prometheus/tsdb/wal/wal_test.go
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2020-01-02 15:54:09 +01:00

482 lines
12 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 wal
import (
"bytes"
"fmt"
"io/ioutil"
"math/rand"
"os"
"path/filepath"
"testing"
"github.com/prometheus/prometheus/tsdb/fileutil"
client_testutil "github.com/prometheus/client_golang/prometheus/testutil"
"github.com/prometheus/prometheus/util/testutil"
)
// 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)
testutil.Ok(t, err)
_, err = f.Write([]byte{byte(recFirst)})
testutil.Ok(t, err)
},
8,
},
// Ensures that the page buffer is big enough to fit
// an entire page size without panicking.
// https://github.com/prometheus/prometheus/tsdb/pull/414
"bad_header": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte{byte(recPageTerm)})
testutil.Ok(t, err)
},
4,
},
"bad_fragment_sequence": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte{byte(recLast)})
testutil.Ok(t, err)
},
4,
},
"bad_fragment_flag": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte{123})
testutil.Ok(t, err)
},
4,
},
"bad_checksum": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+4, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte{0})
testutil.Ok(t, err)
},
4,
},
"bad_length": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+2, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte{0})
testutil.Ok(t, err)
},
4,
},
"bad_content": {
1,
func(f *os.File) {
_, err := f.Seek(pageSize+100, 0)
testutil.Ok(t, err)
_, err = f.Write([]byte("beef"))
testutil.Ok(t, err)
},
4,
},
} {
t.Run(name, func(t *testing.T) {
dir, err := ioutil.TempDir("", "wal_repair")
testutil.Ok(t, err)
defer func() {
testutil.Ok(t, os.RemoveAll(dir))
}()
// 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, false)
testutil.Ok(t, err)
var records [][]byte
for i := 1; i <= 9; i++ {
b := make([]byte, pageSize-recordHeaderSize)
b[0] = byte(i)
records = append(records, b)
testutil.Ok(t, w.Log(b))
}
first, last, err := w.Segments()
testutil.Ok(t, err)
testutil.Equals(t, 3, 1+last-first, "wal creation didn't result in expected number of segments")
testutil.Ok(t, w.Close())
f, err := os.OpenFile(SegmentName(dir, test.corrSgm), os.O_RDWR, 0666)
testutil.Ok(t, err)
// Apply corruption function.
test.corrFunc(f)
testutil.Ok(t, f.Close())
w, err = NewSize(nil, nil, dir, segSize, false)
testutil.Ok(t, err)
defer w.Close()
first, last, err = w.Segments()
testutil.Ok(t, err)
// Backfill segments from the most recent checkpoint onwards.
for i := first; i <= last; i++ {
s, err := OpenReadSegment(SegmentName(w.Dir(), i))
testutil.Ok(t, err)
sr := NewSegmentBufReader(s)
testutil.Ok(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
}
testutil.Ok(t, w.Repair(r.Err()))
break
}
sr, err := NewSegmentsReader(dir)
testutil.Ok(t, err)
defer sr.Close()
r := NewReader(sr)
var result [][]byte
for r.Next() {
var b []byte
result = append(result, append(b, r.Record()...))
}
testutil.Ok(t, r.Err())
testutil.Equals(t, test.intactRecs, len(result), "Wrong number of intact records")
for i, r := range result {
if !bytes.Equal(records[i], r) {
t.Fatalf("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 = w.Segments()
testutil.Ok(t, err)
testutil.Equals(t, test.corrSgm+1, last)
fi, err := os.Stat(SegmentName(dir, last))
testutil.Ok(t, err)
testutil.Equals(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, err := ioutil.TempDir("", "wal_repair")
testutil.Ok(t, err)
defer func() {
testutil.Ok(t, os.RemoveAll(dir))
}()
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, false)
testutil.Ok(t, err)
for i := 0; i < 18; i++ {
buf := make([]byte, recordSize)
_, err := rand.Read(buf)
testutil.Ok(t, err)
err = w.Log(buf)
testutil.Ok(t, err)
}
err = w.Close()
testutil.Ok(t, err)
}
// Check all the segments are the correct size.
{
segments, err := listSegments(dir)
testutil.Ok(t, err)
for _, segment := range segments {
f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%08d", segment.index)), os.O_RDONLY, 0666)
testutil.Ok(t, err)
fi, err := f.Stat()
testutil.Ok(t, err)
t.Log("segment", segment.index, "size", fi.Size())
testutil.Equals(t, int64(segmentSize), fi.Size())
err = f.Close()
testutil.Ok(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, 0666)
testutil.Ok(t, err)
fi, err := f.Stat()
testutil.Ok(t, err)
testutil.Equals(t, int64(segmentSize), fi.Size())
err = f.Truncate(int64(segmentSize / 2))
testutil.Ok(t, err)
err = f.Close()
testutil.Ok(t, err)
}
// Now try and repair this WAL, and write 5 more records to it.
{
sr, err := NewSegmentsReader(dir)
testutil.Ok(t, err)
reader := NewReader(sr)
i := 0
for ; i < 4 && reader.Next(); i++ {
testutil.Equals(t, recordSize, len(reader.Record()))
}
testutil.Equals(t, 4, i, "not enough records")
testutil.Assert(t, !reader.Next(), "unexpected record")
corruptionErr := reader.Err()
testutil.Assert(t, corruptionErr != nil, "expected error")
err = sr.Close()
testutil.Ok(t, err)
w, err := NewSize(logger, nil, dir, segmentSize, false)
testutil.Ok(t, err)
err = w.Repair(corruptionErr)
testutil.Ok(t, err)
// Ensure that we have a completely clean slate after repairing.
testutil.Equals(t, w.segment.Index(), 1) // We corrupted segment 0.
testutil.Equals(t, w.donePages, 0)
for i := 0; i < 5; i++ {
buf := make([]byte, recordSize)
_, err := rand.Read(buf)
testutil.Ok(t, err)
err = w.Log(buf)
testutil.Ok(t, err)
}
err = w.Close()
testutil.Ok(t, err)
}
// Replay the WAL. Should get 9 records.
{
sr, err := NewSegmentsReader(dir)
testutil.Ok(t, err)
reader := NewReader(sr)
i := 0
for ; i < 9 && reader.Next(); i++ {
testutil.Equals(t, recordSize, len(reader.Record()))
}
testutil.Equals(t, 9, i, "wrong number of records")
testutil.Assert(t, !reader.Next(), "unexpected record")
testutil.Equals(t, nil, 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, err := ioutil.TempDir("", "wal_repair")
testutil.Ok(t, err)
defer func() {
testutil.Ok(t, os.RemoveAll(dir))
}()
w, err := NewSize(nil, nil, dir, pageSize, false)
testutil.Ok(t, err)
testutil.Ok(t, w.Close())
testutil.NotOk(t, w.Close())
}
func TestSegmentMetric(t *testing.T) {
var (
segmentSize = pageSize
recordSize = (pageSize / 2) - recordHeaderSize
)
dir, err := ioutil.TempDir("", "segment_metric")
testutil.Ok(t, err)
defer func() {
testutil.Ok(t, os.RemoveAll(dir))
}()
w, err := NewSize(nil, nil, dir, segmentSize, false)
testutil.Ok(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)
testutil.Ok(t, err)
err = w.Log(buf)
testutil.Ok(t, err)
}
testutil.Assert(t, client_testutil.ToFloat64(w.metrics.currentSegment) == initialSegment+1, "segment metric did not increment after segment rotation")
testutil.Ok(t, w.Close())
}
func TestCompression(t *testing.T) {
bootstrap := func(compressed bool) string {
const (
segmentSize = pageSize
recordSize = (pageSize / 2) - recordHeaderSize
records = 100
)
dirPath, err := ioutil.TempDir("", fmt.Sprintf("TestCompression_%t", compressed))
testutil.Ok(t, err)
w, err := NewSize(nil, nil, dirPath, segmentSize, compressed)
testutil.Ok(t, err)
buf := make([]byte, recordSize)
for i := 0; i < records; i++ {
testutil.Ok(t, w.Log(buf))
}
testutil.Ok(t, w.Close())
return dirPath
}
dirCompressed := bootstrap(true)
defer func() {
testutil.Ok(t, os.RemoveAll(dirCompressed))
}()
dirUnCompressed := bootstrap(false)
defer func() {
testutil.Ok(t, os.RemoveAll(dirUnCompressed))
}()
uncompressedSize, err := fileutil.DirSize(dirUnCompressed)
testutil.Ok(t, err)
compressedSize, err := fileutil.DirSize(dirCompressed)
testutil.Ok(t, err)
testutil.Assert(t, float64(uncompressedSize)*0.75 > float64(compressedSize), "Compressing zeroes should save at least 25%% space - uncompressedSize: %d, compressedSize: %d", uncompressedSize, compressedSize)
}
func BenchmarkWAL_LogBatched(b *testing.B) {
for _, compress := range []bool{true, false} {
b.Run(fmt.Sprintf("compress=%t", compress), func(b *testing.B) {
dir, err := ioutil.TempDir("", "bench_logbatch")
testutil.Ok(b, err)
defer func() {
testutil.Ok(b, os.RemoveAll(dir))
}()
w, err := New(nil, nil, dir, compress)
testutil.Ok(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...)
testutil.Ok(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 []bool{true, false} {
b.Run(fmt.Sprintf("compress=%t", compress), func(b *testing.B) {
dir, err := ioutil.TempDir("", "bench_logsingle")
testutil.Ok(b, err)
defer func() {
testutil.Ok(b, os.RemoveAll(dir))
}()
w, err := New(nil, nil, dir, compress)
testutil.Ok(b, err)
defer w.Close()
var buf [2048]byte
b.SetBytes(2048)
for i := 0; i < b.N; i++ {
err := w.Log(buf[:])
testutil.Ok(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()
})
}
}