prometheus/tsdb/wlog/wlog_test.go

564 lines
15 KiB
Go

// Copyright 2017 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 wlog
import (
"bytes"
"crypto/rand"
"fmt"
"io"
"os"
"path/filepath"
"testing"
client_testutil "github.com/prometheus/client_golang/prometheus/testutil"
"github.com/stretchr/testify/require"
"go.uber.org/goleak"
"github.com/prometheus/prometheus/tsdb/fileutil"
"github.com/prometheus/prometheus/util/testutil"
)
func TestMain(m *testing.M) {
goleak.VerifyTestMain(m)
}
// TestWALRepair_ReadingError ensures that a repair is run for an error
// when reading a record.
func TestWALRepair_ReadingError(t *testing.T) {
for name, test := range map[string]struct {
corrSgm int // Which segment to corrupt.
corrFunc func(f *os.File) // Func that applies the corruption.
intactRecs int // Total expected records left after the repair.
}{
"torn_last_record": {
2,
func(f *os.File) {
_, err := f.Seek(pageSize*2, 0)
require.NoError(t, err)
_, err = f.Write([]byte{byte(recFirst)})
require.NoError(t, err)
},
8,
},
// Ensures that the page buffer is big enough to fit
// an entire page size without panicking.
// https://github.com/prometheus/tsdb/pull/414
"bad_header": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
require.NoError(t, err)
_, err = f.Write([]byte{byte(recPageTerm)})
require.NoError(t, err)
},
4,
},
"bad_fragment_sequence": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
require.NoError(t, err)
_, err = f.Write([]byte{byte(recLast)})
require.NoError(t, err)
},
4,
},
"bad_fragment_flag": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
require.NoError(t, err)
_, err = f.Write([]byte{123})
require.NoError(t, err)
},
4,
},
"bad_checksum": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+4, 0)
require.NoError(t, err)
_, err = f.Write([]byte{0})
require.NoError(t, err)
},
4,
},
"bad_length": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+2, 0)
require.NoError(t, err)
_, err = f.Write([]byte{0})
require.NoError(t, err)
},
4,
},
"bad_content": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+100, 0)
require.NoError(t, err)
_, err = f.Write([]byte("beef"))
require.NoError(t, err)
},
4,
},
} {
t.Run(name, func(t *testing.T) {
dir := t.TempDir()
// We create 3 segments with 3 records each and
// then corrupt a given record in a given segment.
// As a result we want a repaired WAL with given intact records.
segSize := 3 * pageSize
w, err := NewSize(nil, nil, dir, segSize, CompressionNone)
require.NoError(t, err)
var records [][]byte
for i := 1; i <= 9; i++ {
b := make([]byte, pageSize-recordHeaderSize)
b[0] = byte(i)
records = append(records, b)
require.NoError(t, w.Log(b))
}
first, last, err := Segments(w.Dir())
require.NoError(t, err)
require.Equal(t, 3, 1+last-first, "wlog creation didn't result in expected number of segments")
require.NoError(t, w.Close())
f, err := os.OpenFile(SegmentName(dir, test.corrSgm), os.O_RDWR, 0o666)
require.NoError(t, err)
// Apply corruption function.
test.corrFunc(f)
require.NoError(t, f.Close())
w, err = NewSize(nil, nil, dir, segSize, CompressionNone)
require.NoError(t, err)
defer w.Close()
first, last, err = Segments(w.Dir())
require.NoError(t, err)
// Backfill segments from the most recent checkpoint onwards.
for i := first; i <= last; i++ {
s, err := OpenReadSegment(SegmentName(w.Dir(), i))
require.NoError(t, err)
sr := NewSegmentBufReader(s)
require.NoError(t, err)
r := NewReader(sr)
for r.Next() {
}
// Close the segment so we don't break things on Windows.
s.Close()
// No corruption in this segment.
if r.Err() == nil {
continue
}
require.NoError(t, w.Repair(r.Err()))
break
}
sr, err := NewSegmentsReader(dir)
require.NoError(t, err)
defer sr.Close()
r := NewReader(sr)
var result [][]byte
for r.Next() {
var b []byte
result = append(result, append(b, r.Record()...))
}
require.NoError(t, r.Err())
require.Len(t, result, test.intactRecs, "Wrong number of intact records")
for i, r := range result {
require.True(t, bytes.Equal(records[i], r), "record %d diverges: want %x, got %x", i, records[i][:10], r[:10])
}
// Make sure there is a new 0 size Segment after the corrupted Segment.
_, last, err = Segments(w.Dir())
require.NoError(t, err)
require.Equal(t, test.corrSgm+1, last)
fi, err := os.Stat(SegmentName(dir, last))
require.NoError(t, err)
require.Equal(t, int64(0), fi.Size())
})
}
}
// TestCorruptAndCarryOn writes a multi-segment WAL; corrupts the first segment and
// ensures that an error during reading that segment are correctly repaired before
// moving to write more records to the WAL.
func TestCorruptAndCarryOn(t *testing.T) {
dir := t.TempDir()
var (
logger = testutil.NewLogger(t)
segmentSize = pageSize * 3
recordSize = (pageSize / 3) - recordHeaderSize
)
// Produce a WAL with a two segments of 3 pages with 3 records each,
// so when we truncate the file we're guaranteed to split a record.
{
w, err := NewSize(logger, nil, dir, segmentSize, CompressionNone)
require.NoError(t, err)
for i := 0; i < 18; i++ {
buf := make([]byte, recordSize)
_, err := rand.Read(buf)
require.NoError(t, err)
err = w.Log(buf)
require.NoError(t, err)
}
err = w.Close()
require.NoError(t, err)
}
// Check all the segments are the correct size.
{
segments, err := listSegments(dir)
require.NoError(t, err)
for _, segment := range segments {
f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%08d", segment.index)), os.O_RDONLY, 0o666)
require.NoError(t, err)
fi, err := f.Stat()
require.NoError(t, err)
t.Log("segment", segment.index, "size", fi.Size())
require.Equal(t, int64(segmentSize), fi.Size())
err = f.Close()
require.NoError(t, err)
}
}
// Truncate the first file, splitting the middle record in the second
// page in half, leaving 4 valid records.
{
f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%08d", 0)), os.O_RDWR, 0o666)
require.NoError(t, err)
fi, err := f.Stat()
require.NoError(t, err)
require.Equal(t, int64(segmentSize), fi.Size())
err = f.Truncate(int64(segmentSize / 2))
require.NoError(t, err)
err = f.Close()
require.NoError(t, err)
}
// Now try and repair this WAL, and write 5 more records to it.
{
sr, err := NewSegmentsReader(dir)
require.NoError(t, err)
reader := NewReader(sr)
i := 0
for ; i < 4 && reader.Next(); i++ {
require.Len(t, reader.Record(), recordSize)
}
require.Equal(t, 4, i, "not enough records")
require.False(t, reader.Next(), "unexpected record")
corruptionErr := reader.Err()
require.Error(t, corruptionErr)
err = sr.Close()
require.NoError(t, err)
w, err := NewSize(logger, nil, dir, segmentSize, CompressionNone)
require.NoError(t, err)
err = w.Repair(corruptionErr)
require.NoError(t, err)
// Ensure that we have a completely clean slate after repairing.
require.Equal(t, 1, w.segment.Index()) // We corrupted segment 0.
require.Equal(t, 0, w.donePages)
for i := 0; i < 5; i++ {
buf := make([]byte, recordSize)
_, err := rand.Read(buf)
require.NoError(t, err)
err = w.Log(buf)
require.NoError(t, err)
}
err = w.Close()
require.NoError(t, err)
}
// Replay the WAL. Should get 9 records.
{
sr, err := NewSegmentsReader(dir)
require.NoError(t, err)
reader := NewReader(sr)
i := 0
for ; i < 9 && reader.Next(); i++ {
require.Len(t, reader.Record(), recordSize)
}
require.Equal(t, 9, i, "wrong number of records")
require.False(t, reader.Next(), "unexpected record")
require.NoError(t, reader.Err())
sr.Close()
}
}
// TestClose ensures that calling Close more than once doesn't panic and doesn't block.
func TestClose(t *testing.T) {
dir := t.TempDir()
w, err := NewSize(nil, nil, dir, pageSize, CompressionNone)
require.NoError(t, err)
require.NoError(t, w.Close())
require.Error(t, w.Close())
}
func TestSegmentMetric(t *testing.T) {
var (
segmentSize = pageSize
recordSize = (pageSize / 2) - recordHeaderSize
)
dir := t.TempDir()
w, err := NewSize(nil, nil, dir, segmentSize, CompressionNone)
require.NoError(t, err)
initialSegment := client_testutil.ToFloat64(w.metrics.currentSegment)
// Write 3 records, each of which is half the segment size, meaning we should rotate to the next segment.
for i := 0; i < 3; i++ {
buf := make([]byte, recordSize)
_, err := rand.Read(buf)
require.NoError(t, err)
err = w.Log(buf)
require.NoError(t, err)
}
require.Equal(t, initialSegment+1, client_testutil.ToFloat64(w.metrics.currentSegment), "segment metric did not increment after segment rotation")
require.NoError(t, w.Close())
}
func TestCompression(t *testing.T) {
bootstrap := func(compressed CompressionType) string {
const (
segmentSize = pageSize
recordSize = (pageSize / 2) - recordHeaderSize
records = 100
)
dirPath := t.TempDir()
w, err := NewSize(nil, nil, dirPath, segmentSize, compressed)
require.NoError(t, err)
buf := make([]byte, recordSize)
for i := 0; i < records; i++ {
require.NoError(t, w.Log(buf))
}
require.NoError(t, w.Close())
return dirPath
}
tmpDirs := make([]string, 0, 3)
defer func() {
for _, dir := range tmpDirs {
require.NoError(t, os.RemoveAll(dir))
}
}()
dirUnCompressed := bootstrap(CompressionNone)
tmpDirs = append(tmpDirs, dirUnCompressed)
for _, compressionType := range []CompressionType{CompressionSnappy, CompressionZstd} {
dirCompressed := bootstrap(compressionType)
tmpDirs = append(tmpDirs, dirCompressed)
uncompressedSize, err := fileutil.DirSize(dirUnCompressed)
require.NoError(t, err)
compressedSize, err := fileutil.DirSize(dirCompressed)
require.NoError(t, err)
require.Greater(t, float64(uncompressedSize)*0.75, float64(compressedSize), "Compressing zeroes should save at least 25%% space - uncompressedSize: %d, compressedSize: %d", uncompressedSize, compressedSize)
}
}
func TestLogPartialWrite(t *testing.T) {
const segmentSize = pageSize * 2
record := []byte{1, 2, 3, 4, 5}
tests := map[string]struct {
numRecords int
faultyRecord int
}{
"partial write when logging first record in a page": {
numRecords: 10,
faultyRecord: 1,
},
"partial write when logging record in the middle of a page": {
numRecords: 10,
faultyRecord: 3,
},
"partial write when logging last record of a page": {
numRecords: (pageSize / (recordHeaderSize + len(record))) + 10,
faultyRecord: pageSize / (recordHeaderSize + len(record)),
},
// TODO the current implementation suffers this:
// "partial write when logging a record overlapping two pages": {
// numRecords: (pageSize / (recordHeaderSize + len(record))) + 10,
// faultyRecord: pageSize/(recordHeaderSize+len(record)) + 1,
// },
}
for testName, testData := range tests {
t.Run(testName, func(t *testing.T) {
dirPath := t.TempDir()
w, err := NewSize(nil, nil, dirPath, segmentSize, CompressionNone)
require.NoError(t, err)
// Replace the underlying segment file with a mocked one that injects a failure.
w.segment.SegmentFile = &faultySegmentFile{
SegmentFile: w.segment.SegmentFile,
writeFailureAfter: ((recordHeaderSize + len(record)) * (testData.faultyRecord - 1)) + 2,
writeFailureErr: io.ErrShortWrite,
}
for i := 1; i <= testData.numRecords; i++ {
if err := w.Log(record); i == testData.faultyRecord {
require.ErrorIs(t, io.ErrShortWrite, err)
} else {
require.NoError(t, err)
}
}
require.NoError(t, w.Close())
// Read it back. We expect no corruption.
s, err := OpenReadSegment(SegmentName(dirPath, 0))
require.NoError(t, err)
defer func() { require.NoError(t, s.Close()) }()
r := NewReader(NewSegmentBufReader(s))
for i := 0; i < testData.numRecords; i++ {
require.True(t, r.Next())
require.NoError(t, r.Err())
require.Equal(t, record, r.Record())
}
require.False(t, r.Next())
require.NoError(t, r.Err())
})
}
}
type faultySegmentFile struct {
SegmentFile
written int
writeFailureAfter int
writeFailureErr error
}
func (f *faultySegmentFile) Write(p []byte) (int, error) {
if f.writeFailureAfter >= 0 && f.writeFailureAfter < f.written+len(p) {
partialLen := f.writeFailureAfter - f.written
if partialLen <= 0 || partialLen >= len(p) {
partialLen = 1
}
// Inject failure.
n, _ := f.SegmentFile.Write(p[:partialLen])
f.written += n
f.writeFailureAfter = -1
return n, f.writeFailureErr
}
// Proxy the write to the underlying file.
n, err := f.SegmentFile.Write(p)
f.written += n
return n, err
}
func BenchmarkWAL_LogBatched(b *testing.B) {
for _, compress := range []CompressionType{CompressionNone, CompressionSnappy, CompressionZstd} {
b.Run(fmt.Sprintf("compress=%s", compress), func(b *testing.B) {
dir := b.TempDir()
w, err := New(nil, nil, dir, compress)
require.NoError(b, err)
defer w.Close()
var buf [2048]byte
var recs [][]byte
b.SetBytes(2048)
for i := 0; i < b.N; i++ {
recs = append(recs, buf[:])
if len(recs) < 1000 {
continue
}
err := w.Log(recs...)
require.NoError(b, err)
recs = recs[:0]
}
// Stop timer to not count fsync time on close.
// If it's counted batched vs. single benchmarks are very similar but
// do not show burst throughput well.
b.StopTimer()
})
}
}
func BenchmarkWAL_Log(b *testing.B) {
for _, compress := range []CompressionType{CompressionNone, CompressionSnappy, CompressionZstd} {
b.Run(fmt.Sprintf("compress=%s", compress), func(b *testing.B) {
dir := b.TempDir()
w, err := New(nil, nil, dir, compress)
require.NoError(b, err)
defer w.Close()
var buf [2048]byte
b.SetBytes(2048)
for i := 0; i < b.N; i++ {
err := w.Log(buf[:])
require.NoError(b, err)
}
// Stop timer to not count fsync time on close.
// If it's counted batched vs. single benchmarks are very similar but
// do not show burst throughput well.
b.StopTimer()
})
}
}