socket實現非阻塞

<?php
ini_set('error_reporting', E_ALL ^ E_NOTICE);
ini_set('display_errors', 1);
// Set time limit to indefinite execution
set_time_limit(0);
// Set the ip and port we will listen on
$address = '127.0.0.1';
$port = 6901;
ob_implicit_flush();
// Create a TCP Stream socket
$sock = socket_create(AF_INET, SOCK_STREAM, 0);
// Bind the socket to an address/port
socket_bind($sock, $address, $port) or die('Could not bind to address');
// Start listening for connections
socket_listen($sock);
// Non block socket type
socket_set_nonblock($sock);
// Clients
$clients = [];
// Loop continuously
while (true) {
    // Accept new connections
    if ($newsock = socket_accept($sock)) {
        if (is_resource($newsock)) {
            // Write something back to the user
            socket_write($newsock, ">", 1).chr(0);
            // Non bloco for the new connection
            //設置新的鏈接才能生效，socket_set_nonblock($sock) 是不生效的;
            socket_set_nonblock($newsock);
            // Do something on the server side
            echo "New client connected\n";
            // Append the new connection to the clients array
            $clients[] = $newsock;
        }
    }
    // Polling for new messages
    if (count($clients)) {
        foreach ($clients AS $k => $v) {
            // Check for new messages
            $string = '';
            if ($char = socket_read($v, 1024)) {
                $string .= $char;
            }
            // New string for a connection
            if ($string) {
                echo "$k:$string\n";
            } else {
                if ($seconds > 60) {
                    // Ping every 5 seconds for live connections
                    if (false === socket_write($v, 'PING')) {
                        // Close non-responsive connection
                        session_close($clients[$k]);
                        // Remove from active connections array
                        unset($clients[$k]);
                    }
                    // Reset counter
                    $seconds = 0;
                }
            }
        }
    }
    sleep(1);
    $seconds++;
}
// Close the master sockets
socket_close($sock);