Go ants中的指数退避算法抢锁技巧

首先看一下指数退避算法的维基百科解释
看不了的直接看图片吧

在go 协成池框架中有一把巧妙的锁：spinLock

import (
	"runtime"
	"sync"
	"sync/atomic"
)

type spinLock uint32

const maxBackoff = 64

func (sl *spinLock) Lock() {
	backoff := 1
	// 巧妙之处
	for !atomic.CompareAndSwapUint32((*uint32)(sl), 0, 1) {
		// Leverage the exponential backoff algorithm 利用指数退避算法
		for i := 0; i < backoff; i++ {
			runtime.Gosched()
		}
		if backoff < maxBackoff {
			backoff <<= 1
		}
	}
}

func (sl *spinLock) Unlock() {
	atomic.StoreUint32((*uint32)(sl), 0)
}

// NewSpinLock instantiates a spin-lock.
func NewSpinLock() sync.Locker {
	return new(spinLock)
}