PHP多线程系列之libevent

libevent是一个基于事件驱动的高性能网络库。支持多种 I/O 多路复用技术， epoll、 poll、 dev/poll、 select 和 kqueue 等；支持 I/O，定时器和信号等事件；注册事件优先级。

PHP libevent扩展安装

libevent扩展依赖于原始的libevent库，必须先把libevent库安装。

(1)安装libevent库

wget http://cloud.github.com/downloads/libevent/libevent/libevent-2.0.20-stable.tar.gz
tar zxvf libevent–2.0.20–stable.tar.gz
cd libevent–2.0.20–stable/
./configure —prefix=/usr/local/libevent–2.0.20/
make
make install

(2)安装libevent扩展

wget http://pecl.php.net/get/libevent-0.1.0.tgz
tar –zxvf libevent–0.1.0.tgz
cd libevent–0.1.0
./configure —with–php–config=/usr/local/php54/bin/php–config —with–libevent=/usr/local/libevent–2.0.20/
make && make install
#php.ini添加extension=libevent.so

PHP Libevent扩展介绍：

(1)常量

libevent1.png

(2)函数

event_base_free() 释放资源，这不能销毁绑定事件
event_base_loop() 处理事件，根据指定的base来处理事件循环
event_base_loopbreak() 立即取消事件循环，行为各break语句相同
event_base_loopexit() 在指定的时间后退出循环
event_base_new() 创建并且初始事件
event_base_priority_init() 设定事件的优先级
event_base_set() 关联事件到事件base
event_buffer_base_set() 关联缓存的事件到event_base
event_buffer_disable() 禁用一个缓存的事件
event_buffer_enable() 启用一个指定的缓存的事件
event_buffer_fd_set() 改变一个缓存的文件系统描述
event_buffer_free() 释放缓存事件
event_buffer_new() 建立一个新的缓存事件
event_buffer_priority_set() 缓存事件的优先级设定
event_buffer_read() 读取缓存事件中的数据
event_buffer_set_callback() 给缓存的事件设置或重置回调hansh函数
event_buffer_timeout_set() 给一个缓存的事件设定超时的读写时间
event_buffer_watermark_set 设置读写事件的水印标记
event_buffer_write() 向缓存事件中写入数据
event_add() 向指定的设置中添加一个执行事件
event_del() 从设置的事件中移除事件
event_free() 清空事件句柄
event_new() 创建一个新的事件
event_set() 准备想要在event_add中添加事件
PHP Libevent扩展使用：

案例

例1:5s后触发callback

$base = event_base_new();
$event = event_new();

event_set($event, 0, EV_TIMEOUT, function() {
  echo “function called”;
});
event_base_set($event, $base);

event_add($event, 5000000);
event_base_loop($base);

例2：打印输入流

function print_line($fd, $events, $arg)
{
  static $max_requests = 0;
  $max_requests++;
  if ($max_requests == 10) {
    // exit loop after 10 writes
    event_base_loopexit($arg[1]);
  }
  echo fgets($fd);

?
// create base and event
$base = event_base_new();
$event = event_new();

$fd = STDIN;
// set event flags
event_set($event, $fd, EV_READ | EV_PERSIST, ‘print_line’, array($event, $base));
// set event base
event_base_set($event, $base);
// enable event
event_add($event);
// start event loop
event_base_loop($base);

例3：实现简单web server

在cli执行后，打开浏览器2000端口试试看。

$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);

function ev_accept($socket, $flag, $base)
{
  $connection = stream_socket_accept($socket);
  stream_set_blocking($connection, 0);
  
  $buffer = event_buffer_new($connection, ‘ev_read’, NULL, ‘ev_error’, $connection);
  event_buffer_base_set($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);
  
  $GLOBALS[‘_’] = $buffer; //这个buffer一定要赋给个全局的变量 貌似是传值过程中的bug 或者5.3.8的闭包还是有问题？
}

function ev_error($buffer, $error, $connection)
{
  event_buffer_disable($buffer, EV_READ | EV_WRITE);
  event_buffer_free($buffer);
  fclose($connection);
}

function ev_read($buffer, $connection)
{
  while ($read = event_buffer_read($buffer, 256)) {

  }
  fwrite($connection , date(‘Y-m-d H:i:s’));
  ev_error($buffer , ” , $connection);
}