ApcuBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface
A caching backend which stores cache entries by using APCu.
The APCu backend is not very good with tagging and scales O(2n) with the number of tags. Do not use this backend if the data to be cached has many tags!
This backend uses the following types of keys:
- tag_xxx xxx is tag name, value is array of associated identifiers identifier. This is "forward" tag index. It is mainly used for obtaining content by tag (get identifier by tag -> get content by identifier)
- ident_xxx xxx is identifier, value is array of associated tags. This is "reverse" tag index. It provides quick access for all tags associated with this identifier and used when removing the identifier
Each key is prepended with a prefix. The prefix makes sure keys from the different installations do not conflict. By default, prefix consists from two parts separated by underscore character and ends in yet another underscore character:
- "TYPO3"
- Hash of path to TYPO3 and user running TYPO3
Table of Contents
Interfaces
- TaggableBackendInterface
- A contract for a cache backend which supports tagging.
- TransientBackendInterface
- A contract for a cache backends which store variables in volatile memory and as such support receiving any variable type to store.
Properties
- $cacheIdentifier : string
- $defaultLifetime : int
- Default lifetime of a cache entry in seconds
Methods
- __construct() : mixed
- Constructs this backend
- collectGarbage() : void
- Does garbage collection
- findIdentifiersByTag() : array<string|int, mixed>
- Finds and returns all cache entry identifiers which are tagged by the specified tag
- flush() : void
- Removes all cache entries of this cache.
- flushByTag() : void
- Removes all cache entries of this cache which are tagged by the specified tag.
- flushByTags() : void
- Removes all cache entries of this cache which are tagged by any of the specified tags.
- get() : mixed
- Loads data from the cache.
- has() : bool
- Checks if a cache entry with the specified identifier exists.
- remove() : bool
- Removes all cache entries matching the specified identifier.
- set() : void
- Saves data in the cache.
- setCache() : void
- Sets a reference to the cache frontend which uses this backend
- setDefaultLifetime() : void
- Sets the default lifetime for this cache backend
Properties
$cacheIdentifier
protected
string
$cacheIdentifier
$defaultLifetime
Default lifetime of a cache entry in seconds
protected
int
$defaultLifetime
= 3600
Methods
__construct()
Constructs this backend
public
__construct([array<string|int, mixed> $options = [] ]) : mixed
Parameters
- $options : array<string|int, mixed> = []
-
Configuration options - unused here
collectGarbage()
Does garbage collection
public
collectGarbage() : void
findIdentifiersByTag()
Finds and returns all cache entry identifiers which are tagged by the specified tag
public
findIdentifiersByTag(string $tag) : array<string|int, mixed>
Parameters
- $tag : string
-
The tag to search for
Return values
array<string|int, mixed> —An array with identifiers of all matching entries. An empty array if no entries matched
flush()
Removes all cache entries of this cache.
public
flush() : void
flushByTag()
Removes all cache entries of this cache which are tagged by the specified tag.
public
flushByTag(string $tag) : void
Parameters
- $tag : string
-
The tag the entries must have
flushByTags()
Removes all cache entries of this cache which are tagged by any of the specified tags.
public
flushByTags(array<string|int, mixed> $tags) : void
Parameters
- $tags : array<string|int, mixed>
-
List of tags
get()
Loads data from the cache.
public
get(string $entryIdentifier) : mixed
Parameters
- $entryIdentifier : string
-
An identifier which describes the cache entry to load
Return values
mixed —The cache entry's content as a string or FALSE if the cache entry could not be loaded
has()
Checks if a cache entry with the specified identifier exists.
public
has(string $entryIdentifier) : bool
Parameters
- $entryIdentifier : string
-
An identifier specifying the cache entry
Return values
bool —TRUE if such an entry exists, FALSE if not
remove()
Removes all cache entries matching the specified identifier.
public
remove(string $entryIdentifier) : bool
Usually this only affects one entry but if - for what reason ever - old entries for the identifier still exist, they are removed as well.
Parameters
- $entryIdentifier : string
-
Specifies the cache entry to remove
Return values
bool —TRUE if (at least) an entry could be removed or FALSE if no entry was found
set()
Saves data in the cache.
public
set(string $entryIdentifier, mixed $data[, array<string|int, mixed> $tags = [] ][, int|null $lifetime = null ]) : void
Parameters
- $entryIdentifier : string
-
An identifier for this specific cache entry
- $data : mixed
-
The data to be stored. mixed is allowed due to TransientBackendInterface
- $tags : array<string|int, mixed> = []
-
Tags to associate with this cache entry. If the backend does not support tags, this option can be ignored.
- $lifetime : int|null = null
-
Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
setCache()
Sets a reference to the cache frontend which uses this backend
public
setCache(FrontendInterface $cache) : void
Parameters
- $cache : FrontendInterface
-
The frontend for this backend
setDefaultLifetime()
Sets the default lifetime for this cache backend
public
setDefaultLifetime(int $defaultLifetime) : void
Parameters
- $defaultLifetime : int
-
Default lifetime of this cache backend in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.
Misused for testing purposes.