mvcc: add "etcd_mvcc_hash_(rev)_duration_seconds"

etcd_mvcc_hash_duration_seconds
etcd_mvcc_hash_rev_duration_seconds

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

mvcc/kvstore.go

@@ -163,12 +163,18 @@ func (s *store) compactBarrier(ctx context.Context, ch chan struct{}) {
 }
 
 func (s *store) Hash() (hash uint32, revision int64, err error) {
+	start := time.Now()
+
 	s.b.ForceCommit()
 	h, err := s.b.Hash(DefaultIgnores)
+
+	hashDurations.Observe(time.Since(start).Seconds())
 	return h, s.currentRev, err
 }
 
 func (s *store) HashByRev(rev int64) (hash uint32, currentRev int64, compactRev int64, err error) {
+	start := time.Now()
+
 	s.mu.RLock()
 	s.revMu.RLock()
 	compactRev, currentRev = s.compactMainRev, s.currentRev
@@ -213,7 +219,10 @@ func (s *store) HashByRev(rev int64) (hash uint32, currentRev int64, compactRev
 		h.Write(v)
 		return nil
 	})
-	return h.Sum32(), currentRev, compactRev, err
+	hash = h.Sum32()
+
+	hashRevDurations.Observe(time.Since(start).Seconds())
+	return hash, currentRev, compactRev, err
 }
 
 func (s *store) Compact(rev int64) (<-chan struct{}, error) {

mvcc/metrics.go

@@ -170,6 +170,30 @@ var (
 	// overridden by mvcc initialization
 	reportDbTotalSizeInUseInBytesMu sync.RWMutex
 	reportDbTotalSizeInUseInBytes   func() float64 = func() float64 { return 0 }
+
+	hashDurations = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd",
+		Subsystem: "mvcc",
+		Name:      "hash_duration_seconds",
+		Help:      "The latency distribution of storage hash operation.",
+
+		// 100 MB usually takes 100 ms, so start with 10 MB of 10 ms
+		// lowest bucket start of upper bound 0.01 sec (10 ms) with factor 2
+		// highest bucket start of 0.01 sec * 2^14 == 163.84 sec
+		Buckets: prometheus.ExponentialBuckets(.01, 2, 15),
+	})
+
+	hashRevDurations = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Namespace: "etcd",
+		Subsystem: "mvcc",
+		Name:      "hash_rev_duration_seconds",
+		Help:      "The latency distribution of storage hash by revision operation.",
+
+		// 100 MB usually takes 100 ms, so start with 10 MB of 10 ms
+		// lowest bucket start of upper bound 0.01 sec (10 ms) with factor 2
+		// highest bucket start of 0.01 sec * 2^14 == 163.84 sec
+		Buckets: prometheus.ExponentialBuckets(.01, 2, 15),
+	})
 )
 
 func init() {
@@ -189,6 +213,8 @@ func init() {
 	prometheus.MustRegister(dbCompactionKeysCounter)
 	prometheus.MustRegister(dbTotalSize)
 	prometheus.MustRegister(dbTotalSizeInUse)
+	prometheus.MustRegister(hashDurations)
+	prometheus.MustRegister(hashRevDurations)
 }
 
 // ReportEventReceived reports that an event is received.