- 實作Redis的database層（核心層：處理命令并回傳）
- https://github.com/csgopher/go-redis
- 本文涉及以下檔案：
dict：定義字典的一些方法
sync_dict：實作dict
db：分資料庫
command：定義指令
ping，keys，string：指令的具體處理邏輯
database：單機版資料庫
datastruct/dict/dict.go
type Consumer func(key string, val interface{}) bool
type Dict interface {
Get(key string) (val interface{}, exists bool)
Len() int
Put(key string, val interface{}) (result int)
PutIfAbsent(key string, val interface{}) (result int)
PutIfExists(key string, val interface{}) (result int)
Remove(key string) (result int)
ForEach(consumer Consumer)
Keys() []string
RandomKeys(limit int) []string
RandomDistinctKeys(limit int) []string
Clear()
}
Dict介面：Redis資料結構的介面，這里我們使用sync.Map作為字典的實作，如果想用別的資料結構，換一個實作即可
Consumer：遍歷字典所有的鍵值對，回傳值是布爾，true繼續遍歷，false停止遍歷
datastruct/dict/sync_dict.go
type SyncDict struct {
m sync.Map
}
func MakeSyncDict() *SyncDict {
return &SyncDict{}
}
func (dict *SyncDict) Get(key string) (val interface{}, exists bool) {
val, ok := dict.m.Load(key)
return val, ok
}
func (dict *SyncDict) Len() int {
length := 0
dict.m.Range(func(k, v interface{}) bool {
length++
return true
})
return length
}
func (dict *SyncDict) Put(key string, val interface{}) (result int) {
_, existed := dict.m.Load(key)
dict.m.Store(key, val)
if existed {
return 0
}
return 1
}
func (dict *SyncDict) PutIfAbsent(key string, val interface{}) (result int) {
_, existed := dict.m.Load(key)
if existed {
return 0
}
dict.m.Store(key, val)
return 1
}
func (dict *SyncDict) PutIfExists(key string, val interface{}) (result int) {
_, existed := dict.m.Load(key)
if existed {
dict.m.Store(key, val)
return 1
}
return 0
}
func (dict *SyncDict) Remove(key string) (result int) {
_, existed := dict.m.Load(key)
dict.m.Delete(key)
if existed {
return 1
}
return 0
}
func (dict *SyncDict) ForEach(consumer Consumer) {
dict.m.Range(func(key, value interface{}) bool {
consumer(key.(string), value)
return true
})
}
func (dict *SyncDict) Keys() []string {
result := make([]string, dict.Len())
i := 0
dict.m.Range(func(key, value interface{}) bool {
result[i] = key.(string)
i++
return true
})
return result
}
func (dict *SyncDict) RandomKeys(limit int) []string {
result := make([]string, limit)
for i := 0; i < limit; i++ {
dict.m.Range(func(key, value interface{}) bool {
result[i] = key.(string)
return false
})
}
return result
}
func (dict *SyncDict) RandomDistinctKeys(limit int) []string {
result := make([]string, limit)
i := 0
dict.m.Range(func(key, value interface{}) bool {
result[i] = key.(string)
i++
if i == limit {
return false
}
return true
})
return result
}
func (dict *SyncDict) Clear() {
*dict = *MakeSyncDict()
}
使用sync.Map實作Dict介面
database/db.go
type DB struct {
index int
data dict.Dict
}
type ExecFunc func(db *DB, args [][]byte) resp.Reply
type CmdLine = [][]byte
func makeDB() *DB {
db := &DB{
data: dict.MakeSyncDict(),
}
return db
}
func (db *DB) Exec(c resp.Connection, cmdLine [][]byte) resp.Reply {
cmdName := strings.ToLower(string(cmdLine[0]))
cmd, ok := cmdTable[cmdName]
if !ok {
return reply.MakeErrReply("ERR unknown command '" + cmdName + "'")
}
if !validateArity(cmd.arity, cmdLine) {
return reply.MakeArgNumErrReply(cmdName)
}
fun := cmd.executor
return fun(db, cmdLine[1:]) // 把 set k v 中的set切掉
}
func validateArity(arity int, cmdArgs [][]byte) bool {
argNum := len(cmdArgs)
if arity >= 0 {
return argNum == arity
}
return argNum >= -arity
}
func (db *DB) GetEntity(key string) (*database.DataEntity, bool) {
raw, ok := db.data.Get(key)
if !ok {
return nil, false
}
entity, _ := raw.(*database.DataEntity)
return entity, true
}
func (db *DB) PutEntity(key string, entity *database.DataEntity) int {
return db.data.Put(key, entity)
}
func (db *DB) PutIfExists(key string, entity *database.DataEntity) int {
return db.data.PutIfExists(key, entity)
}
func (db *DB) PutIfAbsent(key string, entity *database.DataEntity) int {
return db.data.PutIfAbsent(key, entity)
}
func (db *DB) Remove(key string) {
db.data.Remove(key)
}
func (db *DB) Removes(keys ...string) (deleted int) {
deleted = 0
for _, key := range keys {
_, exists := db.data.Get(key)
if exists {
db.Remove(key)
deleted++
}
}
return deleted
}
func (db *DB) Flush() {
db.data.Clear()
}
實作Redis中的分資料庫
ExecFunc：所有Redis的指令都寫成這樣的型別
validateArity方法：
- 定長：set k v => arity=3；
- 變長：exists k1 k2 k3 ... => arity=-2，表示引數>=2個
database/command.go
var cmdTable = make(map[string]*command)
type command struct {
executor ExecFunc
arity int
}
func RegisterCommand(name string, executor ExecFunc, arity int) {
name = strings.ToLower(name)
cmdTable[name] = &command{
executor: executor,
arity: arity,
}
}
command：每一個command結構體都是一個指令，例如ping，keys等等
arity：引數數量
cmdTable：記錄所有指令和command結構體的關系
RegisterCommand：注冊指令的實作，在程式
database/ping.go
func Ping(db *DB, args [][]byte) resp.Reply {
if len(args) == 0 {
return &reply.PongReply{}
} else if len(args) == 1 {
return reply.MakeStatusReply(string(args[0]))
} else {
return reply.MakeErrReply("ERR wrong number of arguments for 'ping' command")
}
}
func init() {
RegisterCommand("ping", Ping, 1)
}
init方法：在啟動程式時就會呼叫這個方法，用于初始化
database/keys.go
func execDel(db *DB, args [][]byte) resp.Reply {
keys := make([]string, len(args))
for i, v := range args {
keys[i] = string(v)
}
deleted := db.Removes(keys...)
return reply.MakeIntReply(int64(deleted))
}
func execExists(db *DB, args [][]byte) resp.Reply {
result := int64(0)
for _, arg := range args {
key := string(arg)
_, exists := db.GetEntity(key)
if exists {
result++
}
}
return reply.MakeIntReply(result)
}
func execFlushDB(db *DB, args [][]byte) resp.Reply {
db.Flush()
return &reply.OkReply{}
}
func execType(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
entity, exists := db.GetEntity(key)
if !exists {
return reply.MakeStatusReply("none")
}
switch entity.Data.(type) {
case []byte:
return reply.MakeStatusReply("string")
}
return &reply.UnknownErrReply{}
}
func execRename(db *DB, args [][]byte) resp.Reply {
if len(args) != 2 {
return reply.MakeErrReply("ERR wrong number of arguments for 'rename' command")
}
src := string(args[0])
dest := string(args[1])
entity, ok := db.GetEntity(src)
if !ok {
return reply.MakeErrReply("no such key")
}
db.PutEntity(dest, entity)
db.Remove(src)
return &reply.OkReply{}
}
func execRenameNx(db *DB, args [][]byte) resp.Reply {
src := string(args[0])
dest := string(args[1])
_, exist := db.GetEntity(dest)
if exist {
return reply.MakeIntReply(0)
}
entity, ok := db.GetEntity(src)
if !ok {
return reply.MakeErrReply("no such key")
}
db.Removes(src, dest)
db.PutEntity(dest, entity)
return reply.MakeIntReply(1)
}
func execKeys(db *DB, args [][]byte) resp.Reply {
pattern := wildcard.CompilePattern(string(args[0]))
result := make([][]byte, 0)
db.data.ForEach(func(key string, val interface{}) bool {
if pattern.IsMatch(key) {
result = append(result, []byte(key))
}
return true
})
return reply.MakeMultiBulkReply(result)
}
func init() {
RegisterCommand("Del", execDel, -2)
RegisterCommand("Exists", execExists, -2)
RegisterCommand("Keys", execKeys, 2)
RegisterCommand("FlushDB", execFlushDB, -1)
RegisterCommand("Type", execType, 2)
RegisterCommand("Rename", execRename, 3)
RegisterCommand("RenameNx", execRenameNx, 3)
}
keys.go實作以下指令：
execDel：del k1 k2 k3 ...
execExists：exist k1 k2 k3 ...
execFlushDB：flushdb
execType：type k1
execRename：rename k1 k2
execRenameNx：renamenx k1 k2
execKeys：keys（依賴lib包的工具類wildcard.go）
database/string.go
func execGet(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
bytes, err := db.getAsString(key)
if err != nil {
return err
}
if bytes == nil {
return &reply.NullBulkReply{}
}
return reply.MakeBulkReply(bytes)
}
func (db *DB) getAsString(key string) ([]byte, reply.ErrorReply) {
entity, ok := db.GetEntity(key)
if !ok {
return nil, nil
}
bytes, ok := entity.Data.([]byte)
if !ok {
return nil, &reply.WrongTypeErrReply{}
}
return bytes, nil
}
func execSet(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
value := args[1]
entity := &database.DataEntity{
Data: value,
}
db.PutEntity(key, entity)
return &reply.OkReply{}
}
func execSetNX(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
value := args[1]
entity := &database.DataEntity{
Data: value,
}
result := db.PutIfAbsent(key, entity)
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})
if !exists {
return reply.MakeNullBulkReply()
}
old := entity.Data.([]byte)
return reply.MakeBulkReply(old)
}
func execStrLen(db *DB, args [][]byte) resp.Reply {
key := string(args[0])
entity, exists := db.GetEntity(key)
if !exists {
return reply.MakeNullBulkReply()
}
old := entity.Data.([]byte)
return reply.MakeIntReply(int64(len(old)))
}
func init() {
RegisterCommand("Get", execGet, 2)
RegisterCommand("Set", execSet, -3)
RegisterCommand("SetNx", execSetNX, 3)
RegisterCommand("GetSet", execGetSet, 3)
RegisterCommand("StrLen", execStrLen, 2)
}
string.go實作以下指令：
execGet：get k1
execSet：set k v
execSetNX：setnex k v
execGetSet：getset k v 回傳舊值
execStrLen：strlen k
database/database.go
type Database struct {
dbSet []*DB
}
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
}
return mdb
}
func (mdb *Database) Exec(c resp.Connection, cmdLine [][]byte) (result resp.Reply) {
defer func() {
if err := recover(); err != nil {
logger.Warn(fmt.Sprintf("error occurs: %v\n%s", err, string(debug.Stack())))
}
}()
cmdName := strings.ToLower(string(cmdLine[0]))
if cmdName == "select" {
if len(cmdLine) != 2 {
return reply.MakeArgNumErrReply("select")
}
return execSelect(c, mdb, cmdLine[1:])
}
dbIndex := c.GetDBIndex()
selectedDB := mdb.dbSet[dbIndex]
return selectedDB.Exec(c, cmdLine)
}
func execSelect(c resp.Connection, mdb *Database, args [][]byte) resp.Reply {
dbIndex, err := strconv.Atoi(string(args[0]))
if err != nil {
return reply.MakeErrReply("ERR invalid DB index")
}
if dbIndex >= len(mdb.dbSet) {
return reply.MakeErrReply("ERR DB index is out of range")
}
c.SelectDB(dbIndex)
return reply.MakeOkReply()
}
func (mdb *Database) Close() {
}
func (mdb *Database) AfterClientClose(c resp.Connection) {
}
Database：一組db的集合
Exec：執行切換db指令或者其他指令
execSelect方法：選擇db（指令：select 2）
resp/handler/handler.go
import (
database2 "go-redis/database"
)
func MakeHandler() *RespHandler {
var db database.Database
db = database2.NewDatabase()
return &RespHandler{
db: db,
}
}
修改實作協議層handler的database實作
架構小結
TCP層服務TCP的連接，然后將連接交給RESP協議層的handler，handler監聽客戶端的連接，將指令決議后發給管道，管道轉給database層（database/database.go），核心層根據命令型別執行不同的方法，然后回傳，
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標籤：其他