statefule goroutines _ golang

In the previous example we used explicit locking with mutexes to synchronize access to shared state across multiple goroutines. Another option is to use the built-in synchronization features of goroutines and channels to achieve the same result. This channel-based approach aligns with Go‘s ideas of sharing memory by communivating and having each piece of data owned by exactly 1 goroutine

package main

import (
    "fmt"
    "math/rand"
    "sync/atomic"
    "time"
)

type read0p struct {
    key  int
    resp chan int
}

type write0p struct {
    key  int
    val  int
    resp chan bool
}

func main() {

    var ops int64 = 0

    reads := make(chan *read0p)
    writes := make(chan *write0p)

    go func() {
        var state = make(map[int]int)
        for {
            select {
            case read := <-reads:
                read.resp <- state[read.key]
            case write := <-writes:
                state[write.key] = write.val
                write.resp <- true
            }
        }
    }()

    for r := 0; r < 100; r++ {
        go func() {
            for {
                read := &read0p{
                    key:  rand.Intn(5),
                    resp: make(chan int),
                }
                reads <- read
                fmt.Println("<-read.resp:", <-read.resp)
                atomic.AddInt64(&ops, 1)
            }
        }()
    }

    for w := 0; w < 10; w++ {
        go func() {
            for {
                write := &write0p{
                    key:  rand.Intn(5),
                    val:  rand.Intn(100),
                    resp: make(chan bool),
                }
                writes <- write
                <-write.resp
                atomic.AddInt64(&ops, 1)
            }
        }()
    }

    time.Sleep(time.Second)

    opsFinal := atomic.LoadInt64(&ops)
    fmt.Println("ops:", opsFinal)
}

ops: 329696

总结 :

　　1 : atomic.AddInt64 原子性的增加一个值