swoole提供了swoole_event_add函数，可以实现异步。此函数可以用在Server或Client模式下。
swoole_event_add属于AsyncIO，必须运行在CLI 模式。
异步tcp客户端
stream_socket_client实现tcp同步客户端 示例：
<?php $start_time = microtime(TRUE); $fp = stream_socket_client("tcp://www.52fhy.com:80", $errno, $errstr, 30); fwrite($fp,"GET /test.json HTTP/1.1\r\nHost: www.52fhy.com\r\n\r\n"); echo $resp = fread($fp, 8192); fclose($fp); echo "Finish\n"; $end_time = microtime(TRUE); echo sprintf("use time:%.3f s\n", $end_time - $start_time);上述代码是同步执行的。如何变成异步呢？
stream_socket_client实现tcp异步客户端 由于fread读取响应数据是同步堵塞的，我们将$fp加入到事件监听后，底层会自动将该socket设置为非阻塞模式。修改fread那一行：
swoole_event_add($fp, function($fp) { echo $resp = fread($fp, 8192); swoole_event_del($fp);//socket处理完成后，从epoll事件中移除socket fclose($fp); }); echo "Finish\n"; //swoole_event_add不会阻塞进程，这行代码会顺序执行执行后输出：
Finish use time:0.087 s HTTP/1.1 200 OK Server: AliyunOSS Date: Sat, 21 Apr 2018 08:36:40 GMT Content-Type: application/json Content-Length: 26 Connection: keep-alive x-oss-request-id: 5ADAF81884D23C965A5D2614 Accept-Ranges: bytes ETag: "3B3B50D9C802324BB72A74FCD9060004" Last-Modified: Sat, 21 Apr 2018 04:43:33 GMT x-oss-object-type: Normal x-oss-hash-crc64ecma: 9917578698767912878 x-oss-storage-class: Standard Content-MD5: OztQ2cgCMku3KnT82QYABA== x-oss-server-time: 5 {"url":"http://52fhy.com"}swoole_event_add函数原型：
bool swoole_event_add(mixed $sock, mixed $read_callback, mixed $write_callback = null, int $flags = null);$sock可以为以下四种类型：
int，就是文件描述符，包括swoole_client->pipe或者其他fd stream资源，就是stream_socket_client/fsockopen创建的资源 sockets资源，就是sockets扩展中socket_create创建的资源，需要在编译时加入 ./configure --enable-sockets object，swoole_process或swoole_client，底层自动转换为管道或客户端连接的socket
多个tcp客户端实时交互
上面的例子，已经实现了异步tcp客户端。接下来的例子会复杂些：可以在客户端A输入，客户端B能实时收到，反之也可以。
首先，我们得创建个tcp_server: swoole_tcp_server.php
<?php $serv = new swoole_server('0.0.0.0', 9001); $serv->on('Start', function(){ echo "Tcp server start. Waiting client... \n"; }); $serv->on('Connect', function($serv, $fd){ echo "New client fd:{$fd}. \n"; }); $serv->on('Receive', function($serv, $fd, $from_id, $data){ echo "Recv msg from fd:{$fd}:{$data}\n"; foreach ($serv->connections as $client) { if($fd != $client){ $serv->send($client, $data); } } }); $serv->on('Close', function($serv, $fd){ echo "Client fd:{$fd} closed. \n"; }); $serv->start();然后实现客户端： event_add_tcp_client.php
<?php $socket = @stream_socket_client("tcp://127.0.0.1:9001", $errno, $errstr, 30); if(!$socket) exit("connect server err!"); function onRead($socket){ $msg = stream_socket_recvfrom($socket, 1024); if(!$msg){ swoole_event_del($socket); } echo "Recv: {$msg}\n"; fwrite(STDOUT, "ENTER MSG:"); } function onWrite($socket){ echo "onWrite\n"; } function onStdin(){ global $socket; $msg = trim(fgets(STDIN)); if($msg == 'exit'){ //必须trim此处才会相等 swoole_event_exit(); // exit(); } fwrite($socket, $msg);//数据量大的时候用swoole_event_write fwrite(STDOUT, "ENTER MSG:"); } swoole_event_add($socket, 'onRead', 'onWrite'); swoole_event_add(STDIN, 'onStdin'); fwrite(STDOUT, "ENTER MSG:"); //swoole_event_add不会阻塞进程，这行代码会顺序执行先运行服务端：
$ php swoole_tcp_server.php Tcp server start. Waiting client...打开两个终端，运行客户端：
$ php event_add_tcp_client.php ENTER MSG:image.png
swoole_client
其实swoole已经提供了异步的swoole_client，无需使用stream_socket_*系列函数：
<?php $client = new swoole_client(SWOOLE_SOCK_TCP, SWOOLE_SOCK_ASYNC); $client->on("connect", function(swoole_client $cli) { }); $client->on("receive", function(swoole_client $cli, $data){ echo "Receive: $data"; $cli->send(str_repeat('A', 100)."\n"); sleep(1); }); $client->on("error", function(swoole_client $cli){ echo "error\n"; }); $client->on("close", function(swoole_client $cli){ echo "Connection close\n"; }); $client->connect('127.0.0.1', 9001);还有swoole实现的tcp/udp同步阻塞客户端：
$client = new swoole_client(SWOOLE_SOCK_TCP); if (!$client->connect('127.0.0.1', 9001, -1)) { exit("connect failed. Error: {$client->errCode}\n"); } $client->send("hello world\n"); echo $client->recv(); $client->close();swoole_client 函数原型：
swoole_client->__construct(int $sock_type, int $is_sync = SWOOLE_SOCK_SYNC, string $key);可以使用swoole提供的宏来之指定类型，请参考 swoole常量定义
sock_type | SWOOLE_SSL可以启用SSL加密 key用于长连接的Key，默认使用IP:PORT作为key。相同key的连接会被复用.php-fpm/apache环境下只能使用同步客户端。异步客户端只能使用在cli命令行环境。
异步http客户端
curl或者file_get_contents发送http请求是同步阻塞的。基swoole_event_add封装可以实现异步。
swoole_event_add实现异步http客户端 event_add_http_client.php:
<?php class HttpClient{ private $callback = null; public function __construct($url, $method = 'GET', $postfields = NULL, $headers = array()){ //子进程发起请求 $process = new swoole_process(function(swoole_process $worker) use($url, $method, $postfields, $headers){ $response = $this->http($url, $method, $postfields, $headers); $worker->write($response); }, true); $process->start(); //异步读取 swoole_event_add($process->pipe, function($pipe) use ($process){ $response = $process->read(); // print_r($response); if(is_callable($this->callback)){ call_user_func($this->callback, $response); //回调 } swoole_event_del($pipe); }); } public function setCallback($callback){ $this->callback = $callback; } /** * http请求 */ private function http($url, $method, $postfields = NULL, $headers = array()) { try{ $ssl = stripos($url,'https://') === 0 ? true : false; $ci = curl_init(); /* Curl settings */ curl_setopt($ci, CURLOPT_USERAGENT, @$_SERVER['HTTP_USER_AGENT']); //在HTTP请求中包含一个"User-Agent: "头的字符串。 curl_setopt($ci, CURLOPT_CONNECTTIMEOUT, 30); curl_setopt($ci, CURLOPT_TIMEOUT, 30); curl_setopt($ci, CURLOPT_RETURNTRANSFER, TRUE); curl_setopt($ci, CURLOPT_ENCODING, ""); if ($ssl) { curl_setopt($ci, CURLOPT_SSL_VERIFYPEER, 0); // 对认证证书来源的检查 curl_setopt($ci, CURLOPT_SSL_VERIFYHOST, 2); // 从证书中检查SSL加密算法是否存在 } curl_setopt($ci, CURLOPT_HEADER, FALSE); switch ($method) { case 'POST': curl_setopt($ci, CURLOPT_POST, TRUE); if (!empty($postfields)) { curl_setopt($ci, CURLOPT_POSTFIELDS, $postfields); } break; } curl_setopt($ci, CURLOPT_URL, $url ); curl_setopt($ci, CURLOPT_HTTPHEADER, $headers ); curl_setopt($ci, CURLINFO_HEADER_OUT, TRUE ); $response = curl_exec($ci); $httpCode = curl_getinfo($ci, CURLINFO_HTTP_CODE); $httpInfo = curl_getinfo($ci); if (FALSE === $response) throw new Exception(curl_error($ci), curl_errno($ci)); } catch(Exception $e) { throw $e; } //echo '<pre>'; //var_dump($response); //var_dump($httpInfo); curl_close ($ci); return $response; } } $client = new HttpClient('http://www.52fhy.com/test.json'); $client->setCallback(function($response){ print_r($response); }); echo "OK\n";运行：
$ php event_add_http_client.php OK {"url":"http://52fhy.com"}[由返回结果可以看出，客户端请求是异步执行的。
Swoole也内置了http异步客户端（swoole>=1.8.0）。
相比curl和file_get_contents这样PHP提供的Http客户端，swoole_http_client最大的优势是支持大量并发。 file_get_contents只能同时请求一个URL，并发只能通过开启多进程实现。curl提供了curl_multi功能实现并发基于select和多线程。并发能力都很差。而swoole_http_client是基于epoll实现的异步客户端，没有并发限制，可在一个进程内同时并发上万请求。
示例：get:
$cli = new swoole_http_client('www.52fhy.com', 80); $cli->setHeaders(['User-Agent' => "swoole"]); $cli->get('/test.json', function ($cli) { echo $cli->body; }); echo "ok\n";输出：
ok {"url":"http://52fhy.com"}post:
$cli = new swoole_http_client('127.0.0.1', 81); $cli->post('/post_demo.php', array("a" => '1234', 'b' => '456'), function ($cli) { echo "Length: " . strlen($cli->body) . "\n"; echo $cli->body; }); echo "ok\n";上传文件 swoole_http_client底层使用了sendfile系统调用实现了http上传超大文件，配合底层的epoll可以实现非常低的消耗完成超巨大文件的上传。sendfile是零拷贝的，占用内存非常少，并且不存在多次内存复制开销。
$cli = new swoole_http_client('127.0.0.1', 80); $cli->addFile(__DIR__.'/post.data', 'post'); $cli->addFile(dirname(__DIR__).'/test.jpg', 'debug'); $cli->post('/dump2.php', array("xxx" => 'abc', 'x2' => 'rango'), function ($cli) { echo $cli->body; $cli->close(); });websocket:
<?php $cli = new swoole_http_client('118.25.40.163', 8088); $cli->on('message', function ($_cli, $frame) { // var_dump($frame); echo $frame->data; }); $cli->upgrade('/', function ($cli) { $cli->push("hello world"); }); echo "ok\n";发送完客户端会立即close。
作者：金星show
