MediaWiki REL1_37
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A cache class that directs writes to one set of servers and reads to another. More...
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, string $tag=null) | |
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, $exptime=6, $rclass='') | |
Acquire an advisory lock on a key string, exclusive to the caller. | |
makeGlobalKey ( $collection,... $components) | |
Make a cache key for the default keyspace and given components. | |
makeKey ( $collection,... $components) | |
Make a cache key for the global keyspace and given components. | |
makeKeyInternal ( $keyspace, $components) | |
Make a cache key for the given keyspace and components. | |
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, $flags=0) | |
Set an item. | |
setMockTime (&$time) | |
setMulti (array $valueByKey, $exptime=0, $flags=0) | |
Batch insertion/replace. | |
setNewPreparedValues (array $valueByKey) | |
Make a "generic" reversible cache key from the given components. | |
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. | |
isKeyGlobal ( $key) | |
Check whether a cache key is in the global keyspace. | |
registerWrapperInfoForStats (string $prefixComponent, string $statsGroup, callable $collectionCallback) | |
Register info about a caching layer class that uses BagOStuff as a backing store. | |
setDebug ( $enabled) | |
setLogger (LoggerInterface $logger) | |
Protected Member Functions | |
convertGenericKey ( $key) | |
Convert a "generic" reversible cache key into one for this cache. | |
Protected Member Functions inherited from BagOStuff | |
componentsFromGenericKey ( $key) | |
Extract the components from a "generic" reversible cache key. | |
determineKeyPrefixForStats ( $key) | |
fieldHasFlags ( $field, $flags) | |
genericKeyFromComponents (... $components) | |
At a minimum, there must be a keyspace and collection name component. | |
mergeFlagMaps (array $bags) | |
Merge the flag maps of one or more BagOStuff objects into a "lowest common denominator" map. | |
proxyCall ( $method, $arg0Sig, $resSig, array $genericArgs) | |
Call a method on behalf of wrapper BagOStuff instance that uses "generic" keys. | |
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. | |
Public Attributes inherited from Wikimedia\LightweightObjectStore\StorageAwareness | |
const | ATTR_DURABILITY = 2 |
Durability of writes; see QOS_DURABILITY_* (higher means stronger) | |
const | ATTR_EMULATION = 1 |
Emulation/fallback mode; see QOS_EMULATION_*; higher is better. | |
const | ERR_NO_RESPONSE = 1 |
Storage medium failed to yield a response. | |
const | ERR_NONE = 0 |
No storage medium error. | |
const | ERR_UNEXPECTED = 3 |
Storage medium operation failed due to usage limitations or an I/O error. | |
const | ERR_UNREACHABLE = 2 |
Storage medium could not be reached. | |
const | QOS_DURABILITY_DISK = 4 |
Data is saved to disk and writes do not usually block on fsync() | |
const | QOS_DURABILITY_NONE = 1 |
Data is never saved to begin with (blackhole store) | |
const | QOS_DURABILITY_RDBMS = 5 |
Data is saved to disk and writes usually block on fsync(), like a standard RDBMS. | |
const | QOS_DURABILITY_SCRIPT = 2 |
Data is lost at the end of the current web request or CLI script. | |
const | QOS_DURABILITY_SERVICE = 3 |
Data is lost once the service storing the data restarts. | |
const | QOS_EMULATION_SQL = 1 |
Fallback disk-based SQL store. | |
const | QOS_UNKNOWN = INF |
Generic "unknown" value; useful for comparisons (always "good enough") | |
Protected Attributes inherited from BagOStuff | |
callable null | $asyncHandler |
int[] | $attrMap = [] |
Map of (ATTR_* class constant => QOS_* class constant) | |
bool | $debugMode = true |
Whether to send debug log entries to the SPI logger instance. | |
string | $keyspace |
Default keyspace; used by makeKey() | |
LoggerInterface | $logger |
StatsdDataFactoryInterface | $stats |
array< string, array > | $wrapperInfoByPrefix = [] |
Cache key processing callbacks and info for metrics. | |
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.
Definition at line 34 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::__construct | ( | $params | ) |
Constructor.
Parameters are:
array | $params |
InvalidArgumentException |
Definition at line 60 of file ReplicatedBagOStuff.php.
References BagOStuff\mergeFlagMaps().
ReplicatedBagOStuff::add | ( | $key, | |
$value, | |||
$exptime = 0 , |
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$flags = 0 |
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) |
Insert an item if it does not already exist.
string | $key | |
mixed | $value | |
int | $exptime | |
int | $flags | Bitfield of BagOStuff::WRITE_* constants (since 1.33) |
Reimplemented from BagOStuff.
Definition at line 116 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
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.
callable | $workCallback |
Reimplemented from BagOStuff.
Definition at line 287 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::changeTTL | ( | $key, | |
$exptime = 0 , |
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$flags = 0 |
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) |
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.
string | $key | |
int | $exptime | TTL or UNIX timestamp |
int | $flags | Bitfield of BagOStuff::WRITE_* constants (since 1.33) |
Reimplemented from BagOStuff.
Definition at line 138 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::changeTTLMulti | ( | array | $keys, |
$exptime, | |||
$flags = 0 |
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) |
Change the expiration of multiple keys that exist.
string[] | $keys | List of keys |
int | $exptime | TTL or UNIX timestamp |
int | $flags | Bitfield of BagOStuff::WRITE_* constants (since 1.33) |
Reimplemented from BagOStuff.
Definition at line 216 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::clearLastError | ( | ) |
Clear the "last error" registry.
Reimplemented from BagOStuff.
Definition at line 266 of file ReplicatedBagOStuff.php.
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protected |
Convert a "generic" reversible cache key into one for this cache.
string | $key | Keyspace-prepended list of encoded components as a colon-separated value |
Reimplemented from BagOStuff.
Definition at line 283 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::decr | ( | $key, | |
$value = 1 , |
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$flags = 0 |
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) |
Decrease stored value of $key by $value while preserving its TTL.
string | $key | |
int | $value | Value to subtract from $key (default: 1) [optional] |
int | $flags | Bit field of class WRITE_* constants [optional] |
Reimplemented from BagOStuff.
Definition at line 238 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::delete | ( | $key, | |
$flags = 0 |
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) |
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.
string | $key |
int | $flags | Bitfield of BagOStuff::WRITE_* constants |
Reimplemented from BagOStuff.
Definition at line 105 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::deleteMulti | ( | array | $keys, |
$flags = 0 |
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) |
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
string[] | $keys | List of keys |
int | $flags | Bitfield of BagOStuff::WRITE_* constants |
Reimplemented from BagOStuff.
Definition at line 205 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::deleteObjectsExpiringBefore | ( | $timestamp, | |
callable | $progress = null , |
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$limit = INF , |
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string | $tag = null |
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) |
Delete all objects expiring before a certain date.
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] |
string | null | $tag | Tag to purge a single shard only. This is only supported when server tags are used in configuration. |
Reimplemented from BagOStuff.
Definition at line 167 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::get | ( | $key, | |
$flags = 0 |
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) |
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.
string | $key | |
int | $flags | Bitfield of BagOStuff::READ_* constants [optional] |
Reimplemented from BagOStuff.
Definition at line 81 of file ReplicatedBagOStuff.php.
References $readStore, BagOStuff\fieldHasFlags(), hadRecentSessionWrite(), and BagOStuff\proxyCall().
ReplicatedBagOStuff::getLastError | ( | ) |
Get the "last error" registered; clearLastError() should be called manually.
Reimplemented from BagOStuff.
Definition at line 260 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::getMulti | ( | array | $keys, |
$flags = 0 |
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) |
Get an associative array containing the item for each of the keys that have items.
string[] | $keys | List of keys |
int | $flags | Bitfield; supports READ_LATEST [optional] |
Reimplemented from BagOStuff.
Definition at line 181 of file ReplicatedBagOStuff.php.
References $readStore, BagOStuff\fieldHasFlags(), hadRecentSessionWrite(), and BagOStuff\proxyCall().
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private |
string[] | $keys |
Definition at line 310 of file ReplicatedBagOStuff.php.
References BagOStuff\getCurrentTime().
Referenced by get(), and getMulti().
ReplicatedBagOStuff::incr | ( | $key, | |
$value = 1 , |
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$flags = 0 |
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) |
Increase stored value of $key by $value while preserving its TTL.
string | $key | Key to increase |
int | $value | Value to add to $key (default: 1) [optional] |
int | $flags | Bit field of class WRITE_* constants [optional] |
Reimplemented from BagOStuff.
Definition at line 227 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::incrWithInit | ( | $key, | |
$exptime, | |||
$value = 1 , |
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$init = null , |
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$flags = 0 |
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) |
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.
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] |
Reimplemented from BagOStuff.
Definition at line 249 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::lock | ( | $key, | |
$timeout = 6 , |
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$exptime = 6 , |
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$rclass = '' |
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) |
Acquire an advisory lock on a key string, exclusive to the caller.
string | $key | |
int | $timeout | Lock wait timeout; 0 for non-blocking [optional] |
int | $exptime | Lock time-to-live in seconds; 1 day maximum [optional] |
string | $rclass | If this thread already holds the lock, and the lock was acquired using the same value for this parameter, then return true and use reference counting so that only the unlock() call from the outermost lock() caller actually releases the lock (note that only the outermost time-to-live is used) [optional] |
Reimplemented from BagOStuff.
Definition at line 149 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::makeGlobalKey | ( | $collection, | |
$components | |||
) |
Make a cache key for the default keyspace and given components.
string | $collection | Key collection name component |
string|int | ...$components Additional, ordered, key components for entity IDs |
Reimplemented from BagOStuff.
Definition at line 279 of file ReplicatedBagOStuff.php.
References BagOStuff\genericKeyFromComponents().
ReplicatedBagOStuff::makeKey | ( | $collection, | |
$components | |||
) |
Make a cache key for the global keyspace and given components.
string | $collection | Key collection name component |
string|int | ...$components Additional, ordered, key components for entity IDs |
Reimplemented from BagOStuff.
Definition at line 275 of file ReplicatedBagOStuff.php.
References BagOStuff\genericKeyFromComponents().
ReplicatedBagOStuff::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.
string | $keyspace | Keyspace component |
string[] | int[] | $components | Key components (key collection name first) |
Reimplemented from BagOStuff.
Definition at line 271 of file ReplicatedBagOStuff.php.
References BagOStuff\$keyspace, and BagOStuff\genericKeyFromComponents().
ReplicatedBagOStuff::merge | ( | $key, | |
callable | $callback, | ||
$exptime = 0 , |
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$attempts = 10 , |
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$flags = 0 |
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) |
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.
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 |
InvalidArgumentException |
Reimplemented from BagOStuff.
Definition at line 127 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
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private |
string[] | $keys |
Definition at line 325 of file ReplicatedBagOStuff.php.
References BagOStuff\getCurrentTime().
Referenced by add(), changeTTL(), changeTTLMulti(), decr(), delete(), deleteMulti(), incr(), incrWithInit(), merge(), set(), and setMulti().
ReplicatedBagOStuff::set | ( | $key, | |
$value, | |||
$exptime = 0 , |
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$flags = 0 |
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) |
Set an item.
string | $key | |
mixed | $value | |
int | $exptime | Either an interval in seconds or a unix timestamp for expiry |
int | $flags | Bitfield of BagOStuff::WRITE_* constants |
Reimplemented from BagOStuff.
Definition at line 94 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::setMockTime | ( | & | $time | ) |
float | null | &$time | Mock UNIX timestamp |
Reimplemented from BagOStuff.
Definition at line 300 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::setMulti | ( | array | $valueByKey, |
$exptime = 0 , |
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$flags = 0 |
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) |
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
mixed[] | $valueByKey | 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) |
Reimplemented from BagOStuff.
Definition at line 194 of file ReplicatedBagOStuff.php.
References remarkRecentSessionWrite().
ReplicatedBagOStuff::setNewPreparedValues | ( | array | $valueByKey | ) |
Make a "generic" reversible cache key from the given components.
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:
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.
array | $valueByKey | Map of (cache key => PHP variable value to serialize) |
Reimplemented from BagOStuff.
Definition at line 291 of file ReplicatedBagOStuff.php.
ReplicatedBagOStuff::unlock | ( | $key | ) |
Release an advisory lock on a key string.
string | $key |
Reimplemented from BagOStuff.
Definition at line 158 of file ReplicatedBagOStuff.php.
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private |
Seconds to read from the master source for a key after writing to it.
Definition at line 41 of file ReplicatedBagOStuff.php.
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private |
Map of (key => UNIX timestamp)
Definition at line 43 of file ReplicatedBagOStuff.php.
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private |
Definition at line 38 of file ReplicatedBagOStuff.php.
Referenced by get(), and getMulti().
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private |
Definition at line 36 of file ReplicatedBagOStuff.php.