[BP] MB-25798: Log when DcpProducer::Buffer log is full

Log when unable to notify a paused connection because the BufferLog is
full.  And log when space becomes available in the BufferLog allowing a
paused connection to be notified.

Also log when ignoring a request to notify that a stream is ready due
to the associated vbucket already being in the ready queue.

Change-Id: I75f2d25af5d0f11175beb7b23300486092aa86fa
Reviewed-on: http://review.couchbase.org/83521
Well-Formed: Build Bot <[email protected]>
Tested-by: Build Bot <[email protected]>
Reviewed-by: Dave Rigby <[email protected]>

Author: manudhundi

src/dcp/producer.cc

@@ -81,7 +81,16 @@ bool DcpProducer::BufferLog::pauseIfFull() {
 
 void DcpProducer::BufferLog::unpauseIfSpaceAvailable() {
     ReaderLockHolder rlh(logLock);
-    if (getState_UNLOCKED() != Full) {
+    if (getState_UNLOCKED() == Full) {
+        LOG(EXTENSION_LOG_NOTICE, "%s Unable to notify paused connection "
+                    "because DcpProducer::BufferLog is full; "
+                    "ackedBytes:%" PRIu64 ", bytesSent:%" PRIu64 ", "
+                    "maxBytes:%" PRIu64 ,
+                    producer.logHeader(),
+                    uint64_t(ackedBytes),
+                    uint64_t(bytesSent),
+                    uint64_t(maxBytes));
+    } else {
         producer.notifyPaused(true);
     }
 }
@@ -93,6 +102,14 @@ void DcpProducer::BufferLog::acknowledge(size_t bytes) {
         release_UNLOCKED(bytes);
         ackedBytes += bytes;
         if (state == Full) {
+            LOG(EXTENSION_LOG_NOTICE, "%s Notifying paused connection now that "
+                "DcpProducer::Bufferlog is no longer full; "
+                "ackedBytes:%" PRIu64 ", bytesSent:%" PRIu64 ", "
+                "maxBytes:%" PRIu64 ,
+                producer.logHeader(),
+                uint64_t(ackedBytes),
+                uint64_t(bytesSent),
+                uint64_t(maxBytes));
             producer.notifyPaused(true);
         }
     }