Add a tsdb writer interface (#7950)

* add a tsdb writer interface

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* use block writer in tsdbutil block creator

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* pass thru context

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* use block writer in blockutil and also in tests

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* fix link err

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* add err handling for defer

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* add blockwriter test

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* mv initHead into NewBlockWriter, update tests

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

* use blocksize arg, make test more concise

Signed-off-by: jessicagreben <jessicagrebens@gmail.com>

tsdb/block_test.go

@@ -302,12 +302,9 @@ func TestReadIndexFormatV1(t *testing.T) {
 
 // createBlock creates a block with given set of series and returns its dir.
 func createBlock(tb testing.TB, dir string, series []storage.Series) string {
-	chunkDir, err := ioutil.TempDir("", "chunk_dir")
+	blockDir, err := CreateBlock(series, dir, 0, log.NewNopLogger())
 	testutil.Ok(tb, err)
-	defer func() { testutil.Ok(tb, os.RemoveAll(chunkDir)) }()
-	head := createHead(tb, nil, series, chunkDir)
-	defer func() { testutil.Ok(tb, head.Close()) }()
-	return createBlockFromHead(tb, dir, head)
+	return blockDir
 }
 
 func createBlockFromHead(tb testing.TB, dir string, head *Head) string {

tsdb/blockwriter.go

@@ -0,0 +1,122 @@
+// Copyright 2020 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tsdb
+
+import (
+	"context"
+	"io/ioutil"
+	"math"
+	"os"
+
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+	"github.com/oklog/ulid"
+	"github.com/pkg/errors"
+
+	"github.com/prometheus/prometheus/pkg/timestamp"
+	"github.com/prometheus/prometheus/storage"
+	"github.com/prometheus/prometheus/tsdb/chunkenc"
+)
+
+// BlockWriter is a block writer that allows appending and flushing series to disk.
+type BlockWriter struct {
+	logger         log.Logger
+	destinationDir string
+
+	head      *Head
+	blockSize int64 // in ms
+	chunkDir  string
+}
+
+// NewBlockWriter create a new block writer.
+//
+// The returned writer accumulates all the series in the Head block until `Flush` is called.
+//
+// Note that the writer will not check if the target directory exists or
+// contains anything at all. It is the caller's responsibility to
+// ensure that the resulting blocks do not overlap etc.
+// Writer ensures the block flush is atomic (via rename).
+func NewBlockWriter(logger log.Logger, dir string, blockSize int64) (*BlockWriter, error) {
+	w := &BlockWriter{
+		logger:         logger,
+		destinationDir: dir,
+		blockSize:      blockSize,
+	}
+	if err := w.initHead(); err != nil {
+		return nil, err
+	}
+	return w, nil
+}
+
+// initHead creates and initialises a new TSDB head.
+func (w *BlockWriter) initHead() error {
+	chunkDir, err := ioutil.TempDir(os.TempDir(), "head")
+	if err != nil {
+		return errors.Wrap(err, "create temp dir")
+	}
+	w.chunkDir = chunkDir
+
+	h, err := NewHead(nil, w.logger, nil, w.blockSize, w.chunkDir, nil, DefaultStripeSize, nil)
+	if err != nil {
+		return errors.Wrap(err, "tsdb.NewHead")
+	}
+
+	w.head = h
+	return w.head.Init(math.MinInt64)
+}
+
+// Appender returns a new appender on the database.
+// Appender can't be called concurrently. However, the returned Appender can safely be used concurrently.
+func (w *BlockWriter) Appender(ctx context.Context) storage.Appender {
+	return w.head.Appender(ctx)
+}
+
+// Flush implements the Writer interface. This is where actual block writing
+// happens. After flush completes, no writes can be done.
+func (w *BlockWriter) Flush(ctx context.Context) (ulid.ULID, error) {
+	seriesCount := w.head.NumSeries()
+	if w.head.NumSeries() == 0 {
+		return ulid.ULID{}, errors.New("no series appended, aborting")
+	}
+
+	mint := w.head.MinTime()
+	// Add +1 millisecond to block maxt because block intervals are half-open: [b.MinTime, b.MaxTime).
+	// Because of this block intervals are always +1 than the total samples it includes.
+	maxt := w.head.MaxTime() + 1
+	level.Info(w.logger).Log("msg", "flushing", "series_count", seriesCount, "mint", timestamp.Time(mint), "maxt", timestamp.Time(maxt))
+
+	compactor, err := NewLeveledCompactor(ctx,
+		nil,
+		w.logger,
+		[]int64{w.blockSize},
+		chunkenc.NewPool())
+	if err != nil {
+		return ulid.ULID{}, errors.Wrap(err, "create leveled compactor")
+	}
+	id, err := compactor.Write(w.destinationDir, w.head, mint, maxt, nil)
+	if err != nil {
+		return ulid.ULID{}, errors.Wrap(err, "compactor write")
+	}
+
+	return id, nil
+}
+
+func (w *BlockWriter) Close() error {
+	defer func() {
+		if err := os.RemoveAll(w.chunkDir); err != nil {
+			level.Error(w.logger).Log("msg", "error in deleting BlockWriter files", "err", err)
+		}
+	}()
+	return w.head.Close()
+}

tsdb/blockwriter_test.go

@@ -0,0 +1,67 @@
+// Copyright 2020 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tsdb
+
+import (
+	"context"
+	"io/ioutil"
+	"math"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/go-kit/kit/log"
+	"github.com/pkg/errors"
+	"github.com/prometheus/prometheus/pkg/labels"
+	"github.com/prometheus/prometheus/tsdb/tsdbutil"
+	"github.com/prometheus/prometheus/util/testutil"
+)
+
+func TestBlockWriter(t *testing.T) {
+	ctx := context.Background()
+	outputDir, err := ioutil.TempDir(os.TempDir(), "output")
+	testutil.Ok(t, err)
+	w, err := NewBlockWriter(log.NewNopLogger(), outputDir, DefaultBlockDuration)
+	testutil.Ok(t, err)
+
+	// Flush with no series results in error.
+	_, err = w.Flush(ctx)
+	testutil.ErrorEqual(t, err, errors.New("no series appended, aborting"))
+
+	// Add some series.
+	app := w.Appender(ctx)
+	ts1, v1 := int64(44), float64(7)
+	_, err = app.Add(labels.Labels{{Name: "a", Value: "b"}}, ts1, v1)
+	testutil.Ok(t, err)
+	ts2, v2 := int64(55), float64(12)
+	_, err = app.Add(labels.Labels{{Name: "c", Value: "d"}}, ts2, v2)
+	testutil.Ok(t, err)
+	testutil.Ok(t, app.Commit())
+	id, err := w.Flush(ctx)
+	testutil.Ok(t, err)
+
+	// Confirm the block has the correct data.
+	blockpath := filepath.Join(outputDir, id.String())
+	b, err := OpenBlock(nil, blockpath, nil)
+	testutil.Ok(t, err)
+	q, err := NewBlockQuerier(b, math.MinInt64, math.MaxInt64)
+	testutil.Ok(t, err)
+	series := query(t, q, labels.MustNewMatcher(labels.MatchRegexp, "", ".*"))
+	sample1 := []tsdbutil.Sample{sample{t: ts1, v: v1}}
+	sample2 := []tsdbutil.Sample{sample{t: ts2, v: v2}}
+	expectedSeries := map[string][]tsdbutil.Sample{"{a=\"b\"}": sample1, "{c=\"d\"}": sample2}
+	testutil.Equals(t, expectedSeries, series)
+
+	testutil.Ok(t, w.Close())
+}

tsdb/tsdbblockutil.go

@@ -16,72 +16,61 @@ package tsdb
 import (
 	"context"
 	"fmt"
-	"os"
 	"path/filepath"
 
 	"github.com/go-kit/kit/log"
-	"github.com/prometheus/prometheus/pkg/labels"
+	"github.com/prometheus/prometheus/storage"
 )
 
 var ErrInvalidTimes = fmt.Errorf("max time is lesser than min time")
 
-type MetricSample struct {
-	TimestampMs int64
-	Value       float64
-	Labels      labels.Labels
-}
-
-// CreateHead creates a TSDB writer head to write the sample data to.
-func CreateHead(samples []*MetricSample, chunkRange int64, chunkDir string, logger log.Logger) (*Head, error) {
-	head, err := NewHead(nil, logger, nil, chunkRange, chunkDir, nil, DefaultStripeSize, nil)
-
-	if err != nil {
-		return nil, err
-	}
-	app := head.Appender(context.TODO())
-	for _, sample := range samples {
-		_, err = app.Add(sample.Labels, sample.TimestampMs, sample.Value)
-		if err != nil {
-			return nil, err
-		}
-	}
-	err = app.Commit()
-	if err != nil {
-		return nil, err
-	}
-	return head, nil
-}
-
 // CreateBlock creates a chunkrange block from the samples passed to it, and writes it to disk.
-func CreateBlock(samples []*MetricSample, dir string, mint, maxt int64, logger log.Logger) (string, error) {
-	chunkRange := maxt - mint
+func CreateBlock(series []storage.Series, dir string, chunkRange int64, logger log.Logger) (string, error) {
 	if chunkRange == 0 {
 		chunkRange = DefaultBlockDuration
 	}
 	if chunkRange < 0 {
 		return "", ErrInvalidTimes
 	}
-	chunkDir := filepath.Join(dir, "chunks_tmp")
+
+	w, err := NewBlockWriter(logger, dir, chunkRange)
+	if err != nil {
+		return "", err
+	}
 	defer func() {
-		os.RemoveAll(chunkDir)
+		if err := w.Close(); err != nil {
+			logger.Log("err closing blockwriter", err.Error())
+		}
 	}()
-	head, err := CreateHead(samples, chunkRange, chunkDir, logger)
-	if err != nil {
-		return "", err
-	}
-	defer head.Close()
 
-	compactor, err := NewLeveledCompactor(context.Background(), nil, logger, ExponentialBlockRanges(DefaultBlockDuration, 3, 5), nil)
-	if err != nil {
+	ctx := context.Background()
+	app := w.Appender(ctx)
+
+	for _, s := range series {
+		ref := uint64(0)
+		it := s.Iterator()
+		for it.Next() {
+			t, v := it.At()
+			if ref != 0 {
+				if err := app.AddFast(ref, t, v); err == nil {
+					continue
+				}
+			}
+			ref, err = app.Add(s.Labels(), t, v)
+			if err != nil {
+				return "", err
+			}
+		}
+		if it.Err() != nil {
+			return "", it.Err()
+		}
+	}
+
+	if err = app.Commit(); err != nil {
 		return "", err
 	}
 
-	err = os.MkdirAll(dir, 0777)
-	if err != nil {
-		return "", err
-	}
-
-	ulid, err := compactor.Write(dir, head, mint, maxt, nil)
+	ulid, err := w.Flush(ctx)
 	if err != nil {
 		return "", err
 	}