Merge pull request #880 from prometheus/beorn7/fix

Fix the storage corruption bug.

storage/local/chunk.go

@@ -25,6 +25,7 @@ import (
 	"github.com/prometheus/prometheus/storage/metric"
 )
 
+// The DefaultChunkEncoding can be changed via a flag.
 var DefaultChunkEncoding = doubleDelta
 
 type chunkEncoding byte

storage/local/crashrecovery.go

@@ -254,7 +254,7 @@ func (p *persistence) sanitizeSeries(
 			// disk. Treat this series as a freshly unarchived one
 			// by loading the chunkDescs and setting all parameters
 			// based on the loaded chunkDescs.
-			cds, err := p.loadChunkDescs(fp, clientmodel.Latest)
+			cds, err := p.loadChunkDescs(fp, 0)
 			if err != nil {
 				log.Errorf(
 					"Failed to load chunk descriptors for metric %v, fingerprint %v: %s",
@@ -286,8 +286,7 @@ func (p *persistence) sanitizeSeries(
 		// First, throw away the chunkDescs without chunks.
 		s.chunkDescs = s.chunkDescs[s.persistWatermark:]
 		numMemChunkDescs.Sub(float64(s.persistWatermark))
-		// Load all the chunk descs.
-		cds, err := p.loadChunkDescs(fp, clientmodel.Latest)
+		cds, err := p.loadChunkDescs(fp, 0)
 		if err != nil {
 			log.Errorf(
 				"Failed to load chunk descriptors for metric %v, fingerprint %v: %s",
@@ -407,7 +406,7 @@ func (p *persistence) cleanUpArchiveIndexes(
 		if _, err := p.archivedFingerprintToMetrics.Delete(fp); err != nil {
 			return err
 		}
-		cds, err := p.loadChunkDescs(clientmodel.Fingerprint(fp), clientmodel.Latest)
+		cds, err := p.loadChunkDescs(clientmodel.Fingerprint(fp), 0)
 		if err != nil {
 			return err
 		}

storage/local/index/index.go

@@ -33,6 +33,7 @@ const (
 	labelPairToFingerprintsDir = "labelpair_to_fingerprints"
 )
 
+// LevelDB cache sizes, changeable via flags.
 var (
 	FingerprintMetricCacheSize     = 10 * 1024 * 1024
 	FingerprintTimeRangeCacheSize  = 5 * 1024 * 1024

storage/local/instrumentation.go

@@ -89,6 +89,8 @@ func init() {
 var (
 	// Global counter, also used internally, so not implemented as
 	// metrics. Collected in memorySeriesStorage.Collect.
+	// TODO(beorn7): As it is used internally, it is actually very bad style
+	// to have it as a global variable.
 	numMemChunks int64
 
 	// Metric descriptors for the above.

storage/local/persistence.go

@@ -444,10 +444,11 @@ func (p *persistence) loadChunks(fp clientmodel.Fingerprint, indexes []int, inde
 	return chunks, nil
 }
 
-// loadChunkDescs loads chunkDescs for a series up until a given time.  It is
-// the caller's responsibility to not persist or drop anything for the same
+// loadChunkDescs loads the chunkDescs for a series from disk. offsetFromEnd is
+// the number of chunkDescs to skip from the end of the series file. It is the
+// caller's responsibility to not persist or drop anything for the same
 // fingerprint concurrently.
-func (p *persistence) loadChunkDescs(fp clientmodel.Fingerprint, beforeTime clientmodel.Timestamp) ([]*chunkDesc, error) {
+func (p *persistence) loadChunkDescs(fp clientmodel.Fingerprint, offsetFromEnd int) ([]*chunkDesc, error) {
 	f, err := p.openChunkFileForReading(fp)
 	if os.IsNotExist(err) {
 		return nil, nil
@@ -469,8 +470,8 @@ func (p *persistence) loadChunkDescs(fp clientmodel.Fingerprint, beforeTime clie
 		)
 	}
 
-	numChunks := int(fi.Size()) / chunkLenWithHeader
-	cds := make([]*chunkDesc, 0, numChunks)
+	numChunks := int(fi.Size())/chunkLenWithHeader - offsetFromEnd
+	cds := make([]*chunkDesc, numChunks)
 	chunkTimesBuf := make([]byte, 16)
 	for i := 0; i < numChunks; i++ {
 		_, err := f.Seek(offsetForChunkIndex(i)+chunkHeaderFirstTimeOffset, os.SEEK_SET)
@@ -482,15 +483,10 @@ func (p *persistence) loadChunkDescs(fp clientmodel.Fingerprint, beforeTime clie
 		if err != nil {
 			return nil, err
 		}
-		cd := &chunkDesc{
+		cds[i] = &chunkDesc{
 			chunkFirstTime: clientmodel.Timestamp(binary.LittleEndian.Uint64(chunkTimesBuf)),
 			chunkLastTime:  clientmodel.Timestamp(binary.LittleEndian.Uint64(chunkTimesBuf[8:])),
 		}
-		if !cd.chunkLastTime.Before(beforeTime) {
-			// From here on, we have chunkDescs in memory already.
-			break
-		}
-		cds = append(cds, cd)
 	}
 	chunkDescOps.WithLabelValues(load).Add(float64(len(cds)))
 	numMemChunkDescs.Add(float64(len(cds)))

storage/local/persistence_test.go

@@ -122,7 +122,7 @@ func testPersistLoadDropChunks(t *testing.T, encoding chunkEncoding) {
 			}
 		}
 		// Load all chunk descs.
-		actualChunkDescs, err := p.loadChunkDescs(fp, 10)
+		actualChunkDescs, err := p.loadChunkDescs(fp, 0)
 		if len(actualChunkDescs) != 10 {
 			t.Errorf("Got %d chunkDescs, want %d.", len(actualChunkDescs), 10)
 		}
@@ -974,7 +974,7 @@ func BenchmarkLoadChunkDescs(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		for _, s := range fpStrings {
 			fp.LoadFromString(s)
-			cds, err := p.loadChunkDescs(fp, clientmodel.Latest)
+			cds, err := p.loadChunkDescs(fp, 0)
 			if err != nil {
 				b.Error(err)
 			}

storage/local/series.go

@@ -384,7 +384,7 @@ func (s *memorySeries) preloadChunksForRange(
 		firstChunkDescTime = s.chunkDescs[0].firstTime()
 	}
 	if s.chunkDescsOffset != 0 && from.Before(firstChunkDescTime) {
-		cds, err := mss.loadChunkDescs(fp, firstChunkDescTime)
+		cds, err := mss.loadChunkDescs(fp, s.persistWatermark)
 		if err != nil {
 			return nil, err
 		}

storage/local/storage.go

@@ -589,7 +589,7 @@ func (s *memorySeriesStorage) getOrCreateSeries(fp clientmodel.Fingerprint, m cl
 			// end up with a series without any chunkDescs for a
 			// while (which is confusing as it makes the series
 			// appear as archived or purged).
-			cds, err = s.loadChunkDescs(fp, clientmodel.Latest)
+			cds, err = s.loadChunkDescs(fp, 0)
 			if err != nil {
 				log.Errorf("Error loading chunk descs for fingerprint %v (metric %v): %v", fp, m, err)
 			}
@@ -979,7 +979,7 @@ func (s *memorySeriesStorage) maintainMemorySeries(
 		return
 	}
 	// If we are here, the series is not archived, so check for chunkDesc
-	// eviction next
+	// eviction next.
 	series.evictChunkDescs(iOldestNotEvicted)
 
 	return series.dirty && !seriesWasDirty
@@ -1107,8 +1107,8 @@ func (s *memorySeriesStorage) loadChunks(fp clientmodel.Fingerprint, indexes []i
 }
 
 // See persistence.loadChunkDescs for detailed explanation.
-func (s *memorySeriesStorage) loadChunkDescs(fp clientmodel.Fingerprint, beforeTime clientmodel.Timestamp) ([]*chunkDesc, error) {
-	return s.persistence.loadChunkDescs(fp, beforeTime)
+func (s *memorySeriesStorage) loadChunkDescs(fp clientmodel.Fingerprint, offsetFromEnd int) ([]*chunkDesc, error) {
+	return s.persistence.loadChunkDescs(fp, offsetFromEnd)
 }
 
 // getNumChunksToPersist returns numChunksToPersist in a goroutine-safe way.

storage/local/storage_test.go

@@ -1116,6 +1116,78 @@ func TestEvictAndPurgeSeriesChunkType1(t *testing.T) {
 	testEvictAndPurgeSeries(t, 1)
 }
 
+func testEvictAndLoadChunkDescs(t *testing.T, encoding chunkEncoding) {
+	samples := make(clientmodel.Samples, 10000)
+	for i := range samples {
+		samples[i] = &clientmodel.Sample{
+			Timestamp: clientmodel.Timestamp(2 * i),
+			Value:     clientmodel.SampleValue(float64(i * i)),
+		}
+	}
+	// Give last sample a timestamp of now so that the head chunk will not
+	// be closed (which would then archive the time series later as
+	// everything will get evicted).
+	samples[len(samples)-1] = &clientmodel.Sample{
+		Timestamp: clientmodel.Now(),
+		Value:     clientmodel.SampleValue(3.14),
+	}
+
+	s, closer := NewTestStorage(t, encoding)
+	defer closer.Close()
+
+	// Adjust memory chunks to lower value to see evictions.
+	s.maxMemoryChunks = 1
+
+	for _, sample := range samples {
+		s.Append(sample)
+	}
+	s.WaitForIndexing()
+
+	fp := clientmodel.Metric{}.FastFingerprint()
+
+	series, ok := s.fpToSeries.get(fp)
+	if !ok {
+		t.Fatal("could not find series")
+	}
+
+	oldLen := len(series.chunkDescs)
+	// Maintain series without any dropped chunks.
+	s.maintainMemorySeries(fp, 0)
+	// Give the evict goroutine an opportunity to run.
+	time.Sleep(10 * time.Millisecond)
+	// Maintain series again to trigger chunkDesc eviction
+	s.maintainMemorySeries(fp, 0)
+
+	if oldLen <= len(series.chunkDescs) {
+		t.Errorf("Expected number of chunkDescs to decrease, old number %d, current number %d.", oldLen, len(series.chunkDescs))
+	}
+
+	// Load everything back.
+	p := s.NewPreloader()
+	p.PreloadRange(fp, 0, 100000, time.Hour)
+
+	if oldLen != len(series.chunkDescs) {
+		t.Errorf("Expected number of chunkDescs to have reached old value again, old number %d, current number %d.", oldLen, len(series.chunkDescs))
+	}
+
+	p.Close()
+
+	// Now maintain series with drops to make sure nothing crazy happens.
+	s.maintainMemorySeries(fp, 100000)
+
+	if len(series.chunkDescs) != 1 {
+		t.Errorf("Expected exactly one chunkDesc left, got %d.", len(series.chunkDescs))
+	}
+}
+
+func TestEvictAndLoadChunkDescsType0(t *testing.T) {
+	testEvictAndLoadChunkDescs(t, 0)
+}
+
+func TestEvictAndLoadChunkDescsType1(t *testing.T) {
+	testEvictAndLoadChunkDescs(t, 1)
+}
+
 func benchmarkAppend(b *testing.B, encoding chunkEncoding) {
 	samples := make(clientmodel.Samples, b.N)
 	for i := range samples {
@@ -1437,7 +1509,7 @@ func TestAppendOutOfOrder(t *testing.T) {
 
 	err = pl.PreloadRange(fp, 0, 2, 5*time.Minute)
 	if err != nil {
-		t.Fatalf("error preloading chunks: %s", err)
+		t.Fatalf("Error preloading chunks: %s", err)
 	}
 
 	it := s.NewIterator(fp)