- 將使用者發來的指令以RESP協議的形式儲存在本地的AOF檔案，重啟Redis後執行此檔案恢復資料
- https://github.com/csgopher/go-redis
- 本文涉及以下檔案：
redis.conf：配置檔案
aof：實現aof
redis.conf
appendonly yes
appendfilename appendonly.aof
aof/aof.go
type CmdLine = [][]byte
const (
aofQueueSize = 1 << 16
)
type payload struct {
cmdLine CmdLine
dbIndex int
}
type AofHandler struct {
db databaseface.Database
aofChan chan *payload
aofFile *os.File
aofFilename string
currentDB int
}
func NewAOFHandler(db databaseface.Database) (*AofHandler, error) {
handler := &AofHandler{}
handler.aofFilename = config.Properties.AppendFilename
handler.db = db
handler.LoadAof()
aofFile, err := os.OpenFile(handler.aofFilename, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0600)
if err != nil {
return nil, err
}
handler.aofFile = aofFile
handler.aofChan = make(chan *payload, aofQueueSize)
go func() {
handler.handleAof()
}()
return handler, nil
}
func (handler *AofHandler) AddAof(dbIndex int, cmdLine CmdLine) {
if config.Properties.AppendOnly && handler.aofChan != nil {
handler.aofChan <- &payload{
cmdLine: cmdLine,
dbIndex: dbIndex,
}
}
}
func (handler *AofHandler) handleAof() {
handler.currentDB = 0
for p := range handler.aofChan {
if p.dbIndex != handler.currentDB {
// select db
data := reply.MakeMultiBulkReply(utils.ToCmdLine("SELECT", strconv.Itoa(p.dbIndex))).ToBytes()
_, err := handler.aofFile.Write(data)
if err != nil {
logger.Warn(err)
continue
}
handler.currentDB = p.dbIndex
}
data := reply.MakeMultiBulkReply(p.cmdLine).ToBytes()
_, err := handler.aofFile.Write(data)
if err != nil {
logger.Warn(err)
}
}
}
func (handler *AofHandler) LoadAof() {
file, err := os.Open(handler.aofFilename)
if err != nil {
logger.Warn(err)
return
}
defer file.Close()
ch := parser.ParseStream(file)
fakeConn := &connection.Connection{}
for p := range ch {
if p.Err != nil {
if p.Err == io.EOF {
break
}
logger.Error("parse error: " + p.Err.Error())
continue
}
if p.Data == nil {
logger.Error("empty payload")
continue
}
r, ok := p.Data.(*reply.MultiBulkReply)
if !ok {
logger.Error("require multi bulk reply")
continue
}
ret := handler.db.Exec(fakeConn, r.Args)
if reply.IsErrorReply(ret) {
logger.Error("exec err", err)
}
}
}
AofHandler：1.從管道中接收資料 2.寫入AOF檔案
AddAof：使用者的指令包裝成payload放入管道
handleAof：將管道中的payload寫入磁碟
LoadAof：重啟Redis後載入aof檔案
database/database.go
type Database struct {
dbSet []*DB
aofHandler *aof.AofHandler
}
func NewDatabase() *Database {
mdb := &Database{}
if config.Properties.Databases == 0 {
config.Properties.Databases = 16
}
mdb.dbSet = make([]*DB, config.Properties.Databases)
for i := range mdb.dbSet {
singleDB := makeDB()
singleDB.index = i
mdb.dbSet[i] = singleDB
}
if config.Properties.AppendOnly {
aofHandler, err := aof.NewAOFHandler(mdb)
if err != nil {
panic(err)
}
mdb.aofHandler = aofHandler
for _, db := range mdb.dbSet {
singleDB := db
singleDB.addAof = func(line CmdLine) {
mdb.aofHandler.AddAof(singleDB.index, line)
}
}
}
return mdb
}
將AOF加入到database裡
使用singleDB的原因：因為在迴圈中獲取返回變數的地址都完全相同，因此當我們想要訪問陣列中元素所在的地址時，不應該直接獲取 range 返回的變數地址 db，而應該使用 singleDB := db
database/db.go
type DB struct {
index int
data dict.Dict
addAof func(CmdLine)
}
func makeDB() *DB {
db := &DB{
data: dict.MakeSyncDict(),
addAof: func(line CmdLine) {},
}
return db
}
由於分資料庫db引用不到aof，所以新增一個addAof匿名函式，在NewDatabase中用這個匿名函式呼叫AddAof
database/keys.go
func execDel(db *DB, args [][]byte) resp.Reply {
......
if deleted > 0 {
db.addAof(utils.ToCmdLine2("del", args...))
}
return reply.MakeIntReply(int64(deleted))
}
func execFlushDB(db *DB, args [][]byte) resp.Reply {
db.Flush()
db.addAof(utils.ToCmdLine2("flushdb", args...))
return &reply.OkReply{}
}
func execRename(db *DB, args [][]byte) resp.Reply {
......
db.addAof(utils.ToCmdLine2("rename", args...))
return &reply.OkReply{}
}
func execRenameNx(db *DB, args [][]byte) resp.Reply {
......
db.addAof(utils.ToCmdLine2("renamenx", args...))
return reply.MakeIntReply(1)
}
database/string.go
func execSet(db *DB, args [][]byte) resp.Reply {
......
db.addAof(utils.ToCmdLine2("set", args...))
return &reply.OkReply{}
}
func execSetNX(db *DB, args [][]byte) resp.Reply {
......
db.addAof(utils.ToCmdLine2("setnx", args...))
return reply.MakeIntReply(int64(result))
}
func execGetSet(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
value := args[1]
entity, exists := db.GetEntity(key)
db.PutEntity(key, &database.DataEntity{Data: value})
db.addAof(utils.ToCmdLine2("getset", args...))
......
}
新增addAof方法
測試命令
*3\r\n$3\r\nSET\r\n$3\r\nkey\r\n$5\r\nvalue\r\n
*2\r\n$3\r\nGET\r\n$3\r\nkey\r\n
*2\r\n$6\r\nSELECT\r\n$1\r\n1\r\n