Merge pull request #184 from havvg/feature/cache-resolver

add CacheResolver

Imagine/Cache/Resolver/CacheResolver.php

@@ -0,0 +1,246 @@
+<?php
+
+namespace Liip\ImagineBundle\Imagine\Cache\Resolver;
+
+use Doctrine\Common\Cache\Cache;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+use Symfony\Component\OptionsResolver\OptionsResolverInterface;
+
+class CacheResolver implements ResolverInterface
+{
+    /**
+     * @var Cache
+     */
+    protected $cache;
+
+    protected $options = array();
+
+    /**
+     * @var ResolverInterface
+     */
+    protected $resolver;
+
+    /**
+     * Constructor.
+     *
+     * Available options:
+     * * global_prefix
+     *   A prefix for all keys within the cache. This is useful to avoid colliding keys when using the same cache for different systems.
+     * * prefix
+     *   A "local" prefix for this wrapper. This is useful when re-using the same resolver for multiple filters.
+     * * index_key
+     *   The name of the index key being used to save a list of created cache keys regarding one image and filter pairing.
+     *
+     * @param Cache $cache
+     * @param ResolverInterface $cacheResolver
+     * @param array $options
+     * @param OptionsResolverInterface $optionsResolver
+     */
+    public function __construct(Cache $cache, ResolverInterface $cacheResolver, array $options = array(), OptionsResolverInterface $optionsResolver = null)
+    {
+        $this->cache = $cache;
+        $this->resolver = $cacheResolver;
+
+        if (null === $optionsResolver) {
+            $optionsResolver = new OptionsResolver();
+        }
+
+        $this->setDefaultOptions($optionsResolver);
+        $this->options = $optionsResolver->resolve($options);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function resolve(Request $request, $path, $filter)
+    {
+        $key = $this->generateCacheKey('resolve', $path, $filter);
+        if ($this->cache->contains($key)) {
+            return $this->cache->fetch($key);
+        }
+
+        $targetPath = $this->resolver->resolve($request, $path, $filter);
+        $this->saveToCache($key, $targetPath);
+
+        /*
+         * The targetPath being a string will be forwarded to the ResolverInterface::store method.
+         * As there is no way to reverse this operation by the interface, we store this information manually.
+         *
+         * If it's not a string, it's a Response it will be returned as it without calling the store method.
+         */
+        if (is_string($targetPath)) {
+            $reverseKey = $this->generateCacheKey('reverse', $targetPath, $filter);
+            $this->saveToCache($reverseKey, $path);
+        }
+
+        return $targetPath;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function store(Response $response, $targetPath, $filter)
+    {
+        return $this->resolver->store($response, $targetPath, $filter);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getBrowserPath($path, $filter, $absolute = false)
+    {
+        $key = $this->generateCacheKey('getBrowserPath', $path, $filter, array(
+            $absolute ? 'absolute' : 'relative',
+        ));
+
+        if ($this->cache->contains($key)) {
+            return $this->cache->fetch($key);
+        }
+
+        $result = $this->resolver->getBrowserPath($path, $filter, $absolute);
+        $this->saveToCache($key, $result);
+
+        return $result;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function remove($targetPath, $filter)
+    {
+        $removed = $this->resolver->remove($targetPath, $filter);
+
+        // If the resolver did not remove the content, we can leave the cache.
+        if ($removed) {
+            $reverseKey = $this->generateCacheKey('reverse', $targetPath, $filter);
+            if ($this->cache->contains($reverseKey)) {
+                $path = $this->cache->fetch($reverseKey);
+
+                // The indexKey is not utilizing the method so the value is not important.
+                $indexKey = $this->generateIndexKey($this->generateCacheKey(null, $path, $filter));
+
+                // Retrieve the index and remove the content from the cache.
+                $index = $this->cache->fetch($indexKey);
+                foreach ($index as $eachCacheKey) {
+                    $this->cache->delete($eachCacheKey);
+                }
+
+                // Remove the auxiliary keys.
+                $this->cache->delete($indexKey);
+                $this->cache->delete($reverseKey);
+            }
+        }
+
+        return $removed;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function clear($cachePrefix)
+    {
+        // TODO: implement cache clearing
+    }
+
+    /**
+     * Generate a unique cache key based on the given parameters.
+     *
+     * When overriding this method, ensure generateIndexKey is adjusted accordingly.
+     *
+     * @param string $method The cached method.
+     * @param string $path The image path in use.
+     * @param string $filter The filter in use.
+     * @param array $suffixes An optional list of additional parameters to use to create the key.
+     *
+     * @return string
+     */
+    public function generateCacheKey($method, $path, $filter, array $suffixes = array())
+    {
+        $keyStack = array(
+            $this->options['global_prefix'],
+            $this->options['prefix'],
+            $filter,
+            $path,
+            $method,
+        );
+
+        return implode('.', array_merge($keyStack, $suffixes));
+    }
+
+    /**
+     * Generate the index key for the given cacheKey.
+     *
+     * The index contains a list of cache keys related to an image and a filter.
+     *
+     * @param string $cacheKey
+     *
+     * @return string
+     */
+    protected function generateIndexKey($cacheKey)
+    {
+        $cacheKeyStack = explode('.', $cacheKey);
+
+        $indexKeyStack = array(
+            $this->options['global_prefix'],
+            $this->options['prefix'],
+            $this->options['index_key'],
+            $cacheKeyStack[2], // filter
+            $cacheKeyStack[3], // path
+        );
+
+        return implode('.', $indexKeyStack);
+    }
+
+    /**
+     * Save the given content to the cache and update the cache index.
+     *
+     * @param string $cacheKey
+     * @param mixed $content
+     *
+     * @return bool
+     */
+    protected function saveToCache($cacheKey, $content)
+    {
+        // Create or update the index list containing all cache keys for a given image and filter pairing.
+        $indexKey = $this->generateIndexKey($cacheKey);
+        if ($this->cache->contains($indexKey)) {
+            $index = $this->cache->fetch($indexKey);
+
+            if (!in_array($cacheKey, $index)) {
+                $index[] = $cacheKey;
+            }
+        } else {
+            $index = array($cacheKey);
+        }
+
+        /*
+         * Only save the content, if the index has been updated successfully.
+         * This is required to have a (hopefully) synchron state between cache and backend.
+         *
+         * "Hopefully" because there are caches (like Memcache) which will remove keys by themselves.
+         */
+        if ($this->cache->save($indexKey, $index)) {
+            return $this->cache->save($cacheKey, $content);
+        }
+
+        return false;
+    }
+
+    protected function setDefaultOptions(OptionsResolverInterface $resolver)
+    {
+        $resolver->setDefaults(array(
+            'global_prefix' => 'liip_imagine.resolver_cache',
+            'prefix' => get_class($this->resolver),
+            'index_key' => 'index',
+        ));
+
+        $resolver->setAllowedTypes(array(
+            'global_prefix' => 'string',
+            'prefix' => 'string',
+            'index_key' => 'string',
+        ));
+    }
+}

Resources/doc/cache-resolver/cache.md

@@ -0,0 +1,61 @@
+# CacheResolver
+
+The `CacheResolver` requires the [Doctrine Cache](https://github.com/doctrine/cache).
+
+This resolver wraps another resolver around a `Cache`.
+
+Now you can set up the services required; by example using the `AmazonS3Resolver`.
+
+``` yaml
+services:
+    acme.amazon_s3:
+        class: AmazonS3
+        arguments:
+            -
+                key: %amazon_s3.key%
+                secret: %amazon_s3.secret%
+
+    acme.imagine.cache.resolver.amazon_s3:
+        class: Liip\ImagineBundle\Imagine\Cache\Resolver\AmazonS3Resolver
+        arguments:
+            - "@acme.amazon_s3"
+            - "%amazon_s3.bucket%"
+
+    memcache:
+        class: Memcache
+        calls:
+            - [ 'connect', [ '127.0.0.1', 11211 ] ]
+
+    cache.memcache:
+        class: Doctrine\Common\Cache\MemcacheCache
+        calls:
+            - [ 'setMemcache', [ '@memcache' ] ]
+
+    # The actual
+    acme.imagine.cache.resolver.amazon_s3.cache:
+        class: Liip\ImagineBundle\Imagine\Cache\Resolver\CacheResolver
+        arguments:
+            - "@cache.memcache"
+            - "@acme.imagine.cache.resolver.amazon_s3"
+            -
+                prefix: "amazon_s3"
+        tags:
+            - { name: 'liip_imagine.cache.resolver', resolver: 'cached_amazon_s3' }
+```
+
+There are currently three options available when configuring the `CacheResolver`:
+
+* `global_prefix` A prefix for all keys within the cache. This is useful to avoid colliding keys when using the same cache for different systems.
+* `prefix` A "local" prefix for this wrapper. This is useful when re-using the same resolver for multiple filters. This mainly affects the clear method.
+* `index_key` The name of the index key being used to save a list of created cache keys regarding one image and filter pairing.
+
+Now you are ready to use the `CacheResolver` by configuring the bundle.
+The following example will configure the resolver is default.
+
+``` yaml
+liip_imagine:
+    cache: 'cached_amazon_s3'
+```
+
+- [Back to cache resolvers](../cache-resolvers.md)
+- [Back to the index](../index.md)

Resources/doc/cache-resolvers.md

@@ -1,6 +1,7 @@
 # Built-In CacheResolver
 
 * [AmazonS3](cache-resolver/amazons3.md)
+* [CacheResolver](cache-resolver/cache.md)
 
 # Custom cache resolver
 

Tests/Fixtures/MemoryCache.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Liip\ImagineBundle\Tests\Fixtures;
+
+use Doctrine\Common\Cache\Cache;
+
+class MemoryCache implements Cache
+{
+    public $data = array();
+
+    public function fetch($id)
+    {
+        return (isset($this->data[$id])) ? $this->data[$id] : false;
+    }
+
+    public function contains($id)
+    {
+        return isset($this->data[$id]);
+    }
+
+    public function save($id, $data, $lifeTime = 0)
+    {
+        $this->data[$id] = $data;
+
+        return true;
+    }
+
+    public function delete($id)
+    {
+        unset($this->data[$id]);
+
+        return true;
+    }
+
+    public function getStats()
+    {
+        return null;
+    }
+}