How can we use channels in Go in place of mutex?

Issue

Channels combine communication—the exchange of a value—with synchronization—guaranteeing that two calculations (goroutines) are in a known state.

How is it possible to use the channels in Google Go to perform the functionality of mutex?

package main

import "sync"

var global int = 0
var m sync.Mutex

func thread1(){
    m.Lock()
    global = 1
    m.Unlock()
}

func thread2(){
    m.Lock()
    global = 2
    m.Unlock()
}

func main(){
   go thread1()
   go thread2()
}

Solution

An example of using a Channel as a Mutex:

package main

var global int = 0
var c = make(chan int, 1)

func thread1(){
    <-c // Grab the ticket
    global = 1
    c <- 1 // Give it back
}

func thread2(){
    <-c
    global = 2
    c <- 1
}

func main() {
   c <- 1 // Put the initial value into the channel
   go thread1()
   go thread2()
}

You could also use chan struct{} instead of chan int to reduce the memory size. The value that goes into it is struct{}{} (type struct{} and an empty content {}). See Ivan black’s comment for an example.

Answered By – Markus Jarderot

Answer Checked By – David Marino (GoLangFix Volunteer)

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