The stream socket functions are incredibly useful and obviate the need for
the sockets extension for the vast majority of potential use-cases.
However, it's currently it's not possible bind a socket and listen for
connections in separate steps using stream_socket_server().
This _can_ be done with the aid of ext/sockets like so:
$stream = stream_socket_server('tcp://0.0.0.0:0', $errno, $errstr,
STREAM_SERVER_BIND);
$sock = socket_import_stream($stream);
socket_listen($sock);
Why is this useful? Well, for example, binding to a port in the main
process and then listening individually in child forks/threads trivializes
scaling socket servers. By listening on the same bound socket in multiple
processes you get the advantage of the OS distributing new client
connections to the individual workers instead of routing them in userland.
Additionally, newer linux kernel versions (3.9x) now support the
SO_REUSEPORT socket option which only makes this functionality more
attractive. Admittedly you still need ext/sockets to reap the benefits of
SO_REUSEPORT, but this may not always be the case.
My proposed patch adds a very simple function so that listening may be
decoupled from binding without the need for ext/sockets:
$stream = stream_socket_server('tcp://0.0.0.0:0', $errNo, $errStr,
STREAM_SERVER_BIND);
// do stuff, fork, etc. Then in the child process:
stream_socket_listen($server);
Existing functionality is not modified and there are no BC breaks. I.E. you
can still bind + listen in a single step like before:
$stream = stream_socket_server('tcp://0.0.0.0:0', $errNo, $errStr,
STREAM_SERVER_BIND | STREAM_SERVER_LISTEN);
This addition seemed a bit trivial for an RFC, so and I didn't bother
hitting the wiki. The link to the relevant pull request follows. Any
thoughts, comments and opinions are welcome:
https://github.com/php/php-src/pull/431
