--- /dev/null
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Cache
+ */
+
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+
+/**
+ * Multi-datacenter aware caching interface
+ *
+ * All operations go to the local datacenter cache, except for delete(),
+ * touchCheckKey(), and resetCheckKey(), which broadcast to all datacenters.
+ *
+ * This class is intended for caching data from primary stores.
+ * If the get() method does not return a value, then the caller
+ * should query the new value and backfill the cache using set().
+ * The preferred way to do this logic is through getWithSetCallback().
+ * When querying the store on cache miss, the closest DB replica
+ * should be used. Try to avoid heavyweight DB master or quorum reads.
+ * When the source data changes, a purge method should be called.
+ * Since purges are expensive, they should be avoided. One can do so if:
+ * - a) The object cached is immutable; or
+ * - b) Validity is checked against the source after get(); or
+ * - c) Using a modest TTL is reasonably correct and performant
+ *
+ * The simplest purge method is delete().
+ *
+ * There are three supported ways to handle broadcasted operations:
+ * - a) Configure the 'purge' EventRelayer to point to a valid PubSub endpoint
+ * that has subscribed listeners on the cache servers applying the cache updates.
+ * - b) Ignore the 'purge' EventRelayer configuration (default is NullEventRelayer)
+ * and set up mcrouter as the underlying cache backend, using one of the memcached
+ * BagOStuff classes as 'cache'. Use OperationSelectorRoute in the mcrouter settings
+ * to configure 'set' and 'delete' operations to go to all DCs via AllAsyncRoute and
+ * configure other operations to go to the local DC via PoolRoute (for reference,
+ * see https://github.com/facebook/mcrouter/wiki/List-of-Route-Handles).
+ * - c) Ignore the 'purge' EventRelayer configuration (default is NullEventRelayer)
+ * and set up dynomite as cache middleware between the web servers and either
+ * memcached or redis. This will also broadcast all key setting operations, not just purges,
+ * which can be useful for cache warming. Writes are eventually consistent via the
+ * Dynamo replication model (see https://github.com/Netflix/dynomite).
+ *
+ * Broadcasted operations like delete() and touchCheckKey() are done asynchronously
+ * in all datacenters this way, though the local one should likely be near immediate.
+ *
+ * This means that callers in all datacenters may see older values for however many
+ * milliseconds that the purge took to reach that datacenter. As with any cache, this
+ * should not be relied on for cases where reads are used to determine writes to source
+ * (e.g. non-cache) data stores, except when reading immutable data.
+ *
+ * All values are wrapped in metadata arrays. Keys use a "WANCache:" prefix
+ * to avoid collisions with keys that are not wrapped as metadata arrays. The
+ * prefixes are as follows:
+ * - a) "WANCache:v" : used for regular value keys
+ * - b) "WANCache:i" : used for temporarily storing values of tombstoned keys
+ * - c) "WANCache:t" : used for storing timestamp "check" keys
+ * - d) "WANCache:m" : used for temporary mutex keys to avoid cache stampedes
+ *
+ * @ingroup Cache
+ * @since 1.26
+ */
+class WANObjectCache implements IExpiringStore, LoggerAwareInterface {
+ /** @var BagOStuff The local datacenter cache */
+ protected $cache;
+ /** @var HashBagOStuff[] Map of group PHP instance caches */
+ protected $processCaches = [];
+ /** @var string Purge channel name */
+ protected $purgeChannel;
+ /** @var EventRelayer Bus that handles purge broadcasts */
+ protected $purgeRelayer;
+ /** @var LoggerInterface */
+ protected $logger;
+
+ /** @var int ERR_* constant for the "last error" registry */
+ protected $lastRelayError = self::ERR_NONE;
+
+ /** @var int Callback stack depth for getWithSetCallback() */
+ private $callbackDepth = 0;
+ /** @var mixed[] Temporary warm-up cache */
+ private $warmupCache = [];
+ /** @var int Key fetched */
+ private $warmupKeyMisses = 0;
+
+ /** Max time expected to pass between delete() and DB commit finishing */
+ const MAX_COMMIT_DELAY = 3;
+ /** Max replication+snapshot lag before applying TTL_LAGGED or disallowing set() */
+ const MAX_READ_LAG = 7;
+ /** Seconds to tombstone keys on delete() */
+ const HOLDOFF_TTL = 11; // MAX_COMMIT_DELAY + MAX_READ_LAG + 1
+
+ /** Seconds to keep dependency purge keys around */
+ const CHECK_KEY_TTL = self::TTL_YEAR;
+ /** Seconds to keep lock keys around */
+ const LOCK_TTL = 10;
+ /** Default remaining TTL at which to consider pre-emptive regeneration */
+ const LOW_TTL = 30;
+ /** Default time-since-expiry on a miss that makes a key "hot" */
+ const LOCK_TSE = 1;
+
+ /** Never consider performing "popularity" refreshes until a key reaches this age */
+ const AGE_NEW = 60;
+ /** The time length of the "popularity" refresh window for hot keys */
+ const HOT_TTR = 900;
+ /** Hits/second for a refresh to be expected within the "popularity" window */
+ const HIT_RATE_HIGH = 1;
+ /** Seconds to ramp up to the "popularity" refresh chance after a key is no longer new */
+ const RAMPUP_TTL = 30;
+
+ /** Idiom for getWithSetCallback() callbacks to avoid calling set() */
+ const TTL_UNCACHEABLE = -1;
+ /** Idiom for getWithSetCallback() callbacks to 'lockTSE' logic */
+ const TSE_NONE = -1;
+ /** Max TTL to store keys when a data sourced is lagged */
+ const TTL_LAGGED = 30;
+ /** Idiom for delete() for "no hold-off" */
+ const HOLDOFF_NONE = 0;
+ /** Idiom for getWithSetCallback() for "no minimum required as-of timestamp" */
+ const MIN_TIMESTAMP_NONE = 0.0;
+
+ /** Tiny negative float to use when CTL comes up >= 0 due to clock skew */
+ const TINY_NEGATIVE = -0.000001;
+
+ /** Cache format version number */
+ const VERSION = 1;
+
+ const FLD_VERSION = 0; // key to cache version number
+ const FLD_VALUE = 1; // key to the cached value
+ const FLD_TTL = 2; // key to the original TTL
+ const FLD_TIME = 3; // key to the cache time
+ const FLD_FLAGS = 4; // key to the flags bitfield
+ const FLD_HOLDOFF = 5; // key to any hold-off TTL
+
+ /** @var int Treat this value as expired-on-arrival */
+ const FLG_STALE = 1;
+
+ const ERR_NONE = 0; // no error
+ const ERR_NO_RESPONSE = 1; // no response
+ const ERR_UNREACHABLE = 2; // can't connect
+ const ERR_UNEXPECTED = 3; // response gave some error
+ const ERR_RELAY = 4; // relay broadcast failed
+
+ const VALUE_KEY_PREFIX = 'WANCache:v:';
+ const INTERIM_KEY_PREFIX = 'WANCache:i:';
+ const TIME_KEY_PREFIX = 'WANCache:t:';
+ const MUTEX_KEY_PREFIX = 'WANCache:m:';
+
+ const PURGE_VAL_PREFIX = 'PURGED:';
+
+ const VFLD_DATA = 'WOC:d'; // key to the value of versioned data
+ const VFLD_VERSION = 'WOC:v'; // key to the version of the value present
+
+ const PC_PRIMARY = 'primary:1000'; // process cache name and max key count
+
+ const DEFAULT_PURGE_CHANNEL = 'wancache-purge';
+
+ /**
+ * @param array $params
+ * - cache : BagOStuff object for a persistent cache
+ * - channels : Map of (action => channel string). Actions include "purge".
+ * - relayers : Map of (action => EventRelayer object). Actions include "purge".
+ * - logger : LoggerInterface object
+ */
+ public function __construct( array $params ) {
+ $this->cache = $params['cache'];
+ $this->purgeChannel = isset( $params['channels']['purge'] )
+ ? $params['channels']['purge']
+ : self::DEFAULT_PURGE_CHANNEL;
+ $this->purgeRelayer = isset( $params['relayers']['purge'] )
+ ? $params['relayers']['purge']
+ : new EventRelayerNull( [] );
+ $this->setLogger( isset( $params['logger'] ) ? $params['logger'] : new NullLogger() );
+ }
+
+ public function setLogger( LoggerInterface $logger ) {
+ $this->logger = $logger;
+ }
+
+ /**
+ * Get an instance that wraps EmptyBagOStuff
+ *
+ * @return WANObjectCache
+ */
+ public static function newEmpty() {
+ return new self( [
+ 'cache' => new EmptyBagOStuff(),
+ 'pool' => 'empty'
+ ] );
+ }
+
+ /**
+ * Fetch the value of a key from cache
+ *
+ * If supplied, $curTTL is set to the remaining TTL (current time left):
+ * - a) INF; if $key exists, has no TTL, and is not expired by $checkKeys
+ * - b) float (>=0); if $key exists, has a TTL, and is not expired by $checkKeys
+ * - c) float (<0); if $key is tombstoned, stale, or existing but expired by $checkKeys
+ * - d) null; if $key does not exist and is not tombstoned
+ *
+ * If a key is tombstoned, $curTTL will reflect the time since delete().
+ *
+ * The timestamp of $key will be checked against the last-purge timestamp
+ * of each of $checkKeys. Those $checkKeys not in cache will have the last-purge
+ * initialized to the current timestamp. If any of $checkKeys have a timestamp
+ * greater than that of $key, then $curTTL will reflect how long ago $key
+ * became invalid. Callers can use $curTTL to know when the value is stale.
+ * The $checkKeys parameter allow mass invalidations by updating a single key:
+ * - a) Each "check" key represents "last purged" of some source data
+ * - b) Callers pass in relevant "check" keys as $checkKeys in get()
+ * - c) When the source data that "check" keys represent changes,
+ * the touchCheckKey() method is called on them
+ *
+ * Source data entities might exists in a DB that uses snapshot isolation
+ * (e.g. the default REPEATABLE-READ in innoDB). Even for mutable data, that
+ * isolation can largely be maintained by doing the following:
+ * - a) Calling delete() on entity change *and* creation, before DB commit
+ * - b) Keeping transaction duration shorter than delete() hold-off TTL
+ *
+ * However, pre-snapshot values might still be seen if an update was made
+ * in a remote datacenter but the purge from delete() didn't relay yet.
+ *
+ * Consider using getWithSetCallback() instead of get() and set() cycles.
+ * That method has cache slam avoiding features for hot/expensive keys.
+ *
+ * @param string $key Cache key
+ * @param mixed &$curTTL Approximate TTL left on the key if present/tombstoned [returned]
+ * @param array $checkKeys List of "check" keys
+ * @param float &$asOf UNIX timestamp of cached value; null on failure [returned]
+ * @return mixed Value of cache key or false on failure
+ */
+ final public function get( $key, &$curTTL = null, array $checkKeys = [], &$asOf = null ) {
+ $curTTLs = [];
+ $asOfs = [];
+ $values = $this->getMulti( [ $key ], $curTTLs, $checkKeys, $asOfs );
+ $curTTL = isset( $curTTLs[$key] ) ? $curTTLs[$key] : null;
+ $asOf = isset( $asOfs[$key] ) ? $asOfs[$key] : null;
+
+ return isset( $values[$key] ) ? $values[$key] : false;
+ }
+
+ /**
+ * Fetch the value of several keys from cache
+ *
+ * @see WANObjectCache::get()
+ *
+ * @param array $keys List of cache keys
+ * @param array &$curTTLs Map of (key => approximate TTL left) for existing keys [returned]
+ * @param array $checkKeys List of check keys to apply to all $keys. May also apply "check"
+ * keys to specific cache keys only by using cache keys as keys in the $checkKeys array.
+ * @param float[] &$asOfs Map of (key => UNIX timestamp of cached value; null on failure)
+ * @return array Map of (key => value) for keys that exist and are not tombstoned
+ */
+ final public function getMulti(
+ array $keys, &$curTTLs = [], array $checkKeys = [], array &$asOfs = []
+ ) {
+ $result = [];
+ $curTTLs = [];
+ $asOfs = [];
+
+ $vPrefixLen = strlen( self::VALUE_KEY_PREFIX );
+ $valueKeys = self::prefixCacheKeys( $keys, self::VALUE_KEY_PREFIX );
+
+ $checkKeysForAll = [];
+ $checkKeysByKey = [];
+ $checkKeysFlat = [];
+ foreach ( $checkKeys as $i => $checkKeyGroup ) {
+ $prefixed = self::prefixCacheKeys( (array)$checkKeyGroup, self::TIME_KEY_PREFIX );
+ $checkKeysFlat = array_merge( $checkKeysFlat, $prefixed );
+ // Is this check keys for a specific cache key, or for all keys being fetched?
+ if ( is_int( $i ) ) {
+ $checkKeysForAll = array_merge( $checkKeysForAll, $prefixed );
+ } else {
+ $checkKeysByKey[$i] = isset( $checkKeysByKey[$i] )
+ ? array_merge( $checkKeysByKey[$i], $prefixed )
+ : $prefixed;
+ }
+ }
+
+ // Fetch all of the raw values
+ $keysGet = array_merge( $valueKeys, $checkKeysFlat );
+ if ( $this->warmupCache ) {
+ $wrappedValues = array_intersect_key( $this->warmupCache, array_flip( $keysGet ) );
+ $keysGet = array_diff( $keysGet, array_keys( $wrappedValues ) ); // keys left to fetch
+ $this->warmupKeyMisses += count( $keysGet );
+ } else {
+ $wrappedValues = [];
+ }
+ if ( $keysGet ) {
+ $wrappedValues += $this->cache->getMulti( $keysGet );
+ }
+ // Time used to compare/init "check" keys (derived after getMulti() to be pessimistic)
+ $now = microtime( true );
+
+ // Collect timestamps from all "check" keys
+ $purgeValuesForAll = $this->processCheckKeys( $checkKeysForAll, $wrappedValues, $now );
+ $purgeValuesByKey = [];
+ foreach ( $checkKeysByKey as $cacheKey => $checks ) {
+ $purgeValuesByKey[$cacheKey] =
+ $this->processCheckKeys( $checks, $wrappedValues, $now );
+ }
+
+ // Get the main cache value for each key and validate them
+ foreach ( $valueKeys as $vKey ) {
+ if ( !isset( $wrappedValues[$vKey] ) ) {
+ continue; // not found
+ }
+
+ $key = substr( $vKey, $vPrefixLen ); // unprefix
+
+ list( $value, $curTTL ) = $this->unwrap( $wrappedValues[$vKey], $now );
+ if ( $value !== false ) {
+ $result[$key] = $value;
+
+ // Force dependant keys to be invalid for a while after purging
+ // to reduce race conditions involving stale data getting cached
+ $purgeValues = $purgeValuesForAll;
+ if ( isset( $purgeValuesByKey[$key] ) ) {
+ $purgeValues = array_merge( $purgeValues, $purgeValuesByKey[$key] );
+ }
+ foreach ( $purgeValues as $purge ) {
+ $safeTimestamp = $purge[self::FLD_TIME] + $purge[self::FLD_HOLDOFF];
+ if ( $safeTimestamp >= $wrappedValues[$vKey][self::FLD_TIME] ) {
+ // How long ago this value was expired by *this* check key
+ $ago = min( $purge[self::FLD_TIME] - $now, self::TINY_NEGATIVE );
+ // How long ago this value was expired by *any* known check key
+ $curTTL = min( $curTTL, $ago );
+ }
+ }
+ }
+ $curTTLs[$key] = $curTTL;
+ $asOfs[$key] = ( $value !== false ) ? $wrappedValues[$vKey][self::FLD_TIME] : null;
+ }
+
+ return $result;
+ }
+
+ /**
+ * @since 1.27
+ * @param array $timeKeys List of prefixed time check keys
+ * @param array $wrappedValues
+ * @param float $now
+ * @return array List of purge value arrays
+ */
+ private function processCheckKeys( array $timeKeys, array $wrappedValues, $now ) {
+ $purgeValues = [];
+ foreach ( $timeKeys as $timeKey ) {
+ $purge = isset( $wrappedValues[$timeKey] )
+ ? self::parsePurgeValue( $wrappedValues[$timeKey] )
+ : false;
+ if ( $purge === false ) {
+ // Key is not set or invalid; regenerate
+ $newVal = $this->makePurgeValue( $now, self::HOLDOFF_TTL );
+ $this->cache->add( $timeKey, $newVal, self::CHECK_KEY_TTL );
+ $purge = self::parsePurgeValue( $newVal );
+ }
+ $purgeValues[] = $purge;
+ }
+ return $purgeValues;
+ }
+
+ /**
+ * Set the value of a key in cache
+ *
+ * Simply calling this method when source data changes is not valid because
+ * the changes do not replicate to the other WAN sites. In that case, delete()
+ * should be used instead. This method is intended for use on cache misses.
+ *
+ * If the data was read from a snapshot-isolated transactions (e.g. the default
+ * REPEATABLE-READ in innoDB), use 'since' to avoid the following race condition:
+ * - a) T1 starts
+ * - b) T2 updates a row, calls delete(), and commits
+ * - c) The HOLDOFF_TTL passes, expiring the delete() tombstone
+ * - d) T1 reads the row and calls set() due to a cache miss
+ * - e) Stale value is stuck in cache
+ *
+ * Setting 'lag' and 'since' help avoids keys getting stuck in stale states.
+ *
+ * Example usage:
+ * @code
+ * $dbr = wfGetDB( DB_REPLICA );
+ * $setOpts = Database::getCacheSetOptions( $dbr );
+ * // Fetch the row from the DB
+ * $row = $dbr->selectRow( ... );
+ * $key = $cache->makeKey( 'building', $buildingId );
+ * $cache->set( $key, $row, $cache::TTL_DAY, $setOpts );
+ * @endcode
+ *
+ * @param string $key Cache key
+ * @param mixed $value
+ * @param int $ttl Seconds to live. Special values are:
+ * - WANObjectCache::TTL_INDEFINITE: Cache forever
+ * @param array $opts Options map:
+ * - lag : Seconds of replica DB lag. Typically, this is either the replica DB lag
+ * before the data was read or, if applicable, the replica DB lag before
+ * the snapshot-isolated transaction the data was read from started.
+ * Use false to indicate that replication is not running.
+ * Default: 0 seconds
+ * - since : UNIX timestamp of the data in $value. Typically, this is either
+ * the current time the data was read or (if applicable) the time when
+ * the snapshot-isolated transaction the data was read from started.
+ * Default: 0 seconds
+ * - pending : Whether this data is possibly from an uncommitted write transaction.
+ * Generally, other threads should not see values from the future and
+ * they certainly should not see ones that ended up getting rolled back.
+ * Default: false
+ * - lockTSE : if excessive replication/snapshot lag is detected, then store the value
+ * with this TTL and flag it as stale. This is only useful if the reads for
+ * this key use getWithSetCallback() with "lockTSE" set.
+ * Default: WANObjectCache::TSE_NONE
+ * - staleTTL : Seconds to keep the key around if it is stale. The get()/getMulti()
+ * methods return such stale values with a $curTTL of 0, and getWithSetCallback()
+ * will call the regeneration callback in such cases, passing in the old value
+ * and its as-of time to the callback. This is useful if adaptiveTTL() is used
+ * on the old value's as-of time when it is verified as still being correct.
+ * Default: 0.
+ * @note Options added in 1.28: staleTTL
+ * @return bool Success
+ */
+ final public function set( $key, $value, $ttl = 0, array $opts = [] ) {
+ $now = microtime( true );
+ $lockTSE = isset( $opts['lockTSE'] ) ? $opts['lockTSE'] : self::TSE_NONE;
+ $age = isset( $opts['since'] ) ? max( 0, $now - $opts['since'] ) : 0;
+ $lag = isset( $opts['lag'] ) ? $opts['lag'] : 0;
+ $staleTTL = isset( $opts['staleTTL'] ) ? $opts['staleTTL'] : 0;
+
+ // Do not cache potentially uncommitted data as it might get rolled back
+ if ( !empty( $opts['pending'] ) ) {
+ $this->logger->info( "Rejected set() for $key due to pending writes." );
+
+ return true; // no-op the write for being unsafe
+ }
+
+ $wrapExtra = []; // additional wrapped value fields
+ // Check if there's a risk of writing stale data after the purge tombstone expired
+ if ( $lag === false || ( $lag + $age ) > self::MAX_READ_LAG ) {
+ // Case A: read lag with "lockTSE"; save but record value as stale
+ if ( $lockTSE >= 0 ) {
+ $ttl = max( 1, (int)$lockTSE ); // set() expects seconds
+ $wrapExtra[self::FLD_FLAGS] = self::FLG_STALE; // mark as stale
+ // Case B: any long-running transaction; ignore this set()
+ } elseif ( $age > self::MAX_READ_LAG ) {
+ $this->logger->info( "Rejected set() for $key due to snapshot lag." );
+
+ return true; // no-op the write for being unsafe
+ // Case C: high replication lag; lower TTL instead of ignoring all set()s
+ } elseif ( $lag === false || $lag > self::MAX_READ_LAG ) {
+ $ttl = $ttl ? min( $ttl, self::TTL_LAGGED ) : self::TTL_LAGGED;
+ $this->logger->warning( "Lowered set() TTL for $key due to replication lag." );
+ // Case D: medium length request with medium replication lag; ignore this set()
+ } else {
+ $this->logger->info( "Rejected set() for $key due to high read lag." );
+
+ return true; // no-op the write for being unsafe
+ }
+ }
+
+ // Wrap that value with time/TTL/version metadata
+ $wrapped = $this->wrap( $value, $ttl, $now ) + $wrapExtra;
+
+ $func = function ( $cache, $key, $cWrapped ) use ( $wrapped ) {
+ return ( is_string( $cWrapped ) )
+ ? false // key is tombstoned; do nothing
+ : $wrapped;
+ };
+
+ return $this->cache->merge( self::VALUE_KEY_PREFIX . $key, $func, $ttl + $staleTTL, 1 );
+ }
+
+ /**
+ * Purge a key from all datacenters
+ *
+ * This should only be called when the underlying data (being cached)
+ * changes in a significant way. This deletes the key and starts a hold-off
+ * period where the key cannot be written to for a few seconds (HOLDOFF_TTL).
+ * This is done to avoid the following race condition:
+ * - a) Some DB data changes and delete() is called on a corresponding key
+ * - b) A request refills the key with a stale value from a lagged DB
+ * - c) The stale value is stuck there until the key is expired/evicted
+ *
+ * This is implemented by storing a special "tombstone" value at the cache
+ * key that this class recognizes; get() calls will return false for the key
+ * and any set() calls will refuse to replace tombstone values at the key.
+ * For this to always avoid stale value writes, the following must hold:
+ * - a) Replication lag is bounded to being less than HOLDOFF_TTL; or
+ * - b) If lag is higher, the DB will have gone into read-only mode already
+ *
+ * Note that set() can also be lag-aware and lower the TTL if it's high.
+ *
+ * When using potentially long-running ACID transactions, a good pattern is
+ * to use a pre-commit hook to issue the delete. This means that immediately
+ * after commit, callers will see the tombstone in cache upon purge relay.
+ * It also avoids the following race condition:
+ * - a) T1 begins, changes a row, and calls delete()
+ * - b) The HOLDOFF_TTL passes, expiring the delete() tombstone
+ * - c) T2 starts, reads the row and calls set() due to a cache miss
+ * - d) T1 finally commits
+ * - e) Stale value is stuck in cache
+ *
+ * Example usage:
+ * @code
+ * $dbw->startAtomic( __METHOD__ ); // start of request
+ * ... <execute some stuff> ...
+ * // Update the row in the DB
+ * $dbw->update( ... );
+ * $key = $cache->makeKey( 'homes', $homeId );
+ * // Purge the corresponding cache entry just before committing
+ * $dbw->onTransactionPreCommitOrIdle( function() use ( $cache, $key ) {
+ * $cache->delete( $key );
+ * } );
+ * ... <execute some stuff> ...
+ * $dbw->endAtomic( __METHOD__ ); // end of request
+ * @endcode
+ *
+ * The $ttl parameter can be used when purging values that have not actually changed
+ * recently. For example, a cleanup script to purge cache entries does not really need
+ * a hold-off period, so it can use HOLDOFF_NONE. Likewise for user-requested purge.
+ * Note that $ttl limits the effective range of 'lockTSE' for getWithSetCallback().
+ *
+ * If called twice on the same key, then the last hold-off TTL takes precedence. For
+ * idempotence, the $ttl should not vary for different delete() calls on the same key.
+ *
+ * @param string $key Cache key
+ * @param int $ttl Tombstone TTL; Default: WANObjectCache::HOLDOFF_TTL
+ * @return bool True if the item was purged or not found, false on failure
+ */
+ final public function delete( $key, $ttl = self::HOLDOFF_TTL ) {
+ $key = self::VALUE_KEY_PREFIX . $key;
+
+ if ( $ttl <= 0 ) {
+ // Publish the purge to all datacenters
+ $ok = $this->relayDelete( $key );
+ } else {
+ // Publish the purge to all datacenters
+ $ok = $this->relayPurge( $key, $ttl, self::HOLDOFF_NONE );
+ }
+
+ return $ok;
+ }
+
+ /**
+ * Fetch the value of a timestamp "check" key
+ *
+ * The key will be *initialized* to the current time if not set,
+ * so only call this method if this behavior is actually desired
+ *
+ * The timestamp can be used to check whether a cached value is valid.
+ * Callers should not assume that this returns the same timestamp in
+ * all datacenters due to relay delays.
+ *
+ * The level of staleness can roughly be estimated from this key, but
+ * if the key was evicted from cache, such calculations may show the
+ * time since expiry as ~0 seconds.
+ *
+ * Note that "check" keys won't collide with other regular keys.
+ *
+ * @param string $key
+ * @return float UNIX timestamp of the check key
+ */
+ final public function getCheckKeyTime( $key ) {
+ $key = self::TIME_KEY_PREFIX . $key;
+
+ $purge = self::parsePurgeValue( $this->cache->get( $key ) );
+ if ( $purge !== false ) {
+ $time = $purge[self::FLD_TIME];
+ } else {
+ // Casting assures identical floats for the next getCheckKeyTime() calls
+ $now = (string)microtime( true );
+ $this->cache->add( $key,
+ $this->makePurgeValue( $now, self::HOLDOFF_TTL ),
+ self::CHECK_KEY_TTL
+ );
+ $time = (float)$now;
+ }
+
+ return $time;
+ }
+
+ /**
+ * Purge a "check" key from all datacenters, invalidating keys that use it
+ *
+ * This should only be called when the underlying data (being cached)
+ * changes in a significant way, and it is impractical to call delete()
+ * on all keys that should be changed. When get() is called on those
+ * keys, the relevant "check" keys must be supplied for this to work.
+ *
+ * The "check" key essentially represents a last-modified field.
+ * When touched, the field will be updated on all cache servers.
+ * Keys using it via get(), getMulti(), or getWithSetCallback() will
+ * be invalidated. It is treated as being HOLDOFF_TTL seconds in the future
+ * by those methods to avoid race conditions where dependent keys get updated
+ * with stale values (e.g. from a DB replica DB).
+ *
+ * This is typically useful for keys with hardcoded names or in some cases
+ * dynamically generated names where a low number of combinations exist.
+ * When a few important keys get a large number of hits, a high cache
+ * time is usually desired as well as "lockTSE" logic. The resetCheckKey()
+ * method is less appropriate in such cases since the "time since expiry"
+ * cannot be inferred, causing any get() after the reset to treat the key
+ * as being "hot", resulting in more stale value usage.
+ *
+ * Note that "check" keys won't collide with other regular keys.
+ *
+ * @see WANObjectCache::get()
+ * @see WANObjectCache::getWithSetCallback()
+ * @see WANObjectCache::resetCheckKey()
+ *
+ * @param string $key Cache key
+ * @param int $holdoff HOLDOFF_TTL or HOLDOFF_NONE constant
+ * @return bool True if the item was purged or not found, false on failure
+ */
+ final public function touchCheckKey( $key, $holdoff = self::HOLDOFF_TTL ) {
+ // Publish the purge to all datacenters
+ return $this->relayPurge( self::TIME_KEY_PREFIX . $key, self::CHECK_KEY_TTL, $holdoff );
+ }
+
+ /**
+ * Delete a "check" key from all datacenters, invalidating keys that use it
+ *
+ * This is similar to touchCheckKey() in that keys using it via get(), getMulti(),
+ * or getWithSetCallback() will be invalidated. The differences are:
+ * - a) The "check" key will be deleted from all caches and lazily
+ * re-initialized when accessed (rather than set everywhere)
+ * - b) Thus, dependent keys will be known to be invalid, but not
+ * for how long (they are treated as "just" purged), which
+ * effects any lockTSE logic in getWithSetCallback()
+ * - c) Since "check" keys are initialized only on the server the key hashes
+ * to, any temporary ejection of that server will cause the value to be
+ * seen as purged as a new server will initialize the "check" key.
+ *
+ * The advantage is that this does not place high TTL keys on every cache
+ * server, making it better for code that will cache many different keys
+ * and either does not use lockTSE or uses a low enough TTL anyway.
+ *
+ * This is typically useful for keys with dynamically generated names
+ * where a high number of combinations exist.
+ *
+ * Note that "check" keys won't collide with other regular keys.
+ *
+ * @see WANObjectCache::get()
+ * @see WANObjectCache::getWithSetCallback()
+ * @see WANObjectCache::touchCheckKey()
+ *
+ * @param string $key Cache key
+ * @return bool True if the item was purged or not found, false on failure
+ */
+ final public function resetCheckKey( $key ) {
+ // Publish the purge to all datacenters
+ return $this->relayDelete( self::TIME_KEY_PREFIX . $key );
+ }
+
+ /**
+ * Method to fetch/regenerate cache keys
+ *
+ * On cache miss, the key will be set to the callback result via set()
+ * (unless the callback returns false) and that result will be returned.
+ * The arguments supplied to the callback are:
+ * - $oldValue : current cache value or false if not present
+ * - &$ttl : a reference to the TTL which can be altered
+ * - &$setOpts : a reference to options for set() which can be altered
+ * - $oldAsOf : generation UNIX timestamp of $oldValue or null if not present (since 1.28)
+ *
+ * It is strongly recommended to set the 'lag' and 'since' fields to avoid race conditions
+ * that can cause stale values to get stuck at keys. Usually, callbacks ignore the current
+ * value, but it can be used to maintain "most recent X" values that come from time or
+ * sequence based source data, provided that the "as of" id/time is tracked. Note that
+ * preemptive regeneration and $checkKeys can result in a non-false current value.
+ *
+ * Usage of $checkKeys is similar to get() and getMulti(). However, rather than the caller
+ * having to inspect a "current time left" variable (e.g. $curTTL, $curTTLs), a cache
+ * regeneration will automatically be triggered using the callback.
+ *
+ * The simplest way to avoid stampedes for hot keys is to use
+ * the 'lockTSE' option in $opts. If cache purges are needed, also:
+ * - a) Pass $key into $checkKeys
+ * - b) Use touchCheckKey( $key ) instead of delete( $key )
+ *
+ * Example usage (typical key):
+ * @code
+ * $catInfo = $cache->getWithSetCallback(
+ * // Key to store the cached value under
+ * $cache->makeKey( 'cat-attributes', $catId ),
+ * // Time-to-live (in seconds)
+ * $cache::TTL_MINUTE,
+ * // Function that derives the new key value
+ * function ( $oldValue, &$ttl, array &$setOpts ) {
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * return $dbr->selectRow( ... );
+ * }
+ * );
+ * @endcode
+ *
+ * Example usage (key that is expensive and hot):
+ * @code
+ * $catConfig = $cache->getWithSetCallback(
+ * // Key to store the cached value under
+ * $cache->makeKey( 'site-cat-config' ),
+ * // Time-to-live (in seconds)
+ * $cache::TTL_DAY,
+ * // Function that derives the new key value
+ * function ( $oldValue, &$ttl, array &$setOpts ) {
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * return CatConfig::newFromRow( $dbr->selectRow( ... ) );
+ * },
+ * [
+ * // Calling touchCheckKey() on this key invalidates the cache
+ * 'checkKeys' => [ $cache->makeKey( 'site-cat-config' ) ],
+ * // Try to only let one datacenter thread manage cache updates at a time
+ * 'lockTSE' => 30,
+ * // Avoid querying cache servers multiple times in a web request
+ * 'pcTTL' => $cache::TTL_PROC_LONG
+ * ]
+ * );
+ * @endcode
+ *
+ * Example usage (key with dynamic dependencies):
+ * @code
+ * $catState = $cache->getWithSetCallback(
+ * // Key to store the cached value under
+ * $cache->makeKey( 'cat-state', $cat->getId() ),
+ * // Time-to-live (seconds)
+ * $cache::TTL_HOUR,
+ * // Function that derives the new key value
+ * function ( $oldValue, &$ttl, array &$setOpts ) {
+ * // Determine new value from the DB
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * return CatState::newFromResults( $dbr->select( ... ) );
+ * },
+ * [
+ * // The "check" keys that represent things the value depends on;
+ * // Calling touchCheckKey() on any of them invalidates the cache
+ * 'checkKeys' => [
+ * $cache->makeKey( 'sustenance-bowls', $cat->getRoomId() ),
+ * $cache->makeKey( 'people-present', $cat->getHouseId() ),
+ * $cache->makeKey( 'cat-laws', $cat->getCityId() ),
+ * ]
+ * ]
+ * );
+ * @endcode
+ *
+ * Example usage (hot key holding most recent 100 events):
+ * @code
+ * $lastCatActions = $cache->getWithSetCallback(
+ * // Key to store the cached value under
+ * $cache->makeKey( 'cat-last-actions', 100 ),
+ * // Time-to-live (in seconds)
+ * 10,
+ * // Function that derives the new key value
+ * function ( $oldValue, &$ttl, array &$setOpts ) {
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * // Start off with the last cached list
+ * $list = $oldValue ?: [];
+ * // Fetch the last 100 relevant rows in descending order;
+ * // only fetch rows newer than $list[0] to reduce scanning
+ * $rows = iterator_to_array( $dbr->select( ... ) );
+ * // Merge them and get the new "last 100" rows
+ * return array_slice( array_merge( $new, $list ), 0, 100 );
+ * },
+ * [
+ * // Try to only let one datacenter thread manage cache updates at a time
+ * 'lockTSE' => 30,
+ * // Use a magic value when no cache value is ready rather than stampeding
+ * 'busyValue' => 'computing'
+ * ]
+ * );
+ * @endcode
+ *
+ * @see WANObjectCache::get()
+ * @see WANObjectCache::set()
+ *
+ * @param string $key Cache key
+ * @param int $ttl Seconds to live for key updates. Special values are:
+ * - WANObjectCache::TTL_INDEFINITE: Cache forever
+ * - WANObjectCache::TTL_UNCACHEABLE: Do not cache at all
+ * @param callable $callback Value generation function
+ * @param array $opts Options map:
+ * - checkKeys: List of "check" keys. The key at $key will be seen as invalid when either
+ * touchCheckKey() or resetCheckKey() is called on any of these keys.
+ * Default: [].
+ * - lockTSE: If the key is tombstoned or expired (by checkKeys) less than this many seconds
+ * ago, then try to have a single thread handle cache regeneration at any given time.
+ * Other threads will try to use stale values if possible. If, on miss, the time since
+ * expiration is low, the assumption is that the key is hot and that a stampede is worth
+ * avoiding. Setting this above WANObjectCache::HOLDOFF_TTL makes no difference. The
+ * higher this is set, the higher the worst-case staleness can be.
+ * Use WANObjectCache::TSE_NONE to disable this logic.
+ * Default: WANObjectCache::TSE_NONE.
+ * - busyValue: If no value exists and another thread is currently regenerating it, use this
+ * as a fallback value (or a callback to generate such a value). This assures that cache
+ * stampedes cannot happen if the value falls out of cache. This can be used as insurance
+ * against cache regeneration becoming very slow for some reason (greater than the TTL).
+ * Default: null.
+ * - pcTTL: Process cache the value in this PHP instance for this many seconds. This avoids
+ * network I/O when a key is read several times. This will not cache when the callback
+ * returns false, however. Note that any purges will not be seen while process cached;
+ * since the callback should use replica DBs and they may be lagged or have snapshot
+ * isolation anyway, this should not typically matter.
+ * Default: WANObjectCache::TTL_UNCACHEABLE.
+ * - pcGroup: Process cache group to use instead of the primary one. If set, this must be
+ * of the format ALPHANUMERIC_NAME:MAX_KEY_SIZE, e.g. "mydata:10". Use this for storing
+ * large values, small yet numerous values, or some values with a high cost of eviction.
+ * It is generally preferable to use a class constant when setting this value.
+ * This has no effect unless pcTTL is used.
+ * Default: WANObjectCache::PC_PRIMARY.
+ * - version: Integer version number. This allows for callers to make breaking changes to
+ * how values are stored while maintaining compatability and correct cache purges. New
+ * versions are stored alongside older versions concurrently. Avoid storing class objects
+ * however, as this reduces compatibility (due to serialization).
+ * Default: null.
+ * - minAsOf: Reject values if they were generated before this UNIX timestamp.
+ * This is useful if the source of a key is suspected of having possibly changed
+ * recently, and the caller wants any such changes to be reflected.
+ * Default: WANObjectCache::MIN_TIMESTAMP_NONE.
+ * - hotTTR: Expected time-till-refresh for keys that average ~1 hit/second.
+ * This should be greater than "ageNew". Keys with higher hit rates will regenerate
+ * more often. This is useful when a popular key is changed but the cache purge was
+ * delayed or lost. Seldom used keys are rarely affected by this setting, unless an
+ * extremely low "hotTTR" value is passed in.
+ * Default: WANObjectCache::HOT_TTR.
+ * - lowTTL: Consider pre-emptive updates when the current TTL (seconds) of the key is less
+ * than this. It becomes more likely over time, becoming certain once the key is expired.
+ * Default: WANObjectCache::LOW_TTL.
+ * - ageNew: Consider popularity refreshes only once a key reaches this age in seconds.
+ * Default: WANObjectCache::AGE_NEW.
+ * @return mixed Value found or written to the key
+ * @note Options added in 1.28: version, busyValue, hotTTR, ageNew, pcGroup, minAsOf
+ * @note Callable type hints are not used to avoid class-autoloading
+ */
+ final public function getWithSetCallback( $key, $ttl, $callback, array $opts = [] ) {
+ $pcTTL = isset( $opts['pcTTL'] ) ? $opts['pcTTL'] : self::TTL_UNCACHEABLE;
+
+ // Try the process cache if enabled and the cache callback is not within a cache callback.
+ // Process cache use in nested callbacks is not lag-safe with regard to HOLDOFF_TTL since
+ // the in-memory value is further lagged than the shared one since it uses a blind TTL.
+ if ( $pcTTL >= 0 && $this->callbackDepth == 0 ) {
+ $group = isset( $opts['pcGroup'] ) ? $opts['pcGroup'] : self::PC_PRIMARY;
+ $procCache = $this->getProcessCache( $group );
+ $value = $procCache->get( $key );
+ } else {
+ $procCache = false;
+ $value = false;
+ }
+
+ if ( $value === false ) {
+ // Fetch the value over the network
+ if ( isset( $opts['version'] ) ) {
+ $version = $opts['version'];
+ $asOf = null;
+ $cur = $this->doGetWithSetCallback(
+ $key,
+ $ttl,
+ function ( $oldValue, &$ttl, &$setOpts, $oldAsOf )
+ use ( $callback, $version ) {
+ if ( is_array( $oldValue )
+ && array_key_exists( self::VFLD_DATA, $oldValue )
+ ) {
+ $oldData = $oldValue[self::VFLD_DATA];
+ } else {
+ // VFLD_DATA is not set if an old, unversioned, key is present
+ $oldData = false;
+ }
+
+ return [
+ self::VFLD_DATA => $callback( $oldData, $ttl, $setOpts, $oldAsOf ),
+ self::VFLD_VERSION => $version
+ ];
+ },
+ $opts,
+ $asOf
+ );
+ if ( $cur[self::VFLD_VERSION] === $version ) {
+ // Value created or existed before with version; use it
+ $value = $cur[self::VFLD_DATA];
+ } else {
+ // Value existed before with a different version; use variant key.
+ // Reflect purges to $key by requiring that this key value be newer.
+ $value = $this->doGetWithSetCallback(
+ 'cache-variant:' . md5( $key ) . ":$version",
+ $ttl,
+ $callback,
+ // Regenerate value if not newer than $key
+ [ 'version' => null, 'minAsOf' => $asOf ] + $opts
+ );
+ }
+ } else {
+ $value = $this->doGetWithSetCallback( $key, $ttl, $callback, $opts );
+ }
+
+ // Update the process cache if enabled
+ if ( $procCache && $value !== false ) {
+ $procCache->set( $key, $value, $pcTTL );
+ }
+ }
+
+ return $value;
+ }
+
+ /**
+ * Do the actual I/O for getWithSetCallback() when needed
+ *
+ * @see WANObjectCache::getWithSetCallback()
+ *
+ * @param string $key
+ * @param int $ttl
+ * @param callback $callback
+ * @param array $opts Options map for getWithSetCallback()
+ * @param float &$asOf Cache generation timestamp of returned value [returned]
+ * @return mixed
+ * @note Callable type hints are not used to avoid class-autoloading
+ */
+ protected function doGetWithSetCallback( $key, $ttl, $callback, array $opts, &$asOf = null ) {
+ $lowTTL = isset( $opts['lowTTL'] ) ? $opts['lowTTL'] : min( self::LOW_TTL, $ttl );
+ $lockTSE = isset( $opts['lockTSE'] ) ? $opts['lockTSE'] : self::TSE_NONE;
+ $checkKeys = isset( $opts['checkKeys'] ) ? $opts['checkKeys'] : [];
+ $busyValue = isset( $opts['busyValue'] ) ? $opts['busyValue'] : null;
+ $popWindow = isset( $opts['hotTTR'] ) ? $opts['hotTTR'] : self::HOT_TTR;
+ $ageNew = isset( $opts['ageNew'] ) ? $opts['ageNew'] : self::AGE_NEW;
+ $minTime = isset( $opts['minAsOf'] ) ? $opts['minAsOf'] : self::MIN_TIMESTAMP_NONE;
+ $versioned = isset( $opts['version'] );
+
+ // Get the current key value
+ $curTTL = null;
+ $cValue = $this->get( $key, $curTTL, $checkKeys, $asOf ); // current value
+ $value = $cValue; // return value
+
+ $preCallbackTime = microtime( true );
+ // Determine if a cached value regeneration is needed or desired
+ if ( $value !== false
+ && $curTTL > 0
+ && $this->isValid( $value, $versioned, $asOf, $minTime )
+ && !$this->worthRefreshExpiring( $curTTL, $lowTTL )
+ && !$this->worthRefreshPopular( $asOf, $ageNew, $popWindow, $preCallbackTime )
+ ) {
+ return $value;
+ }
+
+ // A deleted key with a negative TTL left must be tombstoned
+ $isTombstone = ( $curTTL !== null && $value === false );
+ // Assume a key is hot if requested soon after invalidation
+ $isHot = ( $curTTL !== null && $curTTL <= 0 && abs( $curTTL ) <= $lockTSE );
+ // Use the mutex if there is no value and a busy fallback is given
+ $checkBusy = ( $busyValue !== null && $value === false );
+ // Decide whether a single thread should handle regenerations.
+ // This avoids stampedes when $checkKeys are bumped and when preemptive
+ // renegerations take too long. It also reduces regenerations while $key
+ // is tombstoned. This balances cache freshness with avoiding DB load.
+ $useMutex = ( $isHot || ( $isTombstone && $lockTSE > 0 ) || $checkBusy );
+
+ $lockAcquired = false;
+ if ( $useMutex ) {
+ // Acquire a datacenter-local non-blocking lock
+ if ( $this->cache->add( self::MUTEX_KEY_PREFIX . $key, 1, self::LOCK_TTL ) ) {
+ // Lock acquired; this thread should update the key
+ $lockAcquired = true;
+ } elseif ( $value !== false && $this->isValid( $value, $versioned, $asOf, $minTime ) ) {
+ // If it cannot be acquired; then the stale value can be used
+ return $value;
+ } else {
+ // Use the INTERIM value for tombstoned keys to reduce regeneration load.
+ // For hot keys, either another thread has the lock or the lock failed;
+ // use the INTERIM value from the last thread that regenerated it.
+ $wrapped = $this->cache->get( self::INTERIM_KEY_PREFIX . $key );
+ list( $value ) = $this->unwrap( $wrapped, microtime( true ) );
+ if ( $value !== false && $this->isValid( $value, $versioned, $asOf, $minTime ) ) {
+ $asOf = $wrapped[self::FLD_TIME];
+
+ return $value;
+ }
+ // Use the busy fallback value if nothing else
+ if ( $busyValue !== null ) {
+ return is_callable( $busyValue ) ? $busyValue() : $busyValue;
+ }
+ }
+ }
+
+ if ( !is_callable( $callback ) ) {
+ throw new InvalidArgumentException( "Invalid cache miss callback provided." );
+ }
+
+ // Generate the new value from the callback...
+ $setOpts = [];
+ ++$this->callbackDepth;
+ try {
+ $value = call_user_func_array( $callback, [ $cValue, &$ttl, &$setOpts, $asOf ] );
+ } finally {
+ --$this->callbackDepth;
+ }
+ // When delete() is called, writes are write-holed by the tombstone,
+ // so use a special INTERIM key to pass the new value around threads.
+ if ( ( $isTombstone && $lockTSE > 0 ) && $value !== false && $ttl >= 0 ) {
+ $tempTTL = max( 1, (int)$lockTSE ); // set() expects seconds
+ $newAsOf = microtime( true );
+ $wrapped = $this->wrap( $value, $tempTTL, $newAsOf );
+ // Avoid using set() to avoid pointless mcrouter broadcasting
+ $this->cache->merge(
+ self::INTERIM_KEY_PREFIX . $key,
+ function () use ( $wrapped ) {
+ return $wrapped;
+ },
+ $tempTTL,
+ 1
+ );
+ }
+
+ if ( $value !== false && $ttl >= 0 ) {
+ $setOpts['lockTSE'] = $lockTSE;
+ // Use best known "since" timestamp if not provided
+ $setOpts += [ 'since' => $preCallbackTime ];
+ // Update the cache; this will fail if the key is tombstoned
+ $this->set( $key, $value, $ttl, $setOpts );
+ }
+
+ if ( $lockAcquired ) {
+ // Avoid using delete() to avoid pointless mcrouter broadcasting
+ $this->cache->changeTTL( self::MUTEX_KEY_PREFIX . $key, 1 );
+ }
+
+ return $value;
+ }
+
+ /**
+ * Method to fetch multiple cache keys at once with regeneration
+ *
+ * This works the same as getWithSetCallback() except:
+ * - a) The $keys argument expects the result of WANObjectCache::makeMultiKeys()
+ * - b) The $callback argument expects a callback taking the following arguments:
+ * - $id: ID of an entity to query
+ * - $oldValue : the prior cache value or false if none was present
+ * - &$ttl : a reference to the new value TTL in seconds
+ * - &$setOpts : a reference to options for set() which can be altered
+ * - $oldAsOf : generation UNIX timestamp of $oldValue or null if not present
+ * Aside from the additional $id argument, the other arguments function the same
+ * way they do in getWithSetCallback().
+ * - c) The return value is a map of (cache key => value) in the order of $keyedIds
+ *
+ * @see WANObjectCache::getWithSetCallback()
+ * @see WANObjectCache::getMultiWithUnionSetCallback()
+ *
+ * Example usage:
+ * @code
+ * $rows = $cache->getMultiWithSetCallback(
+ * // Map of cache keys to entity IDs
+ * $cache->makeMultiKeys(
+ * $this->fileVersionIds(),
+ * function ( $id, WANObjectCache $cache ) {
+ * return $cache->makeKey( 'file-version', $id );
+ * }
+ * ),
+ * // Time-to-live (in seconds)
+ * $cache::TTL_DAY,
+ * // Function that derives the new key value
+ * function ( $id, $oldValue, &$ttl, array &$setOpts ) {
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * // Load the row for this file
+ * $row = $dbr->selectRow( 'file', '*', [ 'id' => $id ], __METHOD__ );
+ *
+ * return $row ? (array)$row : false;
+ * },
+ * [
+ * // Process cache for 30 seconds
+ * 'pcTTL' => 30,
+ * // Use a dedicated 500 item cache (initialized on-the-fly)
+ * 'pcGroup' => 'file-versions:500'
+ * ]
+ * );
+ * $files = array_map( [ __CLASS__, 'newFromRow' ], $rows );
+ * @endcode
+ *
+ * @param ArrayIterator $keyedIds Result of WANObjectCache::makeMultiKeys()
+ * @param int $ttl Seconds to live for key updates
+ * @param callable $callback Callback the yields entity regeneration callbacks
+ * @param array $opts Options map
+ * @return array Map of (cache key => value) in the same order as $keyedIds
+ * @since 1.28
+ */
+ final public function getMultiWithSetCallback(
+ ArrayIterator $keyedIds, $ttl, callable $callback, array $opts = []
+ ) {
+ $valueKeys = array_keys( $keyedIds->getArrayCopy() );
+ $checkKeys = isset( $opts['checkKeys'] ) ? $opts['checkKeys'] : [];
+
+ // Load required keys into process cache in one go
+ $this->warmupCache = $this->getRawKeysForWarmup(
+ $this->getNonProcessCachedKeys( $valueKeys, $opts ),
+ $checkKeys
+ );
+ $this->warmupKeyMisses = 0;
+
+ // Wrap $callback to match the getWithSetCallback() format while passing $id to $callback
+ $id = null; // current entity ID
+ $func = function ( $oldValue, &$ttl, &$setOpts, $oldAsOf ) use ( $callback, &$id ) {
+ return $callback( $id, $oldValue, $ttl, $setOpts, $oldAsOf );
+ };
+
+ $values = [];
+ foreach ( $keyedIds as $key => $id ) { // preserve order
+ $values[$key] = $this->getWithSetCallback( $key, $ttl, $func, $opts );
+ }
+
+ $this->warmupCache = [];
+
+ return $values;
+ }
+
+ /**
+ * Method to fetch/regenerate multiple cache keys at once
+ *
+ * This works the same as getWithSetCallback() except:
+ * - a) The $keys argument expects the result of WANObjectCache::makeMultiKeys()
+ * - b) The $callback argument expects a callback returning a map of (ID => new value)
+ * for all entity IDs in $regenById and it takes the following arguments:
+ * - $ids: a list of entity IDs to regenerate
+ * - &$ttls: a reference to the (entity ID => new TTL) map
+ * - &$setOpts: a reference to options for set() which can be altered
+ * - c) The return value is a map of (cache key => value) in the order of $keyedIds
+ * - d) The "lockTSE" and "busyValue" options are ignored
+ *
+ * @see WANObjectCache::getWithSetCallback()
+ * @see WANObjectCache::getMultiWithSetCallback()
+ *
+ * Example usage:
+ * @code
+ * $rows = $cache->getMultiWithUnionSetCallback(
+ * // Map of cache keys to entity IDs
+ * $cache->makeMultiKeys(
+ * $this->fileVersionIds(),
+ * function ( $id, WANObjectCache $cache ) {
+ * return $cache->makeKey( 'file-version', $id );
+ * }
+ * ),
+ * // Time-to-live (in seconds)
+ * $cache::TTL_DAY,
+ * // Function that derives the new key value
+ * function ( array $ids, array &$ttls, array &$setOpts ) {
+ * $dbr = wfGetDB( DB_REPLICA );
+ * // Account for any snapshot/replica DB lag
+ * $setOpts += Database::getCacheSetOptions( $dbr );
+ *
+ * // Load the rows for these files
+ * $rows = [];
+ * $res = $dbr->select( 'file', '*', [ 'id' => $ids ], __METHOD__ );
+ * foreach ( $res as $row ) {
+ * $rows[$row->id] = $row;
+ * $mtime = wfTimestamp( TS_UNIX, $row->timestamp );
+ * $ttls[$row->id] = $this->adaptiveTTL( $mtime, $ttls[$row->id] );
+ * }
+ *
+ * return $rows;
+ * },
+ * ]
+ * );
+ * $files = array_map( [ __CLASS__, 'newFromRow' ], $rows );
+ * @endcode
+ *
+ * @param ArrayIterator $keyedIds Result of WANObjectCache::makeMultiKeys()
+ * @param int $ttl Seconds to live for key updates
+ * @param callable $callback Callback the yields entity regeneration callbacks
+ * @param array $opts Options map
+ * @return array Map of (cache key => value) in the same order as $keyedIds
+ * @since 1.30
+ */
+ final public function getMultiWithUnionSetCallback(
+ ArrayIterator $keyedIds, $ttl, callable $callback, array $opts = []
+ ) {
+ $idsByValueKey = $keyedIds->getArrayCopy();
+ $valueKeys = array_keys( $idsByValueKey );
+ $checkKeys = isset( $opts['checkKeys'] ) ? $opts['checkKeys'] : [];
+ unset( $opts['lockTSE'] ); // incompatible
+ unset( $opts['busyValue'] ); // incompatible
+
+ // Load required keys into process cache in one go
+ $keysGet = $this->getNonProcessCachedKeys( $valueKeys, $opts );
+ $this->warmupCache = $this->getRawKeysForWarmup( $keysGet, $checkKeys );
+ $this->warmupKeyMisses = 0;
+
+ // IDs of entities known to be in need of regeneration
+ $idsRegen = [];
+
+ // Find out which keys are missing/deleted/stale
+ $curTTLs = [];
+ $asOfs = [];
+ $curByKey = $this->getMulti( $keysGet, $curTTLs, $checkKeys, $asOfs );
+ foreach ( $keysGet as $key ) {
+ if ( !array_key_exists( $key, $curByKey ) || $curTTLs[$key] < 0 ) {
+ $idsRegen[] = $idsByValueKey[$key];
+ }
+ }
+
+ // Run the callback to populate the regeneration value map for all required IDs
+ $newSetOpts = [];
+ $newTTLsById = array_fill_keys( $idsRegen, $ttl );
+ $newValsById = $idsRegen ? $callback( $idsRegen, $newTTLsById, $newSetOpts ) : [];
+
+ // Wrap $callback to match the getWithSetCallback() format while passing $id to $callback
+ $id = null; // current entity ID
+ $func = function ( $oldValue, &$ttl, &$setOpts, $oldAsOf )
+ use ( $callback, &$id, $newValsById, $newTTLsById, $newSetOpts )
+ {
+ if ( array_key_exists( $id, $newValsById ) ) {
+ // Value was already regerated as expected, so use the value in $newValsById
+ $newValue = $newValsById[$id];
+ $ttl = $newTTLsById[$id];
+ $setOpts = $newSetOpts;
+ } else {
+ // Pre-emptive/popularity refresh and version mismatch cases are not detected
+ // above and thus $newValsById has no entry. Run $callback on this single entity.
+ $ttls = [ $id => $ttl ];
+ $newValue = $callback( [ $id ], $ttls, $setOpts )[$id];
+ $ttl = $ttls[$id];
+ }
+
+ return $newValue;
+ };
+
+ // Run the cache-aside logic using warmupCache instead of persistent cache queries
+ $values = [];
+ foreach ( $idsByValueKey as $key => $id ) { // preserve order
+ $values[$key] = $this->getWithSetCallback( $key, $ttl, $func, $opts );
+ }
+
+ $this->warmupCache = [];
+
+ return $values;
+ }
+
+ /**
+ * Locally set a key to expire soon if it is stale based on $purgeTimestamp
+ *
+ * This sets stale keys' time-to-live at HOLDOFF_TTL seconds, which both avoids
+ * broadcasting in mcrouter setups and also avoids races with new tombstones.
+ *
+ * @param string $key Cache key
+ * @param int $purgeTimestamp UNIX timestamp of purge
+ * @param bool &$isStale Whether the key is stale
+ * @return bool Success
+ * @since 1.28
+ */
+ public function reap( $key, $purgeTimestamp, &$isStale = false ) {
+ $minAsOf = $purgeTimestamp + self::HOLDOFF_TTL;
+ $wrapped = $this->cache->get( self::VALUE_KEY_PREFIX . $key );
+ if ( is_array( $wrapped ) && $wrapped[self::FLD_TIME] < $minAsOf ) {
+ $isStale = true;
+ $this->logger->warning( "Reaping stale value key '$key'." );
+ $ttlReap = self::HOLDOFF_TTL; // avoids races with tombstone creation
+ $ok = $this->cache->changeTTL( self::VALUE_KEY_PREFIX . $key, $ttlReap );
+ if ( !$ok ) {
+ $this->logger->error( "Could not complete reap of key '$key'." );
+ }
+
+ return $ok;
+ }
+
+ $isStale = false;
+
+ return true;
+ }
+
+ /**
+ * Locally set a "check" key to expire soon if it is stale based on $purgeTimestamp
+ *
+ * @param string $key Cache key
+ * @param int $purgeTimestamp UNIX timestamp of purge
+ * @param bool &$isStale Whether the key is stale
+ * @return bool Success
+ * @since 1.28
+ */
+ public function reapCheckKey( $key, $purgeTimestamp, &$isStale = false ) {
+ $purge = $this->parsePurgeValue( $this->cache->get( self::TIME_KEY_PREFIX . $key ) );
+ if ( $purge && $purge[self::FLD_TIME] < $purgeTimestamp ) {
+ $isStale = true;
+ $this->logger->warning( "Reaping stale check key '$key'." );
+ $ok = $this->cache->changeTTL( self::TIME_KEY_PREFIX . $key, 1 );
+ if ( !$ok ) {
+ $this->logger->error( "Could not complete reap of check key '$key'." );
+ }
+
+ return $ok;
+ }
+
+ $isStale = false;
+
+ return false;
+ }
+
+ /**
+ * @see BagOStuff::makeKey()
+ * @param string $keys,... Key component
+ * @return string
+ * @since 1.27
+ */
+ public function makeKey() {
+ return call_user_func_array( [ $this->cache, __FUNCTION__ ], func_get_args() );
+ }
+
+ /**
+ * @see BagOStuff::makeGlobalKey()
+ * @param string $keys,... Key component
+ * @return string
+ * @since 1.27
+ */
+ public function makeGlobalKey() {
+ return call_user_func_array( [ $this->cache, __FUNCTION__ ], func_get_args() );
+ }
+
+ /**
+ * @param array $entities List of entity IDs
+ * @param callable $keyFunc Callback yielding a key from (entity ID, this WANObjectCache)
+ * @return ArrayIterator Iterator yielding (cache key => entity ID) in $entities order
+ * @since 1.28
+ */
+ public function makeMultiKeys( array $entities, callable $keyFunc ) {
+ $map = [];
+ foreach ( $entities as $entity ) {
+ $map[$keyFunc( $entity, $this )] = $entity;
+ }
+
+ return new ArrayIterator( $map );
+ }
+
+ /**
+ * Get the "last error" registered; clearLastError() should be called manually
+ * @return int ERR_* class constant for the "last error" registry
+ */
+ final public function getLastError() {
+ if ( $this->lastRelayError ) {
+ // If the cache and the relayer failed, focus on the latter.
+ // An update not making it to the relayer means it won't show up
+ // in other DCs (nor will consistent re-hashing see up-to-date values).
+ // On the other hand, if just the cache update failed, then it should
+ // eventually be applied by the relayer.
+ return $this->lastRelayError;
+ }
+
+ $code = $this->cache->getLastError();
+ switch ( $code ) {
+ case BagOStuff::ERR_NONE:
+ return self::ERR_NONE;
+ case BagOStuff::ERR_NO_RESPONSE:
+ return self::ERR_NO_RESPONSE;
+ case BagOStuff::ERR_UNREACHABLE:
+ return self::ERR_UNREACHABLE;
+ default:
+ return self::ERR_UNEXPECTED;
+ }
+ }
+
+ /**
+ * Clear the "last error" registry
+ */
+ final public function clearLastError() {
+ $this->cache->clearLastError();
+ $this->lastRelayError = self::ERR_NONE;
+ }
+
+ /**
+ * Clear the in-process caches; useful for testing
+ *
+ * @since 1.27
+ */
+ public function clearProcessCache() {
+ $this->processCaches = [];
+ }
+
+ /**
+ * @param int $flag ATTR_* class constant
+ * @return int QOS_* class constant
+ * @since 1.28
+ */
+ public function getQoS( $flag ) {
+ return $this->cache->getQoS( $flag );
+ }
+
+ /**
+ * Get a TTL that is higher for objects that have not changed recently
+ *
+ * This is useful for keys that get explicit purges and DB or purge relay
+ * lag is a potential concern (especially how it interacts with CDN cache)
+ *
+ * Example usage:
+ * @code
+ * // Last-modified time of page
+ * $mtime = wfTimestamp( TS_UNIX, $page->getTimestamp() );
+ * // Get adjusted TTL. If $mtime is 3600 seconds ago and $minTTL/$factor left at
+ * // defaults, then $ttl is 3600 * .2 = 720. If $minTTL was greater than 720, then
+ * // $ttl would be $minTTL. If $maxTTL was smaller than 720, $ttl would be $maxTTL.
+ * $ttl = $cache->adaptiveTTL( $mtime, $cache::TTL_DAY );
+ * @endcode
+ *
+ * @param int|float $mtime UNIX timestamp
+ * @param int $maxTTL Maximum TTL (seconds)
+ * @param int $minTTL Minimum TTL (seconds); Default: 30
+ * @param float $factor Value in the range (0,1); Default: .2
+ * @return int Adaptive TTL
+ * @since 1.28
+ */
+ public function adaptiveTTL( $mtime, $maxTTL, $minTTL = 30, $factor = 0.2 ) {
+ if ( is_float( $mtime ) || ctype_digit( $mtime ) ) {
+ $mtime = (int)$mtime; // handle fractional seconds and string integers
+ }
+
+ if ( !is_int( $mtime ) || $mtime <= 0 ) {
+ return $minTTL; // no last-modified time provided
+ }
+
+ $age = time() - $mtime;
+
+ return (int)min( $maxTTL, max( $minTTL, $factor * $age ) );
+ }
+
+ /**
+ * @return int Number of warmup key cache misses last round
+ * @since 1.30
+ */
+ public function getWarmupKeyMisses() {
+ return $this->warmupKeyMisses;
+ }
+
+ /**
+ * Do the actual async bus purge of a key
+ *
+ * This must set the key to "PURGED:<UNIX timestamp>:<holdoff>"
+ *
+ * @param string $key Cache key
+ * @param int $ttl How long to keep the tombstone [seconds]
+ * @param int $holdoff HOLDOFF_* constant controlling how long to ignore sets for this key
+ * @return bool Success
+ */
+ protected function relayPurge( $key, $ttl, $holdoff ) {
+ if ( $this->purgeRelayer instanceof EventRelayerNull ) {
+ // This handles the mcrouter and the single-DC case
+ $ok = $this->cache->set( $key,
+ $this->makePurgeValue( microtime( true ), self::HOLDOFF_NONE ),
+ $ttl
+ );
+ } else {
+ $event = $this->cache->modifySimpleRelayEvent( [
+ 'cmd' => 'set',
+ 'key' => $key,
+ 'val' => 'PURGED:$UNIXTIME$:' . (int)$holdoff,
+ 'ttl' => max( $ttl, 1 ),
+ 'sbt' => true, // substitute $UNIXTIME$ with actual microtime
+ ] );
+
+ $ok = $this->purgeRelayer->notify( $this->purgeChannel, $event );
+ if ( !$ok ) {
+ $this->lastRelayError = self::ERR_RELAY;
+ }
+ }
+
+ return $ok;
+ }
+
+ /**
+ * Do the actual async bus delete of a key
+ *
+ * @param string $key Cache key
+ * @return bool Success
+ */
+ protected function relayDelete( $key ) {
+ if ( $this->purgeRelayer instanceof EventRelayerNull ) {
+ // This handles the mcrouter and the single-DC case
+ $ok = $this->cache->delete( $key );
+ } else {
+ $event = $this->cache->modifySimpleRelayEvent( [
+ 'cmd' => 'delete',
+ 'key' => $key,
+ ] );
+
+ $ok = $this->purgeRelayer->notify( $this->purgeChannel, $event );
+ if ( !$ok ) {
+ $this->lastRelayError = self::ERR_RELAY;
+ }
+ }
+
+ return $ok;
+ }
+
+ /**
+ * Check if a key should be regenerated (using random probability)
+ *
+ * This returns false if $curTTL >= $lowTTL. Otherwise, the chance
+ * of returning true increases steadily from 0% to 100% as the $curTTL
+ * moves from $lowTTL to 0 seconds. This handles widely varying
+ * levels of cache access traffic.
+ *
+ * @param float $curTTL Approximate TTL left on the key if present
+ * @param float $lowTTL Consider a refresh when $curTTL is less than this
+ * @return bool
+ */
+ protected function worthRefreshExpiring( $curTTL, $lowTTL ) {
+ if ( $curTTL >= $lowTTL ) {
+ return false;
+ } elseif ( $curTTL <= 0 ) {
+ return true;
+ }
+
+ $chance = ( 1 - $curTTL / $lowTTL );
+
+ return mt_rand( 1, 1e9 ) <= 1e9 * $chance;
+ }
+
+ /**
+ * Check if a key is due for randomized regeneration due to its popularity
+ *
+ * This is used so that popular keys can preemptively refresh themselves for higher
+ * consistency (especially in the case of purge loss/delay). Unpopular keys can remain
+ * in cache with their high nominal TTL. This means popular keys keep good consistency,
+ * whether the data changes frequently or not, and long-tail keys get to stay in cache
+ * and get hits too. Similar to worthRefreshExpiring(), randomization is used.
+ *
+ * @param float $asOf UNIX timestamp of the value
+ * @param int $ageNew Age of key when this might recommend refreshing (seconds)
+ * @param int $timeTillRefresh Age of key when it should be refreshed if popular (seconds)
+ * @param float $now The current UNIX timestamp
+ * @return bool
+ */
+ protected function worthRefreshPopular( $asOf, $ageNew, $timeTillRefresh, $now ) {
+ $age = $now - $asOf;
+ $timeOld = $age - $ageNew;
+ if ( $timeOld <= 0 ) {
+ return false;
+ }
+
+ // Lifecycle is: new, ramp-up refresh chance, full refresh chance.
+ // Note that the "expected # of refreshes" for the ramp-up time range is half of what it
+ // would be if P(refresh) was at its full value during that time range.
+ $refreshWindowSec = max( $timeTillRefresh - $ageNew - self::RAMPUP_TTL / 2, 1 );
+ // P(refresh) * (# hits in $refreshWindowSec) = (expected # of refreshes)
+ // P(refresh) * ($refreshWindowSec * $popularHitsPerSec) = 1
+ // P(refresh) = 1/($refreshWindowSec * $popularHitsPerSec)
+ $chance = 1 / ( self::HIT_RATE_HIGH * $refreshWindowSec );
+
+ // Ramp up $chance from 0 to its nominal value over RAMPUP_TTL seconds to avoid stampedes
+ $chance *= ( $timeOld <= self::RAMPUP_TTL ) ? $timeOld / self::RAMPUP_TTL : 1;
+
+ return mt_rand( 1, 1e9 ) <= 1e9 * $chance;
+ }
+
+ /**
+ * Check whether $value is appropriately versioned and not older than $minTime (if set)
+ *
+ * @param array $value
+ * @param bool $versioned
+ * @param float $asOf The time $value was generated
+ * @param float $minTime The last time the main value was generated (0.0 if unknown)
+ * @return bool
+ */
+ protected function isValid( $value, $versioned, $asOf, $minTime ) {
+ if ( $versioned && !isset( $value[self::VFLD_VERSION] ) ) {
+ return false;
+ } elseif ( $minTime > 0 && $asOf < $minTime ) {
+ return false;
+ }
+
+ return true;
+ }
+
+ /**
+ * Do not use this method outside WANObjectCache
+ *
+ * @param mixed $value
+ * @param int $ttl [0=forever]
+ * @param float $now Unix Current timestamp just before calling set()
+ * @return array
+ */
+ protected function wrap( $value, $ttl, $now ) {
+ return [
+ self::FLD_VERSION => self::VERSION,
+ self::FLD_VALUE => $value,
+ self::FLD_TTL => $ttl,
+ self::FLD_TIME => $now
+ ];
+ }
+
+ /**
+ * Do not use this method outside WANObjectCache
+ *
+ * @param array|string|bool $wrapped
+ * @param float $now Unix Current timestamp (preferrably pre-query)
+ * @return array (mixed; false if absent/tombstoned/invalid, current time left)
+ */
+ protected function unwrap( $wrapped, $now ) {
+ // Check if the value is a tombstone
+ $purge = self::parsePurgeValue( $wrapped );
+ if ( $purge !== false ) {
+ // Purged values should always have a negative current $ttl
+ $curTTL = min( $purge[self::FLD_TIME] - $now, self::TINY_NEGATIVE );
+ return [ false, $curTTL ];
+ }
+
+ if ( !is_array( $wrapped ) // not found
+ || !isset( $wrapped[self::FLD_VERSION] ) // wrong format
+ || $wrapped[self::FLD_VERSION] !== self::VERSION // wrong version
+ ) {
+ return [ false, null ];
+ }
+
+ $flags = isset( $wrapped[self::FLD_FLAGS] ) ? $wrapped[self::FLD_FLAGS] : 0;
+ if ( ( $flags & self::FLG_STALE ) == self::FLG_STALE ) {
+ // Treat as expired, with the cache time as the expiration
+ $age = $now - $wrapped[self::FLD_TIME];
+ $curTTL = min( -$age, self::TINY_NEGATIVE );
+ } elseif ( $wrapped[self::FLD_TTL] > 0 ) {
+ // Get the approximate time left on the key
+ $age = $now - $wrapped[self::FLD_TIME];
+ $curTTL = max( $wrapped[self::FLD_TTL] - $age, 0.0 );
+ } else {
+ // Key had no TTL, so the time left is unbounded
+ $curTTL = INF;
+ }
+
+ return [ $wrapped[self::FLD_VALUE], $curTTL ];
+ }
+
+ /**
+ * @param array $keys
+ * @param string $prefix
+ * @return string[]
+ */
+ protected static function prefixCacheKeys( array $keys, $prefix ) {
+ $res = [];
+ foreach ( $keys as $key ) {
+ $res[] = $prefix . $key;
+ }
+
+ return $res;
+ }
+
+ /**
+ * @param string $value Wrapped value like "PURGED:<timestamp>:<holdoff>"
+ * @return array|bool Array containing a UNIX timestamp (float) and holdoff period (integer),
+ * or false if value isn't a valid purge value
+ */
+ protected static function parsePurgeValue( $value ) {
+ if ( !is_string( $value ) ) {
+ return false;
+ }
+ $segments = explode( ':', $value, 3 );
+ if ( !isset( $segments[0] ) || !isset( $segments[1] )
+ || "{$segments[0]}:" !== self::PURGE_VAL_PREFIX
+ ) {
+ return false;
+ }
+ if ( !isset( $segments[2] ) ) {
+ // Back-compat with old purge values without holdoff
+ $segments[2] = self::HOLDOFF_TTL;
+ }
+ return [
+ self::FLD_TIME => (float)$segments[1],
+ self::FLD_HOLDOFF => (int)$segments[2],
+ ];
+ }
+
+ /**
+ * @param float $timestamp
+ * @param int $holdoff In seconds
+ * @return string Wrapped purge value
+ */
+ protected function makePurgeValue( $timestamp, $holdoff ) {
+ return self::PURGE_VAL_PREFIX . (float)$timestamp . ':' . (int)$holdoff;
+ }
+
+ /**
+ * @param string $group
+ * @return HashBagOStuff
+ */
+ protected function getProcessCache( $group ) {
+ if ( !isset( $this->processCaches[$group] ) ) {
+ list( , $n ) = explode( ':', $group );
+ $this->processCaches[$group] = new HashBagOStuff( [ 'maxKeys' => (int)$n ] );
+ }
+
+ return $this->processCaches[$group];
+ }
+
+ /**
+ * @param array $keys
+ * @param array $opts
+ * @return array List of keys
+ */
+ private function getNonProcessCachedKeys( array $keys, array $opts ) {
+ $keysFound = [];
+ if ( isset( $opts['pcTTL'] ) && $opts['pcTTL'] > 0 && $this->callbackDepth == 0 ) {
+ $pcGroup = isset( $opts['pcGroup'] ) ? $opts['pcGroup'] : self::PC_PRIMARY;
+ $procCache = $this->getProcessCache( $pcGroup );
+ foreach ( $keys as $key ) {
+ if ( $procCache->get( $key ) !== false ) {
+ $keysFound[] = $key;
+ }
+ }
+ }
+
+ return array_diff( $keys, $keysFound );
+ }
+
+ /**
+ * @param array $keys
+ * @param array $checkKeys
+ * @return array Map of (cache key => mixed)
+ */
+ private function getRawKeysForWarmup( array $keys, array $checkKeys ) {
+ if ( !$keys ) {
+ return [];
+ }
+
+ $keysWarmUp = [];
+ // Get all the value keys to fetch...
+ foreach ( $keys as $key ) {
+ $keysWarmUp[] = self::VALUE_KEY_PREFIX . $key;
+ }
+ // Get all the check keys to fetch...
+ foreach ( $checkKeys as $i => $checkKeyOrKeys ) {
+ if ( is_int( $i ) ) {
+ // Single check key that applies to all value keys
+ $keysWarmUp[] = self::TIME_KEY_PREFIX . $checkKeyOrKeys;
+ } else {
+ // List of check keys that apply to value key $i
+ $keysWarmUp = array_merge(
+ $keysWarmUp,
+ self::prefixCacheKeys( $checkKeyOrKeys, self::TIME_KEY_PREFIX )
+ );
+ }
+ }
+
+ $warmupCache = $this->cache->getMulti( $keysWarmUp );
+ $warmupCache += array_fill_keys( $keysWarmUp, false );
+
+ return $warmupCache;
+ }
+}
scripts.mit.edu / autoinstallsdev / mediawiki.git / blobdiff