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383 lines
11 KiB
383 lines
11 KiB
// Copyright 2018 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package wlog
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import (
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"fmt"
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"io"
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"math"
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"os"
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"path/filepath"
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"sort"
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"strconv"
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"strings"
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"github.com/go-kit/log"
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"github.com/go-kit/log/level"
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"github.com/pkg/errors"
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"github.com/prometheus/prometheus/tsdb/chunks"
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tsdb_errors "github.com/prometheus/prometheus/tsdb/errors"
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"github.com/prometheus/prometheus/tsdb/fileutil"
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"github.com/prometheus/prometheus/tsdb/record"
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"github.com/prometheus/prometheus/tsdb/tombstones"
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)
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// CheckpointStats returns stats about a created checkpoint.
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type CheckpointStats struct {
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DroppedSeries int
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DroppedSamples int // Includes histograms.
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DroppedTombstones int
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DroppedExemplars int
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DroppedMetadata int
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TotalSeries int // Processed series including dropped ones.
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TotalSamples int // Processed float and histogram samples including dropped ones.
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TotalTombstones int // Processed tombstones including dropped ones.
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TotalExemplars int // Processed exemplars including dropped ones.
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TotalMetadata int // Processed metadata including dropped ones.
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}
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// LastCheckpoint returns the directory name and index of the most recent checkpoint.
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// If dir does not contain any checkpoints, ErrNotFound is returned.
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func LastCheckpoint(dir string) (string, int, error) {
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checkpoints, err := listCheckpoints(dir)
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if err != nil {
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return "", 0, err
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}
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if len(checkpoints) == 0 {
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return "", 0, record.ErrNotFound
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}
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checkpoint := checkpoints[len(checkpoints)-1]
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return filepath.Join(dir, checkpoint.name), checkpoint.index, nil
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}
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// DeleteCheckpoints deletes all checkpoints in a directory below a given index.
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func DeleteCheckpoints(dir string, maxIndex int) error {
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checkpoints, err := listCheckpoints(dir)
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if err != nil {
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return err
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}
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errs := tsdb_errors.NewMulti()
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for _, checkpoint := range checkpoints {
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if checkpoint.index >= maxIndex {
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break
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}
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errs.Add(os.RemoveAll(filepath.Join(dir, checkpoint.name)))
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}
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return errs.Err()
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}
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const checkpointPrefix = "checkpoint."
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// Checkpoint creates a compacted checkpoint of segments in range [from, to] in the given WAL.
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// It includes the most recent checkpoint if it exists.
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// All series not satisfying keep, samples/tombstones/exemplars below mint and
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// metadata that are not the latest are dropped.
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//
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// The checkpoint is stored in a directory named checkpoint.N in the same
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// segmented format as the original WAL itself.
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// This makes it easy to read it through the WAL package and concatenate
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// it with the original WAL.
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func Checkpoint(logger log.Logger, w *WL, from, to int, keep func(id chunks.HeadSeriesRef) bool, mint int64) (*CheckpointStats, error) {
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stats := &CheckpointStats{}
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var sgmReader io.ReadCloser
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level.Info(logger).Log("msg", "Creating checkpoint", "from_segment", from, "to_segment", to, "mint", mint)
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{
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var sgmRange []SegmentRange
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dir, idx, err := LastCheckpoint(w.Dir())
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if err != nil && err != record.ErrNotFound {
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return nil, errors.Wrap(err, "find last checkpoint")
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}
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last := idx + 1
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if err == nil {
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if from > last {
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return nil, fmt.Errorf("unexpected gap to last checkpoint. expected:%v, requested:%v", last, from)
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}
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// Ignore WAL files below the checkpoint. They shouldn't exist to begin with.
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from = last
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sgmRange = append(sgmRange, SegmentRange{Dir: dir, Last: math.MaxInt32})
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}
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sgmRange = append(sgmRange, SegmentRange{Dir: w.Dir(), First: from, Last: to})
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sgmReader, err = NewSegmentsRangeReader(sgmRange...)
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if err != nil {
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return nil, errors.Wrap(err, "create segment reader")
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}
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defer sgmReader.Close()
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}
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cpdir := checkpointDir(w.Dir(), to)
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cpdirtmp := cpdir + ".tmp"
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if err := os.RemoveAll(cpdirtmp); err != nil {
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return nil, errors.Wrap(err, "remove previous temporary checkpoint dir")
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}
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if err := os.MkdirAll(cpdirtmp, 0o777); err != nil {
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return nil, errors.Wrap(err, "create checkpoint dir")
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}
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cp, err := New(nil, nil, cpdirtmp, w.CompressionEnabled())
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if err != nil {
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return nil, errors.Wrap(err, "open checkpoint")
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}
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// Ensures that an early return caused by an error doesn't leave any tmp files.
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defer func() {
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cp.Close()
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os.RemoveAll(cpdirtmp)
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}()
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r := NewReader(sgmReader)
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var (
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series []record.RefSeries
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samples []record.RefSample
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histogramSamples []record.RefHistogramSample
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tstones []tombstones.Stone
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exemplars []record.RefExemplar
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metadata []record.RefMetadata
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dec record.Decoder
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enc record.Encoder
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buf []byte
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recs [][]byte
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latestMetadataMap = make(map[chunks.HeadSeriesRef]record.RefMetadata)
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)
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for r.Next() {
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series, samples, histogramSamples, tstones, exemplars, metadata = series[:0], samples[:0], histogramSamples[:0], tstones[:0], exemplars[:0], metadata[:0]
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// We don't reset the buffer since we batch up multiple records
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// before writing them to the checkpoint.
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// Remember where the record for this iteration starts.
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start := len(buf)
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rec := r.Record()
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switch dec.Type(rec) {
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case record.Series:
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series, err = dec.Series(rec, series)
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if err != nil {
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return nil, errors.Wrap(err, "decode series")
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}
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// Drop irrelevant series in place.
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repl := series[:0]
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for _, s := range series {
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if keep(s.Ref) {
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repl = append(repl, s)
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}
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}
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if len(repl) > 0 {
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buf = enc.Series(repl, buf)
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}
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stats.TotalSeries += len(series)
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stats.DroppedSeries += len(series) - len(repl)
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case record.Samples:
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samples, err = dec.Samples(rec, samples)
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if err != nil {
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return nil, errors.Wrap(err, "decode samples")
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}
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// Drop irrelevant samples in place.
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repl := samples[:0]
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for _, s := range samples {
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if s.T >= mint {
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repl = append(repl, s)
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}
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}
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if len(repl) > 0 {
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buf = enc.Samples(repl, buf)
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}
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stats.TotalSamples += len(samples)
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stats.DroppedSamples += len(samples) - len(repl)
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case record.HistogramSamples:
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histogramSamples, err = dec.HistogramSamples(rec, histogramSamples)
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if err != nil {
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return nil, errors.Wrap(err, "decode histogram samples")
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}
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// Drop irrelevant histogramSamples in place.
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repl := histogramSamples[:0]
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for _, h := range histogramSamples {
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if h.T >= mint {
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repl = append(repl, h)
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}
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}
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if len(repl) > 0 {
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buf = enc.HistogramSamples(repl, buf)
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}
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stats.TotalSamples += len(samples)
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stats.DroppedSamples += len(samples) - len(repl)
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case record.Tombstones:
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tstones, err = dec.Tombstones(rec, tstones)
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if err != nil {
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return nil, errors.Wrap(err, "decode deletes")
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}
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// Drop irrelevant tombstones in place.
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repl := tstones[:0]
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for _, s := range tstones {
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for _, iv := range s.Intervals {
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if iv.Maxt >= mint {
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repl = append(repl, s)
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break
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}
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}
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}
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if len(repl) > 0 {
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buf = enc.Tombstones(repl, buf)
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}
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stats.TotalTombstones += len(tstones)
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stats.DroppedTombstones += len(tstones) - len(repl)
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case record.Exemplars:
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exemplars, err = dec.Exemplars(rec, exemplars)
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if err != nil {
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return nil, errors.Wrap(err, "decode exemplars")
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}
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// Drop irrelevant exemplars in place.
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repl := exemplars[:0]
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for _, e := range exemplars {
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if e.T >= mint {
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repl = append(repl, e)
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}
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}
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if len(repl) > 0 {
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buf = enc.Exemplars(repl, buf)
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}
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stats.TotalExemplars += len(exemplars)
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stats.DroppedExemplars += len(exemplars) - len(repl)
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case record.Metadata:
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metadata, err := dec.Metadata(rec, metadata)
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if err != nil {
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return nil, errors.Wrap(err, "decode metadata")
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}
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// Only keep reference to the latest found metadata for each refID.
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repl := 0
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for _, m := range metadata {
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if keep(m.Ref) {
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if _, ok := latestMetadataMap[m.Ref]; !ok {
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repl++
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}
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latestMetadataMap[m.Ref] = m
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}
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}
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stats.TotalMetadata += len(metadata)
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stats.DroppedMetadata += len(metadata) - repl
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default:
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// Unknown record type, probably from a future Prometheus version.
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continue
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}
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if len(buf[start:]) == 0 {
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continue // All contents discarded.
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}
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recs = append(recs, buf[start:])
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// Flush records in 1 MB increments.
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if len(buf) > 1*1024*1024 {
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if err := cp.Log(recs...); err != nil {
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return nil, errors.Wrap(err, "flush records")
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}
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buf, recs = buf[:0], recs[:0]
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}
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}
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// If we hit any corruption during checkpointing, repairing is not an option.
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// The head won't know which series records are lost.
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if r.Err() != nil {
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return nil, errors.Wrap(r.Err(), "read segments")
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}
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// Flush remaining records.
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if err := cp.Log(recs...); err != nil {
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return nil, errors.Wrap(err, "flush records")
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}
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// Flush latest metadata records for each series.
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if len(latestMetadataMap) > 0 {
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latestMetadata := make([]record.RefMetadata, 0, len(latestMetadataMap))
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for _, m := range latestMetadataMap {
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latestMetadata = append(latestMetadata, m)
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}
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if err := cp.Log(enc.Metadata(latestMetadata, buf[:0])); err != nil {
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return nil, errors.Wrap(err, "flush metadata records")
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}
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}
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if err := cp.Close(); err != nil {
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return nil, errors.Wrap(err, "close checkpoint")
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}
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// Sync temporary directory before rename.
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df, err := fileutil.OpenDir(cpdirtmp)
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if err != nil {
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return nil, errors.Wrap(err, "open temporary checkpoint directory")
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}
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if err := df.Sync(); err != nil {
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df.Close()
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return nil, errors.Wrap(err, "sync temporary checkpoint directory")
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}
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if err = df.Close(); err != nil {
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return nil, errors.Wrap(err, "close temporary checkpoint directory")
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}
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if err := fileutil.Replace(cpdirtmp, cpdir); err != nil {
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return nil, errors.Wrap(err, "rename checkpoint directory")
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}
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return stats, nil
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}
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func checkpointDir(dir string, i int) string {
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return filepath.Join(dir, fmt.Sprintf(checkpointPrefix+"%08d", i))
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}
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type checkpointRef struct {
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name string
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index int
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}
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func listCheckpoints(dir string) (refs []checkpointRef, err error) {
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files, err := os.ReadDir(dir)
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if err != nil {
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return nil, err
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}
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for i := 0; i < len(files); i++ {
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fi := files[i]
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if !strings.HasPrefix(fi.Name(), checkpointPrefix) {
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continue
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}
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if !fi.IsDir() {
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return nil, errors.Errorf("checkpoint %s is not a directory", fi.Name())
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}
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idx, err := strconv.Atoi(fi.Name()[len(checkpointPrefix):])
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if err != nil {
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continue
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}
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refs = append(refs, checkpointRef{name: fi.Name(), index: idx})
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}
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sort.Slice(refs, func(i, j int) bool {
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return refs[i].index < refs[j].index
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})
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return refs, nil
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}
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