laravel 的中间件与管道

一、php中的debug_backtrace() php的调试一直是一个比较困难的问题，最近发现debug_backtrace()是一个比较好用函数，可以在任何地方使用，直接在页面上打印出函数堆栈。

class AController extends Controller
{
    public function index(Request $request)
    {
        return debug_backtrace();
    }
}

Route::get('/', function() {
    return debug_backtrace();   
});


在index中使用`debug_backtrace`会发现laravel中使用了很多的Pipeline，其实这就是在使用Middleware对请求进行过滤

二、Pipeline做了什么使用一段示例代码看看Pipeline到底做了什么

<?php
	use Illuminate\Pipeline\Pipeline;

	$pipe1 = function ($poster, Closure $next) {
		$poster += 1;
		echo "pipe1: $poster\n";
		return $next($poster);
	};

	$pipe2 = function ($poster, Closure $next) {
		if ($poster > 7) {
			return $poster;
		}

		$poster += 3;
		echo "pipe2: $poster\n";
		return $next($poster);
	};

	$pipe3 = function ($poster, Closure $next) {
		$result = $next($poster);
		echo "pipe3: $result\n";
		return $result * 2;
	};

	$pipe4 = function ($poster, Closure $next) {
		$poster += 2;
		echo "pipe4 : $poster\n";
		return $next($poster);
	};

	$pipes = [$pipe1, $pipe2, $pipe3, $pipe4];

	function dispatcher($poster, $pipes)
	{
		echo "result: " . (new Pipeline)->send($poster)->through($pipes)->then(function ($poster) {
				echo "received: $poster\n";
				return 3;
			}) . "\n";
	}

	echo "==> action 1:\n";
	dispatcher(5, $pipes);
	echo "==> action 2:\n";
	dispatcher(7, $pipes);

上述代码执行结果如下：

==> action 1: pipe1: 6 pipe2: 9 pipe4 : 11 received: 11 pipe3: 3 result: 6 ==> action 2: pipe1: 8 result: 8