(PHP 4 >= 4.1.0, PHP 5)
socket_listen — Listens for a connection on a socket
After the socket socket has been created using socket_create() and bound to a name with socket_bind(), it may be told to listen for incoming connections on socket.
socket_listen() is applicable only to sockets of type SOCK_STREAM or SOCK_SEQPACKET.
A valid socket resource created with socket_create().
A maximum of backlog incoming connections will be queued for processing. If a connection request arrives with the queue full the client may receive an error with an indication of ECONNREFUSED, or, if the underlying protocol supports retransmission, the request may be ignored so that retries may succeed.
Note:
The maximum number passed to the backlog parameter highly depends on the underlying platform. On Linux, it is silently truncated to SOMAXCONN. On win32, if passed SOMAXCONN, the underlying service provider responsible for the socket will set the backlog to a maximum reasonable value. There is no standard provision to find out the actual backlog value on this platform.
成功时返回 TRUE， 或者在失败时返回 FALSE. The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error.