Synchronous and asynchronous implementation methods of Golang functions

Golang is a high-level programming language that supports concurrent programming. It provides rich concurrent programming mechanisms and syntax features to facilitate developers to implement complex multi-threaded or multi-coroutine programs. Among them, synchronization and asynchronous are two commonly used methods in concurrent programming. This article will introduce the synchronous and asynchronous implementation methods of Golang functions and their usage scenarios.

1. Implementation method of synchronous function

Synchronous function means that during the execution of the function, the program will wait for the function to return the result before continuing to perform the next operation. In Golang, the commonly used synchronization function implementation methods are as follows.

1. Blocking call

Blocking call is the most commonly used method to implement synchronous functions. That is, when a function is called, the program will block until the function completes execution and returns the result before continuing. Next step. For example, the f function in the following code is a blocking call:

func f() int {
    time.Sleep(time.Second * 5)
    return 42
}

func main() {
    x := f()
    fmt.Println(x)
}

The f function in the above code simulates a time-consuming operation and takes 5 seconds to return the result. When the f function is called in the main function, the program will always block and wait for the f function to complete execution and return the result before continuing to the next step.

2. Multi-thread synchronization

Golang provides a multi-thread programming mechanism that can use multiple threads to perform tasks in parallel. When multiple threads access the same resource at the same time, synchronization operations are required to avoid race conditions. Common synchronization methods include mutex locks, condition variables, atomic operations, etc. The following is a sample code that uses a mutex lock to achieve multi-thread synchronization:

var count int
var mut sync.Mutex

func increment() {
    mut.Lock()
    count++
    mut.Unlock()
}

func main() {
    for i := 0; i < 1000; i++ {
        go increment()
    }
    time.Sleep(time.Second)
    fmt.Println(count)
}

In the above code, the increment function is a function that performs an increment operation. Through the mutex lock, multiple threads realize the count variable. Synchronize operations to avoid race conditions. The program executes the increment function 1000 times in parallel through multiple threads, and finally outputs the value of count.

2. Implementation method of asynchronous function

Asynchronous function means that during the execution of the function, the program does not wait for the function to return the result, but directly continues to perform the next operation. When the function is executed, the result will be passed to the program through a callback function or message notification. In Golang, the commonly used asynchronous function implementation methods are as follows.

1. Coroutine

Coroutine is a lightweight thread in Golang that can execute multiple coroutines concurrently in a single thread. Coroutines are very convenient to use and can be started through the go keyword.

The following is a sample code for using coroutines to implement asynchronous functions:

func f() int {
    time.Sleep(time.Second * 5)
    return 42
}

func main() {
    ch := make(chan int)
    go func() {
        ch <- f()
    }()
    fmt.Println("doing other things")
    x := <-ch
    fmt.Println(x)
}

In the above code, the ch channel is used to implement asynchronous operations. Start a coroutine in the main function and pass the execution result of the f function to the main program through the channel ch. After other operations are performed in the main program, the execution result of the f function is received through the channel to complete the asynchronous operation.

2. Callback function

The callback function refers to passing the result to the program by calling the pre-registered callback function after the asynchronous function is executed. The following is a sample code that uses callback functions to implement asynchronous functions:

func f(callback func(int)) {
    time.Sleep(time.Second * 5)
    callback(42)
}

func main() {
    f(func(x int) {
        fmt.Println(x)
    })
    fmt.Println("doing other things")
}

In the above code, the f function uses callback functions to implement asynchronous operations. By calling the pre-registered callback function, the f function execution result is passed to the program. After other operations are performed in the main program, the execution result of the f function is output.

3. Synchronous and asynchronous usage scenarios

Synchronous and asynchronous functions each have their own advantages and disadvantages, and should be selected according to specific business needs.

When you simply need to obtain the execution result of a certain function, such as http request operation, synchronous functions are often used. If you need to perform time-consuming operations or need to operate multiple tasks at the same time, asynchronous functions are more suitable. For example, when downloading large files, you can use asynchronous functions to implement concurrent downloads and increase download speed; when processing network requests, you can use asynchronous functions to process requests and reduce waiting time.

In short, synchronous and asynchronous functions have better usage effects in different scenarios, and we need to choose according to the actual situation.

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