epoll/kqueue 异步阻塞/非阻塞模型
$socket = stream_socket_server (‘tcp://0.0.0.0:2000’, $errno, $errstr);
stream_set_blocking($socket, 0);
$base = event_base_new();
$event = event_new();
event_set($event, $socket, EV_READ | EV_PERSIST, ‘ev_accept’, $base);
event_base_set($event, $base);
event_add($event);
event_base_loop($base);

$GLOBALS[‘connections’] = array();
$GLOBALS[‘buffers’] = array();

function ev_accept($socket, $flag, $base) {
static $id = 0;

$connection = stream_socket_accept($socket);
stream_set_blocking($connection, 0);

$id += 1;

$buffer = event_buffer_new($connection, ‘ev_read’, NULL, ‘ev_error’, $id);
event_buffer_base_set($buffer, $base);
event_buffer_timeout_set($buffer, 30, 30);
event_buffer_watermark_set($buffer, EV_READ, 0, 0xffffff);
event_buffer_priority_set($buffer, 10);
event_buffer_enable($buffer, EV_READ | EV_PERSIST);

// we need to save both buffer and connection outside
$GLOBALS[‘connections’][$id] = $connection;
$GLOBALS[‘buffers’][$id] = $buffer;
}

function ev_error($buffer, $error, $id) {
event_buffer_disable($GLOBALS[‘buffers’][$id], EV_READ | EV_WRITE);
event_buffer_free($GLOBALS[‘buffers’][$id]);
fclose($GLOBALS[‘connections’][$id]);
unset($GLOBALS[‘buffers’][$id], $GLOBALS[‘connections’][$id]);
}

function ev_read($buffer, $id) {
while ($read = event_buffer_read($buffer, 256)) {
var_dump($read);
}
}
以上例子是依赖libevent 实现,需要安装libevent 和php的libevent 扩展
apt-get install libevent-dev
epoll模型就是为了解决select/poll模型的缺点而诞生的,epoll没有连接限制,另外epoll性能不会因为连接数增多而降低