1// Copyright 2015 CoreOS, Inc. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15package wal 16 17import ( 18 "bufio" 19 "encoding/binary" 20 "hash" 21 "io" 22 "sync" 23 24 "github.com/coreos/etcd/pkg/crc" 25 "github.com/coreos/etcd/wal/walpb" 26) 27 28type encoder struct { 29 mu sync.Mutex 30 bw *bufio.Writer 31 32 crc hash.Hash32 33 buf []byte 34 uint64buf []byte 35} 36 37func newEncoder(w io.Writer, prevCrc uint32) *encoder { 38 return &encoder{ 39 bw: bufio.NewWriter(w), 40 crc: crc.New(prevCrc, crcTable), 41 // 1MB buffer 42 buf: make([]byte, 1024*1024), 43 uint64buf: make([]byte, 8), 44 } 45} 46 47func (e *encoder) encode(rec *walpb.Record) error { 48 e.mu.Lock() 49 defer e.mu.Unlock() 50 51 e.crc.Write(rec.Data) 52 rec.Crc = e.crc.Sum32() 53 var ( 54 data []byte 55 err error 56 n int 57 ) 58 59 if rec.Size() > len(e.buf) { 60 data, err = rec.Marshal() 61 if err != nil { 62 return err 63 } 64 } else { 65 n, err = rec.MarshalTo(e.buf) 66 if err != nil { 67 return err 68 } 69 data = e.buf[:n] 70 } 71 if err = writeInt64(e.bw, int64(len(data)), e.uint64buf); err != nil { 72 return err 73 } 74 _, err = e.bw.Write(data) 75 return err 76} 77 78func (e *encoder) flush() error { 79 e.mu.Lock() 80 defer e.mu.Unlock() 81 return e.bw.Flush() 82} 83 84func writeInt64(w io.Writer, n int64, buf []byte) error { 85 // http://golang.org/src/encoding/binary/binary.go 86 binary.LittleEndian.PutUint64(buf, uint64(n)) 87 _, err := w.Write(buf) 88 return err 89} 90