mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-28 23:19:41 -08:00
b40cc43958
In running Prometheus instances, compressing the records was shown to reduce disk usage by half while incurring a negligible CPU cost. Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>
480 lines
12 KiB
Go
480 lines
12 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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"fmt"
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"io/ioutil"
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"math/rand"
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"os"
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"path/filepath"
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"testing"
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client_testutil "github.com/prometheus/client_golang/prometheus/testutil"
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"github.com/prometheus/tsdb/testutil"
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)
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// TestWALRepair_ReadingError ensures that a repair is run for an error
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// when reading a record.
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func TestWALRepair_ReadingError(t *testing.T) {
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for name, test := range map[string]struct {
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corrSgm int // Which segment to corrupt.
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corrFunc func(f *os.File) // Func that applies the corruption.
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intactRecs int // Total expected records left after the repair.
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}{
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"torn_last_record": {
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2,
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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{byte(recFirst)})
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testutil.Ok(t, err)
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},
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8,
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},
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// Ensures that the page buffer is big enough to fit
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// an entire page size without panicing.
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// https://github.com/prometheus/tsdb/pull/414
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"bad_header": {
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1,
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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(recPageTerm)})
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testutil.Ok(t, err)
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},
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4,
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},
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"bad_fragment_sequence": {
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1,
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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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4,
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},
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"bad_fragment_flag": {
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1,
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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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4,
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},
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"bad_checksum": {
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1,
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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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4,
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},
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"bad_length": {
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1,
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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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4,
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},
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"bad_content": {
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1,
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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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4,
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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 func() {
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testutil.Ok(t, os.RemoveAll(dir))
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}()
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// We create 3 segments with 3 records each and
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// then corrupt a given record in a given segment.
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// As a result we want a repaired WAL with given intact records.
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segSize := 3 * pageSize
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w, err := NewSize(nil, nil, dir, segSize, false)
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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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first, last, err := w.Segments()
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testutil.Ok(t, err)
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testutil.Equals(t, 3, 1+last-first, "wal creation didn't result in expected number of segments")
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testutil.Ok(t, w.Close())
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f, err := os.OpenFile(SegmentName(dir, test.corrSgm), os.O_RDWR, 0666)
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testutil.Ok(t, err)
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// Apply corruption function.
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test.corrFunc(f)
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testutil.Ok(t, f.Close())
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w, err = NewSize(nil, nil, dir, segSize, false)
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testutil.Ok(t, err)
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defer w.Close()
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first, last, err = w.Segments()
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testutil.Ok(t, err)
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// Backfill segments from the most recent checkpoint onwards.
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for i := first; i <= last; i++ {
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s, err := OpenReadSegment(SegmentName(w.Dir(), i))
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testutil.Ok(t, err)
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sr := NewSegmentBufReader(s)
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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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//Close the segment so we don't break things on Windows.
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s.Close()
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// No corruption in this segment.
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if r.Err() == nil {
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continue
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}
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testutil.Ok(t, w.Repair(r.Err()))
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break
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}
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sr, err := NewSegmentsReader(dir)
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testutil.Ok(t, err)
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defer sr.Close()
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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, test.intactRecs, len(result), "Wrong number of intact records")
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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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// Make sure there is a new 0 size Segment after the corrupted Segment.
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_, last, err = w.Segments()
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testutil.Ok(t, err)
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testutil.Equals(t, test.corrSgm+1, last)
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fi, err := os.Stat(SegmentName(dir, last))
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testutil.Ok(t, err)
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testutil.Equals(t, int64(0), fi.Size())
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})
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}
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}
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// TestCorruptAndCarryOn writes a multi-segment WAL; corrupts the first segment and
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// ensures that an error during reading that segment are correctly repaired before
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// moving to write more records to the WAL.
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func TestCorruptAndCarryOn(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 func() {
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testutil.Ok(t, os.RemoveAll(dir))
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}()
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var (
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logger = testutil.NewLogger(t)
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segmentSize = pageSize * 3
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recordSize = (pageSize / 3) - recordHeaderSize
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)
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// Produce a WAL with a two segments of 3 pages with 3 records each,
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// so when we truncate the file we're guaranteed to split a record.
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{
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w, err := NewSize(logger, nil, dir, segmentSize, false)
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testutil.Ok(t, err)
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for i := 0; i < 18; i++ {
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buf := make([]byte, recordSize)
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_, err := rand.Read(buf)
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testutil.Ok(t, err)
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err = w.Log(buf)
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testutil.Ok(t, err)
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}
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err = w.Close()
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testutil.Ok(t, err)
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}
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// Check all the segments are the correct size.
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{
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segments, err := listSegments(dir)
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testutil.Ok(t, err)
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for _, segment := range segments {
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f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%08d", segment.index)), os.O_RDONLY, 0666)
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testutil.Ok(t, err)
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fi, err := f.Stat()
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testutil.Ok(t, err)
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t.Log("segment", segment.index, "size", fi.Size())
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testutil.Equals(t, int64(segmentSize), fi.Size())
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err = f.Close()
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testutil.Ok(t, err)
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}
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}
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// Truncate the first file, splitting the middle record in the second
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// page in half, leaving 4 valid records.
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{
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f, err := os.OpenFile(filepath.Join(dir, fmt.Sprintf("%08d", 0)), os.O_RDWR, 0666)
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testutil.Ok(t, err)
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fi, err := f.Stat()
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testutil.Ok(t, err)
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testutil.Equals(t, int64(segmentSize), fi.Size())
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err = f.Truncate(int64(segmentSize / 2))
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testutil.Ok(t, err)
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err = f.Close()
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testutil.Ok(t, err)
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}
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// Now try and repair this WAL, and write 5 more records to it.
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{
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sr, err := NewSegmentsReader(dir)
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testutil.Ok(t, err)
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reader := NewReader(sr)
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i := 0
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for ; i < 4 && reader.Next(); i++ {
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testutil.Equals(t, recordSize, len(reader.Record()))
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}
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testutil.Equals(t, 4, i, "not enough records")
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testutil.Assert(t, !reader.Next(), "unexpected record")
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corruptionErr := reader.Err()
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testutil.Assert(t, corruptionErr != nil, "expected error")
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err = sr.Close()
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testutil.Ok(t, err)
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w, err := NewSize(logger, nil, dir, segmentSize, false)
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testutil.Ok(t, err)
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err = w.Repair(corruptionErr)
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testutil.Ok(t, err)
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// Ensure that we have a completely clean slate after reapiring.
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testutil.Equals(t, w.segment.Index(), 1) // We corrupted segment 0.
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testutil.Equals(t, w.donePages, 0)
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for i := 0; i < 5; i++ {
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buf := make([]byte, recordSize)
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_, err := rand.Read(buf)
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testutil.Ok(t, err)
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err = w.Log(buf)
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testutil.Ok(t, err)
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}
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err = w.Close()
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testutil.Ok(t, err)
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}
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// Replay the WAL. Should get 9 records.
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{
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sr, err := NewSegmentsReader(dir)
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testutil.Ok(t, err)
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reader := NewReader(sr)
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i := 0
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for ; i < 9 && reader.Next(); i++ {
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testutil.Equals(t, recordSize, len(reader.Record()))
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}
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testutil.Equals(t, 9, i, "wrong number of records")
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testutil.Assert(t, !reader.Next(), "unexpected record")
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testutil.Equals(t, nil, reader.Err())
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sr.Close()
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}
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}
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// TestClose ensures that calling Close more than once doesn't panic and doesn't block.
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func TestClose(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 func() {
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testutil.Ok(t, os.RemoveAll(dir))
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}()
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w, err := NewSize(nil, nil, dir, pageSize, false)
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testutil.Ok(t, err)
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testutil.Ok(t, w.Close())
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testutil.NotOk(t, w.Close())
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}
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func TestSegmentMetric(t *testing.T) {
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var (
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segmentSize = pageSize
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recordSize = (pageSize / 2) - recordHeaderSize
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)
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dir, err := ioutil.TempDir("", "segment_metric")
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testutil.Ok(t, err)
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defer func() {
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testutil.Ok(t, os.RemoveAll(dir))
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}()
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w, err := NewSize(nil, nil, dir, segmentSize, false)
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testutil.Ok(t, err)
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initialSegment := client_testutil.ToFloat64(w.currentSegment)
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// Write 3 records, each of which is half the segment size, meaning we should rotate to the next segment.
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for i := 0; i < 3; i++ {
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buf := make([]byte, recordSize)
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_, err := rand.Read(buf)
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testutil.Ok(t, err)
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err = w.Log(buf)
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testutil.Ok(t, err)
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}
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testutil.Assert(t, client_testutil.ToFloat64(w.currentSegment) == initialSegment+1, "segment metric did not increment after segment rotation")
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testutil.Ok(t, w.Close())
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}
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func TestCompression(t *testing.T) {
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boostrap := func(compressed bool) string {
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const (
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segmentSize = pageSize
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recordSize = (pageSize / 2) - recordHeaderSize
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records = 100
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)
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dirPath, err := ioutil.TempDir("", fmt.Sprintf("TestCompression_%t", compressed))
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testutil.Ok(t, err)
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w, err := NewSize(nil, nil, dirPath, segmentSize, compressed)
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testutil.Ok(t, err)
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buf := make([]byte, recordSize)
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for i := 0; i < records; i++ {
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testutil.Ok(t, w.Log(buf))
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}
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testutil.Ok(t, w.Close())
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return dirPath
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}
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dirCompressed := boostrap(true)
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defer func() {
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testutil.Ok(t, os.RemoveAll(dirCompressed))
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}()
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dirUnCompressed := boostrap(false)
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defer func() {
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testutil.Ok(t, os.RemoveAll(dirUnCompressed))
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}()
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uncompressedSize, err := testutil.DirSize(dirUnCompressed)
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testutil.Ok(t, err)
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compressedSize, err := testutil.DirSize(dirCompressed)
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testutil.Ok(t, err)
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testutil.Assert(t, float64(uncompressedSize)*0.75 > float64(compressedSize), "Compressing zeroes should save at least 25%% space - uncompressedSize: %d, compressedSize: %d", uncompressedSize, compressedSize)
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}
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func BenchmarkWAL_LogBatched(b *testing.B) {
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for _, compress := range []bool{true, false} {
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b.Run(fmt.Sprintf("compress=%t", compress), func(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 func() {
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testutil.Ok(b, os.RemoveAll(dir))
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}()
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w, err := New(nil, nil, dir, compress)
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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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}
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}
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func BenchmarkWAL_Log(b *testing.B) {
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for _, compress := range []bool{true, false} {
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b.Run(fmt.Sprintf("compress=%t", compress), func(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 func() {
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testutil.Ok(b, os.RemoveAll(dir))
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}()
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w, err := New(nil, nil, dir, compress)
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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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}
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}
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