TYPO3 13.4 API: ApcuBackend

ApcuBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface

FinalYes

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

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.

Constants

DATETIME_EXPIRYTIME_UNLIMITED = '9999-12-31T23:59:59+0000'
UNLIMITED_LIFETIME = 0

Properties

$cache : FrontendInterface: Reference to the cache which uses this backend
$cacheIdentifier : string
$context : string: The current application context
$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() : mixed: Backwards compatibility safeguard since re-introducing flushByTags as API.
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: Initializes the identifier prefix when setting the cache.
setDefaultLifetime() : mixed: Sets the default lifetime for this cache backend
calculateExpiryTime() : DateTime: Calculates the expiry time by the given lifetime. If no lifetime is specified, the default lifetime is used.

DATETIME_EXPIRYTIME_UNLIMITED


    public
        mixed
    DATETIME_EXPIRYTIME_UNLIMITED
    = '9999-12-31T23:59:59+0000'

UNLIMITED_LIFETIME


    public
        mixed
    UNLIMITED_LIFETIME
    = 0

$cache

Reference to the cache which uses this backend


        protected
            FrontendInterface
    $cache

$cacheIdentifier


        protected
            string
    $cacheIdentifier

$context

The current application context


        protected
            string
    $context

This variable is currently unused and set to "production" always. It is only kept to keep backwards compatibility.

$defaultLifetime

Default lifetime of a cache entry in seconds


        protected
            int
    $defaultLifetime
     = 3600

__construct()

Constructs this backend


    public
                    __construct(string $context[, array<string|int, mixed> $options = [] ]) : mixed

Parameters

$context : string: Unused, for backward compatibility only
$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()

Backwards compatibility safeguard since re-introducing flushByTags as API.


    public
                    flushByTags(array<string|int, string> $tags) : mixed

See https://review.typo3.org/#/c/50537/ comments for patch set 14.

The method is here even though it is only required for TaggableBackendInterface. We add it here to ensure third party cache backends do not fail but instead delegate to a less efficient linear flushing behavior.

Parameters

$tags : array<string|int, string>

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 $lifetime = null ]) : void

Parameters

$entryIdentifier : string: An identifier for this specific cache entry
$data : mixed: The data to be stored
$tags : array<string|int, mixed> = []: Tags to associate with this cache entry
$lifetime : int = null: Lifetime of this cache entry in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.

setCache()

Initializes the identifier prefix when setting the cache.


    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) : mixed

Parameters

$defaultLifetime : int: Default lifetime of this cache backend in seconds. If NULL is specified, the default lifetime is used. "0" means unlimited lifetime.

calculateExpiryTime()

Calculates the expiry time by the given lifetime. If no lifetime is specified, the default lifetime is used.


    protected
                    calculateExpiryTime([int $lifetime = null ]) : DateTime

Parameters

$lifetime : int = null: The lifetime in seconds

Return values

DateTime —

The expiry time

ApcuBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface

Table of Contents

Interfaces

Constants

Properties

Methods

Constants

DATETIME_EXPIRYTIME_UNLIMITED

UNLIMITED_LIFETIME

Properties

$cache

$cacheIdentifier

$context

$defaultLifetime

Methods

__construct()

Parameters

Tags

collectGarbage()

findIdentifiersByTag()

Parameters

Return values

flush()

Tags

flushByTag()

Parameters

flushByTags()

Parameters

get()

Parameters

Return values

has()

Parameters

Return values

remove()

Parameters

Return values

set()

Parameters

Tags

setCache()

Parameters

setDefaultLifetime()

Parameters

Tags

calculateExpiryTime()

Parameters

Return values