socket_listen() is applicable only to sockets of
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.
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
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.