Re: Duplicated assignment of slot_name in walsender.c

Andres Freund wrote:

> That seems fairly insignificant. For one this is a rather infrequent and
> expensive operation, for another every decent compiler can optimize
> those away. Note that those duplicate strlen() calls are there in a lot
> of places in walsender.c

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index c6043cd..5487cc0 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -762,10 +762,10 @@ 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;
+ int len;

Assert(!MyReplicationSlot);

@@ -791,14 +791,11 @@ 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 +831,6 @@ 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);
@@ -885,18 +881,21 @@ 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); /* col2 len */
+ pq_sendbytes(&buf, xpos, len);

/* snapshot name */
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); /* col3 len */
+ pq_sendbytes(&buf, snapshot_name, len);
}
else
pq_sendint(&buf, -1, 4); /* col3 len, NULL */
@@ -904,8 +903,9 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
/* plugin */
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); /* col4 len */
+ pq_sendbytes(&buf, cmd->plugin, len);
}
else
pq_sendint(&buf, -1, 4); /* col4 len, NULL */

--
Álvaro Herrera http://www.2ndQuadrant.com/
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