golang sets socket blocking

When using golang for network communication, it is sometimes necessary to control the blocking state of the socket. Golang provides some methods to set socket blocking. In this article, these methods and their usage scenarios will be introduced.

1. Set the socket to non-blocking mode

In golang, you can achieve non-blocking effects by setting the socket's file descriptor (file descriptor) to non-blocking mode. . A file descriptor is an identifier used by the operating system for open files, sockets and other resources. Each open resource corresponds to a file descriptor.

The socket can be set to non-blocking mode by calling the following function:

err := syscall.SetNonblock(socketFD, true)

This function accepts two parameters. The first parameter is the file descriptor of the socket, and the second parameter is a Boolean value specifying whether to set to non-blocking mode.

When the socket is set to non-blocking mode, if there is no data to read or write, the socket-related read and write operations will immediately return an error instead of blocking and waiting for data to arrive. This approach is often used to implement unconventional flow control or asynchronous programming.

2. Set the socket read and write timeout period

Another way to control socket blocking is to set the socket read and write timeout period. In golang, this function can be achieved by setting the properties of the socket file descriptor.

Call the following function to set the timeout for socket reading:

err := syscall.SetsockoptTimeval(socketFD, syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, &syscall.Timeval{Sec: timeoutInSeconds})

This function accepts four parameters. The first parameter is the file descriptor of the socket, and the second parameter represents the socket level. Protocol, the third parameter specifies the option name to be set, and the fourth parameter is a structure pointer containing timeout information.

Call the following function to set the timeout for socket writing:

err := syscall.SetsockoptTimeval(socketFD, syscall.SOL_SOCKET, syscall.SO_SNDTIMEO, &syscall.Timeval{Sec: timeoutInSeconds})

The parameters of this function are similar to the previous function, except that the third parameter specifies the write option.

If the socket is blocked, when the read and write operations are not completed within the timeout period, the related read and write operations will return a timeout error.

3. Set the keep-alive attribute of the socket

The keep-alive attribute is a socket-level health check mechanism. When the keep-alive attribute is turned on, the client connection can periodically send some ping messages to the server to check whether the connection is still alive. If the server does not receive the ping message within a certain period of time, the connection can be closed. This mechanism is usually used to prevent the occurrence of dead connections.

In golang, you can turn on the keep-alive attribute by setting the properties of the socket file descriptor:

err := syscall.SetsockoptInt(socketFD, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1)

This function accepts three parameters, the first parameter is the file descriptor of the socket , the second parameter represents the socket level protocol, the third parameter specifies the option name to be set, and the last parameter is an integer specifying the option value. Here, setting the option value to 1 means turning on the keep-alive attribute.

4. Set the TCP_NODELAY attribute of the socket

The TCP_NODELAY attribute can control the Nagle algorithm of the TCP connection. Nagle's algorithm is an algorithm used to improve network utilization by caching small packets and sending them together when the server sends large packets. If the Nagle algorithm is turned on, although network utilization can be improved, it will increase the delay time of data transmission.

In some scenarios, it is necessary to turn on the TCP_NODELAY attribute and turn off the Nagle algorithm to reduce the delay time of data transmission and thereby increase the data transmission speed.

In golang, you can turn on the TCP_NODELAY attribute by setting the attributes of the socket file descriptor:

err := syscall.SetsockoptInt(socketFD, syscall.IPPROTO_TCP, syscall.TCP_NODELAY, 1)

The parameters of this function are similar to those introduced before, except that the second parameter represents the IP protocol family , the third parameter specifies the option name to be set, and setting the option value to 1 means turning on the TCP_NODELAY attribute.

In necessary scenarios, you can control data transmission by setting socket blocking. By using the functions provided by golang, you can easily set the blocking status and timeout period of the socket to achieve efficient control of the socket.

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