• Drupal.org: FatherShawn
• Twitter: @FatherShawn
• Occasional Blogging: shawnduncan.org
• These slides: talks.shawnduncan.org/cache_bin

Cache services:

Drupal\Core\Cache\MemoryBackend

cache.static

Drupal\Core\Cache\DatabaseBackend

cache.bootstrap

cache.config

cache.default

cache.entity

cache.menu

cache.render

cache.data

cache.discovery

• A cache service in injected
• A cache ID is created - 1:1 mapping between cid and data item
• Before the data is obtained or calculated, check cache and use if found
• Otherwise, generate and cache the data
• Example:

// cacheDefault is injected cache.default service.
$cid = 'module_name:route.name:' . $entity->id . ':' .  
        $entity->field_reference->entity->id;
if ($cache = $this->cacheDefault->get($cid) {
  $data = $cache->data;
}
else {
  $data = my_module_complicated_calculation();
  // optional $expire and $tags parameters omitted for clarity.
  $this->cacheDefault->set($cid, $data);
 }

• If the core cache bins don't meet your needs you can define your own by appropriately defining a service. See Cache Bins for details or search through core.services.yml for cache.bin to see examples.
• Both deletion and invalidation methods are available. Invalidation is better for performance and stability and should be use unless the data must be removed immediately.

• Used to describe dependencies on data.
• Optional argument when caching data. All data with the same tag can be invalidated as a group.
• Convention is [prefix]:[suffix]
  • node:37
  • user:3
• All core entities have built-in support for cache tags.
• You can define your own.

• Used to describe dependencies on context, technically the request
• Can define your own contexts.
• Core contexts:

• drupal site:mode dev will get you most of the way.
• In the generated services.yml set http.response.debug_cacheability_headers to true
• Can manually cache clear - important for seeing how your site interacts with cache
• Cache backend is pluggable - plug it in to the Null Cache service when needed. Use a settings.local.php:

      
  $settings['container_yamls'][] = DRUPAL_ROOT . '/sites/development.services.yml';
  $settings['cache']['bins']['render'] = 'cache.backend.null';
  $settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.null';
      
  

• Renderer::addCacheableDependency for the win!
• Set your context directly.
• Still have time based cache available.

$render_array = (
    '#cache => array(
        'max-age' => 0,
        'tags' => array(),
        'contexts' => array(),
    );
);

• Create a route subscriber
  • Requires a class and a service.
  • drupal generate:event:subscriber
• setCacheControlNoCache
• setExpiresNoCache

Cache API

https://api.drupal.org/api/drupal/
core%21core.api.php/group/cache/8.1.x

Cache API: Developer's Documentation

https://www.drupal.org/developing/api/8/cache

Cache tags

https://www.drupal.org/developing/api/8/cache/tags

Cacheability of render arrays

https://www.drupal.org/developing/api/8/
render/arrays/cacheability

Insure Cache Bubbling in Custom Template

https://www.drupal.org/node/2660002

Varnish

http://www.jeffgeerling.com/blog/2016/
use-drupal-8-cache-tags-varnish-and-purge

Drupal Console

https://drupalconsole.com

“An infinite mystery is the Force.”

“The more we learn, the more we discover how much we do not know.”