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Digg  socket_select
Runs the select() system call on the given arrays of sockets with a specified timeout
(PHP 4 >= 4.0.7, PHP 5)
Example 2298. Understanding socket_select()'s result<?phpExample 2299. socket_select() example<?phpCode Examples / Notes » socket_selectdrenintell
The continuation of my my previous post on 28-Apr-2005 10:19 at http://ca3.php.net/manual/en/function.socket-select.php Here it is: (Link is broken into 2 parts) 'http://gtkphp.org/php_socket_select_hangs _explanation_and_solution.html' ludvig dot ericson
Regarding the comment below, No, it does not, it's a system call and I believe it's rather hard to preserve keys. Additionally, socket_select should be used like it was a user-inputted array, that you don't know what you sent in to. <?php $reads = $clients; $reads[] = $server; socket_select($reads); foreach ($reads as $read) { /* do some stuff */ } ?> calimero dot nospam
Please note that the timeout parameter has important side-effects on the CPU usage of your script. Setting the timeout to 0 will make your CPU looping without any time to have some rest and handle other running processes on your system, causing the system load to increase heavily while your script is running. Personnaly, I use a value of 15 ms for this parameter. this ensures a good listening frequency while letting your system load clear. Example : $read = array($ListeningSocket); $num_changed_sockets = socket_select($read, $write = NULL, $except = NULL, 0, 10); Hope this helps. crimson
Note that the resulting arrays do NOT maintain keys (PHP 4.3.2) after being run through this function: Before: Array ( [Client_Socket] => Resource id #6 [Server_Socket] => Resource id #9 ) After: Array ( [0] => Resource id #6 [1] => Resource id #9 ) It would have been nice to have the keys stay to figure out which stream you need to receive from, but you'll have to use some fancy foreach loop to figure out which sockets to check. richard neill
It is probably a bad idea to watch an array of sockets for input with socket_select, and then socket_read() using PHP_NORMAL_READ. Although this seems desirable, you can end up with a permanently blocked program, if someone sends you malformed input which is missing a trailing \n \r. Guess how I found that out. 23-jan-2007 11:04
If you want to use a simple fractional value for timeout: <?php socket_select(..., floor($timeout), ceil($timeout*1000000)); ?> daveb
If you haven't done any network programming before, PHP's socket_select() might appear a bit strange to you. I've written a simple php "partyline" script to demonstrate the multi-socket use of select'ing at http://dave.dapond.com/socketselect.php.txt
julian dot haupt
hello, i just made a class which acts similiar to Perl's IO::Select in order to make socket selecting very easy your script should look something like that: <?php $server = new Server; $client = new Client; for (;;) { foreach ($select->can_read(0) as $socket) { if ($socket == $client->socket) { // New Client Socket $select->add(socket_accept($client->socket)); } else { //there's something to read on $socket } } } ?> you should of course implement some routines to detect broken sockets and remove them from the select object. you can also do output buffering and check in the main-loop for sockets that are ready to write <?php class select { var $sockets; function select($sockets) { $this->sockets = array(); foreach ($sockets as $socket) { $this->add($socket); } } function add($add_socket) { array_push($this->sockets,$add_socket); } function remove($remove_socket) { $sockets = array(); foreach ($this->sockets as $socket) { if($remove_socket != $socket) $sockets[] = $socket; } $this->sockets = $sockets; } function can_read($timeout) { $read = $this->sockets; socket_select($read,$write = NULL,$except = NULL,$timeout); return $read; } function can_write($timeout) { $write = $this->sockets; socket_select($read = NULL,$write,$except = NULL,$timeout); return $write; } } ?> whosawhatsis
Another solution to the problem of keys not being preserved is to have an additional array for looking up sockets that uses their resource identifiers as keys. This can be obtained using array_flip() in some cases, but is particularly useful if each socket is associated with an object. In this case, you can make the object's constructor add a pointer to itself to the lookup array with its socket resource identifier as a key and use the following code to execute a read method for the object associated with each socket returned by socket_select(): <?php socket_select($reads, $writes, $excepts, 0); foreach ($sockets as $socket) { $lookuparray[$socket]->read(); } ?> vardhan
A simple PHP script using socket_select() to manage multiple connections. connect using "telnet localhost 9050". it broadcasts your messages that you send through telnet to other users connected to the server -- sort of like a chat script #!/usr/local/bin/php <?php $port = 9050; // create a streaming socket, of type TCP/IP $sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); // set the option to reuse the port socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1); // "bind" the socket to the address to "localhost", on port $port // so this means that all connections on this port are now our resposibility to send/recv data, disconnect, etc.. socket_bind($sock, 0, $port); // start listen for connections socket_listen($sock); // create a list of all the clients that will be connected to us.. // add the listening socket to this list $clients = array($sock); while (true) { // create a copy, so $clients doesn't get modified by socket_select() $read = $clients; // get a list of all the clients that have data to be read from // if there are no clients with data, go to next iteration if (socket_select($read, $write = NULL, $except = NULL, 0) < 1) continue; // check if there is a client trying to connect if (in_array($sock, $read)) { // accept the client, and add him to the $clients array $clients[] = $newsock = socket_accept($sock); // send the client a welcome message socket_write($newsock, "no noobs, but ill make an exception :)\n". "There are ".(count($clients) - 1)." client(s) connected to the server\n"); socket_getpeername($newsock, $ip); echo "New client connected: {$ip}\n"; // remove the listening socket from the clients-with-data array $key = array_search($sock, $read); unset($read[$key]); } // loop through all the clients that have data to read from foreach ($read as $read_sock) { // read until newline or 1024 bytes // socket_read while show errors when the client is disconnected, so silence the error messages $data = @socket_read($read_sock, 1024, PHP_NORMAL_READ); // check if the client is disconnected if ($data === false) { // remove client for $clients array $key = array_search($read_sock, $clients); unset($clients[$key]); echo "client disconnected.\n"; // continue to the next client to read from, if any continue; } // trim off the trailing/beginning white spaces $data = trim($data); // check if there is any data after trimming off the spaces if (!empty($data)) { // send this to all the clients in the $clients array (except the first one, which is a listening socket) foreach ($clients as $send_sock) { // if its the listening sock or the client that we got the message from, go to the next one in the list if ($send_sock == $sock || $send_sock == $read_sock) continue; // write the message to the client -- add a newline character to the end of the message socket_write($send_sock, $data."\n"); } // end of broadcast foreach } } // end of reading foreach } // close the listening socket socket_close($sock); ?> |
Change Language
socket_accept socket_bind socket_clear_error socket_close socket_connect socket_create_listen socket_create_pair socket_create socket_get_option socket_getpeername socket_getsockname socket_last_error socket_listen socket_read socket_recv socket_recvfrom socket_select socket_send socket_sendto socket_set_block socket_set_nonblock socket_set_option socket_shutdown socket_strerror socket_write |
