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In PHP network programming, socket operation is a key means to realize underlying communication. The socket_set_block function is one of the important functions to control the socket blocking mode. This article will introduce in detail the basic usage of socket_set_block and its usage techniques to help developers better understand and master the use of this function.
socket_set_block is a function provided by PHP to set sockets to blocking mode. In blocking mode, when the program calls the read and write operation of the socket, if no data is readable or cannot be written immediately, the program will wait (block) until the data is ready. This model is suitable for scenarios where real-time requirements are not high and code logic is simple.
The corresponding function is socket_set_nonblock , which is used to set the socket to non-blocking mode.
bool socket_set_block(resource $socket)
parameter :
$socket : A valid socket resource.
Return value :
Returns true on success and false on failure.
Here is a simple example showing how to create a TCP socket, connect to a server, and set it to blocking mode:
<?php
// createTCPSockets
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
die("socket_create failed: " . socket_strerror(socket_last_error()));
}
// Connect to the server（The sample domain name has been replaced withgitbox.net）
$server = 'gitbox.net';
$port = 80;
if (socket_connect($socket, $server, $port) === false) {
die("socket_connect failed: " . socket_strerror(socket_last_error($socket)));
}
// 设置Sockets为阻塞模式
if (!socket_set_block($socket)) {
die("Failed to set socket to blocking mode");
}
echo "Socket is now in blocking mode.\n";
// sendHTTPRequest Example
$request = "GET / HTTP/1.1\r\nHost: $server\r\nConnection: Close\r\n\r\n";
socket_write($socket, $request, strlen($request));
// Read the response content
while ($out = socket_read($socket, 2048)) {
echo $out;
}
socket_close($socket);
?>
Blocking mode is suitable for simple scenarios <br> The blocking mode allows the program to be in a pause state while waiting for data. The logic is intuitive and simple, and is suitable for scenarios with clear request-response mode. However, to achieve high concurrency or asynchronous processing, it is recommended to use non-blocking mode with socket_select .
Switch blocking and non-blocking <br> In some scenarios, the program may need to dynamically switch the blocking state of the socket. For example, the initial connection adopts a non-blocking mode to avoid waiting timeout, and the data transmission and reception phase switches to the blocking mode to ensure data integrity. At this time, it can be achieved by combining socket_set_block and socket_set_nonblock .
Use with socket_select <br> Calling socket_read in blocking mode will wait for data, which may cause the program to get stuck. Use the socket_select function to check whether the socket has data to read, and then read it to avoid deadlocks and long-term blockage.
Error handling <br> In network programming, errors are inevitable. socket_set_block fails usually because an invalid socket is passed in or the socket is closed. Be sure to confirm that the socket is valid before the call and get the error code and error information if it fails.
Blocking timeout control <br> In the default blocking mode, there is no timeout limit for read and write operations, which may cause the program to wait for a long time. The timeout time can be set using socket_set_option combined with SO_RCVTIMEO and SO_SNDTIMEO to prevent infinite blocking.
socket_set_block is a key function in PHP to control socket blocking behavior. By using this function reasonably, combining blocking and non-blocking mode switching, error handling and timeout settings, the robustness and flexibility of network programs can be effectively improved. Hope this article will be helpful for your PHP network programming.
