Cache
Scope
Caching of complex variables, and variables which are expensive to generate.
Like configuration, localization and service responses., (*1)
Not page caching, no stampede protection., (*2)
Cache abstraction
CacheBroker decouples code using cache from the actual PSR-16 cache implementation., (*3)
Defines three cache class aliases:, (*4)
- _variable time-to-live_ (default ttl and set() arg ttl)
- _fixed time-to-live_ (default ttl, set() arg ttl ignored)
- _persistent_ (default ttl 'forever' and set() arg ttl ignored)
Plus three like the above which allow long keys; length 128 instead of the PSR-16 compliant 64., (*5)
How to use
Ask CacheBroker for an aliased type of cache instance - do not instantiate a particular cache class., (*6)
Extend CacheBroker, if you later want to switch from say file-based to database-based caching., (*7)
Dependency injection container ID: cache-broker
Recommendation: access (and thus instantiate) the cache broker via DI container ID 'cache-broker'.
See SimpleComplex Utils Dependency., (*8)
File-based caching
FileCache is a thorough and cautious PSR-16 Simple Cache implementation; file-based.
Coded defensively - key (and other argument) validation., (*9)
Addresses:, (*10)
- default time-to-live; ignore set() arg ttl option; no time-to-live
- garbage collection
- clearing all items or expired items only
- exporting all items, to JSON
- building/replacing a cache store during production (using a 'candidate' store)
- CLI interface for clearing items, e.g. via cron
- concurrency issues (storage-wise only)
Cache management, replacement and backup
Defines two extensions to the PSR-16 CacheInterface, implemented by FileCache., (*11)
ManageableCacheInterface, (*12)
- is the cache store new or empty?
- setting default time-to-live; setting 'ignore' set() arg ttl
- clearing and exporting
- listing all cache stores
BackupCacheInterface, (*13)
- backup/restore
- replacing a store, by building a 'candidate' and switching to that when it's complete
Example
// Bootstrap.
Dependency::genericSet('cache-broker', function () {
return new \SimpleComplex\Cache\CacheBroker();
});
// ...
// Use.
/** @var \Psr\Container\ContainerInterface $container */
$container = Dependency::container();
/** @var \SimpleComplex\Cache\CacheBroker $cache_broker */
$cache_broker = $container->get('cache-broker');
/**
* Create or re-initialize a cache store.
*
* @var \SimpleComplex\Cache\FileCache $cache_store
*/
$cache_store = $cache_broker->getStore(
'some-cache-store',
CacheBroker::CACHE_VARIABLE_TTL
);
unset($cache_broker);
/** @var mixed $whatever */
$whatever = $cache_store->get('some-key', 'the default value');
CLI commands
# List all cache commands and their help.
php cli.php cache -h
# One command's help.
php cli.php cache-xxx -h
# List existing cache stores.
php cli.php cache-list-stores
# Display/get value of a cache item.
php cli.php cache-get store key
# Delete a cache item.
php cli.php cache-delete store key
# Delete all expired items of one or all cache stores.
php cli.php cache-clear-expired
# Delete all items of one or all cache stores.
php cli.php cache-clear
# Backup a cache store.
php cli.php cache-backup store
# Restore a cache store from backup.
php cli.php cache-restore store
# Destroy one or all cache stores.
php cli.php cache-destroy
Installation
Create a 'private' files directory alongside the document root dir
and make it writable for the webserver user (www-data or apache)., (*14)
Like:
/var/www/my-host/http
/var/www/my-host/private, (*15)
On first cache store instantiation, FileCache will create directory
private/lib/simplecomplex/file-cache, (*16)
If that directory structure isn't suitable, do either:
- supply CacheBroker (or FileCache constructor directly) with a 'path' argument
- extend FileCache and override it's class constant PATH_DEFAULT, (*17)
Requirements
Suggestions
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