mvcc: HashKV gets keep from kvindex.Keep

mvcc/kvstore.go

@@ -45,8 +45,6 @@ var (
 	ErrClosed    = errors.New("mvcc: closed")
 
 	plog = capnslog.NewPackageLogger("github.com/coreos/etcd", "mvcc")
-
-	emptyKeep = make(map[revision]struct{})
 )
 
 const (
@@ -101,12 +99,6 @@ type store struct {
 	fifoSched schedule.Scheduler
 
 	stopc chan struct{}
-
-	// keepMu protects keep
-	keepMu sync.RWMutex
-	// keep contains all revisions <= compactMainRev to be kept for the
-	// ongoing compaction; nil otherwise.
-	keep map[revision]struct{}
 }
 
 // NewStore returns a new store. It is useful to create a store inside
@@ -170,33 +162,25 @@ func (s *store) Hash() (hash uint32, revision int64, err error) {
 }
 
 func (s *store) HashByRev(rev int64) (hash uint32, currentRev int64, compactRev int64, err error) {
-	s.mu.Lock()
+	s.mu.RLock()
 	s.revMu.RLock()
 	compactRev, currentRev = s.compactMainRev, s.currentRev
 	s.revMu.RUnlock()
 
 	if rev > 0 && rev <= compactRev {
-		s.mu.Unlock()
+		s.mu.RUnlock()
 		return 0, 0, compactRev, ErrCompacted
 	} else if rev > 0 && rev > currentRev {
-		s.mu.Unlock()
+		s.mu.RUnlock()
 		return 0, currentRev, 0, ErrFutureRev
 	}
 
-	s.keepMu.Lock()
+	keep := s.kvindex.Keep(rev)
-	if s.keep == nil {
-		// ForceCommit ensures that txnRead begins after backend
-		// has committed all the changes from the prev completed compaction.
-		s.b.ForceCommit()
-		s.keep = emptyKeep
-	}
-	keep := s.keep
-	s.keepMu.Unlock()
 
 	tx := s.b.ReadTx()
 	tx.Lock()
 	defer tx.Unlock()
-	s.mu.Unlock()
+	s.mu.RUnlock()
 
 	if rev == 0 {
 		rev = currentRev
@@ -257,9 +241,6 @@ func (s *store) Compact(rev int64) (<-chan struct{}, error) {
 	s.b.ForceCommit()
 
 	keep := s.kvindex.Compact(rev)
-	s.keepMu.Lock()
-	s.keep = keep
-	s.keepMu.Unlock()
 	ch := make(chan struct{})
 	var j = func(ctx context.Context) {
 		if ctx.Err() != nil {
@@ -271,9 +252,6 @@ func (s *store) Compact(rev int64) (<-chan struct{}, error) {
 			return
 		}
 		close(ch)
-		s.keepMu.Lock()
-		s.keep = nil
-		s.keepMu.Unlock()
 	}
 
 	s.fifoSched.Schedule(j)