prometheus/storage/local/crashrecovery.go

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// Copyright 2015 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 local
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"sync/atomic"
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"github.com/prometheus/common/log"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/storage/local/codable"
"github.com/prometheus/prometheus/storage/local/index"
)
// recoverFromCrash is called by loadSeriesMapAndHeads if the persistence
// appears to be dirty after the loading (either because the loading resulted in
// an error or because the persistence was dirty from the start). Not goroutine
// safe. Only call before anything else is running (except index processing
// queue as started by newPersistence).
func (p *persistence) recoverFromCrash(fingerprintToSeries map[model.Fingerprint]*memorySeries) error {
// TODO(beorn): We need proper tests for the crash recovery.
log.Warn("Starting crash recovery. Prometheus is inoperational until complete.")
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log.Warn("To avoid crash recovery in the future, shut down Prometheus with SIGTERM or a HTTP POST to /-/quit.")
fpsSeen := map[model.Fingerprint]struct{}{}
count := 0
seriesDirNameFmt := fmt.Sprintf("%%0%dx", seriesDirNameLen)
// Delete the fingerprint mapping file as it might be stale or
// corrupt. We'll rebuild the mappings as we go.
if err := os.RemoveAll(p.mappingsFileName()); err != nil {
return fmt.Errorf("couldn't remove old fingerprint mapping file %s: %s", p.mappingsFileName(), err)
}
// The mappings to rebuild.
fpm := fpMappings{}
log.Info("Scanning files.")
for i := 0; i < 1<<(seriesDirNameLen*4); i++ {
dirname := filepath.Join(p.basePath, fmt.Sprintf(seriesDirNameFmt, i))
dir, err := os.Open(dirname)
if os.IsNotExist(err) {
continue
}
if err != nil {
return err
}
defer dir.Close()
for fis := []os.FileInfo{}; err != io.EOF; fis, err = dir.Readdir(1024) {
if err != nil {
return err
}
for _, fi := range fis {
fp, ok := p.sanitizeSeries(dirname, fi, fingerprintToSeries, fpm)
if ok {
fpsSeen[fp] = struct{}{}
}
count++
if count%10000 == 0 {
log.Infof("%d files scanned.", count)
}
}
}
}
log.Infof("File scan complete. %d series found.", len(fpsSeen))
log.Info("Checking for series without series file.")
for fp, s := range fingerprintToSeries {
if _, seen := fpsSeen[fp]; !seen {
// fp exists in fingerprintToSeries, but has no representation on disk.
if s.persistWatermark == len(s.chunkDescs) {
// Oops, everything including the head chunk was
// already persisted, but nothing on disk.
// Thus, we lost that series completely. Clean
// up the remnants.
delete(fingerprintToSeries, fp)
if err := p.purgeArchivedMetric(fp); err != nil {
// Purging the archived metric didn't work, so try
// to unindex it, just in case it's in the indexes.
p.unindexMetric(fp, s.metric)
}
log.Warnf("Lost series detected: fingerprint %v, metric %v.", fp, s.metric)
continue
}
// If we are here, the only chunks we have are the chunks in the checkpoint.
// Adjust things accordingly.
if s.persistWatermark > 0 || s.chunkDescsOffset != 0 {
minLostChunks := s.persistWatermark + s.chunkDescsOffset
if minLostChunks <= 0 {
log.Warnf(
"Possible loss of chunks for fingerprint %v, metric %v.",
fp, s.metric,
)
} else {
log.Warnf(
"Lost at least %d chunks for fingerprint %v, metric %v.",
minLostChunks, fp, s.metric,
)
}
s.chunkDescs = append(
make([]*chunkDesc, 0, len(s.chunkDescs)-s.persistWatermark),
s.chunkDescs[s.persistWatermark:]...,
)
numMemChunkDescs.Sub(float64(s.persistWatermark))
s.persistWatermark = 0
s.chunkDescsOffset = 0
}
maybeAddMapping(fp, s.metric, fpm)
fpsSeen[fp] = struct{}{} // Add so that fpsSeen is complete.
}
}
log.Info("Check for series without series file complete.")
if err := p.cleanUpArchiveIndexes(fingerprintToSeries, fpsSeen, fpm); err != nil {
return err
}
if err := p.rebuildLabelIndexes(fingerprintToSeries); err != nil {
return err
}
// Finally rewrite the mappings file if there are any mappings.
if len(fpm) > 0 {
if err := p.checkpointFPMappings(fpm); err != nil {
return err
}
}
p.setDirty(false, nil)
log.Warn("Crash recovery complete.")
return nil
}
// sanitizeSeries sanitizes a series based on its series file as defined by the
// provided directory and FileInfo. The method returns the fingerprint as
// derived from the directory and file name, and whether the provided file has
// been sanitized. A file that failed to be sanitized is moved into the
// "orphaned" sub-directory, if possible.
//
// The following steps are performed:
//
// - A file whose name doesn't comply with the naming scheme of a series file is
// simply moved into the orphaned directory.
//
// - If the size of the series file isn't a multiple of the chunk size,
// extraneous bytes are truncated. If the truncation fails, the file is
// moved into the orphaned directory.
//
// - A file that is empty (after truncation) is deleted.
//
// - A series that is not archived (i.e. it is in the fingerprintToSeries map)
// is checked for consistency of its various parameters (like persist
// watermark, offset of chunkDescs etc.). In particular, overlap between an
// in-memory head chunk with the most recent persisted chunk is
// checked. Inconsistencies are rectified.
//
// - A series that is archived (i.e. it is not in the fingerprintToSeries map)
// is checked for its presence in the index of archived series. If it cannot
// be found there, it is moved into the orphaned directory.
func (p *persistence) sanitizeSeries(
dirname string, fi os.FileInfo,
fingerprintToSeries map[model.Fingerprint]*memorySeries,
fpm fpMappings,
) (model.Fingerprint, bool) {
var (
fp model.Fingerprint
err error
filename = filepath.Join(dirname, fi.Name())
s *memorySeries
)
purge := func() {
if fp != 0 {
var metric model.Metric
if s != nil {
metric = s.metric
}
if err = p.quarantineSeriesFile(
fp, errors.New("purge during crash recovery"), metric,
); err == nil {
return
}
log.
With("file", filename).
With("error", err).
Error("Failed to move lost series file to orphaned directory.")
}
// If we are here, we are either purging an incorrectly named
// file, or quarantining has failed. So simply delete the file.
if err = os.Remove(filename); err != nil {
log.
With("file", filename).
With("error", err).
Error("Failed to delete lost series file.")
}
}
if len(fi.Name()) != fpLen-seriesDirNameLen+len(seriesFileSuffix) ||
!strings.HasSuffix(fi.Name(), seriesFileSuffix) {
log.Warnf("Unexpected series file name %s.", filename)
purge()
return fp, false
}
if fp, err = model.FingerprintFromString(filepath.Base(dirname) + fi.Name()[:fpLen-seriesDirNameLen]); err != nil {
log.Warnf("Error parsing file name %s: %s", filename, err)
purge()
return fp, false
}
bytesToTrim := fi.Size() % int64(chunkLenWithHeader)
chunksInFile := int(fi.Size()) / chunkLenWithHeader
modTime := fi.ModTime()
if bytesToTrim != 0 {
log.Warnf(
"Truncating file %s to exactly %d chunks, trimming %d extraneous bytes.",
filename, chunksInFile, bytesToTrim,
)
f, err := os.OpenFile(filename, os.O_WRONLY, 0640)
if err != nil {
log.Errorf("Could not open file %s: %s", filename, err)
purge()
return fp, false
}
if err := f.Truncate(fi.Size() - bytesToTrim); err != nil {
log.Errorf("Failed to truncate file %s: %s", filename, err)
purge()
return fp, false
}
}
if chunksInFile == 0 {
log.Warnf("No chunks left in file %s.", filename)
purge()
return fp, false
}
s, ok := fingerprintToSeries[fp]
if ok { // This series is supposed to not be archived.
if s == nil {
panic("fingerprint mapped to nil pointer")
}
maybeAddMapping(fp, s.metric, fpm)
if !p.pedanticChecks &&
bytesToTrim == 0 &&
s.chunkDescsOffset != -1 &&
chunksInFile == s.chunkDescsOffset+s.persistWatermark &&
modTime.Equal(s.modTime) {
// Everything is consistent. We are good.
return fp, true
}
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// If we are here, we cannot be sure the series file is
// consistent with the checkpoint, so we have to take a closer
// look.
if s.headChunkClosed {
// This is the easy case as we have all chunks on
// disk. Treat this series as a freshly unarchived one
// by loading the chunkDescs and setting all parameters
// based on the loaded chunkDescs.
cds, err := p.loadChunkDescs(fp, 0)
if err != nil {
log.Errorf(
"Failed to load chunk descriptors for metric %v, fingerprint %v: %s",
s.metric, fp, err,
)
purge()
return fp, false
}
log.Warnf(
"Treating recovered metric %v, fingerprint %v, as freshly unarchived, with %d chunks in series file.",
s.metric, fp, len(cds),
)
s.chunkDescs = cds
s.chunkDescsOffset = 0
s.savedFirstTime = cds[0].firstTime()
s.lastTime, err = cds[len(cds)-1].lastTime()
if err != nil {
log.Errorf(
"Failed to determine time of the last sample for metric %v, fingerprint %v: %s",
s.metric, fp, err,
)
purge()
return fp, false
}
s.persistWatermark = len(cds)
s.modTime = modTime
return fp, true
}
// This is the tricky one: We have chunks from heads.db, but
// some of those chunks might already be in the series
// file. Strategy: Take the last time of the most recent chunk
// in the series file. Then find the oldest chunk among those
// from heads.db that has a first time later or equal to the
// last time from the series file. Throw away the older chunks
// from heads.db and stitch the parts together.
// First, throw away the chunkDescs without chunks.
s.chunkDescs = s.chunkDescs[s.persistWatermark:]
numMemChunkDescs.Sub(float64(s.persistWatermark))
cds, err := p.loadChunkDescs(fp, 0)
if err != nil {
log.Errorf(
"Failed to load chunk descriptors for metric %v, fingerprint %v: %s",
s.metric, fp, err,
)
purge()
return fp, false
}
s.persistWatermark = len(cds)
s.chunkDescsOffset = 0
s.savedFirstTime = cds[0].firstTime()
s.modTime = modTime
lastTime, err := cds[len(cds)-1].lastTime()
if err != nil {
log.Errorf(
"Failed to determine time of the last sample for metric %v, fingerprint %v: %s",
s.metric, fp, err,
)
purge()
return fp, false
}
keepIdx := -1
for i, cd := range s.chunkDescs {
if cd.firstTime() >= lastTime {
keepIdx = i
break
}
}
if keepIdx == -1 {
log.Warnf(
"Recovered metric %v, fingerprint %v: all %d chunks recovered from series file.",
s.metric, fp, chunksInFile,
)
numMemChunkDescs.Sub(float64(len(s.chunkDescs)))
atomic.AddInt64(&numMemChunks, int64(-len(s.chunkDescs)))
s.chunkDescs = cds
s.headChunkClosed = true
return fp, true
}
log.Warnf(
"Recovered metric %v, fingerprint %v: recovered %d chunks from series file, recovered %d chunks from checkpoint.",
s.metric, fp, chunksInFile, len(s.chunkDescs)-keepIdx,
)
numMemChunkDescs.Sub(float64(keepIdx))
atomic.AddInt64(&numMemChunks, int64(-keepIdx))
s.chunkDescs = append(cds, s.chunkDescs[keepIdx:]...)
return fp, true
}
// This series is supposed to be archived.
metric, err := p.archivedMetric(fp)
if err != nil {
log.Errorf(
"Fingerprint %v assumed archived but couldn't be looked up in archived index: %s",
fp, err,
)
purge()
return fp, false
}
if metric == nil {
log.Warnf(
"Fingerprint %v assumed archived but couldn't be found in archived index.",
fp,
)
purge()
return fp, false
}
// This series looks like a properly archived one.
maybeAddMapping(fp, metric, fpm)
return fp, true
}
func (p *persistence) cleanUpArchiveIndexes(
fpToSeries map[model.Fingerprint]*memorySeries,
fpsSeen map[model.Fingerprint]struct{},
fpm fpMappings,
) error {
log.Info("Cleaning up archive indexes.")
var fp codable.Fingerprint
var m codable.Metric
count := 0
if err := p.archivedFingerprintToMetrics.ForEach(func(kv index.KeyValueAccessor) error {
count++
if count%10000 == 0 {
log.Infof("%d archived metrics checked.", count)
}
if err := kv.Key(&fp); err != nil {
return err
}
_, fpSeen := fpsSeen[model.Fingerprint(fp)]
inMemory := false
if fpSeen {
_, inMemory = fpToSeries[model.Fingerprint(fp)]
}
if !fpSeen || inMemory {
if inMemory {
log.Warnf("Archive clean-up: Fingerprint %v is not archived. Purging from archive indexes.", model.Fingerprint(fp))
}
if !fpSeen {
log.Warnf("Archive clean-up: Fingerprint %v is unknown. Purging from archive indexes.", model.Fingerprint(fp))
}
// It's fine if the fp is not in the archive indexes.
if _, err := p.archivedFingerprintToMetrics.Delete(fp); err != nil {
return err
}
// Delete from timerange index, too.
_, err := p.archivedFingerprintToTimeRange.Delete(fp)
return err
}
// fp is legitimately archived. Now we need the metric to check for a mapped fingerprint.
if err := kv.Value(&m); err != nil {
return err
}
maybeAddMapping(model.Fingerprint(fp), model.Metric(m), fpm)
// Make sure it is in timerange index, too.
has, err := p.archivedFingerprintToTimeRange.Has(fp)
if err != nil {
return err
}
if has {
return nil // All good.
}
log.Warnf("Archive clean-up: Fingerprint %v is not in time-range index. Unarchiving it for recovery.")
// Again, it's fine if fp is not in the archive index.
if _, err := p.archivedFingerprintToMetrics.Delete(fp); err != nil {
return err
}
cds, err := p.loadChunkDescs(model.Fingerprint(fp), 0)
if err != nil {
return err
}
series, err := newMemorySeries(model.Metric(m), cds, p.seriesFileModTime(model.Fingerprint(fp)))
if err != nil {
return err
}
fpToSeries[model.Fingerprint(fp)] = series
return nil
}); err != nil {
return err
}
count = 0
if err := p.archivedFingerprintToTimeRange.ForEach(func(kv index.KeyValueAccessor) error {
count++
if count%10000 == 0 {
log.Infof("%d archived time ranges checked.", count)
}
if err := kv.Key(&fp); err != nil {
return err
}
has, err := p.archivedFingerprintToMetrics.Has(fp)
if err != nil {
return err
}
if has {
return nil // All good.
}
log.Warnf("Archive clean-up: Purging unknown fingerprint %v in time-range index.", fp)
deleted, err := p.archivedFingerprintToTimeRange.Delete(fp)
if err != nil {
return err
}
if !deleted {
log.Errorf("Fingerprint %v to be deleted from archivedFingerprintToTimeRange not found. This should never happen.", fp)
}
return nil
}); err != nil {
return err
}
log.Info("Clean-up of archive indexes complete.")
return nil
}
func (p *persistence) rebuildLabelIndexes(
fpToSeries map[model.Fingerprint]*memorySeries,
) error {
count := 0
log.Info("Rebuilding label indexes.")
log.Info("Indexing metrics in memory.")
for fp, s := range fpToSeries {
p.indexMetric(fp, s.metric)
count++
if count%10000 == 0 {
log.Infof("%d metrics queued for indexing.", count)
}
}
log.Info("Indexing archived metrics.")
var fp codable.Fingerprint
var m codable.Metric
if err := p.archivedFingerprintToMetrics.ForEach(func(kv index.KeyValueAccessor) error {
if err := kv.Key(&fp); err != nil {
return err
}
if err := kv.Value(&m); err != nil {
return err
}
p.indexMetric(model.Fingerprint(fp), model.Metric(m))
count++
if count%10000 == 0 {
log.Infof("%d metrics queued for indexing.", count)
}
return nil
}); err != nil {
return err
}
log.Info("All requests for rebuilding the label indexes queued. (Actual processing may lag behind.)")
return nil
}
// maybeAddMapping adds a fingerprint mapping to fpm if the FastFingerprint of m is different from fp.
func maybeAddMapping(fp model.Fingerprint, m model.Metric, fpm fpMappings) {
if rawFP := m.FastFingerprint(); rawFP != fp {
log.Warnf(
"Metric %v with fingerprint %v is mapped from raw fingerprint %v.",
m, fp, rawFP,
)
if mappedFPs, ok := fpm[rawFP]; ok {
mappedFPs[metricToUniqueString(m)] = fp
} else {
fpm[rawFP] = map[string]model.Fingerprint{
metricToUniqueString(m): fp,
}
}
}
}