Add write batch function

src/dbnode/persist/fs/commitlog/commit_log.go

@@ -388,6 +388,7 @@ func (l *commitLog) flushEvery(interval time.Duration) {
 }
 
 func (l *commitLog) write() {
+outer:
 	for write := range l.writes {
 		if write.eventType == flushEventType {
 			l.writerState.writer.Flush(false)
@@ -456,7 +457,7 @@ func (l *commitLog) write() {
 					l.commitLogFailFn(err)
 				}
 
-				continue
+				break outer
 			}
 		}
 		l.metrics.success.Inc(1)
@@ -548,6 +549,13 @@ func (l *commitLog) Write(
 	})
 }
 
+func (l *commitLog) WriteBatch(
+	ctx context.Context,
+	writes WritesBatch,
+) error {
+	return l.writeFn(ctx, writes)
+}
+
 func (l *commitLog) writeWait(
 	ctx context.Context,
 	writes WritesBatch,

src/dbnode/persist/fs/commitlog/types.go

@@ -62,6 +62,12 @@ type CommitLog interface {
 		annotation ts.Annotation,
 	) error
 
+	// Write does the same thing as Write, but in batches.
+	WriteBatch(
+		ctx context.Context,
+		writes WritesBatch,
+	) error
+
 	// Close the commit log
 	Close() error