版本
golang -- 1.12.4golang協(xié)程同步
1.channel - monitor goroutine
var deposits = make(chan int) // send amount to deposit
var balances = make(chan int) // receive balance
func Deposit(amount int) { deposits <- amount }
func Balance() int { return <-balances }
func teller() {
var balance int // balance is confined to teller goroutine
for {
select {
case amount := <-deposits:
balance += amount
case balances <- balance:
}
}
}
func init() {
go teller() // start the monitor goroutine
}
2.channel - serial confinement
type Cake struct{ state string }
func baker(cooked chan<- *Cake) {
for {
cake := new(Cake)
cake.state = "cooked"
cooked <- cake // baker never touches this cake again
}
}
func icer(iced chan<- *Cake, cooked <-chan *Cake) {
for cake := range cooked {
cake.state = "iced"
iced <- cake // icer never touches this cake again
}
}
3.mutual exclusion
import "sync"
var mu sync.Mutex // guards balance
var balance int
func Deposit(amount int) {
mu.Lock()
balance = balance + amount
mu.Unlock()
}
func Balance() int {
mu.Lock()
defer mu.Unlock()
return balance
}
4.mutual exclusion - RWMutex
import "sync"
var mu sync.RWMutex // guards balance
var balance int
func Deposit(amount int) {
mu.Lock()
balance = balance + amount
mu.Unlock()
}
func Balance() int {
mu.RLock() //readers lock
defer mu.RUnlock()
return balance
}
RLock允許讀取并行，寫入和讀取完全互斥，多次讀取，一次寫入
5.Lazy Initialization - sync.Once
var loadIconsOnce sync.Once
var icons map[string]image.Image
// Concurrency-safe.
func Icon(name string) image.Image {
loadIconsOnce.Do(loadIcons)
return icons[name]
}
