server: Return error from scheduleCompaction

Signed-off-by: Marek Siarkowicz <siarkowicz@google.com>

server/mvcc/kvstore.go

@@ -236,7 +236,8 @@ func (s *store) compact(trace *traceutil.Trace, rev int64) (<-chan struct{}, err
 		start := time.Now()
 		keep := s.kvindex.Compact(rev)
 		indexCompactionPauseMs.Observe(float64(time.Since(start) / time.Millisecond))
-		if !s.scheduleCompaction(rev, keep) {
+		if err := s.scheduleCompaction(rev, keep); err != nil {
+			s.lg.Warn("Failed compaction", zap.Error(err))
 			s.compactBarrier(context.TODO(), ch)
 			return
 		}

server/mvcc/kvstore_compaction.go

@@ -16,13 +16,14 @@ package mvcc
 
 import (
 	"encoding/binary"
+	"fmt"
 	"time"
 
 	"go.etcd.io/etcd/server/v3/mvcc/buckets"
 	"go.uber.org/zap"
 )
 
-func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struct{}) bool {
+func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struct{}) error {
 	totalStart := time.Now()
 	defer func() { dbCompactionTotalMs.Observe(float64(time.Since(totalStart) / time.Millisecond)) }()
 	keyCompactions := 0
@@ -59,7 +60,7 @@ func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struc
 				zap.Int64("compact-revision", compactMainRev),
 				zap.Duration("took", time.Since(totalStart)),
 			)
-			return true
+			return nil
 		}
 
 		// update last
@@ -72,7 +73,7 @@ func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struc
 		select {
 		case <-time.After(10 * time.Millisecond):
 		case <-s.stopc:
-			return false
+			return fmt.Errorf("interrupted due to stop signal")
 		}
 	}
 }

server/mvcc/kvstore_compaction_test.go

@@ -79,7 +79,10 @@ func TestScheduleCompaction(t *testing.T) {
 		}
 		tx.Unlock()
 
-		s.scheduleCompaction(tt.rev, tt.keep)
+		err := s.scheduleCompaction(tt.rev, tt.keep)
+		if err != nil {
+			t.Fatal(err)
+		}
 
 		tx.Lock()
 		for _, rev := range tt.wrevs {