diff --git a/retrieval/helpers_test.go b/retrieval/helpers_test.go
index c5f1c68e9..2f1cb6001 100644
--- a/retrieval/helpers_test.go
+++ b/retrieval/helpers_test.go
@@ -27,10 +27,10 @@ func (a nopAppendable) Appender() (storage.Appender, error) {
 
 type nopAppender struct{}
 
-func (a nopAppender) SetSeries(labels.Labels) (uint64, error) { return 0, nil }
-func (a nopAppender) Add(uint64, int64, float64) error        { return nil }
-func (a nopAppender) Commit() error                           { return nil }
-func (a nopAppender) Rollback() error                         { return nil }
+func (a nopAppender) Add(labels.Labels, int64, float64) (uint64, error) { return 0, nil }
+func (a nopAppender) AddFast(uint64, int64, float64) error              { return nil }
+func (a nopAppender) Commit() error                                     { return nil }
+func (a nopAppender) Rollback() error                                   { return nil }
 
 type collectResultAppender struct {
 	refs   map[uint64]labels.Labels
diff --git a/template/template_test.go b/template/template_test.go
index 647cb5389..178e63c5b 100644
--- a/template/template_test.go
+++ b/template/template_test.go
@@ -210,14 +210,11 @@ func TestTemplateExpansion(t *testing.T) {
 		t.Fatalf("get appender: %s", err)
 	}
 
-	aref, err := app.SetSeries(labels.FromStrings(labels.MetricName, "metric", "instance", "a"))
+	_, err = app.Add(labels.FromStrings(labels.MetricName, "metric", "instance", "a"), 0, 11)
 	require.NoError(t, err)
-	bref, err := app.SetSeries(labels.FromStrings(labels.MetricName, "metric", "instance", "b"))
+	_, err = app.Add(labels.FromStrings(labels.MetricName, "metric", "instance", "b"), 0, 21)
 	require.NoError(t, err)
 
-	app.Add(aref, 0, 11)
-	app.Add(bref, 0, 21)
-
 	if err := app.Commit(); err != nil {
 		t.Fatalf("commit samples: %s", err)
 	}
diff --git a/util/testutil/storage.go b/util/testutil/storage.go
index d37ac361e..6aa341f5e 100644
--- a/util/testutil/storage.go
+++ b/util/testutil/storage.go
@@ -3,6 +3,7 @@ package testutil
 import (
 	"io/ioutil"
 	"os"
+	"time"
 
 	"github.com/prometheus/common/log"
 	"github.com/prometheus/prometheus/storage"
@@ -20,8 +21,8 @@ func NewStorage(t T) storage.Storage {
 	log.With("dir", dir).Debugln("opening test storage")
 
 	db, err := tsdb.Open(dir, &tsdb.Options{
-		MinBlockDuration: 2 * 60 * 60 * 1000,
-		MaxBlockDuration: 24 * 60 * 60 * 1000,
+		MinBlockDuration: 2 * time.Hour,
+		MaxBlockDuration: 24 * time.Hour,
 		AppendableBlocks: 10,
 	})
 	if err != nil {
diff --git a/vendor/github.com/fabxc/tsdb/block.go b/vendor/github.com/fabxc/tsdb/block.go
index ca7c48f46..db63e14f2 100644
--- a/vendor/github.com/fabxc/tsdb/block.go
+++ b/vendor/github.com/fabxc/tsdb/block.go
@@ -7,7 +7,6 @@ import (
 	"path/filepath"
 	"sort"
 
-	"github.com/coreos/etcd/pkg/fileutil"
 	"github.com/pkg/errors"
 )
 
@@ -130,11 +129,11 @@ func newPersistedBlock(dir string) (*persistedBlock, error) {
 		return nil, errors.Wrap(err, "open index file")
 	}
 
-	sr, err := newSeriesReader(chunksf.b)
+	sr, err := newSeriesReader([][]byte{chunksf.b})
 	if err != nil {
 		return nil, errors.Wrap(err, "create series reader")
 	}
-	ir, err := newIndexReader(sr, indexf.b)
+	ir, err := newIndexReader(indexf.b)
 	if err != nil {
 		return nil, errors.Wrap(err, "create index reader")
 	}
@@ -175,14 +174,12 @@ func indexFileName(path string) string {
 }
 
 type mmapFile struct {
-	f *fileutil.LockedFile
+	f *os.File
 	b []byte
 }
 
 func openMmapFile(path string) (*mmapFile, error) {
-	// We have to open the file in RDWR for the lock to work with fileutil.
-	// TODO(fabxc): use own flock call that supports multi-reader.
-	f, err := fileutil.TryLockFile(path, os.O_RDWR, 0666)
+	f, err := os.Open(path)
 	if err != nil {
 		return nil, errors.Wrap(err, "try lock file")
 	}
@@ -191,7 +188,7 @@ func openMmapFile(path string) (*mmapFile, error) {
 		return nil, errors.Wrap(err, "stat")
 	}
 
-	b, err := mmap(f.File, int(info.Size()))
+	b, err := mmap(f, int(info.Size()))
 	if err != nil {
 		return nil, errors.Wrap(err, "mmap")
 	}
diff --git a/vendor/github.com/fabxc/tsdb/compact.go b/vendor/github.com/fabxc/tsdb/compact.go
index 412a24788..6a0d67499 100644
--- a/vendor/github.com/fabxc/tsdb/compact.go
+++ b/vendor/github.com/fabxc/tsdb/compact.go
@@ -158,26 +158,25 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 		c.metrics.duration.Observe(time.Since(start).Seconds())
 	}()
 
-	if fileutil.Exist(dir) {
-		if err = os.RemoveAll(dir); err != nil {
-			return err
-		}
+	if err = os.RemoveAll(dir); err != nil {
+		return err
 	}
-	if err = os.MkdirAll(dir, 0755); err != nil {
+
+	if err = os.MkdirAll(dir, 0777); err != nil {
 		return err
 	}
 
-	chunkf, err := fileutil.LockFile(chunksFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
+	chunkf, err := os.OpenFile(chunksFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
 	if err != nil {
 		return errors.Wrap(err, "create chunk file")
 	}
-	indexf, err := fileutil.LockFile(indexFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
+	indexf, err := os.OpenFile(indexFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
 	if err != nil {
 		return errors.Wrap(err, "create index file")
 	}
 
 	indexw := newIndexWriter(indexf)
-	chunkw := newSeriesWriter(chunkf, indexw)
+	chunkw := newChunkWriter(chunkf)
 
 	if err = c.write(dir, blocks, indexw, chunkw); err != nil {
 		return errors.Wrap(err, "write compaction")
@@ -189,10 +188,10 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 	if err = indexw.Close(); err != nil {
 		return errors.Wrap(err, "close index writer")
 	}
-	if err = fileutil.Fsync(chunkf.File); err != nil {
+	if err = fileutil.Fsync(chunkf); err != nil {
 		return errors.Wrap(err, "fsync chunk file")
 	}
-	if err = fileutil.Fsync(indexf.File); err != nil {
+	if err = fileutil.Fsync(indexf); err != nil {
 		return errors.Wrap(err, "fsync index file")
 	}
 	if err = chunkf.Close(); err != nil {
@@ -204,7 +203,7 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 	return nil
 }
 
-func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw SeriesWriter) error {
+func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw ChunkWriter) error {
 	var set compactionSet
 
 	for i, b := range blocks {
@@ -238,10 +237,12 @@ func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw
 
 	for set.Next() {
 		lset, chunks := set.At()
-		if err := chunkw.WriteSeries(i, lset, chunks); err != nil {
+		if err := chunkw.WriteChunks(chunks...); err != nil {
 			return err
 		}
 
+		indexw.AddSeries(i, lset, chunks...)
+
 		meta.Stats.NumChunks += uint64(len(chunks))
 		meta.Stats.NumSeries++
 
diff --git a/vendor/github.com/fabxc/tsdb/db.go b/vendor/github.com/fabxc/tsdb/db.go
index 72b82c778..10253ca1d 100644
--- a/vendor/github.com/fabxc/tsdb/db.go
+++ b/vendor/github.com/fabxc/tsdb/db.go
@@ -21,6 +21,7 @@ import (
 	"github.com/coreos/etcd/pkg/fileutil"
 	"github.com/fabxc/tsdb/labels"
 	"github.com/go-kit/kit/log"
+	"github.com/nightlyone/lockfile"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -28,10 +29,11 @@ import (
 // DefaultOptions used for the DB. They are sane for setups using
 // millisecond precision timestampdb.
 var DefaultOptions = &Options{
-	WALFlushInterval: 5 * time.Second,
-	MinBlockDuration: 3 * 60 * 60 * 1000,  // 2 hours in milliseconds
-	MaxBlockDuration: 24 * 60 * 60 * 1000, // 1 days in milliseconds
-	AppendableBlocks: 2,
+	WALFlushInterval:  5 * time.Second,
+	RetentionDuration: 15 * 24 * 60 * 60 * 1000, // 15 days in milliseconds
+	MinBlockDuration:  3 * 60 * 60 * 1000,       // 2 hours in milliseconds
+	MaxBlockDuration:  24 * 60 * 60 * 1000,      // 1 days in milliseconds
+	AppendableBlocks:  2,
 }
 
 // Options of the DB storage.
@@ -39,6 +41,9 @@ type Options struct {
 	// The interval at which the write ahead log is flushed to disc.
 	WALFlushInterval time.Duration
 
+	// Duration of persisted data to keep.
+	RetentionDuration uint64
+
 	// The timestamp range of head blocks after which they get persisted.
 	// It's the minimum duration of any persisted block.
 	MinBlockDuration uint64
@@ -82,6 +87,7 @@ const sep = '\xff'
 // a hashed partition of a seriedb.
 type DB struct {
 	dir     string
+	lockf   lockfile.Lockfile
 	logger  log.Logger
 	metrics *dbMetrics
 	opts    *Options
@@ -126,13 +132,24 @@ func newDBMetrics(r prometheus.Registerer) *dbMetrics {
 
 // Open returns a new DB in the given directory.
 func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
-	if !fileutil.Exist(dir) {
-		if err := os.MkdirAll(dir, 0777); err != nil {
-			return nil, err
-		}
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		return nil, err
+	}
+
+	absdir, err := filepath.Abs(dir)
+	if err != nil {
+		return nil, err
+	}
+	lockf, err := lockfile.New(filepath.Join(absdir, "lock"))
+	if err != nil {
+		return nil, err
+	}
+	if err := lockf.TryLock(); err != nil {
+		return nil, errors.Wrapf(err, "open DB in %s", dir)
 	}
-	// var r prometheus.Registerer
-	r := prometheus.DefaultRegisterer
+
+	var r prometheus.Registerer
+	// r := prometheus.DefaultRegisterer
 
 	if opts == nil {
 		opts = DefaultOptions
@@ -143,6 +160,7 @@ func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
 
 	db = &DB{
 		dir:      dir,
+		lockf:    lockf,
 		logger:   logger,
 		metrics:  newDBMetrics(r),
 		opts:     opts,
@@ -284,6 +302,37 @@ func (db *DB) compact(i, j int) error {
 			return errors.Wrap(err, "removing old block")
 		}
 	}
+	return db.retentionCutoff()
+}
+
+func (db *DB) retentionCutoff() error {
+	if db.opts.RetentionDuration == 0 {
+		return nil
+	}
+	h := db.heads[len(db.heads)-1]
+	t := h.meta.MinTime - int64(db.opts.RetentionDuration)
+
+	var (
+		blocks = db.blocks()
+		i      int
+		b      Block
+	)
+	for i, b = range blocks {
+		if b.Meta().MinTime >= t {
+			break
+		}
+	}
+	if i <= 1 {
+		return nil
+	}
+	db.logger.Log("msg", "retention cutoff", "idx", i-1)
+	db.removeBlocks(0, i)
+
+	for _, b := range blocks[:i] {
+		if err := os.RemoveAll(b.Dir()); err != nil {
+			return errors.Wrap(err, "removing old block")
+		}
+	}
 	return nil
 }
 
@@ -299,7 +348,7 @@ func (db *DB) initBlocks() error {
 	}
 
 	for _, dir := range dirs {
-		if fileutil.Exist(filepath.Join(dir, walFileName)) {
+		if fileutil.Exist(filepath.Join(dir, walDirName)) {
 			h, err := openHeadBlock(dir, db.logger)
 			if err != nil {
 				return err
@@ -339,6 +388,8 @@ func (db *DB) Close() error {
 		merr.Add(hb.Close())
 	}
 
+	merr.Add(db.lockf.Unlock())
+
 	return merr.Err()
 }
 
@@ -566,7 +617,7 @@ func (db *DB) blocksForInterval(mint, maxt int64) []Block {
 func (db *DB) cut(mint int64) (*headBlock, error) {
 	maxt := mint + int64(db.opts.MinBlockDuration)
 
-	dir, seq, err := nextBlockDir(db.dir)
+	dir, seq, err := nextSequenceFile(db.dir, "b-")
 	if err != nil {
 		return nil, err
 	}
@@ -616,7 +667,32 @@ func blockDirs(dir string) ([]string, error) {
 	return dirs, nil
 }
 
-func nextBlockDir(dir string) (string, int, error) {
+func sequenceFiles(dir, prefix string) ([]string, error) {
+	files, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return nil, err
+	}
+	var res []string
+
+	for _, fi := range files {
+		if isSequenceFile(fi, prefix) {
+			res = append(res, filepath.Join(dir, fi.Name()))
+		}
+	}
+	return res, nil
+}
+
+func isSequenceFile(fi os.FileInfo, prefix string) bool {
+	if !strings.HasPrefix(fi.Name(), prefix) {
+		return false
+	}
+	if _, err := strconv.ParseUint(fi.Name()[len(prefix):], 10, 32); err != nil {
+		return false
+	}
+	return true
+}
+
+func nextSequenceFile(dir, prefix string) (string, int, error) {
 	names, err := fileutil.ReadDir(dir)
 	if err != nil {
 		return "", 0, err
@@ -624,16 +700,16 @@ func nextBlockDir(dir string) (string, int, error) {
 
 	i := uint64(0)
 	for _, n := range names {
-		if !strings.HasPrefix(n, "b-") {
+		if !strings.HasPrefix(n, prefix) {
 			continue
 		}
-		j, err := strconv.ParseUint(n[2:], 10, 32)
+		j, err := strconv.ParseUint(n[len(prefix):], 10, 32)
 		if err != nil {
 			continue
 		}
 		i = j
 	}
-	return filepath.Join(dir, fmt.Sprintf("b-%0.6d", i+1)), int(i + 1), nil
+	return filepath.Join(dir, fmt.Sprintf("%s%0.6d", prefix, i+1)), int(i + 1), nil
 }
 
 // PartitionedDB is a time series storage.
diff --git a/vendor/github.com/fabxc/tsdb/head.go b/vendor/github.com/fabxc/tsdb/head.go
index 1c69ac3bb..d9ab2944c 100644
--- a/vendor/github.com/fabxc/tsdb/head.go
+++ b/vendor/github.com/fabxc/tsdb/head.go
@@ -43,6 +43,7 @@ type headBlock struct {
 
 	activeWriters uint64
 
+	symbols map[string]struct{}
 	// descs holds all chunk descs for the head block. Each chunk implicitly
 	// is assigned the index as its ID.
 	series []*memSeries
@@ -97,25 +98,26 @@ func openHeadBlock(dir string, l log.Logger) (*headBlock, error) {
 		meta:     *meta,
 	}
 
-	// Replay contents of the write ahead log.
-	if err = wal.ReadAll(&walHandler{
-		series: func(lset labels.Labels) error {
+	r := wal.Reader()
+
+	for r.Next() {
+		series, samples := r.At()
+
+		for _, lset := range series {
 			h.create(lset.Hash(), lset)
 			h.meta.Stats.NumSeries++
-			return nil
-		},
-		sample: func(s refdSample) error {
+		}
+		for _, s := range samples {
 			h.series[s.ref].append(s.t, s.v)
 
 			if !h.inBounds(s.t) {
-				return ErrOutOfBounds
+				return nil, errors.Wrap(ErrOutOfBounds, "consume WAL")
 			}
-
 			h.meta.Stats.NumSamples++
-			return nil
-		},
-	}); err != nil {
-		return nil, err
+		}
+	}
+	if err := r.Err(); err != nil {
+		return nil, errors.Wrap(err, "consume WAL")
 	}
 
 	h.updateMapping()
@@ -362,14 +364,17 @@ type headSeriesReader struct {
 }
 
 // Chunk returns the chunk for the reference number.
-func (h *headSeriesReader) Chunk(ref uint32) (chunks.Chunk, error) {
+func (h *headSeriesReader) Chunk(ref uint64) (chunks.Chunk, error) {
 	h.mtx.RLock()
 	defer h.mtx.RUnlock()
 
+	si := ref >> 32
+	ci := (ref << 32) >> 32
+
 	c := &safeChunk{
-		Chunk: h.series[ref>>8].chunks[int((ref<<24)>>24)].chunk,
-		s:     h.series[ref>>8],
-		i:     int((ref << 24) >> 24),
+		Chunk: h.series[si].chunks[ci].chunk,
+		s:     h.series[si],
+		i:     int(ci),
 	}
 	return c, nil
 }
@@ -438,7 +443,7 @@ func (h *headIndexReader) Series(ref uint32) (labels.Labels, []ChunkMeta, error)
 		metas = append(metas, ChunkMeta{
 			MinTime: c.minTime,
 			MaxTime: c.maxTime,
-			Ref:     (ref << 8) | uint32(i),
+			Ref:     (uint64(ref) << 32) | uint64(i),
 		})
 	}
 
diff --git a/vendor/github.com/fabxc/tsdb/querier.go b/vendor/github.com/fabxc/tsdb/querier.go
index df17ad270..c09bab885 100644
--- a/vendor/github.com/fabxc/tsdb/querier.go
+++ b/vendor/github.com/fabxc/tsdb/querier.go
@@ -491,7 +491,7 @@ type chunkSeries struct {
 
 	// chunk is a function that retrieves chunks based on a reference
 	// number contained in the chunk meta information.
-	chunk func(ref uint32) (chunks.Chunk, error)
+	chunk func(ref uint64) (chunks.Chunk, error)
 }
 
 func (s *chunkSeries) Labels() labels.Labels {
diff --git a/vendor/github.com/fabxc/tsdb/reader.go b/vendor/github.com/fabxc/tsdb/reader.go
index a49fb794b..630c11a99 100644
--- a/vendor/github.com/fabxc/tsdb/reader.go
+++ b/vendor/github.com/fabxc/tsdb/reader.go
@@ -13,32 +13,45 @@ import (
 // SeriesReader provides reading access of serialized time series data.
 type SeriesReader interface {
 	// Chunk returns the series data chunk with the given reference.
-	Chunk(ref uint32) (chunks.Chunk, error)
+	Chunk(ref uint64) (chunks.Chunk, error)
 }
 
 // seriesReader implements a SeriesReader for a serialized byte stream
 // of series data.
 type seriesReader struct {
-	// The underlying byte slice holding the encoded series data.
-	b []byte
+	// The underlying bytes holding the encoded series data.
+	bs [][]byte
 }
 
-func newSeriesReader(b []byte) (*seriesReader, error) {
-	if len(b) < 4 {
-		return nil, errors.Wrap(errInvalidSize, "index header")
-	}
-	// Verify magic number.
-	if m := binary.BigEndian.Uint32(b[:4]); m != MagicSeries {
-		return nil, fmt.Errorf("invalid magic number %x", m)
+func newSeriesReader(bs [][]byte) (*seriesReader, error) {
+	s := &seriesReader{bs: bs}
+
+	for i, b := range bs {
+		if len(b) < 4 {
+			return nil, errors.Wrapf(errInvalidSize, "validate magic in segment %d", i)
+		}
+		// Verify magic number.
+		if m := binary.BigEndian.Uint32(b[:4]); m != MagicSeries {
+			return nil, fmt.Errorf("invalid magic number %x", m)
+		}
 	}
-	return &seriesReader{b: b}, nil
+	return s, nil
 }
 
-func (s *seriesReader) Chunk(offset uint32) (chunks.Chunk, error) {
-	if int(offset) > len(s.b) {
-		return nil, errors.Errorf("offset %d beyond data size %d", offset, len(s.b))
+func (s *seriesReader) Chunk(ref uint64) (chunks.Chunk, error) {
+	var (
+		seq = int(ref >> 32)
+		off = int((ref << 32) >> 32)
+	)
+	if seq >= len(s.bs) {
+		return nil, errors.Errorf("reference sequence %d out of range", seq)
 	}
-	b := s.b[offset:]
+	b := s.bs[seq]
+
+	if int(off) >= len(b) {
+		return nil, errors.Errorf("offset %d beyond data size %d", off, len(b))
+	}
+	b = b[off:]
 
 	l, n := binary.Uvarint(b)
 	if n < 0 {
@@ -78,8 +91,6 @@ type StringTuples interface {
 }
 
 type indexReader struct {
-	series SeriesReader
-
 	// The underlying byte slice holding the encoded series data.
 	b []byte
 
@@ -93,14 +104,11 @@ var (
 	errInvalidFlag = fmt.Errorf("invalid flag")
 )
 
-func newIndexReader(s SeriesReader, b []byte) (*indexReader, error) {
+func newIndexReader(b []byte) (*indexReader, error) {
 	if len(b) < 4 {
 		return nil, errors.Wrap(errInvalidSize, "index header")
 	}
-	r := &indexReader{
-		series: s,
-		b:      b,
-	}
+	r := &indexReader{b: b}
 
 	// Verify magic number.
 	if m := binary.BigEndian.Uint32(b[:4]); m != MagicIndex {
@@ -299,7 +307,7 @@ func (r *indexReader) Series(ref uint32) (labels.Labels, []ChunkMeta, error) {
 		b = b[n:]
 
 		chunks = append(chunks, ChunkMeta{
-			Ref:     uint32(o),
+			Ref:     o,
 			MinTime: firstTime,
 			MaxTime: lastTime,
 		})
diff --git a/vendor/github.com/fabxc/tsdb/wal.go b/vendor/github.com/fabxc/tsdb/wal.go
index 5731bba14..a923f5b3d 100644
--- a/vendor/github.com/fabxc/tsdb/wal.go
+++ b/vendor/github.com/fabxc/tsdb/wal.go
@@ -3,6 +3,7 @@ package tsdb
 import (
 	"bufio"
 	"encoding/binary"
+	"hash"
 	"hash/crc32"
 	"io"
 	"math"
@@ -20,11 +21,19 @@ import (
 // WALEntryType indicates what data a WAL entry contains.
 type WALEntryType byte
 
-// The valid WAL entry types.
 const (
-	WALEntrySymbols = 1
-	WALEntrySeries  = 2
-	WALEntrySamples = 3
+	// WALMagic is a 4 byte number every WAL segment file starts with.
+	WALMagic = uint32(0x43AF00EF)
+
+	// WALFormatDefault is the version flag for the default outer segment file format.
+	WALFormatDefault = byte(1)
+)
+
+// Entry types in a segment file.
+const (
+	WALEntrySymbols WALEntryType = 1
+	WALEntrySeries  WALEntryType = 2
+	WALEntrySamples WALEntryType = 3
 )
 
 // WAL is a write ahead log for series data. It can only be written to.
@@ -32,102 +41,201 @@ const (
 type WAL struct {
 	mtx sync.Mutex
 
-	f             *fileutil.LockedFile
-	enc           *walEncoder
+	dirFile *os.File
+	files   []*os.File
+
 	logger        log.Logger
 	flushInterval time.Duration
+	segmentSize   int64
+
+	crc32 hash.Hash32
+	cur   *bufio.Writer
+	curN  int64
 
 	stopc chan struct{}
 	donec chan struct{}
-
-	symbols map[string]uint32
 }
 
-const walFileName = "wal-000"
+const (
+	walDirName          = "wal"
+	walSegmentSizeBytes = 64 * 1000 * 1000 // 64 MB
+)
 
 // OpenWAL opens or creates a write ahead log in the given directory.
 // The WAL must be read completely before new data is written.
 func OpenWAL(dir string, l log.Logger, flushInterval time.Duration) (*WAL, error) {
+	dir = filepath.Join(dir, walDirName)
+
 	if err := os.MkdirAll(dir, 0777); err != nil {
 		return nil, err
 	}
-
-	p := filepath.Join(dir, walFileName)
-
-	f, err := fileutil.TryLockFile(p, os.O_RDWR, 0666)
-	if err != nil {
-		if !os.IsNotExist(err) {
-			return nil, err
-		}
-
-		f, err = fileutil.LockFile(p, os.O_RDWR|os.O_CREATE, 0666)
-		if err != nil {
-			return nil, err
-		}
-		if _, err = f.Seek(0, os.SEEK_END); err != nil {
-			return nil, err
-		}
-	}
-	enc, err := newWALEncoder(f.File)
+	df, err := fileutil.OpenDir(dir)
 	if err != nil {
 		return nil, err
 	}
 
 	w := &WAL{
-		f:             f,
+		dirFile:       df,
 		logger:        l,
-		enc:           enc,
 		flushInterval: flushInterval,
-		symbols:       map[string]uint32{},
 		donec:         make(chan struct{}),
 		stopc:         make(chan struct{}),
+		segmentSize:   walSegmentSizeBytes,
+		crc32:         crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 	}
+	if err := w.initSegments(); err != nil {
+		return nil, err
+	}
+
 	go w.run(flushInterval)
 
 	return w, nil
 }
 
-type walHandler struct {
-	sample func(refdSample) error
-	series func(labels.Labels) error
+// Reader returns a new reader over the the write ahead log data.
+// It must be completely consumed before writing to the WAL.
+func (w *WAL) Reader() *WALReader {
+	var rs []io.ReadCloser
+	for _, f := range w.files {
+		rs = append(rs, f)
+	}
+	return NewWALReader(rs...)
 }
 
-// ReadAll consumes all entries in the WAL and triggers the registered handlers.
-func (w *WAL) ReadAll(h *walHandler) error {
-	dec := &walDecoder{
-		r:       w.f,
-		handler: h,
+// Log writes a batch of new series labels and samples to the log.
+func (w *WAL) Log(series []labels.Labels, samples []refdSample) error {
+	if err := w.encodeSeries(series); err != nil {
+		return err
+	}
+	if err := w.encodeSamples(samples); err != nil {
+		return err
 	}
+	if w.flushInterval <= 0 {
+		return w.Sync()
+	}
+	return nil
+}
 
-	for {
-		if err := dec.entry(); err != nil {
-			if err == io.EOF {
-				return nil
+// initSegments finds all existing segment files and opens them in the
+// appropriate file modes.
+func (w *WAL) initSegments() error {
+	fns, err := sequenceFiles(w.dirFile.Name(), "")
+	if err != nil {
+		return err
+	}
+	if len(fns) == 0 {
+		return nil
+	}
+	if len(fns) > 1 {
+		for _, fn := range fns[:len(fns)-1] {
+			f, err := os.Open(fn)
+			if err != nil {
+				return err
 			}
-			return err
+			w.files = append(w.files, f)
+		}
+	}
+	// The most recent WAL file is the one we have to keep appending to.
+	f, err := os.OpenFile(fns[len(fns)-1], os.O_RDWR, 0666)
+	if err != nil {
+		return err
+	}
+	w.files = append(w.files, f)
+
+	// Consume and validate meta headers.
+	for _, f := range w.files {
+		metab := make([]byte, 8)
+
+		if n, err := f.Read(metab); err != nil {
+			return errors.Wrapf(err, "validate meta %q", f.Name())
+		} else if n != 8 {
+			return errors.Errorf("invalid header size %d in %q", n, f.Name())
+		}
+
+		if m := binary.BigEndian.Uint32(metab[:4]); m != WALMagic {
+			return errors.Errorf("invalid magic header %x in %q", m, f.Name())
+		}
+		if metab[4] != WALFormatDefault {
+			return errors.Errorf("unknown WAL segment format %d in %q", metab[4], f.Name())
 		}
 	}
+
+	return nil
 }
 
-// Log writes a batch of new series labels and samples to the log.
-func (w *WAL) Log(series []labels.Labels, samples []refdSample) error {
-	if err := w.enc.encodeSeries(series); err != nil {
+// cut finishes the currently active segments and open the next one.
+// The encoder is reset to point to the new segment.
+func (w *WAL) cut() error {
+	// Sync current tail to disc and close.
+	if tf := w.tail(); tf != nil {
+		if err := w.sync(); err != nil {
+			return err
+		}
+		off, err := tf.Seek(0, os.SEEK_CUR)
+		if err != nil {
+			return err
+		}
+		if err := tf.Truncate(off); err != nil {
+			return err
+		}
+		if err := tf.Close(); err != nil {
+			return err
+		}
+	}
+
+	p, _, err := nextSequenceFile(w.dirFile.Name(), "")
+	if err != nil {
 		return err
 	}
-	if err := w.enc.encodeSamples(samples); err != nil {
+	f, err := os.Create(p)
+	if err != nil {
 		return err
 	}
-	if w.flushInterval <= 0 {
-		return w.sync()
+	if err = fileutil.Preallocate(f, w.segmentSize, true); err != nil {
+		return err
 	}
+	if err = w.dirFile.Sync(); err != nil {
+		return err
+	}
+
+	// Write header metadata for new file.
+	metab := make([]byte, 8)
+	binary.BigEndian.PutUint32(metab[:4], WALMagic)
+	metab[4] = WALFormatDefault
+
+	if _, err := f.Write(metab); err != nil {
+		return err
+	}
+
+	w.files = append(w.files, f)
+	w.cur = bufio.NewWriterSize(f, 4*1024*1024)
+	w.curN = 8
+
 	return nil
 }
 
+func (w *WAL) tail() *os.File {
+	if len(w.files) == 0 {
+		return nil
+	}
+	return w.files[len(w.files)-1]
+}
+
+func (w *WAL) Sync() error {
+	w.mtx.Lock()
+	defer w.mtx.Unlock()
+
+	return w.sync()
+}
+
 func (w *WAL) sync() error {
-	if err := w.enc.flush(); err != nil {
+	if w.cur == nil {
+		return nil
+	}
+	if err := w.cur.Flush(); err != nil {
 		return err
 	}
-	return fileutil.Fdatasync(w.f.File)
+	return fileutil.Fdatasync(w.tail())
 }
 
 func (w *WAL) run(interval time.Duration) {
@@ -145,7 +253,7 @@ func (w *WAL) run(interval time.Duration) {
 		case <-w.stopc:
 			return
 		case <-tick:
-			if err := w.sync(); err != nil {
+			if err := w.Sync(); err != nil {
 				w.logger.Log("msg", "sync failed", "err", err)
 			}
 		}
@@ -157,16 +265,18 @@ func (w *WAL) Close() error {
 	close(w.stopc)
 	<-w.donec
 
+	w.mtx.Lock()
+	defer w.mtx.Unlock()
+
 	if err := w.sync(); err != nil {
 		return err
 	}
-	return w.f.Close()
-}
-
-type walEncoder struct {
-	mtx sync.Mutex
-	// w   *ioutil.PageWriter
-	w *bufio.Writer
+	// On opening, a WAL must be fully consumed once. Afterwards
+	// only the current segment will still be open.
+	if tf := w.tail(); tf != nil {
+		return tf.Close()
+	}
+	return nil
 }
 
 const (
@@ -178,31 +288,24 @@ const (
 	walPageBytes = 16 * minSectorSize
 )
 
-func newWALEncoder(f *os.File) (*walEncoder, error) {
-	// offset, err := f.Seek(0, os.SEEK_CUR)
-	// if err != nil {
-	// 	return nil, err
-	// }
-	enc := &walEncoder{
-		// w: ioutil.NewPageWriter(f, walPageBytes, int(offset)),
-		w: bufio.NewWriterSize(f, 4*1024*1024),
-	}
-	return enc, nil
-}
-
-func (e *walEncoder) flush() error {
-	e.mtx.Lock()
-	defer e.mtx.Unlock()
+func (w *WAL) entry(et WALEntryType, flag byte, buf []byte) error {
+	w.mtx.Lock()
+	defer w.mtx.Unlock()
 
-	return e.w.Flush()
-}
-
-func (e *walEncoder) entry(et WALEntryType, flag byte, buf []byte) error {
-	e.mtx.Lock()
-	defer e.mtx.Unlock()
+	// Cut to the next segment if exceeds the file size unless it would also
+	// exceed the size of a new segment.
+	var (
+		sz    = int64(6 + 4 + len(buf))
+		newsz = w.curN + sz
+	)
+	if w.cur == nil || w.curN > w.segmentSize || newsz > w.segmentSize && sz <= w.segmentSize {
+		if err := w.cut(); err != nil {
+			return err
+		}
+	}
 
-	h := crc32.NewIEEE()
-	w := io.MultiWriter(h, e.w)
+	w.crc32.Reset()
+	wr := io.MultiWriter(w.crc32, w.cur)
 
 	b := make([]byte, 6)
 	b[0] = byte(et)
@@ -210,16 +313,18 @@ func (e *walEncoder) entry(et WALEntryType, flag byte, buf []byte) error {
 
 	binary.BigEndian.PutUint32(b[2:], uint32(len(buf)))
 
-	if _, err := w.Write(b); err != nil {
+	if _, err := wr.Write(b); err != nil {
 		return err
 	}
-	if _, err := w.Write(buf); err != nil {
+	if _, err := wr.Write(buf); err != nil {
 		return err
 	}
-	if _, err := e.w.Write(h.Sum(nil)); err != nil {
+	if _, err := w.cur.Write(w.crc32.Sum(nil)); err != nil {
 		return err
 	}
 
+	w.curN += sz
+
 	putWALBuffer(buf)
 	return nil
 }
@@ -244,7 +349,7 @@ func putWALBuffer(b []byte) {
 	walBuffers.Put(b)
 }
 
-func (e *walEncoder) encodeSeries(series []labels.Labels) error {
+func (w *WAL) encodeSeries(series []labels.Labels) error {
 	if len(series) == 0 {
 		return nil
 	}
@@ -267,10 +372,10 @@ func (e *walEncoder) encodeSeries(series []labels.Labels) error {
 		}
 	}
 
-	return e.entry(WALEntrySeries, walSeriesSimple, buf)
+	return w.entry(WALEntrySeries, walSeriesSimple, buf)
 }
 
-func (e *walEncoder) encodeSamples(samples []refdSample) error {
+func (w *WAL) encodeSamples(samples []refdSample) error {
 	if len(samples) == 0 {
 		return nil
 	}
@@ -300,25 +405,127 @@ func (e *walEncoder) encodeSamples(samples []refdSample) error {
 		buf = append(buf, b[:8]...)
 	}
 
-	return e.entry(WALEntrySamples, walSamplesSimple, buf)
+	return w.entry(WALEntrySamples, walSamplesSimple, buf)
 }
 
-type walDecoder struct {
-	r       io.Reader
-	handler *walHandler
+// WALReader decodes and emits write ahead log entries.
+type WALReader struct {
+	rs    []io.ReadCloser
+	cur   int
+	buf   []byte
+	crc32 hash.Hash32
 
-	buf []byte
+	err     error
+	labels  []labels.Labels
+	samples []refdSample
 }
 
-func newWALDecoer(r io.Reader, h *walHandler) *walDecoder {
-	return &walDecoder{
-		r:       r,
-		handler: h,
-		buf:     make([]byte, 0, 1024*1024),
+// NewWALReader returns a new WALReader over the sequence of the given ReadClosers.
+func NewWALReader(rs ...io.ReadCloser) *WALReader {
+	return &WALReader{
+		rs:    rs,
+		buf:   make([]byte, 0, 128*4096),
+		crc32: crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 	}
 }
 
-func (d *walDecoder) decodeSeries(flag byte, b []byte) error {
+// At returns the last decoded entry of labels or samples.
+func (r *WALReader) At() ([]labels.Labels, []refdSample) {
+	return r.labels, r.samples
+}
+
+// Err returns the last error the reader encountered.
+func (r *WALReader) Err() error {
+	return r.err
+}
+
+// nextEntry retrieves the next entry. It is also used as a testing hook.
+func (r *WALReader) nextEntry() (WALEntryType, byte, []byte, error) {
+	if r.cur >= len(r.rs) {
+		return 0, 0, nil, io.EOF
+	}
+	cr := r.rs[r.cur]
+
+	et, flag, b, err := r.entry(cr)
+	if err == io.EOF {
+		// Current reader completed, close and move to the next one.
+		if err := cr.Close(); err != nil {
+			return 0, 0, nil, err
+		}
+		r.cur++
+		return r.nextEntry()
+	}
+	return et, flag, b, err
+}
+
+// Next returns decodes the next entry pair and returns true
+// if it was succesful.
+func (r *WALReader) Next() bool {
+	r.labels = r.labels[:0]
+	r.samples = r.samples[:0]
+
+	et, flag, b, err := r.nextEntry()
+	if err != nil {
+		if err != io.EOF {
+			r.err = err
+		}
+		return false
+	}
+
+	switch et {
+	case WALEntrySamples:
+		if err := r.decodeSamples(flag, b); err != nil {
+			r.err = err
+		}
+	case WALEntrySeries:
+		if err := r.decodeSeries(flag, b); err != nil {
+			r.err = err
+		}
+	default:
+		r.err = errors.Errorf("unknown WAL entry type %d", et)
+	}
+	return r.err == nil
+}
+
+func (r *WALReader) entry(cr io.Reader) (WALEntryType, byte, []byte, error) {
+	r.crc32.Reset()
+	tr := io.TeeReader(cr, r.crc32)
+
+	b := make([]byte, 6)
+	if _, err := tr.Read(b); err != nil {
+		return 0, 0, nil, err
+	}
+
+	var (
+		etype  = WALEntryType(b[0])
+		flag   = b[1]
+		length = int(binary.BigEndian.Uint32(b[2:]))
+	)
+	// Exit if we reached pre-allocated space.
+	if etype == 0 {
+		return 0, 0, nil, io.EOF
+	}
+
+	if length > len(r.buf) {
+		r.buf = make([]byte, length)
+	}
+	buf := r.buf[:length]
+
+	if _, err := tr.Read(buf); err != nil {
+		return 0, 0, nil, err
+	}
+	_, err := cr.Read(b[:4])
+	if err != nil {
+		return 0, 0, nil, err
+	}
+	if exp, has := binary.BigEndian.Uint32(b[:4]), r.crc32.Sum32(); has != exp {
+		return 0, 0, nil, errors.Errorf("unexpected CRC32 checksum %x, want %x", has, exp)
+	}
+
+	return etype, flag, buf, nil
+}
+
+func (r *WALReader) decodeSeries(flag byte, b []byte) error {
 	for len(b) > 0 {
 		l, n := binary.Uvarint(b)
 		if n < 1 {
@@ -343,14 +550,12 @@ func (d *walDecoder) decodeSeries(flag byte, b []byte) error {
 			b = b[n+int(vl):]
 		}
 
-		if err := d.handler.series(lset); err != nil {
-			return err
-		}
+		r.labels = append(r.labels, lset)
 	}
 	return nil
 }
 
-func (d *walDecoder) decodeSamples(flag byte, b []byte) error {
+func (r *WALReader) decodeSamples(flag byte, b []byte) error {
 	if len(b) < 16 {
 		return errors.Wrap(errInvalidSize, "header length")
 	}
@@ -384,45 +589,7 @@ func (d *walDecoder) decodeSamples(flag byte, b []byte) error {
 		smpl.v = float64(math.Float64frombits(binary.BigEndian.Uint64(b)))
 		b = b[8:]
 
-		if err := d.handler.sample(smpl); err != nil {
-			return err
-		}
+		r.samples = append(r.samples, smpl)
 	}
 	return nil
 }
-
-func (d *walDecoder) entry() error {
-	b := make([]byte, 6)
-	if _, err := d.r.Read(b); err != nil {
-		return err
-	}
-
-	var (
-		etype  = WALEntryType(b[0])
-		flag   = b[1]
-		length = int(binary.BigEndian.Uint32(b[2:]))
-	)
-
-	if length > len(d.buf) {
-		d.buf = make([]byte, length)
-	}
-	buf := d.buf[:length]
-
-	if _, err := d.r.Read(buf); err != nil {
-		return err
-	}
-	// Read away checksum.
-	// TODO(fabxc): verify it
-	if _, err := d.r.Read(b[:4]); err != nil {
-		return err
-	}
-
-	switch etype {
-	case WALEntrySeries:
-		return d.decodeSeries(flag, buf)
-	case WALEntrySamples:
-		return d.decodeSamples(flag, buf)
-	}
-
-	return errors.Errorf("unknown WAL entry type %q", etype)
-}
diff --git a/vendor/github.com/fabxc/tsdb/writer.go b/vendor/github.com/fabxc/tsdb/writer.go
index a73f2bd11..6b4e31deb 100644
--- a/vendor/github.com/fabxc/tsdb/writer.go
+++ b/vendor/github.com/fabxc/tsdb/writer.go
@@ -3,6 +3,7 @@ package tsdb
 import (
 	"bufio"
 	"encoding/binary"
+	"hash"
 	"hash/crc32"
 	"io"
 	"sort"
@@ -24,12 +25,13 @@ const (
 
 const compactionPageBytes = minSectorSize * 64
 
-// SeriesWriter serializes a time block of chunked series data.
-type SeriesWriter interface {
-	// WriteSeries writes the time series data chunks for a single series.
-	// The reference is used to resolve the correct series in the written index.
-	// It only has to be valid for the duration of the write.
-	WriteSeries(ref uint32, l labels.Labels, chunks []ChunkMeta) error
+// ChunkWriter serializes a time block of chunked series data.
+type ChunkWriter interface {
+	// WriteChunks writes several chunks. The data field of the ChunkMetas
+	// must be populated.
+	// After returning successfully, the Ref fields in the ChunkMetas
+	// is set and can be used to retrieve the chunks from the written data.
+	WriteChunks(chunks ...ChunkMeta) error
 
 	// Size returns the size of the data written so far.
 	Size() int64
@@ -39,33 +41,32 @@ type SeriesWriter interface {
 	Close() error
 }
 
-// seriesWriter implements the SeriesWriter interface for the standard
+// chunkWriter implements the ChunkWriter interface for the standard
 // serialization format.
-type seriesWriter struct {
-	ow io.Writer
-	w  *bufio.Writer
-	n  int64
-	c  int
-
-	index IndexWriter
+type chunkWriter struct {
+	ow    io.Writer
+	w     *bufio.Writer
+	n     int64
+	c     int
+	crc32 hash.Hash
 }
 
-func newSeriesWriter(w io.Writer, index IndexWriter) *seriesWriter {
-	return &seriesWriter{
+func newChunkWriter(w io.Writer) *chunkWriter {
+	return &chunkWriter{
 		ow:    w,
 		w:     bufio.NewWriterSize(w, 1*1024*1024),
 		n:     0,
-		index: index,
+		crc32: crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 	}
 }
 
-func (w *seriesWriter) write(wr io.Writer, b []byte) error {
+func (w *chunkWriter) write(wr io.Writer, b []byte) error {
 	n, err := wr.Write(b)
 	w.n += int64(n)
 	return err
 }
 
-func (w *seriesWriter) writeMeta() error {
+func (w *chunkWriter) writeMeta() error {
 	b := [8]byte{}
 
 	binary.BigEndian.PutUint32(b[:4], MagicSeries)
@@ -74,7 +75,7 @@ func (w *seriesWriter) writeMeta() error {
 	return w.write(w.w, b[:])
 }
 
-func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []ChunkMeta) error {
+func (w *chunkWriter) WriteChunks(chks ...ChunkMeta) error {
 	// Initialize with meta data.
 	if w.n == 0 {
 		if err := w.writeMeta(); err != nil {
@@ -82,9 +83,8 @@ func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []ChunkM
 		}
 	}
 
-	// TODO(fabxc): is crc32 enough for chunks of one series?
-	h := crc32.NewIEEE()
-	wr := io.MultiWriter(h, w.w)
+	w.crc32.Reset()
+	wr := io.MultiWriter(w.crc32, w.w)
 
 	// For normal reads we don't need the number of the chunk section but
 	// it allows us to verify checksums without reading the index file.
@@ -101,7 +101,7 @@ func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []ChunkM
 	for i := range chks {
 		chk := &chks[i]
 
-		chk.Ref = uint32(w.n)
+		chk.Ref = uint64(w.n)
 
 		n = binary.PutUvarint(b[:], uint64(len(chk.Chunk.Bytes())))
 
@@ -117,21 +117,17 @@ func (w *seriesWriter) WriteSeries(ref uint32, lset labels.Labels, chks []ChunkM
 		chk.Chunk = nil
 	}
 
-	if err := w.write(w.w, h.Sum(nil)); err != nil {
+	if err := w.write(w.w, w.crc32.Sum(nil)); err != nil {
 		return err
 	}
-
-	if w.index != nil {
-		w.index.AddSeries(ref, lset, chks...)
-	}
 	return nil
 }
 
-func (w *seriesWriter) Size() int64 {
+func (w *chunkWriter) Size() int64 {
 	return w.n
 }
 
-func (w *seriesWriter) Close() error {
+func (w *chunkWriter) Close() error {
 	// Initialize block in case no data was written to it.
 	if w.n == 0 {
 		if err := w.writeMeta(); err != nil {
@@ -146,7 +142,7 @@ type ChunkMeta struct {
 	// Ref and Chunk hold either a reference that can be used to retrieve
 	// chunk data or the data itself.
 	// Generally, only one of them is set.
-	Ref   uint32
+	Ref   uint64
 	Chunk chunks.Chunk
 
 	MinTime, MaxTime int64 // time range the data covers
@@ -195,6 +191,8 @@ type indexWriter struct {
 	symbols      map[string]uint32 // symbol offsets
 	labelIndexes []hashEntry       // label index offsets
 	postings     []hashEntry       // postings lists offsets
+
+	crc32 hash.Hash
 }
 
 func newIndexWriter(w io.Writer) *indexWriter {
@@ -204,6 +202,7 @@ func newIndexWriter(w io.Writer) *indexWriter {
 		n:       0,
 		symbols: make(map[string]uint32, 4096),
 		series:  make(map[uint32]*indexWriterSeries, 4096),
+		crc32:   crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 	}
 }
 
@@ -215,8 +214,8 @@ func (w *indexWriter) write(wr io.Writer, b []byte) error {
 
 // section writes a CRC32 checksummed section of length l and guarded by flag.
 func (w *indexWriter) section(l uint32, flag byte, f func(w io.Writer) error) error {
-	h := crc32.NewIEEE()
-	wr := io.MultiWriter(h, w.w)
+	w.crc32.Reset()
+	wr := io.MultiWriter(w.crc32, w.w)
 
 	b := [5]byte{flag, 0, 0, 0, 0}
 	binary.BigEndian.PutUint32(b[1:], l)
@@ -228,7 +227,7 @@ func (w *indexWriter) section(l uint32, flag byte, f func(w io.Writer) error) er
 	if err := f(wr); err != nil {
 		return errors.Wrap(err, "contents write func")
 	}
-	if err := w.write(w.w, h.Sum(nil)); err != nil {
+	if err := w.write(w.w, w.crc32.Sum(nil)); err != nil {
 		return errors.Wrap(err, "writing checksum")
 	}
 	return nil
diff --git a/vendor/github.com/nightlyone/lockfile/LICENSE b/vendor/github.com/nightlyone/lockfile/LICENSE
new file mode 100644
index 000000000..eb5b80468
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2012 Ingo Oeser
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/vendor/github.com/nightlyone/lockfile/README.md b/vendor/github.com/nightlyone/lockfile/README.md
new file mode 100644
index 000000000..54ee19cc4
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/README.md
@@ -0,0 +1,52 @@
+lockfile
+=========
+Handle locking via pid files.
+
+[![Build Status Unix][1]][2]
+[![Build status Windows][3]][4]
+
+[1]: https://secure.travis-ci.org/nightlyone/lockfile.png
+[2]: https://travis-ci.org/nightlyone/lockfile
+[3]: https://ci.appveyor.com/api/projects/status/7mojkmauj81uvp8u/branch/master?svg=true
+[4]: https://ci.appveyor.com/project/nightlyone/lockfile/branch/master
+
+
+
+install
+-------
+Install [Go 1][5], either [from source][6] or [with a prepackaged binary][7].
+For Windows suport, Go 1.4 or newer is required.
+
+Then run
+
+	go get github.com/nightlyone/lockfile
+
+[5]: http://golang.org
+[6]: http://golang.org/doc/install/source
+[7]: http://golang.org/doc/install
+
+LICENSE
+-------
+BSD
+
+documentation
+-------------
+[package documentation at godoc.org](http://godoc.org/github.com/nightlyone/lockfile)
+
+install
+-------------------
+	go get github.com/nightlyone/lockfile
+
+
+contributing
+============
+
+Contributions are welcome. Please open an issue or send me a pull request for a dedicated branch.
+Make sure the git commit hooks show it works.
+
+git commit hooks
+-----------------------
+enable commit hooks via
+
+        cd .git ; rm -rf hooks; ln -s ../git-hooks hooks ; cd ..
+
diff --git a/vendor/github.com/nightlyone/lockfile/appveyor.yml b/vendor/github.com/nightlyone/lockfile/appveyor.yml
new file mode 100644
index 000000000..cf72a58b1
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/appveyor.yml
@@ -0,0 +1,12 @@
+clone_folder: c:\gopath\src\github.com\nightlyone\lockfile
+
+environment:
+  GOPATH: c:\gopath
+
+install:
+  - go version
+  - go env
+  - go get -v -t ./...
+
+build_script:
+  - go test -v ./...
diff --git a/vendor/github.com/nightlyone/lockfile/lockfile.go b/vendor/github.com/nightlyone/lockfile/lockfile.go
new file mode 100644
index 000000000..da00bec78
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/lockfile.go
@@ -0,0 +1,201 @@
+// Package lockfile handles pid file based locking.
+// While a sync.Mutex helps against concurrency issues within a single process,
+// this package is designed to help against concurrency issues between cooperating processes
+// or serializing multiple invocations of the same process. You can also combine sync.Mutex
+// with Lockfile in order to serialize an action between different goroutines in a single program
+// and also multiple invocations of this program.
+package lockfile
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// Lockfile is a pid file which can be locked
+type Lockfile string
+
+// TemporaryError is a type of error where a retry after a random amount of sleep should help to mitigate it.
+type TemporaryError string
+
+func (t TemporaryError) Error() string { return string(t) }
+
+// Temporary returns always true.
+// It exists, so you can detect it via
+//	if te, ok := err.(interface{ Temporary() bool }); ok {
+//		fmt.Println("I am a temporay error situation, so wait and retry")
+//	}
+func (t TemporaryError) Temporary() bool { return true }
+
+// Various errors returned by this package
+var (
+	ErrBusy          = TemporaryError("Locked by other process")             // If you get this, retry after a short sleep might help
+	ErrNotExist      = TemporaryError("Lockfile created, but doesn't exist") // If you get this, retry after a short sleep might help
+	ErrNeedAbsPath   = errors.New("Lockfiles must be given as absolute path names")
+	ErrInvalidPid    = errors.New("Lockfile contains invalid pid for system")
+	ErrDeadOwner     = errors.New("Lockfile contains pid of process not existent on this system anymore")
+	ErrRogueDeletion = errors.New("Lockfile owned by me has been removed unexpectedly")
+)
+
+// New describes a new filename located at the given absolute path.
+func New(path string) (Lockfile, error) {
+	if !filepath.IsAbs(path) {
+		return Lockfile(""), ErrNeedAbsPath
+	}
+	return Lockfile(path), nil
+}
+
+// GetOwner returns who owns the lockfile.
+func (l Lockfile) GetOwner() (*os.Process, error) {
+	name := string(l)
+
+	// Ok, see, if we have a stale lockfile here
+	content, err := ioutil.ReadFile(name)
+	if err != nil {
+		return nil, err
+	}
+
+	// try hard for pids. If no pid, the lockfile is junk anyway and we delete it.
+	pid, err := scanPidLine(content)
+	if err != nil {
+		return nil, err
+	}
+	running, err := isRunning(pid)
+	if err != nil {
+		return nil, err
+	}
+
+	if running {
+		proc, err := os.FindProcess(pid)
+		if err != nil {
+			return nil, err
+		}
+		return proc, nil
+	}
+	return nil, ErrDeadOwner
+
+}
+
+// TryLock tries to own the lock.
+// It Returns nil, if successful and and error describing the reason, it didn't work out.
+// Please note, that existing lockfiles containing pids of dead processes
+// and lockfiles containing no pid at all are simply deleted.
+func (l Lockfile) TryLock() error {
+	name := string(l)
+
+	// This has been checked by New already. If we trigger here,
+	// the caller didn't use New and re-implemented it's functionality badly.
+	// So panic, that he might find this easily during testing.
+	if !filepath.IsAbs(name) {
+		panic(ErrNeedAbsPath)
+	}
+
+	tmplock, err := ioutil.TempFile(filepath.Dir(name), "")
+	if err != nil {
+		return err
+	}
+
+	cleanup := func() {
+		_ = tmplock.Close()
+		_ = os.Remove(tmplock.Name())
+	}
+	defer cleanup()
+
+	if err := writePidLine(tmplock, os.Getpid()); err != nil {
+		return err
+	}
+
+	// return value intentionally ignored, as ignoring it is part of the algorithm
+	_ = os.Link(tmplock.Name(), name)
+
+	fiTmp, err := os.Lstat(tmplock.Name())
+	if err != nil {
+		return err
+	}
+	fiLock, err := os.Lstat(name)
+	if err != nil {
+		// tell user that a retry would be a good idea
+		if os.IsNotExist(err) {
+			return ErrNotExist
+		}
+		return err
+	}
+
+	// Success
+	if os.SameFile(fiTmp, fiLock) {
+		return nil
+	}
+
+	proc, err := l.GetOwner()
+	switch err {
+	default:
+		// Other errors -> defensively fail and let caller handle this
+		return err
+	case nil:
+		if proc.Pid != os.Getpid() {
+			return ErrBusy
+		}
+	case ErrDeadOwner, ErrInvalidPid:
+		// cases we can fix below
+	}
+
+	// clean stale/invalid lockfile
+	err = os.Remove(name)
+	if err != nil {
+		// If it doesn't exist, then it doesn't matter who removed it.
+		if !os.IsNotExist(err) {
+			return err
+		}
+	}
+
+	// now that the stale lockfile is gone, let's recurse
+	return l.TryLock()
+}
+
+// Unlock a lock again, if we owned it. Returns any error that happend during release of lock.
+func (l Lockfile) Unlock() error {
+	proc, err := l.GetOwner()
+	switch err {
+	case ErrInvalidPid, ErrDeadOwner:
+		return ErrRogueDeletion
+	case nil:
+		if proc.Pid == os.Getpid() {
+			// we really own it, so let's remove it.
+			return os.Remove(string(l))
+		}
+		// Not owned by me, so don't delete it.
+		return ErrRogueDeletion
+	default:
+		// This is an application error or system error.
+		// So give a better error for logging here.
+		if os.IsNotExist(err) {
+			return ErrRogueDeletion
+		}
+		// Other errors -> defensively fail and let caller handle this
+		return err
+	}
+}
+
+func writePidLine(w io.Writer, pid int) error {
+	_, err := io.WriteString(w, fmt.Sprintf("%d\n", pid))
+	return err
+}
+
+func scanPidLine(content []byte) (int, error) {
+	if len(content) == 0 {
+		return 0, ErrInvalidPid
+	}
+
+	var pid int
+	if _, err := fmt.Sscanln(string(content), &pid); err != nil {
+		return 0, ErrInvalidPid
+	}
+
+	if pid <= 0 {
+		return 0, ErrInvalidPid
+	}
+	return pid, nil
+}
diff --git a/vendor/github.com/nightlyone/lockfile/lockfile_unix.go b/vendor/github.com/nightlyone/lockfile/lockfile_unix.go
new file mode 100644
index 000000000..742b041fb
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/lockfile_unix.go
@@ -0,0 +1,20 @@
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package lockfile
+
+import (
+	"os"
+	"syscall"
+)
+
+func isRunning(pid int) (bool, error) {
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		return false, err
+	}
+
+	if err := proc.Signal(syscall.Signal(0)); err != nil {
+		return false, nil
+	}
+	return true, nil
+}
diff --git a/vendor/github.com/nightlyone/lockfile/lockfile_windows.go b/vendor/github.com/nightlyone/lockfile/lockfile_windows.go
new file mode 100644
index 000000000..482bd91d7
--- /dev/null
+++ b/vendor/github.com/nightlyone/lockfile/lockfile_windows.go
@@ -0,0 +1,30 @@
+package lockfile
+
+import (
+	"syscall"
+)
+
+//For some reason these consts don't exist in syscall.
+const (
+	error_invalid_parameter = 87
+	code_still_active       = 259
+)
+
+func isRunning(pid int) (bool, error) {
+	procHnd, err := syscall.OpenProcess(syscall.PROCESS_QUERY_INFORMATION, true, uint32(pid))
+	if err != nil {
+		if scerr, ok := err.(syscall.Errno); ok {
+			if uintptr(scerr) == error_invalid_parameter {
+				return false, nil
+			}
+		}
+	}
+
+	var code uint32
+	err = syscall.GetExitCodeProcess(procHnd, &code)
+	if err != nil {
+		return false, err
+	}
+
+	return code == code_still_active, nil
+}
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 4b43ef544..6df803d5e 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -368,10 +368,10 @@
 			"revisionTime": "2016-09-30T00:14:02Z"
 		},
 		{
-			"checksumSHA1": "8moNbKzCSmH0RNnoroJikyd95aA=",
+			"checksumSHA1": "edB8coiX4s6hf6BZuYE5+MPJYX8=",
 			"path": "github.com/fabxc/tsdb",
-			"revision": "012cf4ef254e34a10befd0b592bcfa5b1794e92b",
-			"revisionTime": "2017-02-04T10:53:52Z"
+			"revision": "f734773214e1bcb7962d92155863110d01214db5",
+			"revisionTime": "2017-02-19T12:01:19Z"
 		},
 		{
 			"checksumSHA1": "uVzWuLvF646YjiKomsc2CR1ua58=",
@@ -567,6 +567,12 @@
 			"revision": "58f52c57ce9df13460ac68200cef30a008b9c468",
 			"revisionTime": "2016-10-18T06:08:08Z"
 		},
+		{
+			"checksumSHA1": "aCtmlyAgau9n0UHs8Pk+3xfIaVk=",
+			"path": "github.com/nightlyone/lockfile",
+			"revision": "1d49c987357a327b5b03aa84cbddd582c328615d",
+			"revisionTime": "2016-09-28T00:14:32Z"
+		},
 		{
 			"checksumSHA1": "3YJklSuzSE1Rt8A+2dhiWSmf/fw=",
 			"origin": "k8s.io/client-go/1.5/vendor/github.com/pborman/uuid",