Move to using the standard library interfaces for encoding/decoding.

BinaryMarshaler instead of encodable.
BinaryUnmarshaler instead of decodable.

Left 'codable' in place for lack of a better word.

Change-Id: I8a104be7d6db916e8dbc47ff95e6ff73b845ac22

storage/local/index/batch.go

@@ -1,6 +1,8 @@
 package index
 
 import (
+	"encoding"
+
 	"github.com/syndtr/goleveldb/leveldb"
 )
 
@@ -8,12 +10,26 @@ type batch struct {
 	batch *leveldb.Batch
 }
 
-func (b *batch) Put(key, value encodable) {
+func (b *batch) Put(key, value encoding.BinaryMarshaler) error {
-	b.batch.Put(key.encode(), value.encode())
+	k, err := key.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	v, err := value.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	b.batch.Put(k, v)
+	return nil
 }
 
-func (b *batch) Delete(k encodable) {
+func (b *batch) Delete(key encoding.BinaryMarshaler) error {
-	b.batch.Delete(k.encode())
+	k, err := key.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	b.batch.Delete(k)
+	return nil
 }
 
 func (b *batch) Reset() {

storage/local/index/codec.go

@@ -2,6 +2,7 @@ package index
 
 import (
 	"bytes"
+	"encoding"
 	"encoding/binary"
 	"io"
 	"sync"
@@ -12,16 +13,8 @@ import (
 )
 
 type codable interface {
-	encodable
+	encoding.BinaryMarshaler
-	decodable
+	encoding.BinaryUnmarshaler
-}
-
-type encodable interface {
-	encode() []byte
-}
-
-type decodable interface {
-	decode([]byte)
 }
 
 // TODO: yeah, this ain't ideal. A lot of locking and possibly even contention.
@@ -36,27 +29,29 @@ func setTmpBufLen(l int) {
 	}
 }
 
-func encodeVarint(b *bytes.Buffer, i int) {
+func encodeVarint(b *bytes.Buffer, i int) error {
 	tmpBufMtx.Lock()
 	defer tmpBufMtx.Unlock()
 
 	bytesWritten := binary.PutVarint(tmpBuf, int64(i))
 	if _, err := b.Write(tmpBuf[:bytesWritten]); err != nil {
-		panic(err)
+		return err
 	}
+	return nil
 }
 
-func encodeString(b *bytes.Buffer, s string) {
+func encodeString(b *bytes.Buffer, s string) error {
 	encodeVarint(b, len(s))
 	if _, err := b.WriteString(s); err != nil {
-		panic(err)
+		return err
 	}
+	return nil
 }
 
-func decodeString(b *bytes.Reader) string {
+func decodeString(b *bytes.Reader) (string, error) {
 	length, err := binary.ReadVarint(b)
 	if err != nil {
-		panic(err)
+		return "", err
 	}
 
 	tmpBufMtx.Lock()
@@ -64,51 +59,59 @@ func decodeString(b *bytes.Reader) string {
 
 	setTmpBufLen(int(length))
 	if _, err := io.ReadFull(b, tmpBuf); err != nil {
-		panic(err)
+		return "", err
 	}
-	return string(tmpBuf)
+	return string(tmpBuf), nil
 }
 
 type codableMetric clientmodel.Metric
 
-func (m codableMetric) encode() []byte {
+func (m codableMetric) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	encodeVarint(buf, len(m))
 	for l, v := range m {
 		encodeString(buf, string(l))
 		encodeString(buf, string(v))
 	}
-	return buf.Bytes()
+	return buf.Bytes(), nil
 }
 
-func (m codableMetric) decode(buf []byte) {
+func (m codableMetric) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	numLabelPairs, err := binary.ReadVarint(r)
 	if err != nil {
-		panic(err)
+		return err
 	}
 	for ; numLabelPairs > 0; numLabelPairs-- {
-		ln := decodeString(r)
+		ln, err := decodeString(r)
-		lv := decodeString(r)
+		if err != nil {
+			return err
+		}
+		lv, err := decodeString(r)
+		if err != nil {
+			return err
+		}
 		m[clientmodel.LabelName(ln)] = clientmodel.LabelValue(lv)
 	}
+	return nil
 }
 
 type codableFingerprint clientmodel.Fingerprint
 
-func (fp codableFingerprint) encode() []byte {
+func (fp codableFingerprint) MarshalBinary() ([]byte, error) {
 	b := make([]byte, 8)
 	binary.BigEndian.PutUint64(b, uint64(fp))
-	return b
+	return b, nil
 }
 
-func (fp *codableFingerprint) decode(buf []byte) {
+func (fp *codableFingerprint) UnmarshalBinary(buf []byte) error {
 	*fp = codableFingerprint(binary.BigEndian.Uint64(buf))
+	return nil
 }
 
 type codableFingerprints clientmodel.Fingerprints
 
-func (fps codableFingerprints) encode() []byte {
+func (fps codableFingerprints) MarshalBinary() ([]byte, error) {
 	buf := bytes.NewBuffer(make([]byte, 0, binary.MaxVarintLen64+len(fps)*8))
 	encodeVarint(buf, len(fps))
 
@@ -119,17 +122,17 @@ func (fps codableFingerprints) encode() []byte {
 	for _, fp := range fps {
 		binary.BigEndian.PutUint64(tmpBuf, uint64(fp))
 		if _, err := buf.Write(tmpBuf[:8]); err != nil {
-			panic(err)
+			return nil, err
 		}
 	}
-	return buf.Bytes()
+	return buf.Bytes(), nil
 }
 
-func (fps *codableFingerprints) decode(buf []byte) {
+func (fps *codableFingerprints) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	numFPs, err := binary.ReadVarint(r)
 	if err != nil {
-		panic(err)
+		return err
 	}
 	*fps = make(codableFingerprints, numFPs)
 
@@ -137,64 +140,84 @@ func (fps *codableFingerprints) decode(buf []byte) {
 	for i, _ := range *fps {
 		(*fps)[i] = clientmodel.Fingerprint(binary.BigEndian.Uint64(buf[offset+i*8:]))
 	}
+	return nil
 }
 
 type codableLabelPair metric.LabelPair
 
-func (lp codableLabelPair) encode() []byte {
+func (lp codableLabelPair) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	encodeString(buf, string(lp.Name))
 	encodeString(buf, string(lp.Value))
-	return buf.Bytes()
+	return buf.Bytes(), nil
 }
 
-func (lp *codableLabelPair) decode(buf []byte) {
+func (lp *codableLabelPair) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
-	lp.Name = clientmodel.LabelName(decodeString(r))
+	n, err := decodeString(r)
-	lp.Value = clientmodel.LabelValue(decodeString(r))
+	if err != nil {
+		return err
+	}
+	v, err := decodeString(r)
+	if err != nil {
+		return err
+	}
+	lp.Name = clientmodel.LabelName(n)
+	lp.Value = clientmodel.LabelValue(v)
+	return nil
 }
 
 type codableLabelName clientmodel.LabelName
 
-func (l codableLabelName) encode() []byte {
+func (l codableLabelName) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	encodeString(buf, string(l))
-	return buf.Bytes()
+	return buf.Bytes(), nil
 }
 
-func (l *codableLabelName) decode(buf []byte) {
+func (l *codableLabelName) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
-	*l = codableLabelName(decodeString(r))
+	n, err := decodeString(r)
+	if err != nil {
+		return err
+	}
+	*l = codableLabelName(n)
+	return nil
 }
 
 type codableLabelValues clientmodel.LabelValues
 
-func (vs codableLabelValues) encode() []byte {
+func (vs codableLabelValues) MarshalBinary() ([]byte, error) {
 	buf := &bytes.Buffer{}
 	encodeVarint(buf, len(vs))
 	for _, v := range vs {
 		encodeString(buf, string(v))
 	}
-	return buf.Bytes()
+	return buf.Bytes(), nil
 }
 
-func (vs *codableLabelValues) decode(buf []byte) {
+func (vs *codableLabelValues) UnmarshalBinary(buf []byte) error {
 	r := bytes.NewReader(buf)
 	numValues, err := binary.ReadVarint(r)
 	if err != nil {
-		panic(err)
+		return err
 	}
 	*vs = make(codableLabelValues, numValues)
 
 	for i, _ := range *vs {
-		(*vs)[i] = clientmodel.LabelValue(decodeString(r))
+		v, err := decodeString(r)
+		if err != nil {
+			return err
+		}
+		(*vs)[i] = clientmodel.LabelValue(v)
 	}
+	return nil
 }
 
 type codableMembership struct{}
 
-func (m codableMembership) encode() []byte {
+func (m codableMembership) MarshalBinary() ([]byte, error) {
-	return []byte{}
+	return []byte{}, nil
 }
 
-func (m codableMembership) decode(buf []byte) {}
+func (m codableMembership) UnmarshalBinary(buf []byte) error { return nil }

storage/local/index/codec_test.go

@@ -103,10 +103,15 @@ func TestCodec(t *testing.T) {
 	}
 
 	for i, s := range scenarios {
-		encoded := s.in.encode()
+		encoded, err := s.in.MarshalBinary()
-		s.out.decode(encoded)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := s.out.UnmarshalBinary(encoded); err != nil {
+			t.Fatal(err)
+		}
 		if !s.equal(s.in, s.out) {
-			t.Fatalf("%d. Got: %v; want %v; encoded bytes are: %v", i, s.out, s.in, encoded)
+			t.Errorf("%d. Got: %v; want %v; encoded bytes are: %v", i, s.out, s.in, encoded)
 		}
 	}
 }

storage/local/index/index.go

@@ -208,7 +208,7 @@ func (i *SynchronizedIndexer) IndexMetrics(b FingerprintMetricMapping) error {
 	return i.i.IndexMetrics(b)
 }
 
-// TotalIndexer is a MetricIndexer that indexes all standard facets of a metric
+// DiskIndexer is a MetricIndexer that indexes all standard facets of a metric
 // that a user or the Prometheus subsystem would want to query against:
 //
 //    <Fingerprint> -> <existence marker>
@@ -218,7 +218,7 @@ func (i *SynchronizedIndexer) IndexMetrics(b FingerprintMetricMapping) error {
 //
 // This type supports concurrent queries, but only single writes, and it has no
 // locking semantics to enforce this.
-type TotalIndexer struct {
+type DiskIndexer struct {
 	FingerprintToMetric     *FingerprintMetricIndex
 	LabelNameToLabelValues  *LabelNameLabelValuesIndex
 	LabelPairToFingerprints *LabelPairFingerprintIndex
@@ -384,7 +384,7 @@ func extendLabelPairIndex(i *LabelPairFingerprintIndex, b FingerprintMetricMappi
 
 // IndexMetrics adds the facets of all unindexed metrics found in the given
 // FingerprintMetricMapping to the corresponding indices.
-func (i *TotalIndexer) IndexMetrics(b FingerprintMetricMapping) error {
+func (i *DiskIndexer) IndexMetrics(b FingerprintMetricMapping) error {
 	unindexed, err := findUnindexed(i.FingerprintMembership, b)
 	if err != nil {
 		return err
@@ -413,9 +413,8 @@ func (i *TotalIndexer) IndexMetrics(b FingerprintMetricMapping) error {
 	return i.FingerprintMembership.IndexBatch(unindexed)
 }
 
-// UnindexMetrics removes the facets of all indexed metrics found in the given
+// UnindexMetrics implements MetricIndexer.
-// FingerprintMetricMapping to the corresponding indices.
+func (i *DiskIndexer) UnindexMetrics(b FingerprintMetricMapping) error {
-func (i *TotalIndexer) UnindexMetrics(b FingerprintMetricMapping) error {
 	indexed, err := findIndexed(i.FingerprintMembership, b)
 	if err != nil {
 		return err
@@ -441,14 +440,19 @@ func (i *TotalIndexer) UnindexMetrics(b FingerprintMetricMapping) error {
 	return i.FingerprintMembership.UnindexBatch(indexed)
 }
 
-// GetMetricForFingerprint returns the metric associated with the provided fingerprint.
+func (i *DiskIndexer) ArchiveMetrics(fp clientmodel.Fingerprint, first, last clientmodel.Timestamp) error {
-func (i *TotalIndexer) GetMetricForFingerprint(fp clientmodel.Fingerprint) (clientmodel.Metric, error) {
+	// TODO: implement.
+	return nil
+}
+
+// GetMetricForFingerprint implements MetricIndexer.
+func (i *DiskIndexer) GetMetricForFingerprint(fp clientmodel.Fingerprint) (clientmodel.Metric, error) {
 	m, _, err := i.FingerprintToMetric.Lookup(fp)
 	return m, err
 }
 
-// GetFingerprintsForLabelPair returns all fingerprints for the provided label pair.
+// GetFingerprintsForLabelPair implements MetricIndexer.
-func (i *TotalIndexer) GetFingerprintsForLabelPair(ln clientmodel.LabelName, lv clientmodel.LabelValue) (clientmodel.Fingerprints, error) {
+func (i *DiskIndexer) GetFingerprintsForLabelPair(ln clientmodel.LabelName, lv clientmodel.LabelValue) (clientmodel.Fingerprints, error) {
 	fps, _, err := i.LabelPairToFingerprints.Lookup(&metric.LabelPair{
 		Name:  ln,
 		Value: lv,
@@ -456,13 +460,24 @@ func (i *TotalIndexer) GetFingerprintsForLabelPair(ln clientmodel.LabelName, lv
 	return fps, err
 }
 
-// GetLabelValuesForLabelName returns all label values associated with a given label name.
+// GetLabelValuesForLabelName implements MetricIndexer.
-func (i *TotalIndexer) GetLabelValuesForLabelName(ln clientmodel.LabelName) (clientmodel.LabelValues, error) {
+func (i *DiskIndexer) GetLabelValuesForLabelName(ln clientmodel.LabelName) (clientmodel.LabelValues, error) {
 	lvs, _, err := i.LabelNameToLabelValues.Lookup(ln)
 	return lvs, err
 }
 
-// HasFingerprint returns true if a metric with the given fingerprint has been indexed.
+// HasFingerprint implements MetricIndexer.
-func (i *TotalIndexer) HasFingerprint(fp clientmodel.Fingerprint) (bool, error) {
+func (i *DiskIndexer) HasFingerprint(fp clientmodel.Fingerprint) (bool, error) {
+	// TODO: modify.
 	return i.FingerprintMembership.Has(fp)
 }
+
+func (i *DiskIndexer) HasArchivedFingerprint(clientmodel.Fingerprint) (present bool, first, last clientmodel.Timestamp, err error) {
+	// TODO: implement.
+	return false, 0, 0, nil
+}
+
+func (i *DiskIndexer) Close() error {
+	// TODO: implement
+	return nil
+}

storage/local/index/index_test.go

@@ -31,7 +31,7 @@ func newTestDB(t *testing.T) (KeyValueStore, test.Closer) {
 	})
 }
 
-func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMetrics FingerprintMetricMapping, indexer *TotalIndexer) {
+func verifyIndexedState(i int, t *testing.T, b incrementalBatch, indexedFpsToMetrics FingerprintMetricMapping, indexer *DiskIndexer) {
 	for fp, m := range indexedFpsToMetrics {
 		// Compare indexed metrics with input metrics.
 		mOut, ok, err := indexer.FingerprintToMetric.Lookup(fp)
@@ -224,7 +224,7 @@ func TestIndexing(t *testing.T) {
 	fpMsDB, fpMsCloser := newTestDB(t)
 	defer fpMsCloser.Close()
 
-	indexer := TotalIndexer{
+	indexer := DiskIndexer{
 		FingerprintToMetric:     NewFingerprintMetricIndex(fpToMetricDB),
 		LabelNameToLabelValues:  NewLabelNameLabelValuesIndex(lnToLvsDB),
 		LabelPairToFingerprints: NewLabelPairFingerprintIndex(lpToFpDB),

storage/local/index/interface.go

@@ -1,16 +1,28 @@
 package index
 
 import (
+	"encoding"
+
 	clientmodel "github.com/prometheus/client_golang/model"
 )
 
-// MetricIndexer indexes facets of a clientmodel.Metric. The interface makes no
+// MetricIndexer indexes facets of a clientmodel.Metric. Implementers may or may
-// assumptions about the concurrency safety of the underlying implementer.
+// not be concurrency-safe.
 type MetricIndexer interface {
-	// IndexMetrics adds metrics to the index.
+	// IndexMetrics adds metrics to the index. If the metrics was added
+	// before and has been archived in the meantime, it is now un-archived.
 	IndexMetrics(FingerprintMetricMapping) error
 	// UnindexMetrics removes metrics from the index.
 	UnindexMetrics(FingerprintMetricMapping) error
+	// ArchiveMetrics marks the metric with the given fingerprint as
+	// 'archived', which has to be called if upon eviction of the
+	// corresponding time series from memory. By calling this method, the
+	// MetricIndexer learns about the time range of the evicted time series,
+	// which is used later for the decision if an evicted time series has to
+	// be moved back into memory. The implementer of MetricIndexer can make
+	// use of the archived state, e.g. by saving archived metrics in an
+	// on-disk index and non-archived metrics in an in-memory index.
+	ArchiveMetrics(fp clientmodel.Fingerprint, first, last clientmodel.Timestamp) error
 
 	// GetMetricForFingerprint returns the metric associated with the provided fingerprint.
 	GetMetricForFingerprint(clientmodel.Fingerprint) (clientmodel.Metric, error)
@@ -18,16 +30,24 @@ type MetricIndexer interface {
 	GetFingerprintsForLabelPair(l clientmodel.LabelName, v clientmodel.LabelValue) (clientmodel.Fingerprints, error)
 	// GetLabelValuesForLabelName returns all label values associated with a given label name.
 	GetLabelValuesForLabelName(clientmodel.LabelName) (clientmodel.LabelValues, error)
-	// HasFingerprint returns true if a metric with the given fingerprint has been indexed.
+	// HasFingerprint returns true if a metric with the given fingerprint
+	// has been indexed and has NOT been archived yet.
 	HasFingerprint(clientmodel.Fingerprint) (bool, error)
+	// HasArchivedFingerprint returns true if a metric with the given
+	// fingerprint was indexed before and has been archived in the
+	// meantime. In that case, the time range of the archived metric is also
+	// returned.
+	HasArchivedFingerprint(clientmodel.Fingerprint) (present bool, first, last clientmodel.Timestamp, err error)
+
+	Close() error
 }
 
 // KeyValueStore persists key/value pairs.
 type KeyValueStore interface {
-	Put(key, value encodable) error
+	Put(key, value encoding.BinaryMarshaler) error
-	Get(k encodable, v decodable) (bool, error)
+	Get(k encoding.BinaryMarshaler, v encoding.BinaryUnmarshaler) (bool, error)
-	Has(k encodable) (has bool, err error)
+	Has(k encoding.BinaryMarshaler) (has bool, err error)
-	Delete(k encodable) error
+	Delete(k encoding.BinaryMarshaler) error
 
 	NewBatch() Batch
 	Commit(b Batch) error
@@ -37,7 +57,7 @@ type KeyValueStore interface {
 
 // Batch allows KeyValueStore mutations to be pooled and committed together.
 type Batch interface {
-	Put(key, value encodable)
+	Put(key, value encoding.BinaryMarshaler) error
-	Delete(key encodable)
+	Delete(key encoding.BinaryMarshaler) error
 	Reset()
 }

storage/local/index/leveldb.go

@@ -1,6 +1,8 @@
 package index
 
 import (
+	"encoding"
+
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/cache"
 	"github.com/syndtr/goleveldb/leveldb/filter"
@@ -48,31 +50,46 @@ func (l *LevelDB) Close() error {
 	return l.storage.Close()
 }
 
-func (l *LevelDB) Get(k encodable, v decodable) (bool, error) {
+func (l *LevelDB) Get(key encoding.BinaryMarshaler, value encoding.BinaryUnmarshaler) (bool, error) {
-	raw, err := l.storage.Get(k.encode(), l.readOpts)
+	k, err := key.MarshalBinary()
+	if err != nil {
+		return false, nil
+	}
+	raw, err := l.storage.Get(k, l.readOpts)
 	if err == leveldb.ErrNotFound {
 		return false, nil
 	}
 	if err != nil {
 		return false, err
 	}
-	if v == nil {
+	if value == nil {
 		return true, nil
 	}
-	v.decode(raw)
+	return true, value.UnmarshalBinary(raw)
-	return true, err
 }
 
-func (l *LevelDB) Has(k encodable) (has bool, err error) {
+func (l *LevelDB) Has(key encoding.BinaryMarshaler) (has bool, err error) {
-	return l.Get(k, nil)
+	return l.Get(key, nil)
 }
 
-func (l *LevelDB) Delete(k encodable) error {
+func (l *LevelDB) Delete(key encoding.BinaryMarshaler) error {
-	return l.storage.Delete(k.encode(), l.writeOpts)
+	k, err := key.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	return l.storage.Delete(k, l.writeOpts)
 }
 
-func (l *LevelDB) Put(key, value encodable) error {
+func (l *LevelDB) Put(key, value encoding.BinaryMarshaler) error {
-	return l.storage.Put(key.encode(), value.encode(), l.writeOpts)
+	k, err := key.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	v, err := value.MarshalBinary()
+	if err != nil {
+		return err
+	}
+	return l.storage.Put(k, v, l.writeOpts)
 }
 
 func (l *LevelDB) Commit(b Batch) error {

storage/local/interface.go

@@ -2,8 +2,6 @@ package storage_ng
 
 import (
 	clientmodel "github.com/prometheus/client_golang/model"
-
-	"github.com/prometheus/prometheus/storage/local/index"
 	"github.com/prometheus/prometheus/storage/metric"
 )
 
@@ -64,9 +62,7 @@ type Persistence interface {
 	LoadHeads(map[clientmodel.Fingerprint]*memorySeries) error
 
 	// Close releases any held resources.
-	Close()
+	Close() error
-
-	index.MetricIndexer
 }
 
 // A Preloader preloads series data necessary for a query into memory and pins
@@ -86,8 +82,3 @@ type Preloader interface {
 	// Close unpins any previously requested series data from memory.
 	Close()
 }
-
-type Closer interface {
-	// Close cleans up any used resources.
-	Close()
-}

storage/local/persistence.go

@@ -41,9 +41,9 @@ const (
 
 var (
 	fingerprintToMetricCacheSize     = flag.Int("storage.fingerprintToMetricCacheSizeBytes", 25*1024*1024, "The size in bytes for the fingerprint to metric index cache.")
-	labelNameToLabelValuesCacheSize  = flag.Int("storage.labelNameToLabelValuesCacheSizeBytes", 25*1024*1024, "The size in bytes for the label name to label values index.")
+	labelNameToLabelValuesCacheSize  = flag.Int("storage.labelNameToLabelValuesCacheSizeBytes", 25*1024*1024, "The size in bytes for the label name to label values index cache.")
-	labelPairToFingerprintsCacheSize = flag.Int("storage.labelPairToFingerprintsCacheSizeBytes", 25*1024*1024, "The size in bytes for the label pair to fingerprints index.")
+	labelPairToFingerprintsCacheSize = flag.Int("storage.labelPairToFingerprintsCacheSizeBytes", 25*1024*1024, "The size in bytes for the label pair to fingerprints index cache.")
-	fingerprintMembershipCacheSize   = flag.Int("storage.fingerprintMembershipCacheSizeBytes", 5*1024*1024, "The size in bytes for the metric membership index.")
+	fingerprintMembershipCacheSize   = flag.Int("storage.fingerprintMembershipCacheSizeBytes", 5*1024*1024, "The size in bytes for the metric membership index cache.")
 )
 
 type diskPersistence struct {
@@ -94,7 +94,7 @@ func NewDiskPersistence(basePath string, chunkLen int) (Persistence, error) {
 		basePath: basePath,
 		chunkLen: chunkLen,
 		buf:      make([]byte, binary.MaxVarintLen64), // Also sufficient for uint64.
-		MetricIndexer: &index.TotalIndexer{
+		MetricIndexer: &index.DiskIndexer{
 			FingerprintToMetric:     index.NewFingerprintMetricIndex(fingerprintToMetricDB),
 			LabelNameToLabelValues:  index.NewLabelNameLabelValuesIndex(labelNameToLabelValuesDB),
 			LabelPairToFingerprints: index.NewLabelPairFingerprintIndex(labelPairToFingerprintsDB),
@@ -395,25 +395,13 @@ func (p *diskPersistence) LoadHeads(fpToSeries map[clientmodel.Fingerprint]*memo
 	return nil
 }
 
-func (d *diskPersistence) Close() {
+func (d *diskPersistence) Close() error {
+	var lastError error
 	for _, db := range d.indexDBs {
 		if err := db.Close(); err != nil {
 			glog.Error("Error closing index DB: ", err)
+			lastError = err
 		}
 	}
-}
+	return lastError
-
-// Get all of the label values that are associated with a given label name.
-func (d *diskPersistence) GetFingerprintsForLabelPair(l clientmodel.LabelName, v clientmodel.LabelValue) (clientmodel.Fingerprints, error) {
-	return nil, nil
-}
-
-// Get all label values that are associated with a given label name.
-func (d *diskPersistence) GetLabelValuesForLabelName(clientmodel.LabelName) (clientmodel.LabelValues, error) {
-	return nil, nil
-}
-
-// Get the metric associated with the provided fingerprint.
-func (d *diskPersistence) GetMetricForFingerprint(clientmodel.Fingerprint) (clientmodel.Metric, error) {
-	return nil, nil
 }