Re: [HACKERS] Duplicated assignment of slot_name in walsender.c

[Alvaro Herrera]

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/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers