From 0cd836a4e818f049716e47fe81bf5d4800509c57 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Tue, 27 Oct 2015 13:20:40 -0300
Subject: [PATCH] Measure string lengths only once
Bernd Helmle complained that CreateReplicationSlot() was assigning the
same value to the same variable twice, so we could remove one of them.
Code inspection reveals that we can actually remove both assignments:
according to the author the assignment was there for beauty of the
strlen line only, and another possible fix to that is to put the strlen
in its own line, so do that.
To be consistent within the file, refactor all duplicated strlen()
calls, which is what we do elsewhere in the backend anyway. In
basebackup.c, snprintf already returns the right length; no need for
strlen afterwards.
Backpatch to 9.4, where replication slots were introduced, to keep code
identical. Some of this is older, but the patch doesn't apply cleanly
and it's only of cosmetic value anyway.
Discussion: http://www.postgresql.org/message-id/BE2FD71DEA35A2287EA5F018@eje.credativ.lan
---
src/backend/replication/basebackup.c | 30 ++++++----
src/backend/replication/walsender.c | 85 +++++++++++++++++-----------
2 files changed, 70 insertions(+), 45 deletions(-)
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 1e86e4c57b6..1af011ee6e0 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -698,10 +698,15 @@ SendBackupHeader(List *tablespaces)
}
else
{
- pq_sendint(&buf, strlen(ti->oid), 4); /* length */
- pq_sendbytes(&buf, ti->oid, strlen(ti->oid));
- pq_sendint(&buf, strlen(ti->path), 4); /* length */
- pq_sendbytes(&buf, ti->path, strlen(ti->path));
+ Size len;
+
+ len = strlen(ti->oid);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, ti->oid, len);
+
+ len = strlen(ti->path);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, ti->path, len);
}
if (ti->size >= 0)
send_int8_string(&buf, ti->size / 1024);
@@ -724,6 +729,7 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
{
StringInfoData buf;
char str[MAXFNAMELEN];
+ Size len;
pq_beginmessage(&buf, 'T'); /* RowDescription */
pq_sendint(&buf, 2, 2); /* 2 fields */
@@ -742,7 +748,7 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
pq_sendint(&buf, 0, 2); /* attnum */
/*
- * int8 may seem like a surprising data type for this, but in thory int4
+ * int8 may seem like a surprising data type for this, but in theory int4
* would not be wide enough for this, as TimeLineID is unsigned.
*/
pq_sendint(&buf, INT8OID, 4); /* type oid */
@@ -755,13 +761,15 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
pq_beginmessage(&buf, 'D');
pq_sendint(&buf, 2, 2); /* number of columns */
- snprintf(str, sizeof(str), "%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
- pq_sendint(&buf, strlen(str), 4); /* length */
- pq_sendbytes(&buf, str, strlen(str));
+ len = snprintf(str, sizeof(str),
+ "%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, str, len);
+
+ len = snprintf(str, sizeof(str), "%u", tli);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, str, len);
- snprintf(str, sizeof(str), "%u", tli);
- pq_sendint(&buf, strlen(str), 4); /* length */
- pq_sendbytes(&buf, str, strlen(str));
pq_endmessage(&buf);
/* Send a CommandComplete message */
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index c6043cd3ce4..4a4643ef2f2 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -299,6 +299,7 @@ IdentifySystem(void)
char xpos[MAXFNAMELEN];
XLogRecPtr logptr;
char *dbname = NULL;
+ Size len;
/*
* Reply with a result set with one row, four columns. First col is system
@@ -380,21 +381,32 @@ IdentifySystem(void)
/* Send a DataRow message */
pq_beginmessage(&buf, 'D');
pq_sendint(&buf, 4, 2); /* # of columns */
- pq_sendint(&buf, strlen(sysid), 4); /* col1 len */
- pq_sendbytes(&buf, (char *) &sysid, strlen(sysid));
- pq_sendint(&buf, strlen(tli), 4); /* col2 len */
- pq_sendbytes(&buf, (char *) tli, strlen(tli));
- pq_sendint(&buf, strlen(xpos), 4); /* col3 len */
- pq_sendbytes(&buf, (char *) xpos, strlen(xpos));
- /* send NULL if not connected to a database */
+
+ /* column 1: system identifier */
+ len = strlen(sysid);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, (char *) &sysid, len);
+
+ /* column 2: timeline */
+ len = strlen(tli);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, (char *) tli, len);
+
+ /* column 3: xlog position */
+ len = strlen(xpos);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, (char *) xpos, len);
+
+ /* column 4: database name, or NULL if none */
if (dbname)
{
- pq_sendint(&buf, strlen(dbname), 4); /* col4 len */
- pq_sendbytes(&buf, (char *) dbname, strlen(dbname));
+ len = strlen(dbname);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, (char *) dbname, len);
}
else
{
- pq_sendint(&buf, -1, 4); /* col4 len, NULL */
+ pq_sendint(&buf, -1, 4);
}
pq_endmessage(&buf);
@@ -413,6 +425,7 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
int fd;
off_t histfilelen;
off_t bytesleft;
+ Size len;
/*
* Reply with a result set with one row, and two columns. The first col is
@@ -448,8 +461,9 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
/* Send a DataRow message */
pq_beginmessage(&buf, 'D');
pq_sendint(&buf, 2, 2); /* # of columns */
- pq_sendint(&buf, strlen(histfname), 4); /* col1 len */
- pq_sendbytes(&buf, histfname, strlen(histfname));
+ len = strlen(histfname);
+ pq_sendint(&buf, len, 4); /* col1 len */
+ pq_sendbytes(&buf, histfname, len);
fd = OpenTransientFile(path, O_RDONLY | PG_BINARY, 0666);
if (fd < 0)
@@ -674,6 +688,7 @@ StartReplication(StartReplicationCmd *cmd)
{
char tli_str[11];
char startpos_str[8 + 1 + 8 + 1];
+ Size len;
snprintf(tli_str, sizeof(tli_str), "%u", sendTimeLineNextTLI);
snprintf(startpos_str, sizeof(startpos_str), "%X/%X",
@@ -710,11 +725,13 @@ StartReplication(StartReplicationCmd *cmd)
pq_beginmessage(&buf, 'D');
pq_sendint(&buf, 2, 2); /* number of columns */
- pq_sendint(&buf, strlen(tli_str), 4); /* length */
- pq_sendbytes(&buf, tli_str, strlen(tli_str));
+ len = strlen(tli_str);
+ pq_sendint(&buf, len, 4); /* length */
+ pq_sendbytes(&buf, tli_str, len);
- pq_sendint(&buf, strlen(startpos_str), 4); /* length */
- pq_sendbytes(&buf, startpos_str, strlen(startpos_str));
+ len = strlen(startpos_str);
+ pq_sendint(&buf, len, 4); /* length */
+ pq_sendbytes(&buf, startpos_str, len);
pq_endmessage(&buf);
}
@@ -762,10 +779,10 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
static void
CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
- const char *slot_name;
const char *snapshot_name = NULL;
char xpos[MAXFNAMELEN];
StringInfoData buf;
+ Size len;
Assert(!MyReplicationSlot);
@@ -791,14 +808,11 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
initStringInfo(&output_message);
- slot_name = NameStr(MyReplicationSlot->data.name);
-
if (cmd->kind == REPLICATION_KIND_LOGICAL)
{
LogicalDecodingContext *ctx;
- ctx = CreateInitDecodingContext(
- cmd->plugin, NIL,
+ ctx = CreateInitDecodingContext(cmd->plugin, NIL,
logical_read_xlog_page,
WalSndPrepareWrite, WalSndWriteData);
@@ -834,7 +848,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
ReplicationSlotSave();
}
- slot_name = NameStr(MyReplicationSlot->data.name);
snprintf(xpos, sizeof(xpos), "%X/%X",
(uint32) (MyReplicationSlot->data.confirmed_flush >> 32),
(uint32) MyReplicationSlot->data.confirmed_flush);
@@ -885,30 +898,34 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
pq_sendint(&buf, 4, 2); /* # of columns */
/* slot_name */
- pq_sendint(&buf, strlen(slot_name), 4); /* col1 len */
- pq_sendbytes(&buf, slot_name, strlen(slot_name));
+ len = strlen(NameStr(MyReplicationSlot->data.name));
+ pq_sendint(&buf, len, 4); /* col1 len */
+ pq_sendbytes(&buf, NameStr(MyReplicationSlot->data.name), len);
/* consistent wal location */
- pq_sendint(&buf, strlen(xpos), 4); /* col2 len */
- pq_sendbytes(&buf, xpos, strlen(xpos));
+ len = strlen(xpos);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, xpos, len);
- /* snapshot name */
+ /* snapshot name, or NULL if none */
if (snapshot_name != NULL)
{
- pq_sendint(&buf, strlen(snapshot_name), 4); /* col3 len */
- pq_sendbytes(&buf, snapshot_name, strlen(snapshot_name));
+ len = strlen(snapshot_name);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, snapshot_name, len);
}
else
- pq_sendint(&buf, -1, 4); /* col3 len, NULL */
+ pq_sendint(&buf, -1, 4);
- /* plugin */
+ /* plugin, or NULL if none */
if (cmd->plugin != NULL)
{
- pq_sendint(&buf, strlen(cmd->plugin), 4); /* col4 len */
- pq_sendbytes(&buf, cmd->plugin, strlen(cmd->plugin));
+ len = strlen(cmd->plugin);
+ pq_sendint(&buf, len, 4);
+ pq_sendbytes(&buf, cmd->plugin, len);
}
else
- pq_sendint(&buf, -1, 4); /* col4 len, NULL */
+ pq_sendint(&buf, -1, 4);
pq_endmessage(&buf);
--
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