Fix integer overflow in debug message of walreceiver

The message tries to tell the replication apply delay which fails if
the first WAL record is not applied yet. Fix is, instead of telling
overflowed minus numeric, showing "N/A" which indicates that the delay
data is not yet available. Problem reported by me and patch by
Fabrízio de Royes Mello.

Back patched to 9.4, 9.3 and 9.2 stable branches (9.1 and 9.0 do not
have the debug message).

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 62d642ad5ec60acc473277055c1aec2bc61d961d..96ac6a6a602eaa3a87351b3a7f22dfe6b242f815 100644 (file)
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -1199,15 +1199,26 @@ ProcessWalSndrMessage(XLogRecPtr walEnd, TimestampTz sendTime)
    {
        char       *sendtime;
        char       *receipttime;
+       int         applyDelay;
 
        /* Copy because timestamptz_to_str returns a static buffer */
        sendtime = pstrdup(timestamptz_to_str(sendTime));
        receipttime = pstrdup(timestamptz_to_str(lastMsgReceiptTime));
-       elog(DEBUG2, "sendtime %s receipttime %s replication apply delay %d ms transfer latency %d ms",
-            sendtime,
-            receipttime,
-            GetReplicationApplyDelay(),
-            GetReplicationTransferLatency());
+       applyDelay = GetReplicationApplyDelay();
+
+       /* apply delay is not available */
+       if (applyDelay == -1)
+           elog(DEBUG2, "sendtime %s receipttime %s replication apply delay (N/A) transfer latency %d ms",
+                sendtime,
+                receipttime,
+                GetReplicationTransferLatency());
+       else
+           elog(DEBUG2, "sendtime %s receipttime %s replication apply delay %d ms transfer latency %d ms",
+                sendtime,
+                receipttime,
+                applyDelay,
+                GetReplicationTransferLatency());
+
        pfree(sendtime);
        pfree(receipttime);
    }

diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c
index 9870d9cf894f7fa2fa405610b8670b2c5c9e79f2..9e16c20dbb2a042b215d66570586196f5cb174c4 100644 (file)
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -307,7 +307,8 @@ GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI)
 }
 
 /*
- * Returns the replication apply delay in ms
+ * Returns the replication apply delay in ms or -1
+ * if the apply delay info is not available
  */
 int
 GetReplicationApplyDelay(void)
@@ -321,6 +322,8 @@ GetReplicationApplyDelay(void)
    long        secs;
    int         usecs;
 
+   TimestampTz chunckReplayStartTime;
+
    SpinLockAcquire(&walrcv->mutex);
    receivePtr = walrcv->receivedUpto;
    SpinLockRelease(&walrcv->mutex);
@@ -330,7 +333,12 @@ GetReplicationApplyDelay(void)
    if (receivePtr == replayPtr)
        return 0;
 
-   TimestampDifference(GetCurrentChunkReplayStartTime(),
+   chunckReplayStartTime = GetCurrentChunkReplayStartTime();
+
+   if (chunckReplayStartTime == 0)
+       return -1;
+
+   TimestampDifference(chunckReplayStartTime,
                        GetCurrentTimestamp(),
                        &secs, &usecs);