Abstract class for any ephemeral data store. More...

Inherits Wikimedia\LightweightObjectStore\ExpirationAwareness, Wikimedia\ObjectCache\IStoreKeyEncoder, and LoggerAwareInterface.

Inherited by Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

Collaboration diagram for Wikimedia\ObjectCache\BagOStuff:

[legend]

Public Member Functions
	__construct (array $params=[])

	add ( $key, $value, $exptime=0, $flags=0)
	Insert an item if it does not already exist.

	changeTTL ( $key, $exptime=0, $flags=0)
	Change the expiration on an item.

	changeTTLMulti (array $keys, $exptime, $flags=0)
	Change the expiration of multiple items.

	delete ( $key, $flags=0)
	Delete an item if it exists.

	deleteMulti (array $keys, $flags=0)
	Delete a batch of items.

	deleteObjectsExpiringBefore ( $timestamp, ?callable $progress=null, $limit=INF, ?string $tag=null)
	Delete all objects expiring before a certain date.

	get ( $key, $flags=0)
	Get an item.

	getCurrentTime ()

	getLastError ( $watchPoint=0)
	Get the "last error" registry.

	getLogger ()

	getMulti (array $keys, $flags=0)
	Get a batch of items.

	getQoS ( $flag)

	getScopedLock ( $key, $timeout=6, $exptime=30, $rclass='')
	Get a lightweight exclusive self-unlocking lock.

	getSegmentationSize ()

	getSegmentedValueMaxSize ()

	getWithSetCallback ( $key, $exptime, $callback, $flags=0)
	Get an item, regenerating and setting it if not found.

	incrWithInit ( $key, $exptime, $step=1, $init=null, $flags=0)
	Increase the value of the given key (no TTL change) if it exists or create it otherwise.

	isKeyGlobal ( $key)
	Check whether a cache key is in the global keyspace.

	lock ( $key, $timeout=6, $exptime=6, $rclass='')
	Acquire an advisory lock on a key string, exclusive to the caller.

	makeGlobalKey ( $keygroup,... $components)
	Make a cache key from the given components, in the "global" keyspace.

	makeKey ( $keygroup,... $components)
	Make a cache key from the given components, in the default keyspace.

	merge ( $key, callable $callback, $exptime=0, $attempts=10, $flags=0)
	Merge changes into the existing cache value (possibly creating a new one)

	set ( $key, $value, $exptime=0, $flags=0)
	Set an item.

	setLogger (LoggerInterface $logger)

	setMockTime (&$time)

	setMulti (array $valueByKey, $exptime=0, $flags=0)
	Set a batch of items.

	unlock ( $key)
	Release an advisory lock on a key string.

	watchErrors ()
	Get a "watch point" token that can be used to get the "last error" to occur after now.

Public Attributes
const	ATTR_DURABILITY = 2
	Key in getQoS() for durability of storage writes.

const	ERR_NO_RESPONSE = 1
	Storage operation failed to yield a complete response.

const	ERR_NONE = 0
	Storage operation succeeded, or no operation was performed.

const	ERR_UNEXPECTED = 3
	Storage operation failed due to usage limitations or an I/O error.

const	ERR_UNREACHABLE = 2
	Storage operation could not establish a connection.

const	MAX_CONFLICTS_ONE = 1
	Abort after the first merge conflict.

const	QOS_DURABILITY_DISK = 4
	Storage survives on disk on a best-effort basis (e.g.

const	QOS_DURABILITY_NONE = 1
	Storage is disabled or never saves data, not even temporarily (EmptyBagOStuff).

const	QOS_DURABILITY_RDBMS = 5
	Storage survives on disk with high availability (SqlBagOStuff).

const	QOS_DURABILITY_SCRIPT = 2
	Storage survives in memory until the end of the current request or CLI process (HashBagOStuff).

const	QOS_DURABILITY_SERVICE = 3
	Storage survives in memory until a shared service is restarted (e.g.

const	QOS_UNKNOWN = INF
	Generic "unknown" value; useful for comparisons (always "good enough")

const	READ_LATEST = 1
	Bitfield constants for get()/getMulti(); these are only advisory.

const	READ_VERIFIED = 2
	Promise that the caller handles detection of staleness.

const	WRITE_ALLOW_SEGMENTS = 16
	Allow partitioning of the value if it is a large string.

const	WRITE_BACKGROUND = 64
	If supported, do not block on write operation completion; instead, treat writes as succesful based on whether they could be buffered.

const	WRITE_CACHE_ONLY = 8
	Bitfield constants for set()/merge(); these are only advisory.

const	WRITE_PRUNE_SEGMENTS = self::WRITE_ALLOW_SEGMENTS
	Delete all the segments if the value is partitioned.

Protected Member Functions
	fieldHasFlags ( $field, $flags)

	makeFallbackKey (string $key, int $maxLength)
	Re-format a cache key that is too long.

	makeKeyInternal ( $keyspace, $components)
	Make a cache key for the given keyspace and components.

	mergeFlagMaps (array $bags)
	Merge the flag maps of one or more BagOStuff objects into a "lowest common denominator" map.

	proxyCall (string $method, int $arg0Sig, int $resSig, array $genericArgs, BagOStuff $wrapper)
	Call a method on behalf of wrapper BagOStuff instance.

	requireConvertGenericKey ()
	Whether ::proxyCall() must re-encode cache keys before calling read/write methods.

	setLastError ( $error)
	Set the "last error" registry due to a problem encountered during an attempted operation.

Protected Attributes
callable null	$asyncHandler

int[]	$attrMap = []
	Map of (BagOStuff:ATTR_* constant => BagOStuff:QOS_* constant)

string	$keyspace
	Default keyspace; used by makeKey()

int	$lastError = self::ERR_NONE
	BagOStuff:ERR_* constant of the last error that occurred.

int	$lastErrorId = 0
	Error event sequence number of the last error that occurred.

LoggerInterface	$logger

StatsFactory	$stats

Static Protected Attributes
static int	$nextErrorMonitorId = 1
	Next sequence number to use for watch/error events.

Detailed Description

Abstract class for any ephemeral data store.

Class instances should be created with an intended access scope for the dataset, such as:

a) A single PHP thread on a server (e.g. stored in a PHP variable)
b) A single application server (e.g. stored in php-apcu or sqlite)
c) All application servers in datacenter (e.g. stored in memcached or mysql)
d) All application servers in all datacenters (e.g. stored via mcrouter or dynomite)

Callers should use the proper factory methods that yield BagOStuff instances. Site admins should make sure that the configuration for those factory methods match their access scope. BagOStuff subclasses have widely varying levels of support replication features within and among datacenters.

Subclasses should override the default "segmentationSize" field with an appropriate value. The value should not be larger than what the backing store (by default) supports. It also should be roughly informed by common performance bottlenecks (e.g. values over a certain size having poor scalability). The same goes for the "segmentedValueMaxSize" member, which limits the maximum size and chunk count (indirectly) of values.

A few notes about data consistency for BagOStuff instances:

Read operation methods, e.g. get(), should be synchronous in the local datacenter. When used with READ_LATEST, such operations should reflect any prior writes originating from the local datacenter (e.g. by avoiding replica DBs or invoking quorom reads).
Write operation methods, e.g. set(), should be synchronous in the local datacenter, with asynchronous cross-datacenter replication. This replication can be either "best effort" or eventually consistent. If the write succeeded, then any subsequent get() operations with READ_LATEST, regardless of datacenter, should reflect the changes.
Locking operation methods, e.g. lock(), unlock(), and getScopedLock(), should only apply to the local datacenter.
Any set of single-key write operation method calls originating from a single datacenter should observe "best effort" linearizability. In this context, "best effort" means that consistency holds as long as connectivity is strong, network latency is low, and there are no relevant storage server failures. Per https://en.wikipedia.org/wiki/PACELC_theorem, the store should act as a PA/EL distributed system for these operations.

Stability: stable: to extend

Stability: newable

Note: 2003-2004 Brooke Vibber bvibb.nosp@m.er@w.nosp@m.ikime.nosp@m.dia..nosp@m.org

Definition at line 83 of file BagOStuff.php.

Constructor & Destructor Documentation

◆ __construct()

Wikimedia\ObjectCache\BagOStuff::__construct ( array $params = [] )

Stability: stable: to call

Parameters

array

$params

Parameters include:

keyspace: Keyspace to use for keys in makeKey(). [Default: "local"]
asyncHandler: Callable to use for scheduling tasks after the web request ends. In CLI mode, it should run the task immediately. [Default: null]
stats: IStatsdDataFactory instance. [optional]
logger: \Psr\Log\LoggerInterface instance. [optional]

Reimplemented in Wikimedia\ObjectCache\MemcachedBagOStuff, Wikimedia\ObjectCache\APCUBagOStuff, Wikimedia\ObjectCache\EmptyBagOStuff, and Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 220 of file BagOStuff.php.

References Wikimedia\ObjectCache\BagOStuff\$asyncHandler, and Wikimedia\ObjectCache\BagOStuff\setLogger().

Member Function Documentation

◆ add()

Wikimedia\ObjectCache\BagOStuff::add	(	$key,
		$value,
		$exptime = 0,
		$flags = 0 )

abstract

Insert an item if it does not already exist.

Parameters

string	$key
mixed	$value
int	$exptime
int	$flags	Bitfield of BagOStuff::WRITE_* constants (since 1.33)

Returns: bool Success (item created)

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ changeTTL()

Wikimedia\ObjectCache\BagOStuff::changeTTL	(	$key,
		$exptime = 0,
		$flags = 0 )

abstract

Change the expiration on an item.

If an expiry in the past is given then the key will immediately be expired

For large values written using WRITE_ALLOW_SEGMENTS, this only changes the TTL of the main segment list key. While lowering the TTL of the segment list key has the effect of functionally lowering the TTL of the key, it might leave unused blobs in cache for longer. Raising the TTL of such keys is not effective, since the expiration of a single segment key effectively expires the entire value.

Parameters

string	$key
int	$exptime	TTL or UNIX timestamp
int	$flags	Bitfield of BagOStuff::WRITE_* constants (since 1.33)

Returns: bool Success (item found and updated)

Since: 1.28

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ changeTTLMulti()

Wikimedia\ObjectCache\BagOStuff::changeTTLMulti	(	array	$keys,
			$exptime,
			$flags = 0 )

abstract

Change the expiration of multiple items.

See also: BagOStuff::changeTTL()

Parameters

string[]	$keys	List of keys
int	$exptime	TTL or UNIX timestamp
int	$flags	Bitfield of BagOStuff::WRITE_* constants (since 1.33)

Returns: bool Success (all items found and updated)

Since: 1.34

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ delete()

Wikimedia\ObjectCache\BagOStuff::delete	(		$key,
			$flags = 0 )

abstract

Delete an item if it exists.

For large values set with WRITE_ALLOW_SEGMENTS, this only deletes the placeholder key with the segment list. To delete the underlying blobs, include WRITE_ALLOW_SEGMENTS in the flags for delete() as well. While deleting the segment list key has the effect of functionally deleting the key, it leaves unused blobs in storage.

The reason that this is not done automatically, is that to delete underlying blobs, requires first fetching the current segment list. Given that 99% of keys don't use WRITE_ALLOW_SEGMENTS, this would be wasteful.

Parameters

string	$key
int	$flags	Bitfield of BagOStuff::WRITE_* constants

Returns: bool Success (item deleted or not found)

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ deleteMulti()

Wikimedia\ObjectCache\BagOStuff::deleteMulti	(	array	$keys,
			$flags = 0 )

abstract

Delete a batch of items.

This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O

WRITE_BACKGROUND can be used for bulk deletion where the response is not vital

Parameters

string[]	$keys	List of keys
int	$flags	Bitfield of BagOStuff::WRITE_* constants

Returns: bool Success (items deleted and/or not found)

Since: 1.33

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ deleteObjectsExpiringBefore()

Wikimedia\ObjectCache\BagOStuff::deleteObjectsExpiringBefore	(		$timestamp,
		?callable	$progress = null,
			$limit = INF,
		?string	$tag = null )

abstract

Delete all objects expiring before a certain date.

Parameters

string \| int	$timestamp	The reference date in MW or TS_UNIX format
callable \| null	$progress	Optional, a function which will be called regularly during long-running operations with the percentage progress as the first parameter. [optional]
int \| float	$limit	Maximum number of keys to delete [default: INF]
string \| null	$tag	Tag to purge a single shard only. This is only supported when server tags are used in configuration.

Returns: bool Success; false if unimplemented

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, Wikimedia\ObjectCache\MultiWriteBagOStuff, and SqlBagOStuff.

◆ fieldHasFlags()

Wikimedia\ObjectCache\BagOStuff::fieldHasFlags	(		$field,
			$flags )

finalprotected

Parameters

int	$field
int	$flags

Returns: bool

Since: 1.34

Definition at line 668 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\CachedBagOStuff\changeTTLMulti(), Wikimedia\ObjectCache\CachedBagOStuff\delete(), Wikimedia\ObjectCache\MediumSpecificBagOStuff\delete(), Wikimedia\ObjectCache\CachedBagOStuff\deleteMulti(), Wikimedia\ObjectCache\MultiWriteBagOStuff\get(), Wikimedia\ObjectCache\CachedBagOStuff\set(), and Wikimedia\ObjectCache\CachedBagOStuff\setMulti().

◆ get()

Wikimedia\ObjectCache\BagOStuff::get	(		$key,
			$flags = 0 )

abstract

Get an item.

If the key includes a deterministic input hash (e.g. the key can only have the correct value) or complete staleness checks are handled by the caller (e.g. nothing relies on the TTL), then the READ_VERIFIED flag should be set. This lets tiered backends know they can safely upgrade a cached value to higher tiers using standard TTLs.

Parameters

string	$key
int	$flags	Bitfield of BagOStuff::READ_* constants [optional]

Returns: mixed Returns false on failure or if the item does not exist

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

Referenced by Wikimedia\ObjectCache\CachedBagOStuff\get().

◆ getCurrentTime()

Wikimedia\ObjectCache\BagOStuff::getCurrentTime ( )

Access: internal: For testing only

Returns: float UNIX timestamp

Definition at line 876 of file BagOStuff.php.

Referenced by SqlBagOStuff\doChangeTTL(), SqlBagOStuff\doChangeTTLMulti(), SqlBagOStuff\doDelete(), SqlBagOStuff\doDeleteMulti(), SqlBagOStuff\doIncrWithInit(), SqlBagOStuff\doSet(), SqlBagOStuff\doSetMulti(), and Wikimedia\ObjectCache\HashBagOStuff\expire().

◆ getLastError()

Wikimedia\ObjectCache\BagOStuff::getLastError ( $watchPoint = 0 )

Get the "last error" registry.

The method should be invoked by a caller as part of the following pattern:

The caller invokes watchErrors() to get a "since token"
The caller invokes a sequence of cache operation methods
The caller invokes getLastError() with the "since token"

External callers can also invoke this method as part of the following pattern:

The caller invokes clearLastError()
The caller invokes a sequence of cache operation methods
The caller invokes getLastError()

Parameters

int $watchPoint Only consider errors from after this "watch point" [optional]

Returns: int BagOStuff:ERR_* constant for the "last error" registry

Note: Parameters added in 1.38: $watchPoint

Since: 1.23

Definition at line 555 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPeclBagOStuff\doIncrWithInitAsync(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doIncrWithInitAsync(), Wikimedia\ObjectCache\MemcachedPeclBagOStuff\doIncrWithInitSync(), and Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doIncrWithInitSync().

◆ getLogger()

Wikimedia\ObjectCache\BagOStuff::getLogger ( )

Since: 1.35

Returns: LoggerInterface

Definition at line 244 of file BagOStuff.php.

◆ getMulti()

Wikimedia\ObjectCache\BagOStuff::getMulti	(	array	$keys,
			$flags = 0 )

abstract

Get a batch of items.

Parameters

string[]	$keys	List of keys
int	$flags	Bitfield; supports READ_LATEST [optional]

Returns: mixed[] Map of (key => value) for existing keys

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ getQoS()

Wikimedia\ObjectCache\BagOStuff::getQoS ( $flag )

Parameters

int $flag BagOStuff::ATTR_* constant

Returns: int BagOStuff:QOS_* constant

Since: 1.28

Reimplemented in Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 635 of file BagOStuff.php.

◆ getScopedLock()

Wikimedia\ObjectCache\BagOStuff::getScopedLock	(	$key,
		$timeout = 6,
		$exptime = 30,
		$rclass = '' )

final

Get a lightweight exclusive self-unlocking lock.

Note that the same lock cannot be acquired twice.

This is useful for task de-duplication or to avoid obtrusive (though non-corrupting) DB errors like INSERT key conflicts or deadlocks when using LOCK IN SHARE MODE.

Parameters

string	$key
int	$timeout	Lock wait timeout; 0 for non-blocking [optional]
int	$exptime	Lock time-to-live [optional]; 1 day maximum
string	$rclass	Allow reentry if set and the current lock used this value

Returns: ScopedCallback|null Returns null on failure

Since: 1.26

Definition at line 419 of file BagOStuff.php.

◆ getSegmentationSize()

Wikimedia\ObjectCache\BagOStuff::getSegmentationSize ( )

Deprecated: since 1.43, not used anywhere.

Returns: int|float The chunk size, in bytes, of segmented objects (INF for no limit)

Since: 1.34

Reimplemented in Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 644 of file BagOStuff.php.

References wfDeprecated().

◆ getSegmentedValueMaxSize()

Wikimedia\ObjectCache\BagOStuff::getSegmentedValueMaxSize ( )

Deprecated: since 1.43, not used anywhere.

Returns: int|float Maximum total segmented object size in bytes (INF for no limit)

Since: 1.34

Reimplemented in Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 655 of file BagOStuff.php.

References wfDeprecated().

◆ getWithSetCallback()

Wikimedia\ObjectCache\BagOStuff::getWithSetCallback	(	$key,
		$exptime,
		$callback,
		$flags = 0 )

final

Get an item, regenerating and setting it if not found.

The callback can take $exptime as argument by reference and modify it. Nothing is stored nor deleted if the callback returns false.

Parameters

string	$key
int	$exptime	Time-to-live (seconds)
callable	$callback	Callback that derives the new value
int	$flags	Bitfield of BagOStuff::READ_* or BagOStuff::WRITE_* constants [optional]

Returns: mixed The cached value if found or the result of $callback otherwise

Since: 1.27

Definition at line 262 of file BagOStuff.php.

◆ incrWithInit()

Wikimedia\ObjectCache\BagOStuff::incrWithInit	(	$key,
		$exptime,
		$step = 1,
		$init = null,
		$flags = 0 )

abstract

Increase the value of the given key (no TTL change) if it exists or create it otherwise.

This will create the key with the value $init and TTL $exptime instead if not present. Callers should make sure that both ($init - $step) and $exptime are invariants for all operations to any given key. The value of $init should be at least that of $step.

The new value is returned, except if the WRITE_BACKGROUND flag is given, in which case the handler may choose to return true to indicate that the operation has been dispatched.

Parameters

string	$key	Key built via makeKey() or makeGlobalKey()
int	$exptime	Time-to-live (in seconds) or a UNIX timestamp expiration
int	$step	Amount to increase the key value by [default: 1]
int \| null	$init	Value to initialize the key to if it does not exist [default: $step]
int	$flags	Bit field of class WRITE_* constants [optional]

Returns: int|bool New value (or true if asynchronous) on success; false on failure

Since: 1.24

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ isKeyGlobal()

Wikimedia\ObjectCache\BagOStuff::isKeyGlobal ( $key )

Check whether a cache key is in the global keyspace.

Parameters

string $key

Returns: bool

Since: 1.35

Definition at line 625 of file BagOStuff.php.

◆ lock()

Wikimedia\ObjectCache\BagOStuff::lock	(	$key,
		$timeout = 6,
		$exptime = 6,
		$rclass = '' )

abstract

Acquire an advisory lock on a key string, exclusive to the caller.

Parameters

string	$key
int	$timeout	Lock wait timeout; 0 for non-blocking [optional]
int	$exptime	Lock time-to-live in seconds; 1 day maximum [optional]
string	$rclass	If this thread already holds the lock, and the lock was acquired using the same value for this parameter, then return true and use reference counting so that only the unlock() call from the outermost lock() caller actually releases the lock (note that only the outermost time-to-live is used) [optional]

Returns: bool Success

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ makeFallbackKey()

Wikimedia\ObjectCache\BagOStuff::makeFallbackKey	(	string	$key,
		int	$maxLength )

protected

Re-format a cache key that is too long.

Since: 1.45

See also: BagOStuff::makeKeyInternal

Parameters

string	$key
int	$maxLength

Returns: string

Definition at line 736 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedBagOStuff\makeKeyInternal(), and SqlBagOStuff\makeKeyInternal().

◆ makeGlobalKey()

Wikimedia\ObjectCache\BagOStuff::makeGlobalKey	(		$keygroup,
			$components )

Make a cache key from the given components, in the "global" keyspace.

Global keys are shared with and visible to all sites hosted in the same infrastructure (e.g. cross-wiki within the same wiki farm). Others sites may read the stored value from their requests, and they must be able to correctly compute new values from their own request context.

See also: BagOStuff::makeKeyInternal

Since: 1.27

Parameters

string	$keygroup	Key group component, should be under 48 characters.
	string\|int	...$components Additional, ordered, key components for entity IDs

Returns: string Colon-separated, keyspace-prepended, ordered list of encoded components

Implements Wikimedia\ObjectCache\IStoreKeyEncoder.

Definition at line 585 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MediumSpecificBagOStuff\delete().

◆ makeKey()

Wikimedia\ObjectCache\BagOStuff::makeKey	(		$keygroup,
			$components )

Make a cache key from the given components, in the default keyspace.

The default keyspace is unique to a given site. Subsequent web requests to the same site (e.g. local wiki, or same domain name) will interact with the same keyspace.

Requests to other sites hosted on the same infrastructure (e.g. cross-wiki or cross-domain), have their own keyspace that naturally avoids conflicts.

As caller you are responsible for:

Limit the key group (first component) to 48 characters

Internally, the colon is used as delimiter (":"), and this is automatically escaped in supplied components to avoid ambiguity or key conflicts. BagOStuff subclasses are responsible for applying any additional escaping or limits as-needed before sending commands over the network.

See also: BagOStuff::makeKeyInternal

Since: 1.27

Parameters

string	$keygroup	Key group component, should be under 48 characters.
	string\|int	...$components Additional, ordered, key components for entity IDs

Returns: string Colon-separated, keyspace-prepended, ordered list of encoded components

Implements Wikimedia\ObjectCache\IStoreKeyEncoder.

Definition at line 614 of file BagOStuff.php.

Referenced by MediaWiki\Session\SessionBackend\__construct(), and MediaWiki\Cache\FileCacheBase\cacheMissKey().

◆ makeKeyInternal()

Wikimedia\ObjectCache\BagOStuff::makeKeyInternal	(		$keyspace,
			$components )

protected

Make a cache key for the given keyspace and components.

Subclasses may override this method to apply different escaping, or to deal with size constraints (such as MemcachedBagOStuff). For example, by converting long components into hashes.

If you override this method, you MUST override ::requireConvertGenericKey() to return true. This ensures that wrapping classes (e.g. MultiWriteBagOStuff) know to re-encode keys before calling read/write methods. See also ::proxyCall().

See also: BagOStuff::proxyCall

Since: 1.27

Parameters

string	$keyspace
string[] \| int[] \| null[]	$components	Key group and other components

Returns: string

Reimplemented in Wikimedia\ObjectCache\MemcachedBagOStuff, and SqlBagOStuff.

Definition at line 713 of file BagOStuff.php.

◆ merge()

Wikimedia\ObjectCache\BagOStuff::merge	(		$key,
		callable	$callback,
			$exptime = 0,
			$attempts = 10,
			$flags = 0 )

abstract

Merge changes into the existing cache value (possibly creating a new one)

The callback function returns the new value given the current value (which will be false if not present), and takes the arguments: (this BagOStuff, cache key, current value, TTL). The TTL parameter is reference set to $exptime. It can be overridden in the callback. Nothing is stored nor deleted if the callback returns false.

Parameters

string	$key
callable	$callback	Callback method to be executed
int	$exptime	Either an interval in seconds or a unix timestamp for expiry
int	$attempts	The amount of times to attempt a merge in case of failure
int	$flags	Bitfield of BagOStuff::WRITE_* constants

Returns: bool Success

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\EmptyBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ mergeFlagMaps()

Wikimedia\ObjectCache\BagOStuff::mergeFlagMaps ( array $bags )

finalprotected

Merge the flag maps of one or more BagOStuff objects into a "lowest common denominator" map.

Parameters

BagOStuff[] $bags

Returns: int[] Resulting flag map (class ATTR_* constant => class QOS_* constant)

Definition at line 679 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MultiWriteBagOStuff\__construct().

◆ proxyCall()

Wikimedia\ObjectCache\BagOStuff::proxyCall	(	string	$method,
		int	$arg0Sig,
		int	$resSig,
		array	$genericArgs,
		BagOStuff	$wrapper )

protected

Call a method on behalf of wrapper BagOStuff instance.

The "wrapper" BagOStuff subclass that calls proxyCall() MUST NOT override the default makeKeyInternal() implementation, because proxyCall() needs to turn the "generic" key back into an array, and re-format it according to the backend-specific BagOStuff::makeKey implementation.

For example, when using MultiWriteBagOStuff with Memcached as a backend, writes will go via MemcachedBagOStuff::proxyCall(), which then reformats the "generic" result of BagOStuff::makeKey (called as MultiWriteBagOStuff::makeKey) using MemcachedBagOStuff::makeKeyInternal.

Parameters

string	$method	Name of a non-final public method that reads/changes keys
int	$arg0Sig	BagOStuff::ARG0_* constant describing argument 0
int	$resSig	BagOStuff::RES_* constant describing the return value
array	$genericArgs	Method arguments passed to the wrapper instance
BagOStuff	$wrapper	The wrapper BagOStuff instance using this result

Returns: mixed Method result with any keys remapped to "generic" keys

Definition at line 821 of file BagOStuff.php.

References Wikimedia\ObjectCache\BagOStuff\setLastError().

◆ requireConvertGenericKey()

Wikimedia\ObjectCache\BagOStuff::requireConvertGenericKey ( )

protected

Whether ::proxyCall() must re-encode cache keys before calling read/write methods.

Stability: stable: to override

See also: BagOStuff::makeKeyInternal; BagOStuff::proxyCall

Since: 1.41

Returns: bool

Reimplemented in Wikimedia\ObjectCache\MemcachedBagOStuff, and SqlBagOStuff.

Definition at line 768 of file BagOStuff.php.

◆ set()

Wikimedia\ObjectCache\BagOStuff::set	(	$key,
		$value,
		$exptime = 0,
		$flags = 0 )

abstract

Set an item.

Parameters

string	$key
mixed	$value
int	$exptime	Either an interval in seconds or a unix timestamp for expiry
int	$flags	Bitfield of BagOStuff::WRITE_* constants If setting WRITE_ALLOW_SEGMENTS, remember to also set it in any delete() calls.

Returns: bool Success

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

Referenced by MediaWiki\Registration\ExtensionRegistry\saveToCache().

◆ setLastError()

Wikimedia\ObjectCache\BagOStuff::setLastError ( $error )

protected

Set the "last error" registry due to a problem encountered during an attempted operation.

Parameters

int $error BagOStuff:ERR_* constant

Since: 1.23

Definition at line 566 of file BagOStuff.php.

◆ setLogger()

Wikimedia\ObjectCache\BagOStuff::setLogger ( LoggerInterface $logger )

Parameters

LoggerInterface $logger

Returns: void

Reimplemented in Wikimedia\ObjectCache\RESTBagOStuff.

Definition at line 236 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\BagOStuff\__construct().

◆ setMockTime()

Wikimedia\ObjectCache\BagOStuff::setMockTime ( & $time )

Access: internal: For testing only

Parameters

float | null &$time Mock UNIX timestamp

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

Definition at line 887 of file BagOStuff.php.

◆ setMulti()

Wikimedia\ObjectCache\BagOStuff::setMulti	(	array	$valueByKey,
			$exptime = 0,
			$flags = 0 )

abstract

Set a batch of items.

This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O

WRITE_BACKGROUND can be used for bulk insertion where the response is not vital

Parameters

mixed[]	$valueByKey	Map of (key => value)
int	$exptime	Either an interval in seconds or a unix timestamp for expiry
int	$flags	Bitfield of BagOStuff::WRITE_* constants (since 1.33)

Returns: bool Success

Since: 1.24

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ unlock()

Wikimedia\ObjectCache\BagOStuff::unlock ( $key )

abstract

Release an advisory lock on a key string.

Parameters

string $key

Returns: bool Success

Reimplemented in Wikimedia\ObjectCache\CachedBagOStuff, Wikimedia\ObjectCache\MediumSpecificBagOStuff, and Wikimedia\ObjectCache\MultiWriteBagOStuff.

◆ watchErrors()

Wikimedia\ObjectCache\BagOStuff::watchErrors ( )

Get a "watch point" token that can be used to get the "last error" to occur after now.

Returns: int A token to that can be used with getLastError()

Since: 1.38

Definition at line 532 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPeclBagOStuff\doIncrWithInitAsync(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doIncrWithInitAsync(), Wikimedia\ObjectCache\MemcachedPeclBagOStuff\doIncrWithInitSync(), and Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doIncrWithInitSync().

Member Data Documentation

◆ $asyncHandler

callable null Wikimedia\ObjectCache\BagOStuff::$asyncHandler

protected

Definition at line 93 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\BagOStuff\__construct().

◆ $attrMap

int [] Wikimedia\ObjectCache\BagOStuff::$attrMap = []

protected

Map of (BagOStuff:ATTR_* constant => BagOStuff:QOS_* constant)

Definition at line 95 of file BagOStuff.php.

◆ $keyspace

string Wikimedia\ObjectCache\BagOStuff::$keyspace

protected

Default keyspace; used by makeKey()

Definition at line 98 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedBagOStuff\makeKeyInternal(), and SqlBagOStuff\makeKeyInternal().

◆ $lastError

int Wikimedia\ObjectCache\BagOStuff::$lastError = self::ERR_NONE

protected

BagOStuff:ERR_* constant of the last error that occurred.

Definition at line 101 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPeclBagOStuff\doIncrWithInitAsync().

◆ $lastErrorId

int Wikimedia\ObjectCache\BagOStuff::$lastErrorId = 0

protected

Error event sequence number of the last error that occurred.

Definition at line 103 of file BagOStuff.php.

◆ $logger

LoggerInterface Wikimedia\ObjectCache\BagOStuff::$logger

protected

Definition at line 91 of file BagOStuff.php.

◆ $nextErrorMonitorId

int Wikimedia\ObjectCache\BagOStuff::$nextErrorMonitorId = 1

staticprotected

Next sequence number to use for watch/error events.

Definition at line 106 of file BagOStuff.php.

◆ $stats

StatsFactory Wikimedia\ObjectCache\BagOStuff::$stats

protected

Definition at line 89 of file BagOStuff.php.

◆ ATTR_DURABILITY

const Wikimedia\ObjectCache\BagOStuff::ATTR_DURABILITY = 2

Key in getQoS() for durability of storage writes.

This helps middleware distinguish between different kinds of BagOStuff implementations, without hardcoding class names, and in a way that works even through a wrapper like CachedBagOStuff, MultiWriteBagOStuff, or WANObjectCache.

Value must be a QOS_DURABILITY_ constant, where higher means stronger.

Example use cases:

SqlBlobStore::getCacheTTL, skip main cache if the cache is also sql-based.
MediumSpecificBagOStuff::unlock, use stricter logic if the lock is known to be stored in the current process.

See also: BagOStuff::getQoS

Definition at line 138 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\RedisBagOStuff\__construct(), Wikimedia\ObjectCache\RESTBagOStuff\__construct(), Wikimedia\ObjectCache\HashBagOStuff\__construct(), Wikimedia\ObjectCache\MemcachedBagOStuff\__construct(), Wikimedia\ObjectCache\APCUBagOStuff\__construct(), and Wikimedia\ObjectCache\EmptyBagOStuff\__construct().

◆ ERR_NO_RESPONSE

const Wikimedia\ObjectCache\BagOStuff::ERR_NO_RESPONSE = 1

Storage operation failed to yield a complete response.

Definition at line 114 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPeclBagOStuff\checkResult(), and Wikimedia\ObjectCache\WANObjectCache\getLastError().

◆ ERR_NONE

const Wikimedia\ObjectCache\BagOStuff::ERR_NONE = 0

Storage operation succeeded, or no operation was performed.

Exposed via getLastError().

Definition at line 112 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doAdd(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doCas(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doChangeTTL(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doDelete(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doGet(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doGetMulti(), Wikimedia\ObjectCache\MemcachedPhpBagOStuff\doSet(), and Wikimedia\ObjectCache\WANObjectCache\getLastError().

◆ ERR_UNEXPECTED

const Wikimedia\ObjectCache\BagOStuff::ERR_UNEXPECTED = 3

Storage operation failed due to usage limitations or an I/O error.

Definition at line 118 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\WANObjectCache\getLastError(), and Wikimedia\ObjectCache\RedisBagOStuff\handleException().

◆ ERR_UNREACHABLE

const Wikimedia\ObjectCache\BagOStuff::ERR_UNREACHABLE = 2

Storage operation could not establish a connection.

Definition at line 116 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedPeclBagOStuff\checkResult(), Wikimedia\ObjectCache\RedisBagOStuff\getConnectionsForKeys(), and Wikimedia\ObjectCache\WANObjectCache\getLastError().

◆ MAX_CONFLICTS_ONE

const Wikimedia\ObjectCache\BagOStuff::MAX_CONFLICTS_ONE = 1

Abort after the first merge conflict.

Definition at line 187 of file BagOStuff.php.

◆ QOS_DURABILITY_DISK

const Wikimedia\ObjectCache\BagOStuff::QOS_DURABILITY_DISK = 4

Storage survives on disk on a best-effort basis (e.g.

RedisBagOStuff).

Very recent writes may be lost when the service is restarted, because the storage service is not expected to synchronously flush to disk (fsync), and writes are not expected to be replicated in case of server maintenance or replacement.

Definition at line 152 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\RedisBagOStuff\__construct(), and Wikimedia\ObjectCache\RESTBagOStuff\__construct().

◆ QOS_DURABILITY_NONE

const Wikimedia\ObjectCache\BagOStuff::QOS_DURABILITY_NONE = 1

Storage is disabled or never saves data, not even temporarily (EmptyBagOStuff).

Definition at line 140 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\APCUBagOStuff\__construct(), and Wikimedia\ObjectCache\EmptyBagOStuff\__construct().

◆ QOS_DURABILITY_RDBMS

const Wikimedia\ObjectCache\BagOStuff::QOS_DURABILITY_RDBMS = 5

Storage survives on disk with high availability (SqlBagOStuff).

Writes typically wait for flush to disk and/or have replication.

Definition at line 158 of file BagOStuff.php.

◆ QOS_DURABILITY_SCRIPT

const Wikimedia\ObjectCache\BagOStuff::QOS_DURABILITY_SCRIPT = 2

Storage survives in memory until the end of the current request or CLI process (HashBagOStuff).

Definition at line 142 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\HashBagOStuff\__construct(), and Wikimedia\ObjectCache\APCUBagOStuff\__construct().

◆ QOS_DURABILITY_SERVICE

const Wikimedia\ObjectCache\BagOStuff::QOS_DURABILITY_SERVICE = 3

Storage survives in memory until a shared service is restarted (e.g.

MemcachedBagOStuff).

Definition at line 144 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\MemcachedBagOStuff\__construct(), and Wikimedia\ObjectCache\APCUBagOStuff\__construct().

◆ QOS_UNKNOWN

const Wikimedia\ObjectCache\BagOStuff::QOS_UNKNOWN = INF

Generic "unknown" value; useful for comparisons (always "good enough")

Definition at line 160 of file BagOStuff.php.

◆ READ_LATEST

const Wikimedia\ObjectCache\BagOStuff::READ_LATEST = 1

Bitfield constants for get()/getMulti(); these are only advisory.

If supported, avoid reading stale data due to replication

Definition at line 164 of file BagOStuff.php.

◆ READ_VERIFIED

const Wikimedia\ObjectCache\BagOStuff::READ_VERIFIED = 2

Promise that the caller handles detection of staleness.

Definition at line 166 of file BagOStuff.php.

◆ WRITE_ALLOW_SEGMENTS

const Wikimedia\ObjectCache\BagOStuff::WRITE_ALLOW_SEGMENTS = 16

Allow partitioning of the value if it is a large string.

Definition at line 172 of file BagOStuff.php.

◆ WRITE_BACKGROUND

const Wikimedia\ObjectCache\BagOStuff::WRITE_BACKGROUND = 64

If supported, do not block on write operation completion; instead, treat writes as succesful based on whether they could be buffered.

When using this flag with methods that yield item values, the boolean "true" will be used as a placeholder. The next blocking operation (e.g. typical read) will trigger a flush of the operation buffer.

Definition at line 184 of file BagOStuff.php.

◆ WRITE_CACHE_ONLY

const Wikimedia\ObjectCache\BagOStuff::WRITE_CACHE_ONLY = 8

Bitfield constants for set()/merge(); these are only advisory.

Only change state of the in-memory cache

Definition at line 170 of file BagOStuff.php.

Referenced by Wikimedia\ObjectCache\CachedBagOStuff\get().

◆ WRITE_PRUNE_SEGMENTS

const Wikimedia\ObjectCache\BagOStuff::WRITE_PRUNE_SEGMENTS = self::WRITE_ALLOW_SEGMENTS

Delete all the segments if the value is partitioned.

Deprecated: since 1.43 Use WRITE_ALLOW_SEGMENTS instead.

Definition at line 177 of file BagOStuff.php.

The documentation for this class was generated from the following file:

includes/libs/objectcache/BagOStuff.php

Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ add()

◆ changeTTL()

◆ changeTTLMulti()

◆ delete()

◆ deleteMulti()

◆ deleteObjectsExpiringBefore()

◆ fieldHasFlags()

◆ get()

◆ getCurrentTime()

◆ getLastError()

◆ getLogger()

◆ getMulti()

◆ getQoS()

◆ getScopedLock()

◆ getSegmentationSize()

◆ getSegmentedValueMaxSize()

◆ getWithSetCallback()

◆ incrWithInit()

◆ isKeyGlobal()

◆ lock()

◆ makeFallbackKey()

◆ makeGlobalKey()

◆ makeKey()

◆ makeKeyInternal()

◆ merge()

◆ mergeFlagMaps()

◆ proxyCall()

◆ requireConvertGenericKey()

◆ set()

◆ setLastError()

◆ setLogger()

◆ setMockTime()

◆ setMulti()

◆ unlock()

◆ watchErrors()

Member Data Documentation

◆ $asyncHandler

◆ $attrMap

◆ $keyspace

◆ $lastError

◆ $lastErrorId

◆ $logger

◆ $nextErrorMonitorId

◆ $stats

◆ ATTR_DURABILITY

◆ ERR_NO_RESPONSE

◆ ERR_NONE

◆ ERR_UNEXPECTED

◆ ERR_UNREACHABLE

◆ MAX_CONFLICTS_ONE

◆ QOS_DURABILITY_DISK

◆ QOS_DURABILITY_NONE

◆ QOS_DURABILITY_RDBMS

◆ QOS_DURABILITY_SCRIPT

◆ QOS_DURABILITY_SERVICE

◆ QOS_UNKNOWN

◆ READ_LATEST

◆ READ_VERIFIED

◆ WRITE_ALLOW_SEGMENTS

◆ WRITE_BACKGROUND

◆ WRITE_CACHE_ONLY

◆ WRITE_PRUNE_SEGMENTS