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 bfbc02f02ac88704fa1fb9c2625c0a2d0c35277c..9c7710f0dbd3025bb05a973011f8aff0c6ba05e0 100644 (file)
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -1191,15 +1191,26 @@ 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 496605ff84f3d1964b26fd541e37365046f638a1..b26f5fcf63721aa2e8fdc7a95284fbbe42d901c4 100644 (file)
--- a/src/backend/replication/walreceiverfuncs.c
+++ b/src/backend/replication/walreceiverfuncs.c
@@ -314,7 +314,8 @@ 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)
@@ -328,6 +329,8 @@ GetReplicationApplyDelay(void)
    long        secs;
    int         usecs;
 
+   TimestampTz chunckReplayStartTime;
+
    SpinLockAcquire(&walrcv->mutex);
    receivePtr = walrcv->receivedUpto;
    SpinLockRelease(&walrcv->mutex);
@@ -337,7 +340,12 @@ GetReplicationApplyDelay(void)
    if (receivePtr == replayPtr)
        return 0;
 
-   TimestampDifference(GetCurrentChunkReplayStartTime(),
+   chunckReplayStartTime = GetCurrentChunkReplayStartTime();
+
+   if (chunckReplayStartTime == 0)
+       return -1;
+
+   TimestampDifference(chunckReplayStartTime,
                        GetCurrentTimestamp(),
                        &secs, &usecs);