A cache class that directs writes to one set of servers and reads to another. More...

Inheritance diagram for ReplicatedBagOStuff:

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Collaboration diagram for ReplicatedBagOStuff:

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Public Member Functions
	__construct ( $params)
	Constructor.

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

	addBusyCallback (callable $workCallback)
	Let a callback be run to avoid wasting time on special blocking calls.

	changeTTL ( $key, $exptime=0, $flags=0)
	Change the expiration on a key if it exists.

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

	clearLastError ()
	Clear the "last error" registry.

	decr ( $key, $value=1, $flags=0)
	Decrease stored value of $key by $value while preserving its TTL.

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

	deleteMulti (array $keys, $flags=0)
	Batch deletion.

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

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

	getLastError ()
	Get the "last error" registered; clearLastError() should be called manually.

	getMulti (array $keys, $flags=0)
	Get an associative array containing the item for each of the keys that have items.

	incr ( $key, $value=1, $flags=0)
	Increase stored value of $key by $value while preserving its TTL.

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

	lock ( $key, $timeout=6, $expiry=6, $rclass='')
	Acquire an advisory lock on a key string.

	makeGlobalKey ( $class,... $components)
	Make a global cache key.

	makeKey ( $class,... $components)
	Make a cache key, scoped to this instance's keyspace.

	makeKeyInternal ( $keyspace, $args)
	Construct a cache key.

	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.

	setDebug ( $enabled)

	setMockTime (&$time)

	setMulti (array $data, $exptime=0, $flags=0)
	Batch insertion/replace.

	setNewPreparedValues (array $valueByKey)
	Prepare values for storage and get their serialized sizes, or, estimate those sizes.

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

Public Member Functions inherited from BagOStuff
	__construct (array $params=[])
	Parameters include:

	getCurrentTime ()

	getLogger ()

	getQoS ( $flag)

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

	getSegmentationSize ()

	getSegmentedValueMaxSize ()

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

	setLogger (LoggerInterface $logger)

Private Member Functions
	hadRecentSessionWrite (array $keys)

	remarkRecentSessionWrite (array $keys)

Private Attributes
int	$consistencyWindow
	Seconds to read from the master source for a key after writing to it.

float[]	$lastKeyWrites = []
	Map of (key => UNIX timestamp)

BagOStuff	$readStore

BagOStuff	$writeStore

Additional Inherited Members
Public Attributes inherited from BagOStuff
const	READ_LATEST = 1
	Bitfield constants for get()/getMulti(); these are only advisory.

const	READ_VERIFIED = 2

const	WRITE_ALLOW_SEGMENTS = 16

const	WRITE_BACKGROUND = 64

const	WRITE_CACHE_ONLY = 8

const	WRITE_PRUNE_SEGMENTS = 32

const	WRITE_SYNC = 4
	Bitfield constants for set()/merge(); these are only advisory.

Protected Member Functions inherited from BagOStuff
	fieldHasFlags ( $field, $flags)

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

Protected Attributes inherited from BagOStuff
callable null	$asyncHandler

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

bool	$debugMode = false

LoggerInterface	$logger

Detailed Description

A cache class that directs writes to one set of servers and reads to another.

This assumes that the servers used for reads are setup to replica DB those that writes go to. This can easily be used with redis for example.

In the WAN scenario (e.g. multi-datacenter case), this is useful when writes are rare or they usually take place in the primary datacenter.

Since: 1.26

Definition at line 34 of file ReplicatedBagOStuff.php.

Constructor & Destructor Documentation

◆ __construct()

ReplicatedBagOStuff::__construct ( $params )

Constructor.

Parameters are:

writeFactory: ObjectFactory::getObjectFromSpec array yielding BagOStuff. This object will be used for writes (e.g. the master DB).
readFactory: ObjectFactory::getObjectFromSpec array yielding BagOStuff. This object will be used for reads (e.g. a replica DB).
sessionConsistencyWindow: Seconds to read from the master source for a key after writing to it. [Default: ReplicatedBagOStuff::MAX_WRITE_DELAY]

Parameters

array $params

Exceptions

InvalidArgumentException

Definition at line 60 of file ReplicatedBagOStuff.php.

References BagOStuff\mergeFlagMaps().

Member Function Documentation

◆ add()

ReplicatedBagOStuff::add	(	$key,
		$value,
		$exptime = `0`,
		$flags = `0`
	)

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

Reimplemented from BagOStuff.

Definition at line 108 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ addBusyCallback()

ReplicatedBagOStuff::addBusyCallback ( callable $workCallback )

Let a callback be run to avoid wasting time on special blocking calls.

The callbacks may or may not be called ever, in any particular order. They are likely to be invoked when something WRITE_SYNC is used used. They should follow a caching pattern as shown below, so that any code using the work will get it's result no matter what happens.

$result = null;
$workCallback = function () use ( &$result ) {
    if ( !$result ) {
        $result = ....
    }
    return $result;
}

Parameters

callable $workCallback

Since: 1.28

Reimplemented from BagOStuff.

Definition at line 210 of file ReplicatedBagOStuff.php.

◆ changeTTL()

ReplicatedBagOStuff::changeTTL	(	$key,
		$exptime = `0`,
		$flags = `0`
	)

Change the expiration on a key if it exists.

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 Returns false on failure or if the item does not exist

Since: 1.28

Reimplemented from BagOStuff.

Definition at line 120 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ changeTTLMulti()

ReplicatedBagOStuff::changeTTLMulti	(	array	$keys,
			$exptime,
			$flags = `0`
	)

Change the expiration of multiple keys that exist.

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

Since: 1.34

Reimplemented from BagOStuff.

Definition at line 163 of file ReplicatedBagOStuff.php.

References $keys, and remarkRecentSessionWrite().

◆ clearLastError()

ReplicatedBagOStuff::clearLastError ( )

Clear the "last error" registry.

Since: 1.23

Reimplemented from BagOStuff.

Definition at line 193 of file ReplicatedBagOStuff.php.

◆ decr()

ReplicatedBagOStuff::decr	(	$key,
		$value = `1`,
		$flags = `0`
	)

Decrease stored value of $key by $value while preserving its TTL.

Parameters

string	$key
int	$value	Value to subtract from $key (default: 1) [optional]
int	$flags	Bit field of class WRITE_* constants [optional]

Returns: int|bool New value or false on failure

Reimplemented from BagOStuff.

Definition at line 175 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ delete()

ReplicatedBagOStuff::delete	(	$key,
		$flags = `0`
	)

Delete an item.

For large values written using WRITE_ALLOW_SEGMENTS, this only deletes the main segment list key unless WRITE_PRUNE_SEGMENTS is in the flags. While deleting the segment list key has the effect of functionally deleting the key, it leaves unused blobs in cache.

Parameters

string $key

Returns: bool True if the item was deleted or not found, false on failure

Parameters

int $flags Bitfield of BagOStuff::WRITE_* constants

Reimplemented from BagOStuff.

Definition at line 102 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ deleteMulti()

ReplicatedBagOStuff::deleteMulti	(	array	$keys,
			$flags = `0`
	)

Batch deletion.

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

Since: 1.33

Reimplemented from BagOStuff.

Definition at line 157 of file ReplicatedBagOStuff.php.

References $keys, and remarkRecentSessionWrite().

◆ deleteObjectsExpiringBefore()

ReplicatedBagOStuff::deleteObjectsExpiringBefore	(		$timestamp,
		callable	$progress = `null`,
			$limit = `INF`
	)

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	$limit	Maximum number of keys to delete [default: INF]

Returns: bool Success; false if unimplemented

Reimplemented from BagOStuff.

Definition at line 134 of file ReplicatedBagOStuff.php.

◆ get()

ReplicatedBagOStuff::get	(	$key,
		$flags = `0`
	)

Get an item with the given key.

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 from BagOStuff.

Definition at line 87 of file ReplicatedBagOStuff.php.

References BagOStuff\fieldHasFlags(), and hadRecentSessionWrite().

◆ getLastError()

ReplicatedBagOStuff::getLastError ( )

Get the "last error" registered; clearLastError() should be called manually.

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

Since: 1.23

Reimplemented from BagOStuff.

Definition at line 187 of file ReplicatedBagOStuff.php.

◆ getMulti()

ReplicatedBagOStuff::getMulti	(	array	$keys,
			$flags = `0`
	)

Get an associative array containing the item for each of the keys that have items.

Parameters

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

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

Reimplemented from BagOStuff.

Definition at line 142 of file ReplicatedBagOStuff.php.

References $keys, BagOStuff\fieldHasFlags(), and hadRecentSessionWrite().

◆ hadRecentSessionWrite()

ReplicatedBagOStuff::hadRecentSessionWrite ( array $keys )

private

Parameters

string[] $keys

Returns: bool

Definition at line 228 of file ReplicatedBagOStuff.php.

References BagOStuff\getCurrentTime().

Referenced by get(), and getMulti().

◆ incr()

ReplicatedBagOStuff::incr	(	$key,
		$value = `1`,
		$flags = `0`
	)

Increase stored value of $key by $value while preserving its TTL.

Parameters

string	$key	Key to increase
int	$value	Value to add to $key (default: 1) [optional]
int	$flags	Bit field of class WRITE_* constants [optional]

Returns: int|bool New value or false on failure

Reimplemented from BagOStuff.

Definition at line 169 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ incrWithInit()

ReplicatedBagOStuff::incrWithInit	(	$key,
		$exptime,
		$value = `1`,
		$init = `null`,
		$flags = `0`
	)

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 - $value) and $exptime are invariants for all operations to any given key. The value of $init should be at least that of $value.

Parameters

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

Returns: int|bool New value or false on failure

Since: 1.24

Reimplemented from BagOStuff.

Definition at line 181 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ lock()

ReplicatedBagOStuff::lock	(	$key,
		$timeout = `6`,
		$expiry = `6`,
		$rclass = `''`
	)

Acquire an advisory lock on a key string.

Note that if reentry is enabled, duplicate calls ignore $expiry

Parameters

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

Returns: bool Success

Reimplemented from BagOStuff.

Definition at line 126 of file ReplicatedBagOStuff.php.

◆ makeGlobalKey()

ReplicatedBagOStuff::makeGlobalKey	(	$class,
		$components
	)

Make a global cache key.

Since: 1.27

Parameters

string	$class	Key class
	string\|int	...$components Key components (starting with a key collection name)

Returns: string Colon-delimited list of $keyspace followed by escaped components

Reimplemented from BagOStuff.

Definition at line 206 of file ReplicatedBagOStuff.php.

◆ makeKey()

ReplicatedBagOStuff::makeKey	(	$class,
		$components
	)

Make a cache key, scoped to this instance's keyspace.

Since: 1.27

Parameters

string	$class	Key class
	string\|int	...$components Key components (starting with a key collection name)

Returns: string Colon-delimited list of $keyspace followed by escaped components

Reimplemented from BagOStuff.

Definition at line 202 of file ReplicatedBagOStuff.php.

◆ makeKeyInternal()

ReplicatedBagOStuff::makeKeyInternal	(	$keyspace,
		$args
	)

Construct a cache key.

Since: 1.27

Parameters

string	$keyspace
array	$args

Returns: string Colon-delimited list of $keyspace followed by escaped components of $args

Reimplemented from BagOStuff.

Definition at line 198 of file ReplicatedBagOStuff.php.

◆ merge()

ReplicatedBagOStuff::merge	(		$key,
		callable	$callback,
			$exptime = `0`,
			$attempts = `10`,
			$flags = `0`
	)

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 overriden 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

Exceptions

InvalidArgumentException

Reimplemented from BagOStuff.

Definition at line 114 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ remarkRecentSessionWrite()

ReplicatedBagOStuff::remarkRecentSessionWrite ( array $keys )

private

Parameters

string[] $keys

Definition at line 243 of file ReplicatedBagOStuff.php.

References BagOStuff\getCurrentTime().

Referenced by add(), changeTTL(), changeTTLMulti(), decr(), delete(), deleteMulti(), incr(), incrWithInit(), merge(), set(), and setMulti().

◆ set()

ReplicatedBagOStuff::set	(	$key,
		$value,
		$exptime = `0`,
		$flags = `0`
	)

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

Returns: bool Success

Reimplemented from BagOStuff.

Definition at line 96 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ setDebug()

ReplicatedBagOStuff::setDebug ( $enabled )

Parameters

bool $enabled

Reimplemented from BagOStuff.

Definition at line 81 of file ReplicatedBagOStuff.php.

◆ setMockTime()

ReplicatedBagOStuff::setMockTime ( & $time )

Reimplemented from BagOStuff.

Definition at line 218 of file ReplicatedBagOStuff.php.

◆ setMulti()

ReplicatedBagOStuff::setMulti	(	array	$data,
			$exptime = `0`,
			$flags = `0`
	)

Batch insertion/replace.

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[]	$data	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 from BagOStuff.

Definition at line 151 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ setNewPreparedValues()

ReplicatedBagOStuff::setNewPreparedValues ( array $valueByKey )

Prepare values for storage and get their serialized sizes, or, estimate those sizes.

All previously prepared values will be cleared. Each of the new prepared values will be individually cleared as they get used by write operations for that key. This is done to avoid unchecked growth in PHP memory usage.

Example usage:

$valueByKey = [ $key1 => $value1, $key2 => $value2, $key3 => $value3 ];
$cache->setNewPreparedValues( $valueByKey );
$cache->set( $key1, $value1, $cache::TTL_HOUR );
$cache->setMulti( [ $key2 => $value2, $key3 => $value3 ], $cache::TTL_HOUR );

This is only useful if the caller needs an estimate of the serialized object sizes. The caller cannot know the serialization format and even if it did, it could be expensive to serialize complex values twice just to get the size information before writing them to cache. This method solves both problems by making the cache instance do the serialization and having it reuse the result when the cache write happens.

Parameters

array $valueByKey Map of (cache key => PHP variable value to serialize)

Returns: int[]|null[] Corresponding list of size estimates (null for invalid values)

Since: 1.35

Reimplemented from BagOStuff.

Definition at line 214 of file ReplicatedBagOStuff.php.

◆ unlock()

ReplicatedBagOStuff::unlock ( $key )

Release an advisory lock on a key string.

Parameters

string $key

Returns: bool Success

Reimplemented from BagOStuff.

Definition at line 130 of file ReplicatedBagOStuff.php.

Member Data Documentation

◆ $consistencyWindow

int ReplicatedBagOStuff::$consistencyWindow

private

Seconds to read from the master source for a key after writing to it.

Definition at line 41 of file ReplicatedBagOStuff.php.

◆ $lastKeyWrites

float [] ReplicatedBagOStuff::$lastKeyWrites = []

private

Map of (key => UNIX timestamp)

Definition at line 43 of file ReplicatedBagOStuff.php.

◆ $readStore

BagOStuff ReplicatedBagOStuff::$readStore

private

Definition at line 38 of file ReplicatedBagOStuff.php.

◆ $writeStore

BagOStuff ReplicatedBagOStuff::$writeStore

private

Definition at line 36 of file ReplicatedBagOStuff.php.

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

includes/libs/objectcache/ReplicatedBagOStuff.php

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ add()

◆ addBusyCallback()

◆ changeTTL()

◆ changeTTLMulti()

◆ clearLastError()

◆ decr()

◆ delete()

◆ deleteMulti()

◆ deleteObjectsExpiringBefore()

◆ get()

◆ getLastError()

◆ getMulti()

◆ hadRecentSessionWrite()

◆ incr()

◆ incrWithInit()

◆ lock()

◆ makeGlobalKey()

◆ makeKey()

◆ makeKeyInternal()

◆ merge()

◆ remarkRecentSessionWrite()

◆ set()

◆ setDebug()

◆ setMockTime()

◆ setMulti()

◆ setNewPreparedValues()

◆ unlock()

Member Data Documentation

◆ $consistencyWindow

◆ $lastKeyWrites

◆ $readStore

◆ $writeStore