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_http_client
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。
