mirror of
https://github.com/prometheus/prometheus.git
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449a2d0db7
Allow to repair the WAL based on the error returned by a reader during a full scan over all records. Signed-off-by: Fabian Reinartz <freinartz@google.com>
362 lines
8 KiB
Go
362 lines
8 KiB
Go
// Copyright 2017 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 wal
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import (
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"bytes"
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"encoding/binary"
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"hash/crc32"
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"io/ioutil"
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"math/rand"
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"os"
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"testing"
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"github.com/prometheus/tsdb/testutil"
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)
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func encodedRecord(t recType, b []byte) []byte {
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if t == recPageTerm {
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return append([]byte{0}, b...)
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}
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r := make([]byte, recordHeaderSize)
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r[0] = byte(t)
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binary.BigEndian.PutUint16(r[1:], uint16(len(b)))
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binary.BigEndian.PutUint32(r[3:], crc32.Checksum(b, castagnoliTable))
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return append(r, b...)
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}
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// TestReader feeds the reader a stream of encoded records with different types.
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func TestReader(t *testing.T) {
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data := make([]byte, 100000)
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_, err := rand.Read(data)
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testutil.Ok(t, err)
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type record struct {
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t recType
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b []byte
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}
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cases := []struct {
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t []record
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exp [][]byte
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fail bool
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}{
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// Sequence of valid records.
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{
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t: []record{
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{recFull, data[0:200]},
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{recFirst, data[200:300]},
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{recLast, data[300:400]},
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{recFirst, data[400:800]},
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{recMiddle, data[800:900]},
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{recPageTerm, make([]byte, pageSize-900-recordHeaderSize*5-1)}, // exactly lines up with page boundary.
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{recLast, data[900:900]},
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{recFirst, data[900:1000]},
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{recMiddle, data[1000:1200]},
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{recMiddle, data[1200:30000]},
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{recMiddle, data[30000:30001]},
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{recMiddle, data[30001:30001]},
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{recLast, data[30001:32000]},
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},
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exp: [][]byte{
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data[0:200],
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data[200:400],
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data[400:900],
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data[900:32000],
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},
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},
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// Exactly at the limit of one page minus the header size
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{
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t: []record{
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{recFull, data[0 : pageSize-recordHeaderSize]},
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},
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exp: [][]byte{
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data[:pageSize-recordHeaderSize],
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},
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},
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// More than a full page, this exceeds our buffer and can never happen
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// when written by the WAL.
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{
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t: []record{
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{recFull, data[0 : pageSize+1]},
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},
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fail: true,
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},
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// Invalid orders of record types.
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{
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t: []record{{recMiddle, data[:200]}},
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fail: true,
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},
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{
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t: []record{{recLast, data[:200]}},
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fail: true,
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},
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{
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t: []record{
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{recFirst, data[:200]},
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{recFull, data[200:400]},
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},
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fail: true,
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},
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{
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t: []record{
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{recFirst, data[:100]},
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{recMiddle, data[100:200]},
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{recFull, data[200:400]},
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},
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fail: true,
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},
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// Non-zero data after page termination.
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{
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t: []record{
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{recFull, data[:100]},
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{recPageTerm, append(make([]byte, 1000), 1)},
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},
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exp: [][]byte{data[:100]},
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fail: true,
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},
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}
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for i, c := range cases {
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t.Logf("test %d", i)
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var buf []byte
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for _, r := range c.t {
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buf = append(buf, encodedRecord(r.t, r.b)...)
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}
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r := NewReader(bytes.NewReader(buf))
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for j := 0; r.Next(); j++ {
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t.Logf("record %d", j)
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rec := r.Record()
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if j >= len(c.exp) {
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t.Fatal("received more records than inserted")
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}
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testutil.Equals(t, c.exp[j], rec)
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}
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if !c.fail && r.Err() != nil {
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t.Fatalf("unexpected error: %s", r.Err())
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}
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if c.fail && r.Err() == nil {
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t.Fatalf("expected error but got none")
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}
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}
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}
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func TestWAL_FuzzWriteRead(t *testing.T) {
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const count = 25000
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dir, err := ioutil.TempDir("", "walfuzz")
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testutil.Ok(t, err)
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defer os.RemoveAll(dir)
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w, err := NewSize(nil, nil, dir, 128*pageSize)
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testutil.Ok(t, err)
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var input [][]byte
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var recs [][]byte
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for i := 0; i < count; i++ {
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var sz int
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switch i % 5 {
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case 0, 1:
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sz = 50
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case 2, 3:
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sz = pageSize
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default:
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sz = 8 * pageSize
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}
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rec := make([]byte, rand.Intn(sz))
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_, err := rand.Read(rec)
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testutil.Ok(t, err)
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input = append(input, rec)
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recs = append(recs, rec)
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// Randomly batch up records.
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if rand.Intn(4) < 3 {
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testutil.Ok(t, w.Log(recs...))
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recs = recs[:0]
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}
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}
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testutil.Ok(t, w.Log(recs...))
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m, n, err := w.Segments()
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testutil.Ok(t, err)
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rc, err := NewSegmentsRangeReader(dir, m, n)
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testutil.Ok(t, err)
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defer rc.Close()
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rdr := NewReader(rc)
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for i := 0; rdr.Next(); i++ {
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rec := rdr.Record()
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if i >= len(input) {
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t.Fatal("read too many records")
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}
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if !bytes.Equal(input[i], rec) {
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t.Fatalf("record %d (len %d) does not match (expected len %d)",
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i, len(rec), len(input[i]))
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}
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}
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testutil.Ok(t, rdr.Err())
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}
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func TestWAL_Repair(t *testing.T) {
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for name, cf := range map[string]func(f *os.File){
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"bad_fragment_sequence": func(f *os.File) {
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_, err := f.Seek(pageSize, 0)
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testutil.Ok(t, err)
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_, err = f.Write([]byte{byte(recLast)})
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testutil.Ok(t, err)
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},
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"bad_fragment_flag": func(f *os.File) {
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_, err := f.Seek(pageSize, 0)
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testutil.Ok(t, err)
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_, err = f.Write([]byte{123})
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testutil.Ok(t, err)
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},
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"bad_checksum": func(f *os.File) {
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_, err := f.Seek(pageSize+4, 0)
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testutil.Ok(t, err)
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_, err = f.Write([]byte{0})
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testutil.Ok(t, err)
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},
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"bad_length": func(f *os.File) {
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_, err := f.Seek(pageSize+2, 0)
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testutil.Ok(t, err)
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_, err = f.Write([]byte{0})
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testutil.Ok(t, err)
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},
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"bad_content": func(f *os.File) {
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_, err := f.Seek(pageSize+100, 0)
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testutil.Ok(t, err)
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_, err = f.Write([]byte("beef"))
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testutil.Ok(t, err)
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},
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} {
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t.Run(name, func(t *testing.T) {
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dir, err := ioutil.TempDir("", "wal_repair")
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testutil.Ok(t, err)
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defer os.RemoveAll(dir)
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// We create 3 segments with 3 records each and then corrupt the 2nd record
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// of the 2nd segment.
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// As a result we want a repaired WAL with the first 4 records intact.
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w, err := NewSize(nil, nil, dir, 3*pageSize)
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testutil.Ok(t, err)
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var records [][]byte
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for i := 1; i <= 9; i++ {
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b := make([]byte, pageSize-recordHeaderSize)
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b[0] = byte(i)
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records = append(records, b)
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testutil.Ok(t, w.Log(b))
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}
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testutil.Ok(t, w.Close())
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f, err := os.OpenFile(SegmentName(dir, 1), os.O_RDWR, 0666)
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testutil.Ok(t, err)
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// Apply corruption function.
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cf(f)
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testutil.Ok(t, f.Close())
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w, err = New(nil, nil, dir)
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testutil.Ok(t, err)
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sr, err := NewSegmentsReader(dir)
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testutil.Ok(t, err)
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r := NewReader(sr)
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for r.Next() {
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}
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testutil.NotOk(t, r.Err())
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testutil.Ok(t, w.Repair(r.Err()))
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sr, err = NewSegmentsReader(dir)
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testutil.Ok(t, err)
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r = NewReader(sr)
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var result [][]byte
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for r.Next() {
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var b []byte
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result = append(result, append(b, r.Record()...))
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}
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testutil.Ok(t, r.Err())
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testutil.Equals(t, 4, len(result))
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for i, r := range result {
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if !bytes.Equal(records[i], r) {
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t.Fatalf("record %d diverges: want %x, got %x", i, records[i][:10], r[:10])
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}
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}
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})
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}
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}
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func BenchmarkWAL_LogBatched(b *testing.B) {
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dir, err := ioutil.TempDir("", "bench_logbatch")
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testutil.Ok(b, err)
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defer os.RemoveAll(dir)
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w, err := New(nil, nil, "testdir")
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testutil.Ok(b, err)
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defer w.Close()
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var buf [2048]byte
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var recs [][]byte
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b.SetBytes(2048)
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for i := 0; i < b.N; i++ {
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recs = append(recs, buf[:])
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if len(recs) < 1000 {
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continue
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}
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err := w.Log(recs...)
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testutil.Ok(b, err)
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recs = recs[:0]
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}
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// Stop timer to not count fsync time on close.
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// If it's counted batched vs. single benchmarks are very similar but
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// do not show burst throughput well.
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b.StopTimer()
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}
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func BenchmarkWAL_Log(b *testing.B) {
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dir, err := ioutil.TempDir("", "bench_logsingle")
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testutil.Ok(b, err)
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defer os.RemoveAll(dir)
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w, err := New(nil, nil, "testdir")
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testutil.Ok(b, err)
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defer w.Close()
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var buf [2048]byte
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b.SetBytes(2048)
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for i := 0; i < b.N; i++ {
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err := w.Log(buf[:])
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testutil.Ok(b, err)
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}
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// Stop timer to not count fsync time on close.
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// If it's counted batched vs. single benchmarks are very similar but
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// do not show burst throughput well.
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b.StopTimer()
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}
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