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MultiWriteBagOStuff Class Reference

A cache class that replicates all writes to multiple child caches. More...

Inheritance diagram for MultiWriteBagOStuff:
Collaboration diagram for MultiWriteBagOStuff:

Public Member Functions

 __construct ( $params)
 $params include: More...
 
 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...
 
 clearLastError ()
 Clear the "last error" registry. More...
 
 decr ( $key, $value=1, $flags=0)
 Decrease stored value of $key by $value while preserving its TTL. More...
 
 delete ( $key, $flags=0)
 Delete an item. More...
 
 deleteMulti (array $data, $flags=0)
 Batch deletion. More...
 
 deleteObjectsExpiringBefore ( $timestamp, callable $progress=null, $limit=INF)
 Delete all objects expiring before a certain date. More...
 
 get ( $key, $flags=0)
 Get an item with the given key. More...
 
 getLastError ()
 Get the "last error" registered; clearLastError() should be called manually. More...
 
 getMulti (array $keys, $flags=0)
 Get an associative array containing the item for each of the keys that have items. More...
 
 incr ( $key, $value=1, $flags=0)
 Increase stored value of $key by $value while preserving its TTL. More...
 
 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. More...
 
 lock ( $key, $timeout=6, $expiry=6, $rclass='')
 Acquire an advisory lock on a key string. More...
 
 makeGlobalKey ( $class,... $components)
 Make a global cache key. More...
 
 makeKey ( $class,... $components)
 Make a cache key, scoped to this instance's keyspace. More...
 
 makeKeyInternal ( $keyspace, $args)
 Construct a cache key. More...
 
 merge ( $key, callable $callback, $exptime=0, $attempts=10, $flags=0)
 Merge changes into the existing cache value (possibly creating a new one) More...
 
 set ( $key, $value, $exptime=0, $flags=0)
 Set an item. More...
 
 setDebug ( $enabled)
 
 setMockTime (&$time)
 
 setMulti (array $data, $exptime=0, $flags=0)
 Batch insertion/replace. More...
 
 setNewPreparedValues (array $valueByKey)
 Prepare values for storage and get their serialized sizes, or, estimate those sizes. More...
 
 unlock ( $key)
 Release an advisory lock on a key string. More...
 
- Public Member Functions inherited from BagOStuff
 __construct (array $params=[])
 Parameters include: More...
 
 getCurrentTime ()
 
 getLogger ()
 
 getQoS ( $flag)
 
 getScopedLock ( $key, $timeout=6, $expiry=30, $rclass='')
 Get a lightweight exclusive self-unlocking lock. More...
 
 getSegmentationSize ()
 
 getSegmentedValueMaxSize ()
 
 getWithSetCallback ( $key, $exptime, $callback, $flags=0)
 Get an item with the given key, regenerating and setting it if not found. More...
 
 setLogger (LoggerInterface $logger)
 

Protected Member Functions

 doWrite ( $indexes, $asyncWrites, $method, array $args)
 Apply a write method to the backing caches specified by $indexes (in order) More...
 
 usesAsyncWritesGivenFlags ( $flags)
 
- 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. More...
 

Protected Attributes

bool $asyncWrites = false
 Use async secondary writes. More...
 
int[] $cacheIndexes = []
 List of all backing cache indexes. More...
 
BagOStuff[] $caches
 
- Protected Attributes inherited from BagOStuff
callable null $asyncHandler
 
int[] $attrMap = []
 Map of (ATTR_* class constant => QOS_* class constant) More...
 
bool $debugMode = false
 
LoggerInterface $logger
 

Static Private Attributes

static int $UPGRADE_TTL = 3600
 TTL when a key is copied to a higher cache tier. 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...
 

Detailed Description

A cache class that replicates all writes to multiple child caches.

Reads are implemented by reading from the caches in the order they are given in the configuration until a cache gives a positive result.

Note that cache key construction will use the first cache backend in the list, so make sure that the other backends can handle such keys (e.g. via encoding).

Definition at line 35 of file MultiWriteBagOStuff.php.

Constructor & Destructor Documentation

◆ __construct()

MultiWriteBagOStuff::__construct (   $params)

$params include:

  • caches: A numbered array of either ObjectFactory::getObjectFromSpec arrays yielding BagOStuff objects or direct BagOStuff objects. If using the former, the 'args' field must be set. The first cache is the primary one, being the first to be read in the fallback chain. Writes happen to all stores in the order they are defined. However, lock()/unlock() calls only use the primary store.
  • replication: Either 'sync' or 'async'. This controls whether writes to secondary stores are deferred when possible. To use 'async' writes requires the 'asyncHandler' option to be set as well. Async writes can increase the chance of some race conditions or cause keys to expire seconds later than expected. It is safe to use for modules when cached values: are immutable, invalidation uses logical TTLs, invalidation uses etag/timestamp validation against the DB, or merge() is used to handle races.
    Parameters
    array$params-param array{caches:array<int,array|BagOStuff>,replication:string} $params
    Exceptions
    InvalidArgumentException

Definition at line 67 of file MultiWriteBagOStuff.php.

References BagOStuff\mergeFlagMaps().

Member Function Documentation

◆ add()

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

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 BagOStuff.

Definition at line 163 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ addBusyCallback()

MultiWriteBagOStuff::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 366 of file MultiWriteBagOStuff.php.

◆ changeTTL()

MultiWriteBagOStuff::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$key
int$exptimeTTL or UNIX timestamp
int$flagsBitfield 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 196 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ changeTTLMulti()

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

Change the expiration of multiple keys that exist.

See also
BagOStuff::changeTTL()
Parameters
string[]$keysList of keys
int$exptimeTTL or UNIX timestamp
int$flagsBitfield of BagOStuff::WRITE_* constants (since 1.33)
Returns
bool Success
Since
1.34

Reimplemented from BagOStuff.

Definition at line 261 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ clearLastError()

MultiWriteBagOStuff::clearLastError ( )

Clear the "last error" registry.

Since
1.23

Reimplemented from BagOStuff.

Definition at line 301 of file MultiWriteBagOStuff.php.

◆ decr()

MultiWriteBagOStuff::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

Reimplemented from BagOStuff.

Definition at line 279 of file MultiWriteBagOStuff.php.

References doWrite().

◆ delete()

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

Reimplemented from BagOStuff.

Definition at line 154 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ deleteMulti()

MultiWriteBagOStuff::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[]$keysList of keys
int$flagsBitfield of BagOStuff::WRITE_* constants
Returns
bool Success
Since
1.33

Reimplemented from BagOStuff.

Definition at line 252 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ deleteObjectsExpiringBefore()

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

Delete all objects expiring before a certain date.

Parameters
string | int$timestampThe reference date in MW or TS_UNIX format
callable | null$progressOptional, a function which will be called regularly during long-running operations with the percentage progress as the first parameter. [optional]
int$limitMaximum number of keys to delete [default: INF]
Returns
bool Success; false if unimplemented

Reimplemented from BagOStuff.

Definition at line 215 of file MultiWriteBagOStuff.php.

References $cache.

◆ doWrite()

MultiWriteBagOStuff::doWrite (   $indexes,
  $asyncWrites,
  $method,
array  $args 
)
protected

Apply a write method to the backing caches specified by $indexes (in order)

Parameters
int[]$indexesList of backing cache indexes
bool$asyncWrites
string$methodMethod name of backing caches
array$argsArguments to the method of backing caches
Returns
bool

Definition at line 314 of file MultiWriteBagOStuff.php.

References $args, BagOStuff\$asyncHandler, $asyncWrites, $cache, BagOStuff\$logger, serialize(), and unserialize().

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

◆ get()

MultiWriteBagOStuff::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$key
int$flagsBitfield of BagOStuff::READ_* constants [optional]
Returns
mixed Returns false on failure or if the item does not exist

Reimplemented from BagOStuff.

Definition at line 109 of file MultiWriteBagOStuff.php.

References $cache, doWrite(), and BagOStuff\fieldHasFlags().

◆ getLastError()

MultiWriteBagOStuff::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 297 of file MultiWriteBagOStuff.php.

◆ getMulti()

MultiWriteBagOStuff::getMulti ( array  $keys,
  $flags = 0 
)

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

Parameters
string[]$keysList of keys
int$flagsBitfield; supports READ_LATEST [optional]
Returns
mixed[] Map of (key => value) for existing keys

Reimplemented from BagOStuff.

Definition at line 230 of file MultiWriteBagOStuff.php.

References $keys, and $res.

◆ incr()

MultiWriteBagOStuff::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

Reimplemented from BagOStuff.

Definition at line 270 of file MultiWriteBagOStuff.php.

References doWrite().

◆ incrWithInit()

MultiWriteBagOStuff::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$keyKey built via makeKey() or makeGlobalKey()
int$exptimeTime-to-live (in seconds) or a UNIX timestamp expiration
int$valueAmount to increase the key value by [default: 1]
int | null$initValue to initialize the key to if it does not exist [default: $value]
int$flagsBit field of class WRITE_* constants [optional]
Returns
int|bool New value or false on failure
Since
1.24

Reimplemented from BagOStuff.

Definition at line 288 of file MultiWriteBagOStuff.php.

References doWrite().

◆ lock()

MultiWriteBagOStuff::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$key
int$timeoutLock wait timeout; 0 for non-blocking [optional]
int$expiryLock expiry [optional]; 1 day maximum
string$rclassAllow reentry if set and the current lock used this value
Returns
bool Success

Reimplemented from BagOStuff.

Definition at line 205 of file MultiWriteBagOStuff.php.

◆ makeGlobalKey()

MultiWriteBagOStuff::makeGlobalKey (   $class,
  $components 
)

Make a global cache key.

Since
1.27
Parameters
string$classKey class
string|int...$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 362 of file MultiWriteBagOStuff.php.

◆ makeKey()

MultiWriteBagOStuff::makeKey (   $class,
  $components 
)

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

Since
1.27
Parameters
string$classKey class
string|int...$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 358 of file MultiWriteBagOStuff.php.

◆ makeKeyInternal()

MultiWriteBagOStuff::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 354 of file MultiWriteBagOStuff.php.

References $args.

◆ merge()

MultiWriteBagOStuff::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$key
callable$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
Exceptions
InvalidArgumentException

Reimplemented from BagOStuff.

Definition at line 187 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ set()

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

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 BagOStuff.

Definition at line 145 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ setDebug()

MultiWriteBagOStuff::setDebug (   $enabled)
Parameters
bool$enabled

Reimplemented from BagOStuff.

Definition at line 102 of file MultiWriteBagOStuff.php.

References $cache.

◆ setMockTime()

MultiWriteBagOStuff::setMockTime ( $time)

Reimplemented from BagOStuff.

Definition at line 374 of file MultiWriteBagOStuff.php.

References $cache.

◆ setMulti()

MultiWriteBagOStuff::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[]$dataMap of (key => value)
int$exptimeEither an interval in seconds or a unix timestamp for expiry
int$flagsBitfield of BagOStuff::WRITE_* constants (since 1.33)
Returns
bool Success
Since
1.24

Reimplemented from BagOStuff.

Definition at line 243 of file MultiWriteBagOStuff.php.

References doWrite(), and usesAsyncWritesGivenFlags().

◆ setNewPreparedValues()

MultiWriteBagOStuff::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$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 BagOStuff.

Definition at line 370 of file MultiWriteBagOStuff.php.

◆ unlock()

MultiWriteBagOStuff::unlock (   $key)

Release an advisory lock on a key string.

Parameters
string$key
Returns
bool Success

Reimplemented from BagOStuff.

Definition at line 210 of file MultiWriteBagOStuff.php.

◆ usesAsyncWritesGivenFlags()

MultiWriteBagOStuff::usesAsyncWritesGivenFlags (   $flags)
protected
Parameters
int$flags
Returns
bool

Definition at line 350 of file MultiWriteBagOStuff.php.

References $asyncWrites, and BagOStuff\fieldHasFlags().

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

Member Data Documentation

◆ $asyncWrites

bool MultiWriteBagOStuff::$asyncWrites = false
protected

Use async secondary writes.

Definition at line 39 of file MultiWriteBagOStuff.php.

Referenced by doWrite(), and usesAsyncWritesGivenFlags().

◆ $cacheIndexes

int [] MultiWriteBagOStuff::$cacheIndexes = []
protected

List of all backing cache indexes.

Definition at line 41 of file MultiWriteBagOStuff.php.

◆ $caches

BagOStuff [] MultiWriteBagOStuff::$caches
protected

Definition at line 37 of file MultiWriteBagOStuff.php.

◆ $UPGRADE_TTL

int MultiWriteBagOStuff::$UPGRADE_TTL = 3600
staticprivate

TTL when a key is copied to a higher cache tier.

Definition at line 44 of file MultiWriteBagOStuff.php.


The documentation for this class was generated from the following file:
$cache
$cache
Definition: mcc.php:33