Monthly Archives: February 2015

Route Cache in Zend Framework 2

There are several ways to improve the performance of a Zend Framework 2 (ZF2) application and in the “Learn ZF2” I explained some of them. But not all of them. Below you will find an information how to speed up the ZF2 application routing.

In a typical ZF2 application evaluating the routes and finding a match can be time-consuming task. The more non-literal routes your application has the slower the route matching process will be. Below I will present you one possible way to speed up that process.

In ZF2 routing means finding a controller, action and set of parameters that correspond to the current URL and given request parameters. In ZF2 the routing process starts when the MVC ROUTE event is triggered. There is a listener with priority 1(one) attached to this event that takes care to find a route match. What we can do is attach a new listener to the MVC ROUTE event but with higher priority. This way our listener will be executed before the actual matching process is started. In it we can check against a cache system if for the provided path of the URL there is already a cached data that contains the match parameters. In addition we can add a second listener to the MVC ROUTE event with lower priority. It will be executed after the matching is done and we can use it to save the route match data to our caching system. A good initial place to put those listeners will be in the Application Module.php ( module/Application/Module.php )

The initial version of our two listeners looks like this:

<?php
namespace Application;
 
use Zend\Mvc\MvcEvent;
 
class Module
{   public function onBootstrap(MvcEvent $event) 
    {
        $eventManager        = $event->getApplication()->getEventManager();
 
        //..
        $eventManager->attach(MvcEvent::EVENT_ROUTE, array($this, 'routeLoad'), 999);
        $eventManager->attach(MvcEvent::EVENT_ROUTE, array($this, 'routeSave'), 0);
    }
 
    /**
     * Method that tries to load cached routes and speed up the matching
     * @param MvcEvent $event
     */
    public function routeLoad(MvcEvent $event)
    {
        // @todo: check if we have data in our cache
    }
 
    /**
     * Method that tries to save a route match into a cache system
     * @param MvcEvent $event
     */
    public function routeSave(MvcEvent $event)
    {
        $match = $event->getRouteMatch();
        if(!$match) {
            return;
        }
 
        // @todo: save the route match into the cache.
    }

We should take care to cache the route match for URLs that produce the same result. A good example of a request for which the routing can be cached is the case when we have GET request and no query params. For such events we can set a flag route-cacheable. Additionally we should set a flag in the event that specifies if a cached route match was used or it was calculated during this request. That will help us avoid caching already cached routes. So the code will start to look like this

// ...
 
    /**
     * Method that tries to load cached routes and speed up the matching
     * @param MvcEvent $event
     */
    public function routeLoad(MvcEvent $event)
    {
        $request = $event->getRequest(); 
        if(!(
            $request->getMethod() == \Zend\Http\Request::METHOD_GET && 
            $request->getQuery()->count() == 0
            )) {
            // We do not cache route match for requests that can produce
            // different match.    
            return ;
        }
 
        $event->setParam('route-cacheable', true);
 
        // @todo: check if we have data in our cache
        $inCache = false; // @todo: get the actual value
 
        if($inCache) {
            $event->setParam('route-cached', true);
        }
    }
 
    /**
     * Method that tries to save a route match into a cache system
     * @param MvcEvent $event
     */
    public function routeSave(MvcEvent $event)
    {
        $match = $event->getRouteMatch();
        if(!$match) {
            return;
        }
 
        if($event->getParam('route-cached') || !$event->getParam('route-cacheable')) {
            return;
        }
 
        // @todo: save the route match into the cache.
    }

The real trick to speed up the route matching is not to bypass it but to put on the top a route definition that is very fast to match. This definition should use the Literal route type and should contain the route name and route parameters stored in the cache from the actual matching. Creating such a route can be done with:

$cachedRoute = \Zend\Mvc\Router\Http\Literal::factory($cachedData);

The router contains multiple routes ordered in a stack. And this stack is evaluated from top to bottom. On the top are the routes with higher priority and on the bottom are the ones with lower priority. We need to put this cached router on the top of the stack of routes that we have. This can be done with a code like:

$router = $event->getRouter();
$router->addRoute($cachedData['name'], $cachedRoute, 99999);

In the routeLoad method the new code will look like this:

/**
     * Method that tries to load cached routes and speed up the matching
     * @param MvcEvent $event
     */
    public function routeLoad(MvcEvent $event)
    {
        $request = $event->getRequest(); 
        if(!(
            $request->getMethod() == \Zend\Http\Request::METHOD_GET && 
            $request->getQuery()->count() == 0
            )) {
            // We do not cache route match for requests that can produce
            // different match.    
            return ;
        }
 
        $event->setParam('route-cacheable', true);
 
        // @todo: check if we have data in our cache
        $cachedData = false; // @todo: get the actual value
 
        if(!empty($cachedData)) {
            $event->setParam('route-cached', true);
 
            $cachedRoute = \Zend\Mvc\Router\Http\Literal::factory($cachedData);
            $router = $event->getRouter();
            $router->addRoute($cachedData['name'], $cachedRoute, 99999);
        }
    }

Saving the actual route match in the cache should be done in our routeSave method. We can use the var-cache service that you know from the “Learn ZF2” book code. The final version of our routeSave method will look like this:

/**
     * Method that tries to save a route match into a cache system
     * @param MvcEvent $event
     */
    public function routeSave(MvcEvent $event)
    {
        $match = $event->getRouteMatch();
        if(!$match) {
            return;
        }
 
        if($event->getParam('route-cached') || !$event->getParam('route-cacheable')) {
            return;
        }
 
        $path = $event->getRequest()
                ->getUri()
                ->getPath();
 
        // save the route match into the cache.
        $cache = $event->getApplication()->getServiceManager()->get('var-cache');
        $cacheKey = $this->getCacheKey($path);
        $data = array (
          'name' => $event->getRouteMatch()->getMatchedRouteName(),
          'route' => $path,
          'defaults' => $event->getRouteMatch()->getParams(),
        );
        $cache->setItem($cacheKey, $data);
    }

And the final version of the routeLoad method will look like this:

  /**
     * Method that tries to load cached routes and speed up the matching
     * @param MvcEvent $event
     */
    public function routeLoad(MvcEvent $event)
    {
        $request = $event->getRequest(); 
        if(!(
            $request->getMethod() == \Zend\Http\Request::METHOD_GET && 
            $request->getQuery()->count() == 0
            )) {
            // We do not cache route match for requests that can produce
            // different match.    
            return ;
        }
 
        $event->setParam('route-cacheable', true);
 
        // check if we have data in our cache
        $path = $event->getRequest()
                      ->getUri()
                      ->getPath();
 
        $cache = $event->getApplication()->getServiceManager()->get('var-cache');
        $cacheKey = $this->getCacheKey($path);
        $cachedData = $cache->getItem($cacheKey); 
 
        if(!empty($cachedData)) {
            $event->setParam('route-cached', true);
 
            $cachedRoute = \Zend\Mvc\Router\Http\Literal::factory($cachedData);
            $router = $event->getRouter();
            $router->addRoute($cachedData['name'], $cachedRoute, 99999);
        }
    }

Update: 2nd of April, 2015: We have create a composer package that you can use directly in your ZF2 application and take speed up your route matching. Take a look the github page of the project  for information how to install and setup the plugin.

Happy ZF2 coding and good luck with improving the performance of your ZF2 application!