<?php
error_reporting(E_ALL);
set_time_limit(0);
ini_set("allow_call_time_pass_reference",true);

//监听端口
$PORT = 8888;
//最大连接池
$MAX_USERS = 50;
//创建监听端口
$sock = socket_create_listen($PORT);
if (!$sock)
{
    exit(1);
}
//不阻塞
socket_set_nonblock($sock);

$connections = array();
$input = array();
$close = array();

while (true)
{
    $readfds = array_merge($connections, array($sock));
    $writefds = array();

    //选择一个连接，获取读、写连接通道
    if (socket_select($readfds, $writefds, $e = null, $t=60))
    {
        foreach ($readfds as $rfd)
        {
            //如果是当前服务端的监听连接
            if ($rfd == $sock)
            {
                //接受客户端连接
                $newconn = socket_accept($sock);
                $i = (int)$newconn;
                $reject = '';
                if (count($connections) >= $MAX_USERS)
                {
                    $reject = "Server full. Try again later.\n";                  
                }                
                //将当前客户端连接放如socket_select选择
                $connections[$i] = $newconn;
                //输入的连接资源缓存容器
                $writefds[$i] = $newconn;              
                //连接不正常
                if ($reject)
                {                  
                    $close[$i] = true;
                }
                else
                {
                    echo "Welcome to the PHP Chat Server!\n";                  
                }              
                //初始化当前连接读取内容的缓存容器
                $input[$i] = "";
                continue;
            }
            //客户端连接
            $i = (int)$rfd;
            //读取
            $tmp = @socket_read($rfd, 2048, PHP_NORMAL_READ);
            if (!$tmp)
            {
                //读取不到内容              
                print "connection closed on socket $i\n";
                close($i);
                continue;
            }
            $input[$i] .= $tmp;
            $tmp = substr($input[$i], -1);
            if ($tmp != "\r" && $tmp != "\n")
            {
                // no end of line, more data coming
                continue;
            }
            $line = trim($input[$i]);
            $input[$i] = "";
            echo 'Client >>'.$line.'\n';
        }
        foreach ($writefds as $wfd)
        {
            $i = (int)$wfd;
            $w = socket_write($wfd, "hello");
        }
    }  
}

function close($i)
{
    global $connections, $input, $close;
    socket_shutdown($connections[$i]);
    socket_close($connections[$i]);
    unset($connections[$i]);
    unset($input[$i]);  
    unset($close[$i]);
}
?>