Let's talk about how to use channels in Go language

Channel (channel) in Go language is a special data type that can be used to transfer data between different Go processes. It is similar to a pipe that allows different goroutines to exchange information through it. In this article, we will introduce the usage of channels in Go language.

Create channel

In the Go language, you can use the make function to create a channel. The syntax of the make function is as follows:

make(chan data_type, buffer_size)

Among them, data_type is the data type to be transferred in the channel, and buffer_size indicates the buffer size of the channel. If the buffer size is not specified, it means that the channel is unbuffered.

For example, in the following code, an unbuffered channel is created:

ch := make(chan int)

Here, a channel is created that passes an integer type. Unbuffered channels can be used for synchronous operations, such as blocking and waiting between two goroutines.

The following is an example of creating a buffered channel:

ch := make(chan string, 10)

Here, a channel is created to pass a string type, and the buffer size is set to 10. Buffered channels can be used for asynchronous operations, which means that send and receive operations do not block program execution.

Sending and receiving data

In the Go language, you can use the arrow operator (<-) of the channel to send and receive data. Arrows pointing in the direction of the channel indicate the direction of data flow.

For example, the following code sends an integer to a channel:

ch := make(chan int)
ch <- 123

Here, the integer 123 is sent to channel ch using the arrow operator (<-).

The following code receives an integer from a channel:

ch := make(chan int)
x := <- ch

Here, an integer is received from channel ch using the arrow operator (<-). Here x is an integer variable used to store the value received from the channel.

Blocking and waiting

In an unbuffered channel, both send and receive operations will cause blocking. For example, if a goroutine sends data to an unbuffered channel, but no other goroutine is waiting to receive data, the send operation will block until other goroutines start waiting to receive data.

Similarly, if a goroutine receives data from an unbuffered channel, but no other goroutine is waiting to send data, the receive operation will block until other goroutines start sending data.

When the buffer is of limited size, the send operation may also block. If the buffer is full, the send operation will wait until other goroutines read data from the channel.

For example, the following code shows how to create an unbuffered channel and let two goroutines exchange data through the channel:

func main() {
  ch := make(chan int)

  go func() {
    x := 1 + 1
    ch <- x
  }()

  y := <-ch

  fmt.Println(y)
}

Here, an unbuffered channel ch is created , and then starts a new goroutine to send the value 2 to channel ch. At this point, the receiving operation will block until the new Gor process sends the value 2, and finally print the received value to the console.

Close channel

In Go language, you can use the built-in function close to close a channel. After closing the channel, all unread data can be discarded, while data that has been read can still be accessed.

Close the channel to let the receiver know that no more data will be sent, which allows the receiver to exit the loop normally and end the program.

For example, the following code example demonstrates how to end the program by closing the channel:

func main() {
  ch := make(chan int)

  go func() {
    for i := 0; i < 5; i++ {
      ch <- i
    }
    close(ch)
  }()

  for v := range ch {
    fmt.Println(v)
  }
}

Here, an unbuffered channel ch is created and a new goroutine is started, using To send an integer value to channel ch. After all integer values ​​have been sent, channel ch is closed. Next, use a for loop to iterate over all values ​​in channel ch and print to the console.

Summary

In the Go language, channel is a powerful tool that can be used to achieve data communication between different Go processes. You can use channels to send and receive data, and use the arrow operator (<-) to identify the flow of data. You can create unbuffered or buffered channels and exchange data between goroutines. By closing the channel, the receiver knows that no more data is being sent and stops program execution.

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