TYPO3 13.4 API: MemcachedBackend

MemcachedBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface

A caching backend which stores cache entries by using Memcached.

This backend uses the following types of Memcache 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. By default prefix consists from two parts separated by underscore character and ends in yet another underscore character:

"TYPO3"
Current site path obtained from Environment::getProjectPath() This prefix makes sure that keys from the different installations do not conflict.

Note: When using the Memcached backend to store values of more than ~1 MB, the data will be split into chunks to make them fit into the memcached limits.

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'
MAX_BUCKET_SIZE = 1048534: Max bucket size, (1024*1024)-42 bytes
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
$flags : int: Indicates whether the memcache uses compression or not (requires zlib), either 0 or \Memcached::OPT_COMPRESSION / MEMCACHE_COMPRESSED
$identifierPrefix : string: A prefix to separate stored data from other data possibly stored in the memcache
$memcache : Memcache|Memcached: Instance of the PHP Memcache class
$servers : array<string|int, mixed>: Array of Memcache server configurations
$usedPeclModule : string: Used PECL module for memcached

Methods

__construct() : mixed: Constructs this backend
collectGarbage() : mixed: Does nothing, as memcached does GC itself
findIdentifiersByTag() : array<string|int, mixed>: Finds and returns all cache entry identifiers which are tagged by the specified tag.
flush() : mixed: Removes all cache entries of this cache.
flushByTag() : mixed: 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.
initializeObject() : mixed: Initializes the identifier prefix
remove() : bool: Removes all cache entries matching the specified identifier.
set() : mixed: Saves data in the cache.
setCache() : mixed: Initializes the identifier prefix when setting the cache.
setDefaultLifetime() : mixed: Sets the default lifetime for this cache backend
setPeclModule() : mixed: Sets the preferred PECL module
addIdentifierToTags() : mixed: Associates the identifier with the given tags
calculateExpiryTime() : DateTime: Calculates the expiry time by the given lifetime. If no lifetime is specified, the default lifetime is used.
findTagsByIdentifier() : array<string|int, mixed>: Finds all tags for the given identifier. This function uses reverse tag index to search for tags.
getCompression() : bool: Getter for compression flag
removeIdentifierFromAllTags() : mixed: Removes association of the identifier with the given tags
setCompression() : mixed: Setter for compression flags bit
setInternal() : bool: Stores the actual data inside memcache/memcached
setServers() : mixed: Setter for servers to be used. Expects an array, the values are expected to be formatted like "<host>[:<port>]" or "unix://<path>"

DATETIME_EXPIRYTIME_UNLIMITED


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

MAX_BUCKET_SIZE

Max bucket size, (1024*1024)-42 bytes


    public
        int
    MAX_BUCKET_SIZE
    = 1048534

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

$flags

Indicates whether the memcache uses compression or not (requires zlib), either 0 or \Memcached::OPT_COMPRESSION / MEMCACHE_COMPRESSED


    protected
        int
    $flags

$identifierPrefix

A prefix to separate stored data from other data possibly stored in the memcache


    protected
        string
    $identifierPrefix

$memcache

Instance of the PHP Memcache class


    protected
        Memcache|Memcached
    $memcache

$servers

Array of Memcache server configurations


    protected
        array<string|int, mixed>
    $servers
     = []

$usedPeclModule

Used PECL module for memcached


    protected
        string
    $usedPeclModule
     = ''

__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 - depends on the actual backend

collectGarbage()

Does nothing, as memcached does GC itself


    public
                    collectGarbage() : mixed

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 of entries with all matching entries. An empty array if no entries matched

flush()

Removes all cache entries of this cache.


    public
                    flush() : mixed

flushByTag()

Removes all cache entries of this cache which are tagged by the specified tag.


    public
                    flushByTag(string $tag) : mixed

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

initializeObject()

Initializes the identifier prefix


    public
                    initializeObject() : mixed

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, string $data[, array<string|int, mixed> $tags = [] ][, int $lifetime = null ]) : mixed

Parameters

$entryIdentifier : string: An identifier for this specific cache entry
$data : string: 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) : mixed

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.

setPeclModule()

Sets the preferred PECL module


    public
                    setPeclModule(string $peclModule) : mixed

Parameters

$peclModule : string

addIdentifierToTags()

Associates the identifier with the given tags


    protected
                    addIdentifierToTags(string $entryIdentifier, array<string|int, mixed> $tags) : mixed

Parameters

$entryIdentifier : string
$tags : array<string|int, mixed>

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

findTagsByIdentifier()

Finds all tags for the given identifier. This function uses reverse tag index to search for tags.


    protected
                    findTagsByIdentifier(string $identifier) : array<string|int, mixed>

Parameters

$identifier : string: Identifier to find tags by

Return values

array<string|int, mixed>

getCompression()

Getter for compression flag


    protected
                    getCompression() : bool

Return values

bool

removeIdentifierFromAllTags()

Removes association of the identifier with the given tags


    protected
                    removeIdentifierFromAllTags(string $entryIdentifier) : mixed

Parameters

$entryIdentifier : string

setCompression()

Setter for compression flags bit


    protected
                    setCompression(bool $useCompression) : mixed

Parameters

$useCompression : bool

setInternal()

Stores the actual data inside memcache/memcached


    protected
                    setInternal(string $entryIdentifier, mixed $data, int $expiration) : bool

Parameters

$entryIdentifier : string
$data : mixed
$expiration : int

Return values

bool

setServers()

Setter for servers to be used. Expects an array, the values are expected to be formatted like "<host>[:<port>]" or "unix://<path>"


    protected
                    setServers(array<string|int, mixed> $servers) : mixed

Parameters

$servers : array<string|int, mixed>: An array of servers to add.

MemcachedBackend extends AbstractBackend implements TaggableBackendInterface, TransientBackendInterface

Table of Contents

Interfaces

Constants

Properties

Methods

Constants

DATETIME_EXPIRYTIME_UNLIMITED

MAX_BUCKET_SIZE

UNLIMITED_LIFETIME

Properties

$cache

$cacheIdentifier

$context

$defaultLifetime

$flags

$identifierPrefix

$memcache

$servers

$usedPeclModule

Methods

__construct()

Parameters

Tags

collectGarbage()

findIdentifiersByTag()

Parameters

Return values

flush()

Tags

flushByTag()

Parameters

flushByTags()

Parameters

get()

Parameters

Return values

has()

Parameters

Return values

initializeObject()

Tags

remove()

Parameters

Return values

set()

Parameters

Tags

setCache()

Parameters

setDefaultLifetime()

Parameters

Tags

setPeclModule()

Parameters

Tags

addIdentifierToTags()

Parameters

calculateExpiryTime()

Parameters

Return values

findTagsByIdentifier()

Parameters

Return values

getCompression()

Return values

removeIdentifierFromAllTags()

Parameters

setCompression()

Parameters

setInternal()

Parameters

Return values

setServers()

Parameters