Store key-value data via an HTTP service. More...

Inherits Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Collaboration diagram for Wikimedia\ObjectCache\RESTBagOStuff:

[legend]

Public Member Functions
	__construct (array $params)

	setLogger (LoggerInterface $logger)

Public Member Functions inherited from Wikimedia\ObjectCache\MediumSpecificBagOStuff
	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 a key if it exists.

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

	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 with the given key.

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

	getQoS ( $flag)

	getSegmentationSize ()

	getSegmentedValueMaxSize ()

	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.

	lock ( $key, $timeout=6, $exptime=6, $rclass='')

	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.

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

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

Public Member Functions inherited from Wikimedia\ObjectCache\BagOStuff
	getCurrentTime ()

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

	getLogger ()

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

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

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

	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.

	setMockTime (&$time)

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

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

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

	doGet ( $key, $flags=0, &$casToken=null)
	Get an item.

	doIncrWithInit ( $key, $exptime, $step, $init, $flags)

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

Protected Member Functions inherited from Wikimedia\ObjectCache\MediumSpecificBagOStuff
	cas ( $casToken, $key, $value, $exptime=0, $flags=0)
	Set an item if the current CAS token matches the provided CAS token.

	debug ( $text)

	doCas ( $casToken, $key, $value, $exptime=0, $flags=0)
	Set an item if the current CAS token matches the provided CAS token.

	doChangeTTL ( $key, $exptime, $flags)

	doChangeTTLMulti (array $keys, $exptime, $flags=0)

	doDeleteMulti (array $keys, $flags=0)

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

	doLock ( $key, $timeout, $exptime)

	doSetMulti (array $data, $exptime=0, $flags=0)

	doUnlock ( $key)

	getExpirationAsTimestamp ( $exptime)
	Convert an optionally relative timestamp to an absolute time.

	getExpirationAsTTL ( $exptime)
	Convert an optionally absolute expiry time to a relative time.

	getSerialized ( $value, $key)
	Get the serialized form a value, logging a warning if it involves custom classes.

	isInteger ( $value)
	Check if a value is an integer.

	isRelativeExpiration ( $exptime)

	makeLockKey ( $key)

	makeValueOrSegmentList ( $key, $value, $exptime, $flags, &$ok)
	Make the entry to store at a key (inline or segment list), storing any segments.

	mergeViaCas ( $key, callable $callback, $exptime, $attempts, $flags)

	resolveSegments ( $key, $mainValue)
	Get and reassemble the chunks of blob at the given key.

	serialize ( $value)

	tokensMatch ( $value, $otherValue)

	unserialize ( $value)

	updateOpStats (string $op, array $keyInfo)

Protected Member Functions inherited from Wikimedia\ObjectCache\BagOStuff
	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.

Additional Inherited Members
Public Attributes inherited from Wikimedia\ObjectCache\BagOStuff
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 Attributes inherited from Wikimedia\ObjectCache\MediumSpecificBagOStuff
array< string, array >	$locks = []
	Map of (key => (class LOCK_* constant => value)

float	$maxLockSendDelay = 0.05
	Seconds; maximum expected seconds for a lock ping to reach the backend.

int	$segmentationSize
	Bytes; chunk size of segmented cache values.

int	$segmentedValueMaxSize
	Bytes; maximum total size of a segmented cache value.

const	LOCK_DEPTH = 1

const	LOCK_EXPIRY = 3

const	LOCK_RCLASS = 0

const	LOCK_TIME = 2

const	METRIC_OP_ADD = 'add'

const	METRIC_OP_CAS = 'cas'

const	METRIC_OP_CHANGE_TTL = 'change_ttl'

const	METRIC_OP_DECR = 'decr'

const	METRIC_OP_DELETE = 'delete'

const	METRIC_OP_GET = 'get'

const	METRIC_OP_INCR = 'incr'

const	METRIC_OP_SET = 'set'

const	PASS_BY_REF = -1
	Idiom for doGet() to return extra information by reference.

Protected Attributes inherited from Wikimedia\ObjectCache\BagOStuff
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 inherited from Wikimedia\ObjectCache\BagOStuff
static int	$nextErrorMonitorId = 1
	Next sequence number to use for watch/error events.

Detailed Description

Store key-value data via an HTTP service.

Important caveats

This interface is currently an incomplete BagOStuff implementation, supported only for use with MediaWiki features that accept a dedicated cache type to use for a narrow set of cache keys that share the same key expiry and replication requirements, and where the key-value server in question is statically configured with domain knowledge of said key expiry and replication requirements.

Specifically, RESTBagOStuff has the following limitations:

The expiry parameter is ignored in methods like set().

There is not currently an agreed protocol for sending this to a server. This class is written for use with MediaWiki\Session\SessionManager and Kask/Cassandra at WMF, which does not expose a customizable expiry.

As such, it is not recommended to use RESTBagOStuff to back a general purpose cache type (such as MediaWiki's main cache, or main stash). Instead, it is only supported for MediaWiki features where a cache type can be pointed to a narrow set of keys that naturally share the same TTL anyway, or where the feature behaves correctly even if the logical expiry is longer than specified (e.g. immutable keys, or value verification)
Most methods are non-atomic.

The class should only be used for get, set, and delete operations. Advanced methods like incr(), add() and lock() do exist but inherit a native and best-effort implementation based on get+set. These should not be relied upon.

Backend requirements

The HTTP server will receive requests for URLs like {baseURL}/{KEY}. It must implement the GET, PUT and DELETE methods.

E.g., when the base URL is /sessions/v1, then set() will:

PUT /sessions/v1/mykeyhere

and get() would do:

GET /sessions/v1/mykeyhere

and delete() would do:

DELETE /sessions/v1/mykeyhere

Example configuration

Minimal generic configuration:

$wgObjectCaches['sessions'] = array(
 'class' => 'RESTBagOStuff',
 'url' => 'http://localhost:7231/example/'
);

Configuration for Kask session store:

$wgObjectCaches['sessions'] = array(
 'class' => 'RESTBagOStuff',
 'url' => 'https://kaskhost:1234/sessions/v1/',
 'httpParams' => [
    'readHeaders' => [],
    'writeHeaders' => [ 'content-type' => 'application/octet-stream' ],
    'deleteHeaders' => [],
    'writeMethod' => 'POST',
 ],
 'serialization_type' => 'JSON',
    'extendedErrorBodyFields' => [ 'type', 'title', 'detail', 'instance' ]
);
$wgSessionCacheType = 'sessions';

Definition at line 89 of file RESTBagOStuff.php.

Constructor & Destructor Documentation

◆ __construct()

Wikimedia\ObjectCache\RESTBagOStuff::__construct ( array $params )

See also

BagOStuff::__construct() Additional $params options include:

logger: Psr\Log\LoggerInterface instance
reportDupes: Whether to emit warning log messages for all keys that were requested more than once (requires an asyncHandler).
segmentationSize: The chunk size, in bytes, of segmented values. The value should not exceed the maximum size of values in the storage backend, as configured by the site administrator.
segmentedValueMaxSize: The maximum total size, in bytes, of segmented values. This should be configured to a reasonable size give the site traffic and the amount of I/O between application and cache servers that the network can handle.

Parameters

array $params

@phpcs:ignore Generic.Files.LineLength

Reimplemented from Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 140 of file RESTBagOStuff.php.

References Wikimedia\ObjectCache\BagOStuff\ATTR_DURABILITY, and Wikimedia\ObjectCache\BagOStuff\QOS_DURABILITY_DISK.

Member Function Documentation

◆ doAdd()

Wikimedia\ObjectCache\RESTBagOStuff::doAdd	(	$key,
		$value,
		$exptime = 0,
		$flags = 0 )

protected

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 Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 234 of file RESTBagOStuff.php.

◆ doDelete()

Wikimedia\ObjectCache\RESTBagOStuff::doDelete	(		$key,
			$flags = 0 )

protected

Delete an item.

Parameters

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

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

Reimplemented from Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 244 of file RESTBagOStuff.php.

◆ doGet()

Wikimedia\ObjectCache\RESTBagOStuff::doGet	(		$key,
			$flags = 0,
		&	$casToken = null )

protected

Get an item.

The CAS token should be null if the key does not exist or the value is corrupt

Parameters

string	$key
int	$flags	Bitfield of BagOStuff::READ_* constants [optional]
mixed	&$casToken	CAS token if MediumSpecificBagOStuff::PASS_BY_REF [returned]

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

Reimplemented from Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 184 of file RESTBagOStuff.php.

◆ doIncrWithInit()

Wikimedia\ObjectCache\RESTBagOStuff::doIncrWithInit	(	$key,
		$exptime,
		$step,
		$init,
		$flags )

protected

Parameters

string	$key
int	$exptime
int	$step
int	$init
int	$flags

Returns: int|bool New value or false on failure

Reimplemented from Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 263 of file RESTBagOStuff.php.

◆ doSet()

Wikimedia\ObjectCache\RESTBagOStuff::doSet	(	$key,
		$value,
		$exptime = 0,
		$flags = 0 )

protected

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 Wikimedia\ObjectCache\MediumSpecificBagOStuff.

Definition at line 214 of file RESTBagOStuff.php.

◆ setLogger()

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

Parameters

LoggerInterface $logger

Returns: void

Reimplemented from Wikimedia\ObjectCache\BagOStuff.

Definition at line 179 of file RESTBagOStuff.php.

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

includes/libs/objectcache/RESTBagOStuff.php

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Important caveats

Backend requirements

Example configuration

Constructor & Destructor Documentation

◆ __construct()

Member Function Documentation

◆ doAdd()

◆ doDelete()

◆ doGet()

◆ doIncrWithInit()

◆ doSet()

◆ setLogger()