打造先进的内存KV数据库-7 反射以及并发锁

反射

反射作为一种代码组织形式，带来了极大的不安全因素，同时也带来了许多便利之处，通过方法、对象、类型名称来获得具体实例，可以避免大量if-else分支，使得代码优雅，monkeyDB的服务端代码最后采用反射组织。

并发锁

多线程访问同一资源时，需要对资源加锁，否则可能会得到预料之外的后果。由于内存数据库优越的读写性能，锁的粒度可以尽量大，monkeyDB使用库级锁（相当于表级锁）来保证线程安全。

MonkeyDB项目已开源至 https://github.com/InsZVA/MonkeyDB 采用GPL协议

代码

//server.go
package main
// #cgo LDFLAGS: -L ./lib -lmonkeyS
// #include "./lib/core.h"
// #include <stdlib.h>
import "C"
import (
"unsafe"
"fmt"
"net"
"strings"
"./tcp"
"./convert"
"reflect"
"./minheap"
"strconv"
"flag"
"sync"
)

////////////////////////////////////// 库级锁   ////////////////////////////////////////////////////////////////

var mutex map[C.Database]*sync.RWMutex

////////////////////////////////////// MinHeap ////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////// command类型 用于解析处理各种数据库命令 //////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////////////////////
var (
acceptedCmd = []string{"set","get","delete","remove","createdb","switchdb","dropdb",/*"push","pop","destroy",*/"listdb"}
port = flag.String("p","1517","侦听端口号")
)

type command []byte

func (cmd command) Set(db **C.Database) []byte {
//锁并发
_,ok := mutex[**db];
if !ok {
mutex[**db] = new(sync.RWMutex)
}
mutex[**db].Lock()
defer mutex[**db].Unlock()

response := []byte{}
key,next := convert.ParseUntil(cmd,' ',4)
value,_ := convert.ParseUntil(cmd,0,next+1)
//fmt.Println("set ",key,value)
r := C.Set(&(*db).tIndex,(*C.char)(convert.Bytes2C(key)),(convert.Bytes2C(value)))
for i := 0;;i++ {
response = append(response,byte(r.msg[i]))
if response[i] == 0 { break; }
}
return response
}

func (cmd command) Get(db **C.Database) []byte {
//锁并发
_,ok := mutex[**db];
if !ok {
mutex[**db] = new(sync.RWMutex)
}
mutex[**db].RLock()
defer mutex[**db].RUnlock()

response := []byte{}
key,_ := convert.ParseUntil(cmd,0,4)
r := C.Get(&(*db).tIndex,(*C.char)(convert.Bytes2C(key)))
if int(r.code) == 0 {
for i := 0;;i++ {
response = append(response,byte(*(*C.char)(unsafe.Pointer((uintptr(r.pData)+uintptr(i))))))
if response[i] == 0 { break; }
}
}else {
}
return response
}

func (cmd command) Delete(db **C.Database) []byte {
return cmd.Remove(db)
}

func (cmd command) Remove(db **C.Database) []byte {
//锁并发
_,ok := mutex[**db];
if !ok {
mutex[**db] = new(sync.RWMutex)
}
mutex[**db].Lock()
defer mutex[**db].Unlock()

response := []byte{}
key,_ := convert.ParseUntil(cmd,0,7)
r := C.Delete(&(*db).tIndex,(*C.char)(convert.Bytes2C(key)))
for i := 0;;i++ {
response = append(response,byte(r.msg[i]))
if response[i] == 0 { break; }
}
return response
}

func (cmd command) Createdb(db **C.Database) []byte {
response := []byte{}
key,_ := convert.ParseUntil(cmd,0,9)
d := C.CreateDB((*C.char)(convert.Bytes2C(key)))
if d != nil {
*db = d
response = []byte("Already exist,switched\n")
}else {
response = []byte("Created\n")
}
return response
}

func (cmd command) Switchdb(db **C.Database) []byte {
response := []byte{}
key,_ := convert.ParseUntil(cmd,0,9)
d := C.SwitchDB((*C.char)(convert.Bytes2C(key)))
if d != nil {
*db = d
response = []byte("ok\n")
}else {
response = []byte("fail\n")
}
return response
}

func (cmd command) Dropdb(db **C.Database) []byte {
//锁并发
_,ok := mutex[**db];
if !ok {
mutex[**db] = new(sync.RWMutex)
}
mutex[**db].Lock()
defer mutex[**db].Unlock()

response := []byte{}
key,_ := convert.ParseUntil(cmd,0,7)
*db = C.DropDB((*C.char)(convert.Bytes2C(key)))
return response
}

func (cmd command) Listdb(db **C.Database) []byte {
response := []byte{}
r := C.ListDB()
for i := 0;i < 1024;i++ {
b := byte(*(*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(r))+uintptr(i))))
response = append(response,b)
if(b == 0){ break; }
}
C.free(unsafe.Pointer(r))
return response
}

func (cmd command) Push(db **C.Database) []byte {
var response []byte
key,next := convert.ParseUntil(cmd,' ',5)
key2,next := convert.ParseUntil(cmd,' ',next+1)
value,_ := convert.ParseUntil(cmd,0,next+1)
var i int
btnode := C.BTree_search((*db).tIndex,(C.KeyType)(C.GetHash((*C.char)(convert.Bytes2C(key)))),(*C.int)(unsafe.Pointer(&i)))
if uintptr(unsafe.Pointer(btnode)) != uintptr(0) {  //B树上有此堆
heap := (*minheap.MinHeap)(btnode.pRecord[i])   //BUG GO GC 会回收掉上次的内存
k,_ := strconv.Atoi(string(key2))
v,_ := strconv.Atoi(string(value))
heap.Push(minheap.Pair{Key:uint32(k),Value:uint32(v)})
response = []byte("Pushed")
}else {                 //建一个新的堆
heap := minheap.New()
C.BTree_insert(&(*db).tIndex, (C.KeyType)(C.GetHash((*C.char)(convert.Bytes2C(key)))), unsafe.Pointer(&heap))
k,_ := strconv.Atoi(string(key2))
v,_ := strconv.Atoi(string(value))
heap.Push(minheap.Pair{Key:uint32(k),Value:uint32(v)})
response = []byte("Created and pushed")
}
return response
}
//////////////////////////////////////////////////////////////////////////////////////////////////////////////
func initDB() { //初始化数据库

str0 := "monkey"
C.CreateDB((*C.char)(convert.String2C(str0)))   //创建基础数据库
str0 = "config"                     //配置数据库
C.CreateDB((*C.char)(convert.String2C(str0)))
key := "passwd"     //初始密码
data := "monkey"
db := C.SwitchDB((*C.char)(convert.String2C(str0)))
C.Set(&(db.tIndex),(*C.char)(convert.String2C(key)),(convert.String2C(data)))

}

func listen() {

servicePort := ":"+*port
tcpAddr,err := net.ResolveTCPAddr("tcp4",servicePort)
if err != nil {
panic(err)
}
l,err := net.ListenTCP("tcp",tcpAddr)   //侦听TCP
if err != nil {
panic(err)
}
fmt.Println("Server Started on "+*port+"!")
for{
conn,err := l.AcceptTCP()
conn.SetKeepAlive(true)
conn.SetNoDelay(true)
if err != nil {
panic(err)
}
s := tcp.TCPSession{Conn:conn}
s.Init()
go Handler(&s)
}
}

func main() {
flag.Parse()
//初始化锁
mutex = make(map[C.Database]*sync.RWMutex)
initDB()
listen()
}

func auth(s *tcp.TCPSession) bool {
buff := s.ReadMessage()
params := strings.Split(string(buff)," ")
str0 := "config"
db := C.SwitchDB((*C.char)(convert.String2C(str0)))
if params[0] != "auth" {
s.SendMessage([]byte("Please auth first!"))
return false
}
r := C.Get(&(db.tIndex),(*C.char)(convert.String2C("passwd")))
if int(r.code) == 0 {
passwd := []byte{}
for i := 0;;i++ {
passwd = append(passwd,byte(*(*C.char)(unsafe.Pointer((uintptr(r.pData)+uintptr(i))))))
if passwd[i] == 0 {
break
}
}
if convert.Equal(passwd,[]byte(params[1])) {
s.SendMessage([]byte("Auth success"))
return true
} else {
s.SendMessage([]byte("Auth fail"))
return false
}
}else {
s.SendMessage([]byte("Auth success"))
return true
}
}

func Handler(s *tcp.TCPSession) {
for !auth(s){
}
str := "monkey"
db := C.SwitchDB((*C.char)(convert.String2C(str)))//环境变量-当前数据库
for {
if s.Closed {
return
}
buff := s.ReadMessage()
// if err != nil {
//  conn.Close()
//  break
// }
if len(buff) == 0 {
return
}
//commands := bytes.Split(buff,[]byte{0})
//for _,cmd := range commands {
TranslateMessage2(s,&db,buff)
//}                     //解析消息
}

}

func TranslateMessage2(s *tcp.TCPSession,db **C.Database,message []byte) {
com := command(message)
//fmt.Println("处理：",string(message))
response := []byte{}
for _,cmd := range acceptedCmd {
if convert.StartBy(message,cmd) {
result := reflect.ValueOf(com).MethodByName(convert.UpperHead(cmd)).Call([]reflect.Value{reflect.ValueOf(db)})
response = result[0].Interface().([]byte)
break
}
}
s.SendMessage(response)
}

////////////////////////////////////////Dumplated//////////////////////////////////////////////////////////////////////////
func TranslateMessage(s *tcp.TCPSession,db **C.Database,message []byte) {
command := string(message)
params := strings.Split(command," ")
//fmt.Println(params)
response := []byte{}
if params[0] == "set" {
r := C.Set(&(*db).tIndex,(*C.char)(convert.String2C(params[1])),(convert.String2C(params[2])))
for i := 0;;i++ {
response = append(response,byte(r.msg[i]))
if response[i] == 0 { break; }
}
}else if params[0] == "get" {
r := C.Get(&(*db).tIndex,(*C.char)(convert.String2C(params[1])))
// for i := 0;;i++ {
//  response = append(response,byte(r.msg[i]))
//  if response[i] == 0 { break; }
// }
if int(r.code) == 0 {
for i := 0;;i++ {
response = append(response,byte(*(*C.char)(unsafe.Pointer((uintptr(r.pData)+uintptr(i))))))
if response[i] == 0 { break; }
}
}else {
// for i := 0;;i++ {
// response = append(response,byte(r.msg[i]))
// if response[i] == 0 { break; }
// }
}

}else if params[0] == "delete" || params[0] == "remove" {
r := C.Delete(&(*db).tIndex,(*C.char)(convert.String2C(params[1])))
for i := 0;;i++ {
response = append(response,byte(r.msg[i]))
if response[i] == 0 { break; }
}

}else if params[0] == "createdb" {
d := C.CreateDB((*C.char)(convert.String2C(params[1])))
if d != nil {
*db = d
response = []byte("Already exist,switched\n")
}else {
response = []byte("Created\n")
}
}else if params[0] == "switchdb" {
d := C.SwitchDB((*C.char)(convert.String2C(params[1])))
if d != nil {
*db = d
response = []byte("ok\n")
}else {
response = []byte("fail\n")
}
}else if params[0] == "dropdb" {
*db = C.DropDB((*C.char)(convert.String2C(params[1])))
}else if strings.EqualFold("listdb",params[0]) {
r := C.ListDB()
for i := 0;i < 1024;i++ {
b := byte(*(*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(r))+uintptr(i))))
response = append(response,b)
if(b == 0){ break; }
}
C.free(unsafe.Pointer(r))
}else {
//fmt.Println("unkown command:",params[0])
}
s.SendMessage(response)
}