Content cache refresh

The content cache refreshing system enables displaying the current information when objects in the Back Office are modified.

The content cache refresh service is used in the following situations:

• Navigation cache is refreshed for example if one or many navigation nodes are changed
• If a category is changed, the cached names for categories used by the search are updated (CategoryNameService)

Note

You need to have a cron job set up to use this feature.

Set up cron job to refresh caches

To set up a cron job to refresh caches, create a system cron job to run the following console command:

php bin/console silversolutions:cache:refresh

Slot implementation

Note

See SignalSlot documentation for more information about the SignalSlot system.

The ContentModificationSlot pushes content modification data into the queue by using the ContentModificationQueueService.

Definitions

Content modification is an array of information about the modified content.

Attribute (key)	Value type	Description
content_id	int	Content ID of the modified Content item.
action	string	Name of the action which resulted in content modification, e.g. publish or delete.
trigger	string	Legacy trigger name which caused content modification, e.g. post_publish, pre_delete. This attribute is created only to provide additional information for content modification processor developers.

Note

You can find a list of actions and triggers in supported content modification actions and triggers

Content modification processors can provide additional attributes.

Content modification queue is a series of content modifications. It is implemented with Doctrine.

• ContentModificationQueue - Doctrine entity (queue item).
• ContentModificationQueueRepository - Doctrine entity repository for queue items.

ContentModificationQueueService is a service that stores content modifications in the queue and runs processors to handle content modifications.

Content modification processor is a service implemented to process information about content modification (e.g. refreshes related caches).

ContentModificationQueueService

ContentModificationQueueService has several responsibilities:

1. Gathers all services that are tagged with siso_tools.content_modification_processor (content modification processors).
2. Fetches all current content modifications from the queue.
3. Gets additional attributes from processors.
4. Pushes content modifications to the queue (table ses_content_modification_queue).
5. Passes every content modification object to every processor service.
6. Removes processed content modifications from the queue.

Content modification processor

Every content modification processor must implement two actions:

1. Get content ID and expose additional attributes that the processor can process later.
   For example, a navigation cache processor retrieves a Content item's language code from the given content ID. This information is added to content modification data along with initial data.
2. Process content modification data (e.g. clear cache).

Content modification processor actions

Content modifications are stored in the content modification queue immediately after content is changed. However, processing of the queue doesn't happen immediately. Shop administrator can process the queue manually with a console script or configure a cron job task.

It means that if a user removes a Content item, there is no data that the processor can use for clearing the cache. For this reason, a content modification processor has to store information about the removed Content item before it is processed.

Content modification processing is usually a resource-consuming operation. Therefore it should be done as a deferred task.

Implementing a new content modification processor

There are two steps to add your own Processor Service to the chain for content cache refresh.

Step 1. Prepare service definition

Prepare service definition to add a service with the tag siso_tools.content_modification_processor.

<!-- your own content modification processor service -->
<service id="domain.yourname_content_modification_processor" class="%domain.yourname_content_modification_processor.class%">
    ...
    <tag name="siso_tools.content_modification_processor" />
</service>

Step 2. Create processor service class

Create a processor service class, which has to implement the ContentModificationProcessorServiceInterface interface.

interface ContentModificationProcessorServiceInterface
{
    /**
     * Processes modified eZ content.
     *
     * @param ContentModificationQueueItemInterface[] $queue
     * @return void
     */
    function process($queue);

    /**
     * Get an array of attributes to use them later on the process stage.
     *
     * @param $contentId
     * @return array|null
     */
    function getContentModificationAttributes($contentId);
}

Example

To understand how the getContentModificationAttributes and process methods cooperate, you can refer to the example of TransContentModificationProcessorService which is responsible for clearing translation caches.

function getContentModificationAttributes($contentId)
{
    // 1. Get services
    $contentService = $this->repository->getContentService();
    $content = $contentService->loadContent($contentId);
    $contentTypeService = $this->repository->getContentTypeService();

    // 2. Get data to store in attributes
    $contentType = $contentTypeService->loadContentType($content->contentInfo->contentTypeId);
    $languageCode = $content->getVersionInfo()->initialLanguageCode;

    // 3. Define array of attributes
    return array(
        'content_type' => $contentType->identifier,
        'language_code' => $languageCode,
    );
}
// ...
public function process($queue)
{
    ...

    foreach($queue as $queueItem) {

        $data = $queueItem->getData();

        // Content type attribute is requested
        if (!isset($data['content_type']) || $data['content_type'] !== self::TRANSLATION_IDENTIFIER) {
            continue;
        }

        if(in_array($data['action'], array('delete','removetranslation', 'hide'))) {
            $this->transService->removeTranslationCache(
                ...
                // Language code attribute is requested
                $data['language_code']
            );
        }
    }
}

Note

Please pay attention that process method uses attributes language_code and content_type which were added to content modification array using the getContentModificationAttributes method.

Supported content modification actions and triggers

Action	Trigger
publish	post_publish
delete	pre_delete
hide	post_hide
move	post_move
swap	post_swap
updateobjectstate	post_updateobjectstate
updatepriority	post_updatepriority
addlocation	post_addlocation
removelocation	pre_removelocation
removetranslation	pre_removetranslation

Implemented content modification processor services

Service	Purpose
NavigationContentModificationProcessorService	Clears navigation cache
TransContentModificationProcessorService	Clears translation cache