Optimize: Keep-Alive follows RFC

RFC: https://www.rfc-editor.org/rfc/rfc2616

HTTP/1.0 默认是短连接，除非传 Connection: Keep-Alive 才是长连接
HTTP/1.1 默认长连接，除非传 Connection: close，才是短连接

Workerman 的不规范实现，可能会对完全遵守 RFC 工具造成影响，比如 ab 非长连接压测。

下面是可以直接测试的代码：（希望 Workerman 尽快引入 phpunit）

server.php:

<?php

use Workerman\Worker;
use Workerman\Connection\TcpConnection;
use Workerman\Protocols\Http\Request;
use Workerman\Protocols\Http\Response;

require __DIR__ . '/vendor/autoload.php';

$worker = new Worker('http://0.0.0.0:8080');

$worker->onMessage = function(TcpConnection $connection, Request $request)
{
    // 下面两种都可以
    // $connection->send("hello:" . $request->connection->id);
    $connection->send(new Response(200, [], "hello:" . $request->connection->id));
};

// 运行worker
Worker::runAll();

test.php:

<?php
function test1_0_close()
{
    echo 'HTTP 1.0 close test:', PHP_EOL;

    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, 'http://127.0.0.1:8080/');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0);

    var_dump($a = curl_exec($ch));
    var_dump($b = curl_exec($ch));

    curl_close($ch);
    if ($a === $b)
    {
        echo 'HTTP/1.0 close test failed', PHP_EOL, PHP_EOL;
    }
}

function test1_0_keep_alive()
{
    echo 'HTTP 1.0 keep-alive test:', PHP_EOL;

    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, 'http://127.0.0.1:8080/');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0);

    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Connection: Keep-Alive',
    ]);

    var_dump($a = curl_exec($ch));
    var_dump($b = curl_exec($ch));

    curl_close($ch);
    if ($a !== $b)
    {
        echo 'HTTP/1.0 keep-alive test failed', PHP_EOL, PHP_EOL;
    }
}

function test1_1_close()
{
    echo 'HTTP 1.1 close test:', PHP_EOL;

    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, 'http://127.0.0.1:8080/');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);

    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Connection: close',
    ]);

    var_dump($a = curl_exec($ch));
    var_dump($b = curl_exec($ch));

    curl_close($ch);
    if ($a === $b)
    {
        echo 'HTTP/1.1 close test failed', PHP_EOL, PHP_EOL;
    }
}

function test1_1_keep_alive()
{
    echo 'HTTP 1.1 keep-alive test:', PHP_EOL;

    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, 'http://127.0.0.1:8080/');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);

    var_dump($a = curl_exec($ch));
    var_dump($b = curl_exec($ch));

    curl_close($ch);
    if ($a !== $b)
    {
        echo 'HTTP/1.1 keep-alive test failed', PHP_EOL, PHP_EOL;
    }
}

test1_0_close();
test1_0_keep_alive();

test1_1_close();
test1_1_keep_alive();