(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
socket_set_block — Sets blocking mode on a socket
The socket_set_block() function removes the
O_NONBLOCK flag on the socket specified by the
socket parameter.
When an operation (e.g. receive, send, connect, accept, ...) is performed on a blocking socket, the script will pause its execution until it receives a signal or it can perform the operation.
Example #1 socket_set_block() example
<?php
$socket = socket_create_listen(1223);
socket_set_block($socket);
socket_accept($socket);
?>
This example creates a listening socket on all interfaces on port 1223 and
sets the socket to O_BLOCK mode.
socket_accept() will hang until there is a connection
to accept.
Besides true and false socket_set_block might return NULL if you're not too careful. That would happen when passing non socket resource as first parameter.
E.g. socket_set_block(false)) would return NULL and emit warning that you're trying to do things with non-socket.