说到长链接大家肯定不陌生，就是复用一个链接持续不断的进行数据交互，它不像那些一夜情似的服务，需要频繁的打开和关闭链接，效率低的同时还增加了业务的复杂度。在裆下很多互联网业务场景都需要长连接的支持，比如：游戏、聊天、信息推送等等等，今天我们就一步一步来揭秘php长连接的玩法。我相信任何一项技术的实施都是因为业务场景的需要，所以这次我们还拿聊天室说事儿。
0x00 初试牛刀
记得以前用php写聊天室还是用polling的方式，毫无疑问，一提到polling,肯定会有人说long polling，没错！long polling也很不错，但在nginx+fpm上面玩这个多少有些费劲，毕竟一个请求需要占一个php进程(就算是用apache+php_mod，也需要一个请求一个线程)，所以要是几个人随便玩玩还行，一旦放到线上人多起来，这基本就废了。所以还是采用polling的方式，这样不会阻塞进程，并且一个请求能立即得到响应，但是带来的新问题是需要不停的向服务器发送请求，而且随着间隔的时间越大导致消息延迟就越大。
0x01 华丽变身
在经历了上面那种一秒一小卡，三秒一大卡的场面！再也看不下去了，于是决定变身为真正的男人，哦不对，应该是真正的长连接。去他妈的polling, 去他妈的long polling,去他妈的webserver，统统靠边站，让flash socket(或者说websocket)来统治这个世界！开始了真正意义上的长连接之旅。要玩长连接总是少不了跟socket打交道吧，作为世界上最好的语言(没有之一)，socket的封装自然是少不了滴。抄起socket_***就开干，于是就有了下面这一托代码，长连接是吧？延迟是吧？socket是吧？汤药费是吧？so easy....
<ol class="dp-c"><li class="alt"><span><span class="vars">$sfd</span><span> = socket_create(AF_INET, SOCK_STREAM, 0); </span></span></li><li><span> </span></li><li class="alt"><span>socket_bind(<span class="vars">$sfd</span><span>, </span><span class="string">"0.0.0.0"</span><span>, 1234); </span></span></li><li><span> </span></li><li class="alt"><span>socket_listen(<span class="vars">$sfd</span><span>, 511); </span></span></li><li><span> </span></li><li class="alt"><span>socket_set_option(<span class="vars">$sfd</span><span>, SOL_SOCKET, SO_REUSEADDR, 1); </span></span></li><li><span> </span></li><li class="alt"><span>socket_set_nonblock(<span class="vars">$sfd</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$rfds</span><span> = </span><span class="keyword">array</span><span>(</span><span class="vars">$sfd</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$wfds</span><span> = </span><span class="keyword">array</span><span>(); </span></span></li><li><span> </span></li><li class="alt"><span><span class="keyword">do</span><span>{ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$rs</span><span> = </span><span class="vars">$rfds</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$ws</span><span> = </span><span class="vars">$wfds</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$es</span><span> = </span><span class="keyword">array</span><span>(); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$ret</span><span> = socket_select(</span><span class="vars">$rs</span><span>, </span><span class="vars">$ws</span><span>, </span><span class="vars">$es</span><span>, 3); </span></span></li><li><span> </span></li><li class="alt"><span> </span></li><li><span> </span></li><li class="alt"><span> <span class="comment">//read event</span><span> </span></span></li><li><span> </span></li><li class="alt"><span> <span class="keyword">foreach</span><span>(</span><span class="vars">$rs</span><span> </span><span class="keyword">as</span><span> </span><span class="vars">$fd</span><span>){ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="keyword">if</span><span>(</span><span class="vars">$fd</span><span> == </span><span class="vars">$sfd</span><span>){ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$cfd</span><span> = socket_accept(</span><span class="vars">$sfd</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> socket_set_nonblock(<span class="vars">$cfd</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$rfds</span><span>[] = </span><span class="vars">$cfd</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span> <span class="func">echo</span><span> </span><span class="string">"new client coming, fd=$cfd\n"</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span> }<span class="keyword">else</span><span>{ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$msg</span><span> = socket_read(</span><span class="vars">$fd</span><span>, 1024); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="keyword">if</span><span>(</span><span class="vars">$msg</span><span> <= 0){ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="comment">//close</span><span> </span></span></li><li><span> </span></li><li class="alt"><span> }<span class="keyword">else</span><span>{ </span></span></li><li><span> </span></li><li class="alt"><span> <span class="comment">//recv msg</span><span> </span></span></li><li><span> </span></li><li class="alt"><span> <span class="func">echo</span><span> </span><span class="string">"on message, fd=$fd data=$msg\n"</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span> } </span></li><li><span> </span></li><li class="alt"><span> } </span></li><li><span> </span></li><li class="alt"><span> } </span></li><li><span> </span></li><li class="alt"><span> </span></li><li><span> </span></li><li class="alt"><span> <span class="comment">//write event</span><span> </span></span></li><li><span> </span></li><li class="alt"><span> <span class="keyword">foreach</span><span>(</span><span class="vars">$ws</span><span> </span><span class="keyword">as</span><span> </span><span class="vars">$fd</span><span>){ </span></span></li><li><span> </span></li><li class="alt"><span> socket_write(<span class="vars">$fd</span><span>, ........); </span></span></li><li><span> </span></li><li class="alt"><span> } </span></li><li><span> </span></li><li class="alt"><span> </span></li><li><span> </span></li><li class="alt"><span>}<span class="keyword">while</span><span>(true); </span></span></li></ol>0x02 登峰造极
从玩socket的那天起，google就轻言细语的跟我说，高并发下的select不要用啊，效率底啊，win要用iocp啊, linux要用epoll啊，blablablabla...哦！好吧，既然google都这么说了，我也不能跟他老人家较真不是，又一次决定(为什么要说又呢？)要听google话，把epoll搞起来，可总不能自己写啊？像我这么懒的人还是整个扩展好了，libevent走你！经过疯狂的编(co)码(py)，神作终于出山，具体能有多高效，能撑多少并发，不造，反正没用select了，我奏是屌！
<ol class="dp-c"><li class="alt"><span><span class="vars">$sfd</span><span> = stream_socket_server (</span><span class="string">'tcp://0.0.0.0:1234'</span><span>, </span><span class="vars">$errno</span><span>, </span><span class="vars">$errstr</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span>stream_set_blocking(<span class="vars">$sfd</span><span>, 0); </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$base</span><span> = event_base_new(); </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$event</span><span> = event_new(); </span></span></li><li><span> </span></li><li class="alt"><span>event_set(<span class="vars">$event</span><span>, </span><span class="vars">$sfd</span><span>, EV_READ | EV_PERSIST, </span><span class="string">'ev_accept'</span><span>, </span><span class="vars">$base</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span>event_base_set(<span class="vars">$event</span><span>, </span><span class="vars">$base</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span>event_add(<span class="vars">$event</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span>event_base_loop(<span class="vars">$base</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="keyword">function</span><span> ev_accept(</span><span class="vars">$socket</span><span>, </span><span class="vars">$flag</span><span>, </span><span class="vars">$base</span><span>) </span></span></li><li><span> </span></li><li class="alt"><span>{ </span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$connection</span><span> = stream_socket_accept(</span><span class="vars">$socket</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> stream_set_blocking(<span class="vars">$connection</span><span>, 0); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$buffer</span><span> = event_buffer_new(</span><span class="vars">$connection</span><span>, </span><span class="string">'ev_read'</span><span>, NULL, </span><span class="string">'ev_error'</span><span>, </span><span class="vars">$connection</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_base_set(<span class="vars">$buffer</span><span>, </span><span class="vars">$base</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_timeout_set(<span class="vars">$buffer</span><span>, 30, 30); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_watermark_set(<span class="vars">$buffer</span><span>, EV_READ, 0, 0xffffff); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_priority_set(<span class="vars">$buffer</span><span>, 10); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_enable(<span class="vars">$buffer</span><span>, EV_READ | EV_PERSIST); </span></span></li><li><span> </span></li><li class="alt"><span>} </span></li><li><span> </span></li><li class="alt"><span><span class="keyword">function</span><span> ev_error(</span><span class="vars">$buffer</span><span>, </span><span class="vars">$error</span><span>, </span><span class="vars">$connection</span><span>) </span></span></li><li><span> </span></li><li class="alt"><span>{ </span></li><li><span> </span></li><li class="alt"><span> event_buffer_disable(<span class="vars">$buffer</span><span>, EV_READ | EV_WRITE); </span></span></li><li><span> </span></li><li class="alt"><span> event_buffer_free(<span class="vars">$buffer</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span> fclose(<span class="vars">$connection</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span>} </span></li><li><span> </span></li><li class="alt"><span><span class="keyword">function</span><span> ev_read(</span><span class="vars">$buffer</span><span>, </span><span class="vars">$connection</span><span>) </span></span></li><li><span> </span></li><li class="alt"><span>{ </span></li><li><span> </span></li><li class="alt"><span> <span class="vars">$read</span><span> = event_buffer_read(</span><span class="vars">$buffer</span><span>, 256); </span></span></li><li><span> </span></li><li class="alt"><span> <span class="comment">//do something....</span><span> </span></span></li><li><span> </span></li><li class="alt"><span>} </span></li></ol>0x03 绝处逢生
随着人数的增长，并发的提升，单个进程已经满足不了需求了，田伯光的故事告诉我们，单挑是斗不过群P的，咋整？俗话说，大事化小，小事化，停！！别化了，再化就没了。拆吧，把单进程拆成多进程，可是拆完之后又面临新的问题，进程间通信、负载均衡、session唯一等。既然已经提出这样的问题，肯定是有解决方案，现成的就有扩展和库来解决这个事，比如：swoole,workerman等？相比之下swoole更屌一些，性、功能，呃！好像这样简写不太雅观，好吧，性能和功能更屌一些(桶哥，请原谅我的无聊~)。。。。等一下！！！但是，我们在使用php来开发web的时候，也没有使用webserver相关的库来做开发对不对？咱只是简单的echo而已。这些繁杂的事都交给了nginx或者是apache，是他们义无反顾的顶在前面，让我们可以专心写逻辑。写web我们只需要简单的配置nginx和fpm就好了，那写socket服务呢？我们为什么不能像nginx+fpm一样简单配置就好了呢？？当然能，必须能。。。。。看这个剧情怕是广告要来了。。。
0x04 出其不意
写socket服务不比写web高级，都是打码，都是完成需求，通信那层都是固定的，只不过一个由nginx完成，另一个由自己完成。。可是现在不需要自己完成了，类似nginx+fpm的方案，fooking+fpm=php长连接，gateway用于承载连接，router用于转发消息，进程间通信？负载均衡？session唯一？so easy..
<ol class="dp-c"><li class="alt"><span><span class="vars">$sid</span><span> = </span><span class="vars">$_SERVER</span><span>[</span><span class="string">'SESSIONID'</span><span>];</span><span class="comment">//这是sessionid</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$data</span><span> = </span><span class="func">file_get_contents</span><span>(</span><span class="string">"php://input"</span><span>);//这样就能拿到请求内容了 </span></span></li><li><span> </span></li><li class="alt"><span><span class="comment">//想要返回消息只需要两步</span><span> </span></span></li><li><span> </span></li><li class="alt"><span>header(<span class="string">'Content-Length: 11'</span><span>);</span><span class="comment">//返回给客户端字节数</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="func">echo</span><span> </span><span class="string">"hello world"</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span><span class="comment">//想要给别的用户发消息</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="keyword">include</span><span> </span><span class="string">'api.php'</span><span>; </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$router</span><span> = </span><span class="keyword">new</span><span> RouterClient(</span><span class="string">'router host'</span><span>, </span><span class="string">'router port'</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$router</span><span>->sendMsg(用户sessionid, </span><span class="string">"fuck you"</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="comment">//想要给所有人要消息</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$router</span><span>->sendAllMsg(</span><span class="string">"fuck all"</span><span>); </span></span></li><li><span> </span></li><li class="alt"><span><span class="comment">//想给指定组发消息(类似redis的pub/sub)</span><span> </span></span></li><li><span> </span></li><li class="alt"><span><span class="vars">$router</span><span>->publish(</span><span class="string">"channel name"</span><span>, </span><span class="string">"fuck all"</span><span>); </span></span></li></ol>
项目地址: http://git.oschina.net/scgywx/fooking
文档地址(不定期更新)：http://my.oschina.net/scgywx/blog/465186
