allow downstream importers of remote write to turn of the interning code

Signed-off-by: Callum Styan <callumstyan@gmail.com>

storage/remote/queue_manager.go

@@ -441,6 +441,7 @@ type QueueManager struct {
 	dataIn, dataDropped, dataOut, dataOutDuration *ewmaRate
 
 	metrics              *queueManagerMetrics
+	interner             *pool
 	highestRecvTimestamp *maxTimestamp
 }
 
@@ -462,6 +463,7 @@ func NewQueueManager(
 	relabelConfigs []*relabel.Config,
 	client WriteClient,
 	flushDeadline time.Duration,
+	interner *pool,
 	highestRecvTimestamp *maxTimestamp,
 	sm ReadyScrapeManager,
 	enableExemplarRemoteWrite bool,
@@ -506,6 +508,7 @@ func NewQueueManager(
 		dataOutDuration: newEWMARate(ewmaWeight, shardUpdateDuration),
 
 		metrics:              metrics,
+		interner:             interner,
 		highestRecvTimestamp: highestRecvTimestamp,
 
 		protoMsg: protoMsg,
@@ -955,6 +958,14 @@ func (t *QueueManager) Stop() {
 		t.metadataWatcher.Stop()
 	}
 
+	// On shutdown, release the strings in the labels from the intern pool.
+	if t.interner != nil {
+		t.seriesMtx.Lock()
+		for _, labels := range t.seriesLabels {
+			t.releaseLabels(labels)
+		}
+		t.seriesMtx.Unlock()
+	}
 	t.metrics.unregister()
 }
 
@@ -976,6 +987,17 @@ func (t *QueueManager) StoreSeries(series []record.RefSeries, index int) {
 			continue
 		}
 		lbls := t.builder.Labels()
+		if t.interner != nil {
+			t.internLabels(lbls)
+
+			// We should not ever be replacing a series labels in the map, but just
+			// in case we do we need to ensure we do not leak the replaced interned
+			// strings.
+			if orig, ok := t.seriesLabels[s.Ref]; ok {
+				t.releaseLabels(orig)
+			}
+		}
+
 		t.seriesLabels[s.Ref] = lbls
 	}
 }
@@ -1023,6 +1045,10 @@ func (t *QueueManager) SeriesReset(index int) {
 			delete(t.seriesLabels, k)
 			delete(t.seriesMetadata, k)
 			delete(t.droppedSeries, k)
+
+			if t.interner != nil {
+				t.releaseLabels(t.seriesLabels[k])
+			}
 		}
 	}
 }
@@ -1041,6 +1067,14 @@ func (t *QueueManager) client() WriteClient {
 	return t.storeClient
 }
 
+func (t *QueueManager) internLabels(lbls labels.Labels) {
+	lbls.InternStrings(t.interner.intern)
+}
+
+func (t *QueueManager) releaseLabels(ls labels.Labels) {
+	ls.ReleaseStrings(t.interner.release)
+}
+
 // processExternalLabels merges externalLabels into b. If b contains
 // a label in externalLabels, the value in b wins.
 func processExternalLabels(b *labels.Builder, externalLabels []labels.Label) {

storage/remote/storage.go

@@ -72,7 +72,7 @@ func NewStorage(l log.Logger, reg prometheus.Registerer, stCallback startTimeCal
 		logger:                 logger,
 		localStartTimeCallback: stCallback,
 	}
-	s.rws = NewWriteStorage(s.logger, reg, walDir, flushDeadline, sm, metadataInWAL)
+	s.rws = NewWriteStorage(s.logger, reg, walDir, flushDeadline, sm, metadataInWAL, true)
 	return s
 }
 

storage/remote/write.go

@@ -69,6 +69,7 @@ type WriteStorage struct {
 	metadataInWAL     bool
 	samplesIn         *ewmaRate
 	flushDeadline     time.Duration
+	interner          *pool
 	scraper           ReadyScrapeManager
 	quit              chan struct{}
 
@@ -77,7 +78,7 @@ type WriteStorage struct {
 }
 
 // NewWriteStorage creates and runs a WriteStorage.
-func NewWriteStorage(logger log.Logger, reg prometheus.Registerer, dir string, flushDeadline time.Duration, sm ReadyScrapeManager, metadataInWal bool) *WriteStorage {
+func NewWriteStorage(logger log.Logger, reg prometheus.Registerer, dir string, flushDeadline time.Duration, sm ReadyScrapeManager, metadataInWal, shouldIntern bool) *WriteStorage {
 	if logger == nil {
 		logger = log.NewNopLogger()
 	}
@@ -102,6 +103,9 @@ func NewWriteStorage(logger log.Logger, reg prometheus.Registerer, dir string, f
 			}),
 		},
 	}
+	if shouldIntern {
+		rws.interner = newPool()
+	}
 	if reg != nil {
 		reg.MustRegister(rws.highestTimestamp)
 	}
@@ -208,6 +212,7 @@ func (rws *WriteStorage) ApplyConfig(conf *config.Config) error {
 			rwConf.WriteRelabelConfigs,
 			c,
 			rws.flushDeadline,
+			rws.interner,
 			rws.highestTimestamp,
 			rws.scraper,
 			rwConf.SendExemplars,