mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-26 14:09:41 -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>
550 lines
13 KiB
Go
550 lines
13 KiB
Go
// Copyright 2019 The Prometheus Authors
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//
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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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"fmt"
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"hash/crc32"
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"io"
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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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"runtime"
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"strconv"
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"testing"
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"time"
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"github.com/go-kit/kit/log"
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tsdb_errors "github.com/prometheus/tsdb/errors"
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"github.com/prometheus/tsdb/testutil"
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)
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type reader interface {
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Next() bool
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Err() error
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Record() []byte
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Offset() int64
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}
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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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var readerConstructors = map[string]func(io.Reader) reader{
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"Reader": func(r io.Reader) reader {
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return NewReader(r)
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},
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"LiveReader": func(r io.Reader) reader {
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lr := NewLiveReader(log.NewNopLogger(), nil, r)
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lr.eofNonErr = true
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return lr
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},
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}
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var data = make([]byte, 100000)
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var testReaderCases = []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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// Two records the together are too big for a page.
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// NB currently the non-live reader succeeds on this. I think this is a bug.
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// but we've seen it in production.
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{
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t: []record{
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{recFull, data[:pageSize/2]},
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{recFull, data[:pageSize/2]},
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},
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exp: [][]byte{
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data[:pageSize/2],
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data[:pageSize/2],
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},
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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, pageSize-recordHeaderSize-102), 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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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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for name, fn := range readerConstructors {
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for i, c := range testReaderCases {
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t.Run(fmt.Sprintf("%s/%d", name, i), func(t *testing.T) {
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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 := fn(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 expected")
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}
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testutil.Equals(t, c.exp[j], rec, "Bytes within record did not match expected Bytes")
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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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}
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}
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func TestReader_Live(t *testing.T) {
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logger := testutil.NewLogger(t)
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for i := range testReaderCases {
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t.Run(strconv.Itoa(i), func(t *testing.T) {
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writeFd, err := ioutil.TempFile("", "TestReader_Live")
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testutil.Ok(t, err)
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defer os.Remove(writeFd.Name())
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go func(i int) {
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for _, rec := range testReaderCases[i].t {
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rec := encodedRecord(rec.t, rec.b)
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_, err := writeFd.Write(rec)
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testutil.Ok(t, err)
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runtime.Gosched()
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}
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writeFd.Close()
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}(i)
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// Read from a second FD on the same file.
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readFd, err := os.Open(writeFd.Name())
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testutil.Ok(t, err)
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reader := NewLiveReader(logger, nil, readFd)
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for _, exp := range testReaderCases[i].exp {
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for !reader.Next() {
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testutil.Assert(t, reader.Err() == io.EOF, "expect EOF, got: %v", reader.Err())
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runtime.Gosched()
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}
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actual := reader.Record()
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testutil.Equals(t, exp, actual, "read wrong record")
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}
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testutil.Assert(t, !reader.Next(), "unexpected record")
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if testReaderCases[i].fail {
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testutil.Assert(t, reader.Err() != nil, "expected error")
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}
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})
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}
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}
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const fuzzLen = 500
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func generateRandomEntries(w *WAL, records chan []byte) error {
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var recs [][]byte
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for i := 0; i < fuzzLen; i++ {
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var sz int64
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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 = pageSize * 8
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}
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rec := make([]byte, rand.Int63n(sz))
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if _, err := rand.Read(rec); err != nil {
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return err
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}
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records <- rec
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// Randomly batch up records.
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recs = append(recs, rec)
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if rand.Intn(4) < 3 {
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if err := w.Log(recs...); err != nil {
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return err
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}
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recs = recs[:0]
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}
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}
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return w.Log(recs...)
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}
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type multiReadCloser struct {
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reader io.Reader
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closers []io.Closer
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}
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func (m *multiReadCloser) Read(p []byte) (n int, err error) {
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return m.reader.Read(p)
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}
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func (m *multiReadCloser) Close() error {
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var merr tsdb_errors.MultiError
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for _, closer := range m.closers {
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merr.Add(closer.Close())
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}
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return merr.Err()
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}
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func allSegments(dir string) (io.ReadCloser, error) {
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seg, err := listSegments(dir)
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if err != nil {
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return nil, err
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}
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var readers []io.Reader
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var closers []io.Closer
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for _, r := range seg {
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f, err := os.Open(filepath.Join(dir, r.name))
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if err != nil {
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return nil, err
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}
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readers = append(readers, f)
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closers = append(closers, f)
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}
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return &multiReadCloser{
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reader: io.MultiReader(readers...),
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closers: closers,
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}, nil
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}
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func TestReaderFuzz(t *testing.T) {
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for name, fn := range readerConstructors {
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for _, compress := range []bool{false, true} {
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t.Run(fmt.Sprintf("%s,compress=%t", name, compress), func(t *testing.T) {
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dir, err := ioutil.TempDir("", "wal_fuzz_live")
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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, 128*pageSize, compress)
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testutil.Ok(t, err)
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// Buffering required as we're not reading concurrently.
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input := make(chan []byte, fuzzLen)
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err = generateRandomEntries(w, input)
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testutil.Ok(t, err)
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close(input)
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err = w.Close()
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testutil.Ok(t, err)
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sr, err := allSegments(w.Dir())
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testutil.Ok(t, err)
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defer sr.Close()
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reader := fn(sr)
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for expected := range input {
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testutil.Assert(t, reader.Next(), "expected record: %v", reader.Err())
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testutil.Equals(t, expected, reader.Record(), "read wrong record")
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}
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testutil.Assert(t, !reader.Next(), "unexpected record")
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})
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}
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}
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}
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func TestReaderFuzz_Live(t *testing.T) {
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logger := testutil.NewLogger(t)
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for _, compress := range []bool{false, true} {
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t.Run(fmt.Sprintf("compress=%t", compress), func(t *testing.T) {
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dir, err := ioutil.TempDir("", "wal_fuzz_live")
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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, 128*pageSize, compress)
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testutil.Ok(t, err)
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defer w.Close()
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// In the background, generate a stream of random records and write them
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// to the WAL.
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input := make(chan []byte, fuzzLen/10) // buffering required as we sometimes batch WAL writes.
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done := make(chan struct{})
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go func() {
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err := generateRandomEntries(w, input)
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testutil.Ok(t, err)
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time.Sleep(100 * time.Millisecond)
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close(done)
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}()
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// Tail the WAL and compare the results.
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m, _, err := w.Segments()
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testutil.Ok(t, err)
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seg, err := OpenReadSegment(SegmentName(dir, m))
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testutil.Ok(t, err)
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defer seg.Close()
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r := NewLiveReader(logger, nil, seg)
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segmentTicker := time.NewTicker(100 * time.Millisecond)
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readTicker := time.NewTicker(10 * time.Millisecond)
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readSegment := func(r *LiveReader) bool {
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for r.Next() {
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rec := r.Record()
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expected, ok := <-input
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testutil.Assert(t, ok, "unexpected record")
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testutil.Equals(t, expected, rec, "record does not match expected")
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}
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testutil.Assert(t, r.Err() == io.EOF, "expected EOF, got: %v", r.Err())
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return true
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}
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outer:
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for {
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select {
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case <-segmentTicker.C:
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// check if new segments exist
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_, last, err := w.Segments()
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testutil.Ok(t, err)
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if last <= seg.i {
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continue
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}
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// read to end of segment.
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readSegment(r)
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fi, err := os.Stat(SegmentName(dir, seg.i))
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testutil.Ok(t, err)
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testutil.Assert(t, r.Offset() == fi.Size(), "expected to have read whole segment, but read %d of %d", r.Offset(), fi.Size())
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seg, err = OpenReadSegment(SegmentName(dir, seg.i+1))
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testutil.Ok(t, err)
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defer seg.Close()
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r = NewLiveReader(logger, nil, seg)
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case <-readTicker.C:
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readSegment(r)
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case <-done:
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readSegment(r)
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break outer
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}
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}
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testutil.Assert(t, r.Err() == io.EOF, "expected EOF")
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})
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}
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}
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func TestLiveReaderCorrupt_ShortFile(t *testing.T) {
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// Write a corrupt WAL segment, there is one record of pageSize in length,
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// but the segment is only half written.
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logger := testutil.NewLogger(t)
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dir, err := ioutil.TempDir("", "wal_live_corrupt")
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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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rec := make([]byte, pageSize-recordHeaderSize)
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_, err = rand.Read(rec)
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testutil.Ok(t, err)
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err = w.Log(rec)
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testutil.Ok(t, err)
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err = w.Close()
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testutil.Ok(t, err)
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segmentFile, err := os.OpenFile(filepath.Join(dir, "00000000"), os.O_RDWR, 0666)
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testutil.Ok(t, err)
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err = segmentFile.Truncate(pageSize / 2)
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testutil.Ok(t, err)
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err = segmentFile.Close()
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testutil.Ok(t, err)
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// Try and LiveReader it.
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m, _, err := w.Segments()
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testutil.Ok(t, err)
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seg, err := OpenReadSegment(SegmentName(dir, m))
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testutil.Ok(t, err)
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defer seg.Close()
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r := NewLiveReader(logger, nil, seg)
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testutil.Assert(t, r.Next() == false, "expected no records")
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testutil.Assert(t, r.Err() == io.EOF, "expected error, got: %v", r.Err())
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}
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func TestLiveReaderCorrupt_RecordTooLongAndShort(t *testing.T) {
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// Write a corrupt WAL segment, when record len > page size.
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logger := testutil.NewLogger(t)
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dir, err := ioutil.TempDir("", "wal_live_corrupt")
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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*2, false)
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testutil.Ok(t, err)
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rec := make([]byte, pageSize-recordHeaderSize)
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_, err = rand.Read(rec)
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testutil.Ok(t, err)
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err = w.Log(rec)
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testutil.Ok(t, err)
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err = w.Close()
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testutil.Ok(t, err)
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segmentFile, err := os.OpenFile(filepath.Join(dir, "00000000"), os.O_RDWR, 0666)
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testutil.Ok(t, err)
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// Override the record length
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buf := make([]byte, 3)
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buf[0] = byte(recFull)
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binary.BigEndian.PutUint16(buf[1:], 0xFFFF)
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_, err = segmentFile.WriteAt(buf, 0)
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testutil.Ok(t, err)
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err = segmentFile.Close()
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testutil.Ok(t, err)
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// Try and LiveReader it.
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m, _, err := w.Segments()
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testutil.Ok(t, err)
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seg, err := OpenReadSegment(SegmentName(dir, m))
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testutil.Ok(t, err)
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defer seg.Close()
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r := NewLiveReader(logger, nil, seg)
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testutil.Assert(t, r.Next() == false, "expected no records")
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testutil.Assert(t, r.Err().Error() == "record length greater than a single page: 65542 > 32768", "expected error, got: %v", r.Err())
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}
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func TestReaderData(t *testing.T) {
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dir := os.Getenv("WALDIR")
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if dir == "" {
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return
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}
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for name, fn := range readerConstructors {
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t.Run(name, func(t *testing.T) {
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w, err := New(nil, nil, dir, true)
|
|
testutil.Ok(t, err)
|
|
|
|
sr, err := allSegments(dir)
|
|
testutil.Ok(t, err)
|
|
|
|
reader := fn(sr)
|
|
for reader.Next() {
|
|
}
|
|
testutil.Ok(t, reader.Err())
|
|
|
|
err = w.Repair(reader.Err())
|
|
testutil.Ok(t, err)
|
|
})
|
|
}
|
|
}
|