MB-39745: Remove BGFetcher::notifyBGEvent

It's always called after adding a pending BG fetch so combine the two
functions

Change-Id: Iaa60c9c263de46ccb95e8667979c085fb27e14a8
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/137409
Tested-by: Build Bot <[email protected]>
Reviewed-by: Dave Rigby <[email protected]>

Author: BenHuddleston

engines/ep/src/bgfetcher.cc

@@ -56,7 +56,11 @@ void BgFetcher::stop() {
     ExecutorPool::get()->cancel(taskId);
 }
 
-void BgFetcher::notifyBGEvent() {
+void BgFetcher::addPendingVB(Vbid vbid) {
+    { // Scope for queueMutex
+        LockHolder lh(queueMutex);
+        pendingVbs.insert(vbid);
+    }
     ++stats.numRemainingBgItems;
     wakeUpTaskIfSnoozed();
 }

engines/ep/src/bgfetcher.h

@@ -58,12 +58,12 @@ class BgFetcher {
     void start();
     void stop();
     bool run(GlobalTask *task);
-    void notifyBGEvent();
     void setTaskId(size_t newId) { taskId = newId; }
-    void addPendingVB(Vbid vbId) {
-        LockHolder lh(queueMutex);
-        pendingVbs.insert(vbId);
-    }
+
+    /**
+     * Add a Vbid to pendingVbs and notify the task if necessary
+     */
+    void addPendingVB(Vbid vbId);
 
 private:
     size_t doFetch(Vbid vbId, vb_bgfetch_queue_t& items);

engines/ep/src/ep_vb.cc

@@ -753,9 +753,6 @@ void EPVBucket::bgFetch(const DocKey& key,
             key,
             std::make_unique<FrontEndBGFetchItem>(cookie, isMeta),
             getShard()->getBgFetcher());
-    if (getShard()) {
-        getShard()->getBgFetcher()->notifyBGEvent();
-    }
     EP_LOG_DEBUG("Queued a background fetch, now at {}",
                  uint64_t(bgfetch_size));
 }
@@ -789,8 +786,6 @@ void EPVBucket::bgFetchForCompactionExpiry(const DocKey& key,
             queueBGFetchItem(key,
                              std::make_unique<CompactionBGFetchItem>(item),
                              shard->getBgFetcher());
-    shard->getBgFetcher()->notifyBGEvent();
-
     EP_LOG_DEBUG("Queue a background fetch for compaction expiry, now at {}",
                  bgFetchSize);
 }