laravel cache facade

本文使用版本为laravel5.5

cache get

public function cache()
    {
    	$c=\Cache::get('app');
    	if(!$c) {
    		\Cache::put('app', 'cache', 1);
    	}
    	dump($c);//cache
    }

config/app.php

'aliases' => [

       'App' => Illuminate\Support\Facades\App::class,
       'Artisan' => Illuminate\Support\Facades\Artisan::class,
       'Auth' => Illuminate\Support\Facades\Auth::class,
       'Blade' => Illuminate\Support\Facades\Blade::class,
       'Broadcast' => Illuminate\Support\Facades\Broadcast::class,
       'Bus' => Illuminate\Support\Facades\Bus::class,
       'Cache' => Illuminate\Support\Facades\Cache::class,
       
       ]

使用cache实际调用的是Illuminate\Support\Facades\Cache,这个映射是如何做的？

public/index.php

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$response = $kernel->handle(
$request = Illuminate\Http\Request::capture()
);

bootstarp/app.php

$app->singleton(
    Illuminate\Contracts\Http\Kernel::class,
    App\Http\Kernel::class
);

app/http/kernel.php

use Illuminate\Foundation\Http\Kernel as HttpKernel;

class Kernel extends HttpKernel
{

}

Illuminate/Foundation/Http/Kernel.php

public function handle($request)
{
    try {
        $request->enableHttpMethodParameterOverride();
        $response = $this->sendRequestThroughRouter($request);
    } catch (Exception $e) {
        $this->reportException($e);

        $response = $this->renderException($request, $e);
    } catch (Throwable $e) {
        $this->reportException($e = new FatalThrowableError($e));

        $response = $this->renderException($request, $e);
    }

    $this->app['events']->dispatch(
        new Events\RequestHandled($request, $response)
    );

    return $response;
}
protected function sendRequestThroughRouter($request)
    {
        $this->app->instance('request', $request);

        Facade::clearResolvedInstance('request');

        $this->bootstrap();

        return (new Pipeline($this->app))
                    ->send($request)
                    ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
                    ->then($this->dispatchToRouter());
    }
    public function bootstrap()
    {
        if (! $this->app->hasBeenBootstrapped()) {
            $this->app->bootstrapWith($this->bootstrappers());
        }
    }

Illuminate/Foundation/Application.php

public function bootstrapWith(array $bootstrappers)
    {
        $this->hasBeenBootstrapped = true;

        foreach ($bootstrappers as $bootstrapper) {
            $this['events']->fire('bootstrapping: '.$bootstrapper, [$this]);

            $this->make($bootstrapper)->bootstrap($this);

            $this['events']->fire('bootstrapped: '.$bootstrapper, [$this]);
        }
    }

Illuminate/Foundation/Bootstrap/RegisterFacades.php

public function bootstrap(Application $app)
    {
        Facade::clearResolvedInstances();

        Facade::setFacadeApplication($app);
//将config/app.php 里的aliases数组里面的Facades类设置别名
        AliasLoader::getInstance(array_merge(
            $app->make('config')->get('app.aliases', []),
            $app->make(PackageManifest::class)->aliases()
        ))->register();
    }

Illuminate/Foundation/AliasLoader.php

public function load($alias)
    {
        if (static::$facadeNamespace && strpos($alias, static::$facadeNamespace) === 0) {
            $this->loadFacade($alias);

            return true;
        }

      // $alias来自于config/app.php中aliases数组 
        if (isset($this->aliases[$alias])) {
            //'Route' => Illuminate\Support\Facades\Route::class,
            // class_alias 为一个类创建别名
            return class_alias($this->aliases[$alias], $alias);
        }
    }

Illuminate/Support/Facades/Cache.php

class Cache extends Facade
{
    /**
     * Get the registered name of the component.
     *
     * @return string
     */
    protected static function getFacadeAccessor()
    {
        return 'cache';
    }
}

Illuminate/Support/Facades/Facade.php

这个文件没有get set ，只有__callStatic

public static function __callStatic($method, $args)
    {
        $instance = static::getFacadeRoot();

        if (! $instance) {
            throw new RuntimeException('A facade root has not been set.');
        }

        return $instance->$method(...$args);
    }
   public static function getFacadeRoot()
    {
        return static::resolveFacadeInstance(static::getFacadeAccessor());
    } 
     protected static function resolveFacadeInstance($name)
    {
    //这里$name为cache
        if (is_object($name)) {
            return $name;
        }

        if (isset(static::$resolvedInstance[$name])) {
            return static::$resolvedInstance[$name];
        }
    //$app是容器对象，实现了ArrayAccess接口，最终调用的还是容器的make方法
        return static::$resolvedInstance[$name] = static::$app[$name];
    }

Illuminate\Container\Container.php

public function make($abstract, array $parameters = [])
    {
        return $this->resolve($abstract, $parameters);
    }
    protected function resolve($abstract, $parameters = [])
    {
        $abstract = $this->getAlias($abstract);

        $needsContextualBuild = ! empty($parameters) || ! is_null(
            $this->getContextualConcrete($abstract)
        );

        // If an instance of the type is currently being managed as a singleton we'll
        // just return an existing instance instead of instantiating new instances
        // so the developer can keep using the same objects instance every time.
        if (isset($this->instances[$abstract]) && ! $needsContextualBuild) {
            return $this->instances[$abstract];
        }

        $this->with[] = $parameters;

        $concrete = $this->getConcrete($abstract);

        // We're ready to instantiate an instance of the concrete type registered for
        // the binding. This will instantiate the types, as well as resolve any of
        // its "nested" dependencies recursively until all have gotten resolved.
        if ($this->isBuildable($concrete, $abstract)) {
            $object = $this->build($concrete);
        } else {
            $object = $this->make($concrete);
        }

        // If we defined any extenders for this type, we'll need to spin through them
        // and apply them to the object being built. This allows for the extension
        // of services, such as changing configuration or decorating the object.
        foreach ($this->getExtenders($abstract) as $extender) {
            $object = $extender($object, $this);
        }

        // If the requested type is registered as a singleton we'll want to cache off
        // the instances in "memory" so we can return it later without creating an
        // entirely new instance of an object on each subsequent request for it.
        if ($this->isShared($abstract) && ! $needsContextualBuild) {
            $this->instances[$abstract] = $object;
        }

        $this->fireResolvingCallbacks($abstract, $object);

        // Before returning, we will also set the resolved flag to "true" and pop off
        // the parameter overrides for this build. After those two things are done
        // we will be ready to return back the fully constructed class instance.
        $this->resolved[$abstract] = true;

        array_pop($this->with);

        return $object;
    }

Illuminate/Cache/CacheServiceProvider.php

public function register()
   {
       $this->app->singleton('cache', function ($app) {
           return new CacheManager($app);
       });

       $this->app->singleton('cache.store', function ($app) {
           return $app['cache']->driver();
       });

       $this->app->singleton('memcached.connector', function () {
           return new MemcachedConnector;
       });
   }

get set

$instance->$method(...$args)

由于 PHP 可以处理 WEB 和 CLI 两种接口请求，所以 Laravel 就得需要设计 HttpKernel 和 ConsoleKernel 来处理这两种。
实际上，Laravel 刚刚启动时先启动容器对象 Application，然后加载配置、通过 ServiceProvider 往容器对象里填充一些对象为接下来处理请求做准备，但是真正干活的是 Kernel(HttpKernel 或 ConsoleKernel)，Application 会把活转给 Kernel 来干。$output = Kernel::handle($input)：对于 WEB 请求，输入时 Request，输出是 Response；对于 CLI，输入是 argument + option 命令行变量构成的 Input 对象，输出则是展示在终端的 Output 对象。
所以，依赖注入(IoC 容器) 是 Laravel 的基石，真正干活的是 Kernel。https://laravel-china.org/articles/20507

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