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ReplicatedBagOStuff Class Reference

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

Inheritance diagram for ReplicatedBagOStuff:
Collaboration diagram for ReplicatedBagOStuff:

Public Member Functions

 __construct ( $params)
 Constructor. 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 $keys, $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...
 
 unlock ( $key)
 Release an advisory lock on a key string. More...
 
- Public Member Functions inherited from BagOStuff
 __construct (array $params=[])
 Parameters include: More...
 
 getCurrentTime ()
 
 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)
 

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. More...
 
float[] $lastKeyWrites = []
 Map of (key => UNIX timestamp) More...
 
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. 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 IExpiringStore
const ATTR_EMULATION = 1
 
const ATTR_SYNCWRITES = 2
 
const ERR_NO_RESPONSE = 1
 
const ERR_NONE = 0
 
const ERR_UNEXPECTED = 3
 
const ERR_UNREACHABLE = 2
 
const QOS_EMULATION_SQL = 1
 
const QOS_SYNCWRITES_BE = 2
 
const QOS_SYNCWRITES_NONE = 1
 
const QOS_SYNCWRITES_QC = 3
 
const QOS_SYNCWRITES_SS = 4
 
const QOS_UNKNOWN = INF
 
const TTL_DAY = 86400
 
const TTL_HOUR = 3600
 
const TTL_INDEFINITE = 0
 
const TTL_MINUTE = 60
 
const TTL_MONTH = 2592000
 
const TTL_PROC_LONG = 30
 
const TTL_PROC_SHORT = 3
 
const TTL_SECOND = 1
 
const TTL_WEEK = 604800
 
const TTL_YEAR = 31536000
 
- 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 inherited from BagOStuff
callable null $asyncHandler
 
int[] $attrMap = []
 Map of (ATTR_* class constant => QOS_* class constant) More...
 
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$exptime
int$flagsBitfield 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$key
int$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 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[]$keysList of keys
int$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 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$key
int$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 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$key
Returns
bool True if the item was deleted or not found, false on failure
Parameters
int$flagsBitfield 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[]$keysList of keys
int$flagsBitfield 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$timestampThe reference date in MW or TS_UNIX format
callable | null$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 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$key
int$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 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.

References IExpiringStore\ERR_NONE.

◆ getMulti()

ReplicatedBagOStuff::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 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 224 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$keyKey to increase
int$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 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$keyKey built via makeKey() or makeGlobalKey()
int$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 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$key
int$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 126 of file ReplicatedBagOStuff.php.

◆ makeGlobalKey()

ReplicatedBagOStuff::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 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$classKey class
string|int...$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 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$key
callable$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 114 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ remarkRecentSessionWrite()

ReplicatedBagOStuff::remarkRecentSessionWrite ( array  $keys)
private
Parameters
string[]$keys

Definition at line 239 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$exptimeEither an interval in seconds or a unix timestamp for expiry
int$flagsBitfield of BagOStuff::WRITE_* constants
Returns
bool Success

Reimplemented from BagOStuff.

Definition at line 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 214 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[]$dataMap of (key => value)
int$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 151 of file ReplicatedBagOStuff.php.

References remarkRecentSessionWrite().

◆ 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: