MediaWiki  master
EmptyBagOStuff Class Reference

A BagOStuff object with no objects in it. More...

Inheritance diagram for EmptyBagOStuff:
Collaboration diagram for EmptyBagOStuff:

Public Member Functions

 __construct (array $params=[])
 
 decr ( $key, $value=1, $flags=0)
 Decrease stored value of $key by $value while preserving its TTL. More...
 
 incr ( $key, $value=1, $flags=0)
 Increase stored value of $key by $value while preserving its TTL. More...
 
 makeKeyInternal ( $keyspace, $components)
 Make a cache key for the given keyspace and components. More...
 
 merge ( $key, callable $callback, $exptime=0, $attempts=10, $flags=0)
 Merge changes into the existing cache value (possibly creating a new one) More...
 
 setNewPreparedValues (array $valueByKey)
 Stage a set of new key values for storage and estimate the amount of bytes needed. More...
 
- Public Member Functions inherited from MediumSpecificBagOStuff
 add ( $key, $value, $exptime=0, $flags=0)
 Insert an item if it does not already exist. More...
 
 addBusyCallback (callable $workCallback)
 Let a callback be run to avoid wasting time on special blocking calls. More...
 
 changeTTL ( $key, $exptime=0, $flags=0)
 Change the expiration on a key if it exists. More...
 
 changeTTLMulti (array $keys, $exptime, $flags=0)
 Change the expiration of multiple keys that exist. More...
 
 delete ( $key, $flags=0)
 Delete an item. More...
 
 deleteMulti (array $keys, $flags=0)
 Batch deletion. More...
 
 deleteObjectsExpiringBefore ( $timestamp, callable $progress=null, $limit=INF, string $tag=null)
 Delete all objects expiring before a certain date. More...
 
 get ( $key, $flags=0)
 Get an item with the given key. More...
 
 getMulti (array $keys, $flags=0)
 Get an associative array containing the item for each of the keys that have items. More...
 
 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. More...
 
 lock ( $key, $timeout=6, $exptime=6, $rclass='')
 
 makeGlobalKey ( $collection,... $components)
 Make a cache key for the default keyspace and given components. More...
 
 makeKey ( $collection,... $components)
 Make a cache key for the global keyspace and given components. More...
 
 set ( $key, $value, $exptime=0, $flags=0)
 Set an item. More...
 
 setMulti (array $valueByKey, $exptime=0, $flags=0)
 Batch insertion/replace. More...
 
 unlock ( $key)
 Release an advisory lock on a key string. More...
 
- Public Member Functions inherited from BagOStuff
 clearLastError ()
 Clear the "last error" registry. More...
 
 getCurrentTime ()
 
 getLastError ( $watchPoint=0)
 Get the "last error" registry. More...
 
 getLogger ()
 
 getScopedLock ( $key, $timeout=6, $expiry=30, $rclass='')
 Get a lightweight exclusive self-unlocking lock. More...
 
 getWithSetCallback ( $key, $exptime, $callback, $flags=0)
 Get an item with the given key, regenerating and setting it if not found. More...
 
 isKeyGlobal ( $key)
 Check whether a cache key is in the global keyspace. More...
 
 registerWrapperInfoForStats (string $prefixComponent, string $statsGroup, callable $collectionCallback)
 Register info about a caching layer class that uses BagOStuff as a backing store. More...
 
 setLogger (LoggerInterface $logger)
 
 setMockTime (&$time)
 
 watchErrors ()
 Get a "watch point" token that can be used to get the "last error" to occur after now. More...
 

Protected Member Functions

 convertGenericKey ( $key)
 Convert a "generic" reversible cache key into one for this cache. More...
 
 doAdd ( $key, $value, $exptime=0, $flags=0)
 Insert an item if it does not already exist. More...
 
 doDelete ( $key, $flags=0)
 Delete an item. More...
 
 doGet ( $key, $flags=0, &$casToken=null)
 Get an item. More...
 
 doIncrWithInit ( $key, $exptime, $step, $init, $flags)
 
 doSet ( $key, $value, $exptime=0, $flags=0)
 Set an item. More...
 
- Protected Member Functions inherited from MediumSpecificBagOStuff
 cas ( $casToken, $key, $value, $exptime=0, $flags=0)
 Set an item if the current CAS token matches the provided CAS token. More...
 
 debug ( $text)
 
 doCas ( $casToken, $key, $value, $exptime=0, $flags=0)
 Set an item if the current CAS token matches the provided CAS token. More...
 
 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. More...
 
 doLock ( $key, $timeout, $exptime)
 
 doSetMulti (array $data, $exptime=0, $flags=0)
 
 doUnlock ( $key)
 
 getExpirationAsTimestamp ( $exptime)
 Convert an optionally relative timestamp to an absolute time. More...
 
 getExpirationAsTTL ( $exptime)
 Convert an optionally absolute expiry time to a relative time. More...
 
 getSerialized ( $value, $key)
 Get the serialized form a value, using any applicable prepared value. More...
 
 guessSerialSizeOfValues (array $values)
 Estimate the size of a each variable once serialized. More...
 
 guessSerialValueSize ( $value, $depth=0, &$loops=0)
 Estimate the size of a variable once serialized. More...
 
 isInteger ( $value)
 Check if a value is an integer. More...
 
 isRelativeExpiration ( $exptime)
 
 makeLockKey ( $key)
 
 makeValueOrSegmentList ( $key, $value, $exptime, $flags)
 Determine the entry (inline or segment list) to store under a key to save the value. More...
 
 mergeViaCas ( $key, callable $callback, $exptime, $attempts, $flags)
 
 resolveSegments ( $key, $mainValue)
 Get and reassemble the chunks of blob at the given key. More...
 
 serialize ( $value)
 
 tokensMatch ( $value, $otherValue)
 
 unserialize ( $value)
 
 updateOpStats (string $op, array $keyInfo)
 
- Protected Member Functions inherited from BagOStuff
 componentsFromGenericKey ( $key)
 Extract the components from a "generic" reversible cache key. More...
 
 determineKeyPrefixForStats ( $key)
 
 fieldHasFlags ( $field, $flags)
 
 genericKeyFromComponents (... $components)
 At a minimum, there must be a keyspace and collection name component. More...
 
 mergeFlagMaps (array $bags)
 Merge the flag maps of one or more BagOStuff objects into a "lowest common denominator" map. More...
 
 proxyCall (string $method, int $arg0Sig, int $resSig, array $genericArgs, BagOStuff $wrapper)
 Call a method on behalf of wrapper BagOStuff instance that uses "generic" keys. More...
 
 setLastError ( $error)
 Set the "last error" registry due to a problem encountered during an attempted operation. More...
 

Additional Inherited Members

- Public Attributes inherited from BagOStuff
const READ_LATEST = 1
 Bitfield constants for get()/getMulti(); these are only advisory. More...
 
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. More...
 
- Public Attributes inherited from Wikimedia\LightweightObjectStore\StorageAwareness
const ATTR_DURABILITY = 2
 Durability of writes; see QOS_DURABILITY_* (higher means stronger) More...
 
const ATTR_EMULATION = 1
 Emulation/fallback mode; see QOS_EMULATION_*; higher is better. More...
 
const ERR_NO_RESPONSE = 1
 Storage medium failed to yield a complete response to an operation. More...
 
const ERR_NONE = 0
 No storage medium error. More...
 
const ERR_UNEXPECTED = 3
 Storage medium operation failed due to usage limitations or an I/O error. More...
 
const ERR_UNREACHABLE = 2
 Storage medium could not be reached to establish a connection. More...
 
const QOS_DURABILITY_DISK = 4
 Data is saved to disk and writes do not usually block on fsync() More...
 
const QOS_DURABILITY_NONE = 1
 Data is never saved to begin with (blackhole store) More...
 
const QOS_DURABILITY_RDBMS = 5
 Data is saved to disk and writes usually block on fsync(), like a standard RDBMS. More...
 
const QOS_DURABILITY_SCRIPT = 2
 Data is lost at the end of the current web request or CLI script. More...
 
const QOS_DURABILITY_SERVICE = 3
 Data is lost once the service storing the data restarts. More...
 
const QOS_EMULATION_SQL = 1
 Fallback disk-based SQL store. More...
 
const QOS_UNKNOWN = INF
 Generic "unknown" value; useful for comparisons (always "good enough") More...
 
- Protected Attributes inherited from MediumSpecificBagOStuff
array< string, array > $locks = []
 Map of (key => (class, depth, expiry) More...
 
array[] $preparedValues = []
 Map of (key => (PHP variable value, serialized value)) More...
 
int $segmentationSize
 Bytes; chunk size of segmented cache values. More...
 
int $segmentedValueMaxSize
 Bytes; maximum total size of a segmented cache value. More...
 
int $syncTimeout
 Seconds. More...
 
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'
 
- Protected Attributes inherited from BagOStuff
callable null $asyncHandler
 
int[] $attrMap = []
 Map of (BagOStuff:ATTR_* constant => BagOStuff:QOS_* constant) More...
 
string $keyspace
 Default keyspace; used by makeKey() More...
 
int $lastError = self::ERR_NONE
 BagOStuff:ERR_* constant of the last error that occurred. More...
 
int $lastErrorId = 0
 Error event sequence number of the last error that occurred. More...
 
LoggerInterface $logger
 
StatsdDataFactoryInterface $stats
 
array< string, array > $wrapperInfoByPrefix = []
 Cache key processing callbacks and info for metrics. More...
 
- Static Protected Attributes inherited from BagOStuff
static int $nextErrorMonitorId = 1
 Next sequence number to use for watch/error events. More...
 

Detailed Description

A BagOStuff object with no objects in it.

Used to provide a no-op object to calling code.

Definition at line 29 of file EmptyBagOStuff.php.

Constructor & Destructor Documentation

◆ __construct()

EmptyBagOStuff::__construct ( array  $params = [])
See also
BagOStuff::__construct() Additional $params options include:
  • logger: Psr\Log\LoggerInterface instance
  • reportDupes: Whether to emit warning log messages for all keys that were requested more than once (requires an asyncHandler).
  • syncTimeout: How long to wait with WRITE_SYNC in seconds.
  • segmentationSize: The chunk size, in bytes, of segmented values. The value should not exceed the maximum size of values in the storage backend, as configured by the site administrator.
  • segmentedValueMaxSize: The maximum total size, in bytes, of segmented values. This should be configured to a reasonable size give the site traffic and the amount of I/O between application and cache servers that the network can handle.
Parameters
array$params@phpcs:ignore Generic.Files.LineLength

Reimplemented from MediumSpecificBagOStuff.

Definition at line 30 of file EmptyBagOStuff.php.

References Wikimedia\LightweightObjectStore\StorageAwareness\ATTR_DURABILITY, and Wikimedia\LightweightObjectStore\StorageAwareness\QOS_DURABILITY_NONE.

Member Function Documentation

◆ convertGenericKey()

EmptyBagOStuff::convertGenericKey (   $key)
protected

Convert a "generic" reversible cache key into one for this cache.

See also
BagOStuff::genericKeyFromComponents()
Parameters
string$keyKeyspace-prepended list of encoded components as a colon-separated value
Returns
string Keyspace-prepended list of encoded components as a colon-separated value

Reimplemented from MediumSpecificBagOStuff.

Definition at line 81 of file EmptyBagOStuff.php.

◆ decr()

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

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

Parameters
string$key
int$valueValue to subtract from $key (default: 1) [optional]
int$flagsBit field of class WRITE_* constants [optional]
Returns
int|bool New value or false on failure
Deprecated:
Since 1.38

Reimplemented from BagOStuff.

Definition at line 58 of file EmptyBagOStuff.php.

◆ doAdd()

EmptyBagOStuff::doAdd (   $key,
  $value,
  $exptime = 0,
  $flags = 0 
)
protected

Insert an item if it does not already exist.

Parameters
string$key
mixed$value
int$exptime
int$flagsBitfield of BagOStuff::WRITE_* constants (since 1.33)
Returns
bool Success

Reimplemented from MediumSpecificBagOStuff.

Definition at line 50 of file EmptyBagOStuff.php.

◆ doDelete()

EmptyBagOStuff::doDelete (   $key,
  $flags = 0 
)
protected

Delete an item.

Parameters
string$key
int$flagsBitfield of BagOStuff::WRITE_* constants
Returns
bool True if the item was deleted or not found, false on failure

Reimplemented from MediumSpecificBagOStuff.

Definition at line 46 of file EmptyBagOStuff.php.

◆ doGet()

EmptyBagOStuff::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$key
int$flagsBitfield of BagOStuff::READ_* constants [optional]
mixed&$casTokenCAS token if MediumSpecificBagOStuff::PASS_BY_REF [returned]
Returns
mixed Returns false on failure or if the item does not exist

Reimplemented from MediumSpecificBagOStuff.

Definition at line 36 of file EmptyBagOStuff.php.

◆ doIncrWithInit()

EmptyBagOStuff::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 MediumSpecificBagOStuff.

Definition at line 62 of file EmptyBagOStuff.php.

◆ doSet()

EmptyBagOStuff::doSet (   $key,
  $value,
  $exptime = 0,
  $flags = 0 
)
protected

Set an item.

Parameters
string$key
mixed$value
int$exptimeEither an interval in seconds or a unix timestamp for expiry
int$flagsBitfield of BagOStuff::WRITE_* constants
Returns
bool Success

Reimplemented from MediumSpecificBagOStuff.

Definition at line 42 of file EmptyBagOStuff.php.

◆ incr()

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

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

Parameters
string$keyKey to increase
int$valueValue to add to $key (default: 1) [optional]
int$flagsBit field of class WRITE_* constants [optional]
Returns
int|bool New value or false on failure
Deprecated:
Since 1.38

Reimplemented from BagOStuff.

Definition at line 54 of file EmptyBagOStuff.php.

◆ makeKeyInternal()

EmptyBagOStuff::makeKeyInternal (   $keyspace,
  $components 
)

Make a cache key for the given keyspace and components.

Long components might be converted to respective hashes due to size constraints. In extreme cases, all of them might be combined into a single hash component.

Access: internal
This method should not be used outside of BagOStuff (since 1.36)
Parameters
string$keyspaceKeyspace component
string[] | int[]$componentsKey components (key collection name first)
Returns
string Keyspace-prepended list of encoded components as a colon-separated value
Since
1.27

Reimplemented from BagOStuff.

Definition at line 77 of file EmptyBagOStuff.php.

References BagOStuff\$keyspace, and BagOStuff\genericKeyFromComponents().

◆ merge()

EmptyBagOStuff::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 overridden in the callback. Nothing is stored nor deleted if the callback returns false.

Parameters
string$key
callable$callbackCallback method to be executed
int$exptimeEither an interval in seconds or a unix timestamp for expiry
int$attemptsThe amount of times to attempt a merge in case of failure
int$flagsBitfield of BagOStuff::WRITE_* constants
Returns
bool Success

Reimplemented from MediumSpecificBagOStuff.

Definition at line 67 of file EmptyBagOStuff.php.

◆ setNewPreparedValues()

EmptyBagOStuff::setNewPreparedValues ( array  $valueByKey)

Stage a set of new key values for storage and estimate the amount of bytes needed.

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 );
$cache
Definition: mcc.php:33

This is only useful if the caller needs an estimate of the serialized object sizes, such as cache wrappers with adaptive write slam avoidance or store wrappers with metrics. 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$valueByKeyMap 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 MediumSpecificBagOStuff.

Definition at line 72 of file EmptyBagOStuff.php.

References MediumSpecificBagOStuff\guessSerialSizeOfValues().


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