Introduce backfill_phase_started into master activity events.

Helps with,
MB-30803: Collect rebalance related stats

Part of EPIC,
MB-30894: Rebalance visibility and reporting

Change-Id: If529691a76b0e5b130d81214255f45a3ecd53563
Reviewed-on: http://review.couchbase.org/101819
Reviewed-by: Aliaksey Artamonau <[email protected]>
Tested-by: Abhijeeth Nuthan <[email protected]>

Author: anuthan

src/master_activity_events.erl

@@ -40,6 +40,7 @@
          note_seqno_waiting_ended/4,
          note_takeover_started/4,
          note_takeover_ended/4,
+         note_backfill_phase_started/2,
          note_backfill_phase_ended/2,
          note_wait_index_updated_started/3,
          note_wait_index_updated_ended/3,
@@ -163,6 +164,9 @@ note_takeover_started(BucketName, VBucket, OldMaster, NewMaster) ->
 note_takeover_ended(BucketName, VBucket, OldMaster, NewMaster) ->
     submit_cast({takeover_ended, BucketName, VBucket, OldMaster, NewMaster}).
 
+note_backfill_phase_started(BucketName, VBucket) ->
+    submit_cast({backfill_phase_started, BucketName, VBucket}).
+
 note_backfill_phase_ended(BucketName, VBucket) ->
     submit_cast({backfill_phase_ended, BucketName, VBucket}).
 
@@ -550,6 +554,12 @@ event_to_jsons({TS, indexing_initated, BucketName, Node, VBucket}) ->
                                   {bucket, BucketName},
                                   {vbucket, VBucket}])];
 
+event_to_jsons({TS, backfill_phase_started, BucketName, VBucket}) ->
+    [format_simple_plist_as_json([{type, backfillPhaseStarted},
+                                  {ts, misc:time_to_epoch_float(TS)},
+                                  {bucket, BucketName},
+                                  {vbucket, VBucket}])];
+
 event_to_jsons({TS, backfill_phase_ended, BucketName, VBucket}) ->
     [format_simple_plist_as_json([{type, backfillPhaseEnded},
                                   {ts, misc:time_to_epoch_float(TS)},

src/ns_single_vbucket_mover.erl

@@ -177,6 +177,7 @@ mover_inner_dcp(Parent, Bucket, VBucket,
     %% ep-engine guarantees that it can support indexing
     maybe_initiate_indexing(Bucket, Parent, JustBackfillNodes, ReplicaNodes, VBucket, IndexAware),
 
+    master_activity_events:note_backfill_phase_started(Bucket, VBucket),
     %% wait for backfill on all the opened streams
     AllBuiltNodes = JustBackfillNodes ++ ReplicaNodes,
     wait_dcp_data_move(Bucket, Parent, OldMaster, AllBuiltNodes, VBucket),