MyBackendId;
hdr->m_procpid = MyProcPid;
- hdr->m_databaseid = MyDatabaseId;
- hdr->m_userid = GetSessionUserId();
- memcpy(&hdr->m_clientaddr, &MyProcPort->raddr, sizeof(hdr->m_clientaddr));
}
@@ -1976,10 +1973,8 @@ pgstat_die(SIGNAL_ARGS)
static int
pgstat_add_backend(PgStat_MsgHdr *msg)
{
- PgStat_StatDBEntry *dbentry;
PgStat_StatBeEntry *beentry;
PgStat_StatBeDead *deadbe;
- bool found;
/*
* Check that the backend ID is valid
@@ -1995,19 +1990,19 @@ pgstat_add_backend(PgStat_MsgHdr *msg)
* Get the slot for this backendid.
*/
beentry = &pgStatBeTable[msg->m_backendid - 1];
- if (beentry->databaseid != InvalidOid)
- {
- /*
- * If the slot contains the PID of this backend, everything is
- * fine and we got nothing to do.
- */
- if (beentry->procpid == msg->m_procpid)
- return 0;
- }
+
+ /*
+ * If the slot contains the PID of this backend, everything is
+ * fine and we have nothing to do. Note that all the slots are
+ * zero'd out when the collector is started. We assume that a slot
+ * is "empty" iff procpid == 0.
+ */
+ if (beentry->procpid > 0 && beentry->procpid == msg->m_procpid)
+ return 0;
/*
* Lookup if this backend is known to be dead. This can be caused due
- * to messages arriving in the wrong order - i.e. Postmaster's BETERM
+ * to messages arriving in the wrong order - e.g. postmaster's BETERM
* message might have arrived before we received all the backends
* stats messages, or even a new backend with the same backendid was
* faster in sending his BESTART.
@@ -2024,65 +2019,78 @@ pgstat_add_backend(PgStat_MsgHdr *msg)
* Backend isn't known to be dead. If it's slot is currently used, we
* have to kick out the old backend.
*/
- if (beentry->databaseid != InvalidOid)
+ if (beentry->procpid > 0)
pgstat_sub_backend(beentry->procpid);
- /*
- * Put this new backend into the slot.
- */
- beentry->databaseid = msg->m_databaseid;
+ /* Must be able to distinguish between empty and non-empty slots */
+ Assert(msg->m_procpid > 0);
+
+ /* Put this new backend into the slot */
beentry->procpid = msg->m_procpid;
- beentry->userid = msg->m_userid;
beentry->start_sec =
GetCurrentAbsoluteTimeUsec(&beentry->start_usec);
beentry->activity_start_sec = 0;
beentry->activity_start_usec = 0;
- memcpy(&beentry->clientaddr, &msg->m_clientaddr, sizeof(beentry->clientaddr));
- MemSet(beentry->activity, 0, PGSTAT_ACTIVITY_SIZE);
+ beentry->activity[0] = '\0';
/*
- * Lookup or create the database entry for this backend's DB.
+ * We can't initialize the rest of the data in this slot until we
+ * see the BESTART message. Therefore, we set the database and
+ * user to sentinel values, to indicate "undefined". There is no
+ * easy way to do this for the client address, so make sure to
+ * check that the database or user are defined before accessing
+ * the client address.
*/
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &(msg->m_databaseid),
- HASH_ENTER, &found);
- if (dbentry == NULL)
+ beentry->userid = InvalidOid;
+ beentry->databaseid = InvalidOid;
+
+ return 0;
+}
+
+/*
+ * Lookup the hash table entry for the specified database. If no hash
+ * table entry exists, initialize it.
+ */
+static PgStat_StatDBEntry *
+pgstat_get_db_entry(int databaseid)
+{
+ PgStat_StatDBEntry *result;
+ bool found;
+
+ /* Lookup or create the hash table entry for this database */
+ result = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
+ &databaseid,
+ HASH_ENTER, &found);
+ if (result == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
- errmsg("out of memory in statistics collector --- abort")));
+ errmsg("out of memory in statistics collector --- abort")));
- /*
- * If not found, initialize the new one.
- */
+ /* If not found, initialize the new one. */
if (!found)
{
HASHCTL hash_ctl;
- dbentry->tables = NULL;
- dbentry->n_xact_commit = 0;
- dbentry->n_xact_rollback = 0;
- dbentry->n_blocks_fetched = 0;
- dbentry->n_blocks_hit = 0;
- dbentry->n_connects = 0;
- dbentry->destroy = 0;
+ result->tables = NULL;
+ result->n_xact_commit = 0;
+ result->n_xact_rollback = 0;
+ result->n_blocks_fetched = 0;
+ result->n_blocks_hit = 0;
+ result->destroy = 0;
memset(&hash_ctl, 0, sizeof(hash_ctl));
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
hash_ctl.hash = oid_hash;
- dbentry->tables = hash_create("Per-database table",
+ result->tables = hash_create("Per-database table",
PGSTAT_TAB_HASH_SIZE,
&hash_ctl,
HASH_ELEM | HASH_FUNCTION);
}
- /* Count the number of connects to the database */
- dbentry->n_connects++;
-
- return 0;
+ return result;
}
-
/* ----------
* pgstat_sub_backend() -
*
@@ -2102,8 +2110,7 @@ pgstat_sub_backend(int procpid)
*/
for (i = 0; i < MaxBackends; i++)
{
- if (pgStatBeTable[i].databaseid != InvalidOid &&
- pgStatBeTable[i].procpid == procpid)
+ if (pgStatBeTable[i].procpid == procpid)
{
/*
* That's him. Add an entry to the known to be dead backends.
@@ -2133,7 +2140,7 @@ pgstat_sub_backend(int procpid)
/*
* Declare the backend slot empty.
*/
- pgStatBeTable[i].databaseid = InvalidOid;
+ pgStatBeTable[i].procpid = 0;
return;
}
}
@@ -2263,7 +2270,7 @@ pgstat_write_statsfile(void)
for (i = 0; i < MaxBackends; i++)
{
- if (pgStatBeTable[i].databaseid != InvalidOid)
+ if (pgStatBeTable[i].procpid > 0)
{
fputc('B', fpout);
fwrite(&pgStatBeTable[i], sizeof(PgStat_StatBeEntry), 1, fpout);
@@ -2624,7 +2631,20 @@ backend_read_statsfile(void)
static void
pgstat_recv_bestart(PgStat_MsgBestart *msg, int len)
{
- pgstat_add_backend(&msg->m_hdr);
+ PgStat_StatBeEntry *entry;
+
+ /*
+ * If the backend is known dead, we ignore the message -- we don't
+ * want to update the backend entry's state since this BESTART
+ * message refers to an old, dead backend
+ */
+ if (pgstat_add_backend(&msg->m_hdr) != 0)
+ return;
+
+ entry = &(pgStatBeTable[msg->m_hdr.m_backendid - 1]);
+ entry->userid = msg->m_userid;
+ memcpy(&entry->clientaddr, &msg->m_clientaddr, sizeof(entry->clientaddr));
+ entry->databaseid = msg->m_databaseid;
}
@@ -2690,14 +2710,7 @@ pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len)
if (pgstat_add_backend(&msg->m_hdr) < 0)
return;
- /*
- * Lookup the database in the hashtable.
- */
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &(msg->m_hdr.m_databaseid),
- HASH_FIND, NULL);
- if (!dbentry)
- return;
+ dbentry = pgstat_get_db_entry(msg->m_databaseid);
/*
* If the database is marked for destroy, this is a delayed UDP packet
@@ -2782,14 +2795,7 @@ pgstat_recv_tabpurge(PgStat_MsgTabpurge *msg, int len)
if (pgstat_add_backend(&msg->m_hdr) < 0)
return;
- /*
- * Lookup the database in the hashtable.
- */
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &(msg->m_hdr.m_databaseid),
- HASH_FIND, NULL);
- if (!dbentry)
- return;
+ dbentry = pgstat_get_db_entry(msg->m_databaseid);
/*
* If the database is marked for destroy, this is a delayed UDP packet
@@ -2832,11 +2838,7 @@ pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len)
/*
* Lookup the database in the hashtable.
*/
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &(msg->m_databaseid),
- HASH_FIND, NULL);
- if (!dbentry)
- return;
+ dbentry = pgstat_get_db_entry(msg->m_databaseid);
/*
* Mark the database for destruction.
@@ -2846,9 +2848,9 @@ pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len)
/* ----------
- * pgstat_recv_dropdb() -
+ * pgstat_recv_resetcounter() -
*
- * Arrange for dead database removal
+ * Reset the statistics for the specified database.
* ----------
*/
static void
@@ -2866,15 +2868,11 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
/*
* Lookup the database in the hashtable.
*/
- dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
- (void *) &(msg->m_hdr.m_databaseid),
- HASH_FIND, NULL);
- if (!dbentry)
- return;
+ dbentry = pgstat_get_db_entry(msg->m_databaseid);
/*
- * We simply throw away all the databases table entries by recreating
- * a new hash table for them.
+ * We simply throw away all the database's table entries by
+ * recreating a new hash table for them.
*/
if (dbentry->tables != NULL)
hash_destroy(dbentry->tables);
@@ -2884,7 +2882,6 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
dbentry->n_xact_rollback = 0;
dbentry->n_blocks_fetched = 0;
dbentry->n_blocks_hit = 0;
- dbentry->n_connects = 0;
dbentry->destroy = 0;
memset(&hash_ctl, 0, sizeof(hash_ctl));
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index ae23dbf5d90..90c8ea695bb 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.21 2005/05/09 11:31:33 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.22 2005/05/11 01:41:41 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@@ -283,6 +283,10 @@ pg_stat_get_backend_dbid(PG_FUNCTION_ARGS)
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
PG_RETURN_NULL();
+ /* Not initialized yet? */
+ if (!OidIsValid(beentry->databaseid))
+ PG_RETURN_NULL();
+
PG_RETURN_OID(beentry->databaseid);
}
@@ -298,6 +302,10 @@ pg_stat_get_backend_userid(PG_FUNCTION_ARGS)
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
PG_RETURN_NULL();
+ /* Not initialized yet? */
+ if (!OidIsValid(beentry->userid))
+ PG_RETURN_NULL();
+
PG_RETURN_INT32(beentry->userid);
}
@@ -405,6 +413,10 @@ pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS)
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
PG_RETURN_NULL();
+ /* Not initialized yet? */
+ if (!OidIsValid(beentry->userid))
+ PG_RETURN_NULL();
+
if (!superuser() && beentry->userid != GetUserId())
PG_RETURN_NULL();
@@ -420,7 +432,6 @@ pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS)
}
remote_host[0] = '\0';
-
ret = getnameinfo_all(&beentry->clientaddr.addr, beentry->clientaddr.salen,
remote_host, sizeof(remote_host),
NULL, 0,
@@ -445,6 +456,10 @@ pg_stat_get_backend_client_port(PG_FUNCTION_ARGS)
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
PG_RETURN_NULL();
+ /* Not initialized yet? */
+ if (!OidIsValid(beentry->userid))
+ PG_RETURN_NULL();
+
if (!superuser() && beentry->userid != GetUserId())
PG_RETURN_NULL();
@@ -462,7 +477,6 @@ pg_stat_get_backend_client_port(PG_FUNCTION_ARGS)
}
remote_port[0] = '\0';
-
ret = getnameinfo_all(&beentry->clientaddr.addr,
beentry->clientaddr.salen,
NULL, 0,
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index e38e33536ac..ad1239b985c 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -5,7 +5,7 @@
*
* Copyright (c) 2001-2005, PostgreSQL Global Development Group
*
- * $PostgreSQL: pgsql/src/include/pgstat.h,v 1.28 2005/05/09 11:31:33 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/pgstat.h,v 1.29 2005/05/11 01:41:41 neilc Exp $
* ----------
*/
#ifndef PGSTAT_H
@@ -52,9 +52,6 @@ typedef struct PgStat_MsgHdr
int m_size;
int m_backendid;
int m_procpid;
- Oid m_databaseid;
- AclId m_userid;
- SockAddr m_clientaddr;
} PgStat_MsgHdr;
/* ----------
@@ -102,7 +99,10 @@ typedef struct PgStat_MsgDummy
*/
typedef struct PgStat_MsgBestart
{
- PgStat_MsgHdr m_hdr;
+ PgStat_MsgHdr m_hdr;
+ Oid m_databaseid;
+ AclId m_userid;
+ SockAddr m_clientaddr;
} PgStat_MsgBestart;
/* ----------
@@ -138,6 +138,7 @@ typedef struct PgStat_MsgActivity
typedef struct PgStat_MsgTabstat
{
PgStat_MsgHdr m_hdr;
+ int m_databaseid;
int m_nentries;
int m_xact_commit;
int m_xact_rollback;
@@ -155,6 +156,7 @@ typedef struct PgStat_MsgTabstat
typedef struct PgStat_MsgTabpurge
{
PgStat_MsgHdr m_hdr;
+ Oid m_databaseid;
int m_nentries;
Oid m_tableid[PGSTAT_NUM_TABPURGE];
} PgStat_MsgTabpurge;
@@ -180,6 +182,7 @@ typedef struct PgStat_MsgDropdb
typedef struct PgStat_MsgResetcounter
{
PgStat_MsgHdr m_hdr;
+ Oid m_databaseid;
} PgStat_MsgResetcounter;
@@ -214,7 +217,6 @@ typedef struct PgStat_StatDBEntry
Oid databaseid;
HTAB *tables;
int n_backends;
- PgStat_Counter n_connects;
PgStat_Counter n_xact_commit;
PgStat_Counter n_xact_rollback;
PgStat_Counter n_blocks_fetched;
@@ -229,15 +231,24 @@ typedef struct PgStat_StatDBEntry
*/
typedef struct PgStat_StatBeEntry
{
- Oid databaseid;
- Oid userid;
+ /* An entry is non-empty iff procpid > 0 */
int procpid;
AbsoluteTime start_sec;
int start_usec;
AbsoluteTime activity_start_sec;
int activity_start_usec;
- SockAddr clientaddr;
char activity[PGSTAT_ACTIVITY_SIZE];
+
+ /*
+ * The following fields are initialized by the BESTART message. If
+ * we have received messages from a backend before we have
+ * received its BESTART, these fields will be uninitialized:
+ * userid and databaseid will be InvalidOid, and clientaddr will
+ * be undefined.
+ */
+ Oid userid;
+ Oid databaseid;
+ SockAddr clientaddr;
} PgStat_StatBeEntry;
--
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