golang 高效低精度定时器实现
golang默认定时器是通过time模块提供的，不管是golang,libev,libevent也好，定时器都是通过最小堆实现的，导致加入定时器时间复杂度为O(lgn)，在需要大量定时器时效率较低，所以Linux提供了基于时间轮的实现，我们本次提供的
定时器实现就是标准的Linux时间轮实现方式。当然，我是把Skynet(https://github.com/cloudwu/skynet/blob/master/skynet-src/skynet_timer.c)的定时器移植了过来，偷窃无罪。。。
贴一张Linux时间轮的数据结构，如果比较陌生的话可以参考一下两篇文章：
1.http://www.ibm.com/developerworks/cn/linux/l-cn-timers/
2.http://blog.csdn.net/lonewolfxw/article/details/8034395
先看一下如何使用
package timer
import (
"fmt"
"sync/atomic"
"testing"
"time"
)
var sum int32 = 0
var N int32 = 300
var tt *Timer
func now() {
fmt.Println(time.Now().Format("2006-01-02 15:04:05"))
atomic.AddInt32(&sum, 1)
v := atomic.LoadInt32(&sum)
if v == 2*N {
tt.Stop()
}
}
func TestTimer(t *testing.T) {
timer := New(time.Millisecond * 10)
tt = timer
fmt.Println(timer)
var i int32
for i = 0; i < N; i++ {
timer.NewTimer(time.Millisecond*time.Duration(10*i), now)
timer.NewTimer(time.Millisecond*time.Duration(10*i), now)
}
timer.Start()
if sum != 2*N {
t.Error("failed")
}
}
timer := New(time.Millisecond * 10)我们定义了一个tick为0.01s的定时器，循环了300次每次启动2个timeout，回调中将sum+1，所以最后sum应该等于600。
这是我golang的处女作,可能代码不是很规范，有空请多review review
github地址：https://github.com/Skycrab/code/blob/master/Go/timer/timer.go
package timer
import (
"container/list"
"fmt"
"sync"
"time"
)
//referer https://github.com/cloudwu/skynet/blob/master/skynet-src/skynet_timer.c
const (
TIME_NEAR_SHIFT = 8
TIME_NEAR = 1 << TIME_NEAR_SHIFT
TIME_LEVEL_SHIFT = 6
TIME_LEVEL = 1 << TIME_LEVEL_SHIFT
TIME_NEAR_MASK = TIME_NEAR - 1
TIME_LEVEL_MASK = TIME_LEVEL - 1
)
type Timer struct {
near [TIME_NEAR]*list.List
t [4][TIME_LEVEL]*list.List
sync.Mutex
time uint32
tick time.Duration
quit chan struct{}
}
type Node struct {
expire uint32
f func()
}
func (n *Node) String() string {
return fmt.Sprintf("Node:expire,%d", n.expire)
}
func New(d time.Duration) *Timer {
t := new(Timer)
t.time = 0
t.tick = d
t.quit = make(chan struct{})
var i, j int
for i = 0; i < TIME_NEAR; i++ {
t.near[i] = list.New()
}
for i = 0; i < 4; i++ {
for j = 0; j < TIME_LEVEL; j++ {
t.t[i][j] = list.New()
}
}
return t
}
func (t *Timer) addNode(n *Node) {
expire := n.expire
current := t.time
if (expire | TIME_NEAR_MASK) == (current | TIME_NEAR_MASK) {
t.near[expire&TIME_NEAR_MASK].PushBack(n)
} else {
var i uint32
var mask uint32 = TIME_NEAR << TIME_LEVEL_SHIFT
for i = 0; i < 3; i++ {
if (expire | (mask - 1)) == (current | (mask - 1)) {
break
}
mask <<= TIME_LEVEL_SHIFT
}
t.t[i][(expire>>(TIME_NEAR_SHIFT+i*TIME_LEVEL_SHIFT))&TIME_LEVEL_MASK].PushBack(n)
}
}
func (t *Timer) NewTimer(d time.Duration, f func()) *Node {
n := new(Node)
n.f = f
t.Lock()
n.expire = uint32(d/t.tick) + t.time
t.addNode(n)
t.Unlock()
return n
}
func (t *Timer) String() string {
return fmt.Sprintf("Timer:time:%d, tick:%s", t.time, t.tick)
}
func dispatchList(front *list.Element) {
for e := front; e != nil; e = e.Next() {
node := e.Value.(*Node)
go node.f()
}
}
func (t *Timer) moveList(level, idx int) {
vec := t.t[level][idx]
front := vec.Front()
vec.Init()
for e := front; e != nil; e = e.Next() {
node := e.Value.(*Node)
t.addNode(node)
}
}
func (t *Timer) shift() {
t.Lock()
var mask uint32 = TIME_NEAR
t.time++
ct := t.time
if ct == 0 {
t.moveList(3, 0)
} else {
time := ct >> TIME_NEAR_SHIFT
var i int = 0
for (ct & (mask - 1)) == 0 {
idx := int(time & TIME_LEVEL_MASK)
if idx != 0 {
t.moveList(i, idx)
break
}
mask <<= TIME_LEVEL_SHIFT
time >>= TIME_LEVEL_SHIFT
i++
}
}
t.Unlock()
}
func (t *Timer) execute() {
t.Lock()
idx := t.time & TIME_NEAR_MASK
vec := t.near[idx]
if vec.Len() > 0 {
front := vec.Front()
vec.Init()
t.Unlock()
// dispatch_list don't need lock
dispatchList(front)
return
}
t.Unlock()
}
func (t *Timer) update() {
// try to dispatch timeout 0 (rare condition)
t.execute()
// shift time first, and then dispatch timer message
t.shift()
t.execute()
}
func (t *Timer) Start() {
tick := time.NewTicker(t.tick)
defer tick.Stop()
for {
select {
case <-tick.C:
t.update()
case <-t.quit:
return
}
}
}
func (t *Timer) Stop() {
close(t.quit)
}
熟悉skynet的童鞋看这段代码应该很熟悉，期待出现了golang大牛也写个牛逼的游戏服务器框架，这应该是很多人的心声吧。