protected $asyncHandler;
/** @var float Unix timestamp of the oldest possible valid values */
protected $epoch;
+ /** @var string Stable secret used for hasing long strings into key components */
+ protected $secret;
/** @var int Callback stack depth for getWithSetCallback() */
private $callbackDepth = 0;
* is configured to interpret /<region>/<cluster>/ key prefixes as routes. This
* requires that "region" and "cluster" are both set above. [optional]
* - epoch: lowest UNIX timestamp a value/tombstone must have to be valid. [optional]
+ * - secret: stable secret used for hashing long strings into key components. [optional]
*/
public function __construct( array $params ) {
$this->cache = $params['cache'];
$this->cluster = $params['cluster'] ?? 'wan-main';
$this->mcrouterAware = !empty( $params['mcrouterAware'] );
$this->epoch = $params['epoch'] ?? self::EPOCH_UNIX_ONE_SECOND;
+ $this->secret = $params['secret'] ?? (string)$this->epoch;
$this->setLogger( $params['logger'] ?? new NullLogger() );
$this->stats = $params['stats'] ?? new NullStatsdDataFactory();
*
* @param string $key Cache key made from makeKey() or makeGlobalKey()
* @param mixed|null &$curTTL Approximate TTL left on the key if present/tombstoned [returned]
- * @param array $checkKeys List of "check" keys
+ * @param string[] $checkKeys The "check" keys used to validate the value
* @param mixed|null &$info Key info if WANObjectCache::PASS_BY_REF [returned]
* @return mixed Value of cache key or false on failure
*/
* Othwerwise, $info will transform into a map of (cache key => cached value timestamp).
* Only the cache keys listed in $keys that exists or are tombstoned will have an entry.
*
+ * $checkKeys holds the "check" keys used to validate values of applicable keys. The integer
+ * indexes hold "check" keys that apply to all of $keys while the string indexes hold "check"
+ * keys that only apply to the cache key with that name.
+ *
* @see WANObjectCache::get()
*
- * @param array $keys List of cache keys made from makeKey() or makeGlobalKey()
+ * @param string[] $keys List of cache keys made from makeKey() or makeGlobalKey()
* @param mixed|null &$curTTLs Map of (key => TTL left) for existing/tombstoned 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 string[]|string[][] $checkKeys Map of (integer or cache key => "check" key(s))
* @param mixed|null &$info Map of (key => info) if WANObjectCache::PASS_BY_REF [returned]
- * @return array Map of (key => value) for keys that exist and are not tombstoned
+ * @return mixed[] Map of (key => value) for existing values; order of $keys is preserved
*/
final public function getMulti(
array $keys,
/**
* @since 1.27
- * @param array $timeKeys List of prefixed time check keys
- * @param array $wrappedValues
+ * @param string[] $timeKeys List of prefixed time check keys
+ * @param mixed[] $wrappedValues
* @param float $now
- * @return array List of purge value arrays
+ * @return array[] List of purge value arrays
*/
private function processCheckKeys( array $timeKeys, array $wrappedValues, $now ) {
$purgeValues = [];
* @see WANObjectCache::getCheckKeyTime()
* @see WANObjectCache::getWithSetCallback()
*
- * @param array $keys
+ * @param string[] $keys
* @return float[] Map of (key => UNIX timestamp)
* @since 1.31
*/
final public function getWithSetCallback( $key, $ttl, $callback, array $opts = [] ) {
$version = $opts['version'] ?? null;
$pcTTL = $opts['pcTTL'] ?? self::TTL_UNCACHEABLE;
+ $pCache = ( $pcTTL >= 0 )
+ ? $this->getProcessCache( $opts['pcGroup'] ?? self::PC_PRIMARY )
+ : null;
// Use the process cache if requested as long as no outer cache callback is running.
// Nested callback process cache use is not lag-safe with regard to HOLDOFF_TTL since
// process cached values are more lagged than persistent ones as they are not purged.
- if ( $pcTTL >= 0 && $this->callbackDepth == 0 ) {
- $pCache = $this->getProcessCache( $opts['pcGroup'] ?? self::PC_PRIMARY );
+ if ( $pCache && $this->callbackDepth == 0 ) {
$cached = $pCache->get( $this->getProcessCacheKey( $key, $version ), INF, false );
if ( $cached !== false ) {
return $cached;
}
- } else {
- $pCache = null;
}
$res = $this->fetchOrRegenerate( $key, $ttl, $callback, $opts );
// This avoids stampedes on eviction or preemptive regeneration taking too long.
( $busyValue !== null && $possValue === false );
- // If a regeneration lock is required, threads that do not get the lock will use any
- // available stale or volatile value. If there is none, then the cheap/placeholder
- // value from $busyValue will be used if provided; failing that, all threads will try
- // to regenerate the value and ignore the lock.
- if ( $useRegenerationLock ) {
- $hasLock = $this->cache->add( self::MUTEX_KEY_PREFIX . $key, 1, self::LOCK_TTL );
- if ( !$hasLock ) {
- if ( $this->isValid( $possValue, $possInfo['asOf'], $minAsOf ) ) {
- $this->stats->increment( "wanobjectcache.$kClass.hit.stale" );
-
- return [ $possValue, $possInfo['version'], $curInfo['asOf'] ];
- } elseif ( $busyValue !== null ) {
- $miss = is_infinite( $minAsOf ) ? 'renew' : 'miss';
- $this->stats->increment( "wanobjectcache.$kClass.$miss.busy" );
-
- return [
- is_callable( $busyValue ) ? $busyValue() : $busyValue,
- $version,
- $curInfo['asOf']
- ];
- }
+ // If a regeneration lock is required, threads that do not get the lock will try to use
+ // the stale value, the interim value, or the $busyValue placeholder, in that order. If
+ // none of those are set then all threads will bypass the lock and regenerate the value.
+ $hasLock = $useRegenerationLock && $this->claimStampedeLock( $key );
+ if ( $useRegenerationLock && !$hasLock ) {
+ if ( $this->isValid( $possValue, $possInfo['asOf'], $minAsOf ) ) {
+ $this->stats->increment( "wanobjectcache.$kClass.hit.stale" );
+
+ return [ $possValue, $possInfo['version'], $curInfo['asOf'] ];
+ } elseif ( $busyValue !== null ) {
+ $miss = is_infinite( $minAsOf ) ? 'renew' : 'miss';
+ $this->stats->increment( "wanobjectcache.$kClass.$miss.busy" );
+
+ return [
+ is_callable( $busyValue ) ? $busyValue() : $busyValue,
+ $version,
+ $curInfo['asOf']
+ ];
}
- } else {
- $hasLock = false;
}
// Generate the new value given any prior value with a matching version
) {
// How long it took to generate the value
$walltime = max( $postCallbackTime - $preCallbackTime, 0.0 );
+ $this->stats->timing( "wanobjectcache.$kClass.regen_walltime", 1e3 * $walltime );
// If the key is write-holed then use the (volatile) interim key as an alternative
if ( $isKeyTombstoned ) {
$this->setInterimValue( $key, $value, $lockTSE, $version, $walltime );
}
}
- if ( $hasLock ) {
- $this->cache->changeTTL( self::MUTEX_KEY_PREFIX . $key, (int)$initialTime - 60 );
- }
+ $this->yieldStampedeLock( $key, $hasLock );
$miss = is_infinite( $minAsOf ) ? 'renew' : 'miss';
$this->stats->increment( "wanobjectcache.$kClass.$miss.compute" );
return [ $value, $version, $curInfo['asOf'] ];
}
+ /**
+ * @param string $key
+ * @return bool Success
+ */
+ private function claimStampedeLock( $key ) {
+ // Note that locking is not bypassed due to I/O errors; this avoids stampedes
+ return $this->cache->add( self::MUTEX_KEY_PREFIX . $key, 1, self::LOCK_TTL );
+ }
+
+ /**
+ * @param string $key
+ * @param bool $hasLock
+ */
+ private function yieldStampedeLock( $key, $hasLock ) {
+ if ( $hasLock ) {
+ // The backend might be a mcrouter proxy set to broadcast DELETE to *all* the local
+ // datacenter cache servers via OperationSelectorRoute (for increased consistency).
+ // Since that would be excessive for these locks, use TOUCH to expire the key.
+ $this->cache->changeTTL( self::MUTEX_KEY_PREFIX . $key, $this->getCurrentTime() - 60 );
+ }
+ }
+
/**
* @param float $age Age of volatile/interim key in seconds
* @return bool Whether the age of a volatile value is negligible
* // Map of cache keys to entity IDs
* $cache->makeMultiKeys(
* $this->fileVersionIds(),
- * function ( $id, WANObjectCache $cache ) {
+ * function ( $id ) use ( $cache ) {
* return $cache->makeKey( 'file-version', $id );
* }
* ),
* @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
+ * @return mixed[] 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() );
-
// Load required keys into process cache in one go
$this->warmupCache = $this->getRawKeysForWarmup(
- $this->getNonProcessCachedKeys( $valueKeys, $opts ),
+ $this->getNonProcessCachedMultiKeys( $keyedIds, $opts ),
$opts['checkKeys'] ?? []
);
$this->warmupKeyMisses = 0;
* // Map of cache keys to entity IDs
* $cache->makeMultiKeys(
* $this->fileVersionIds(),
- * function ( $id, WANObjectCache $cache ) {
+ * function ( $id ) use ( $cache ) {
* return $cache->makeKey( 'file-version', $id );
* }
* ),
* @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
+ * @return mixed[] 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 = $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 );
+ $keysByIdGet = $this->getNonProcessCachedMultiKeys( $keyedIds, $opts );
+ $this->warmupCache = $this->getRawKeysForWarmup( $keysByIdGet, $checkKeys );
$this->warmupKeyMisses = 0;
// IDs of entities known to be in need of regeneration
// Find out which keys are missing/deleted/stale
$curTTLs = [];
$asOfs = [];
- $curByKey = $this->getMulti( $keysGet, $curTTLs, $checkKeys, $asOfs );
- foreach ( $keysGet as $key ) {
+ $curByKey = $this->getMulti( $keysByIdGet, $curTTLs, $checkKeys, $asOfs );
+ foreach ( $keysByIdGet as $id => $key ) {
if ( !array_key_exists( $key, $curByKey ) || $curTTLs[$key] < 0 ) {
- $idsRegen[] = $idsByValueKey[$key];
+ $idsRegen[] = $id;
}
}
// Run the cache-aside logic using warmupCache instead of persistent cache queries
$values = [];
- foreach ( $idsByValueKey as $key => $id ) { // preserve order
+ foreach ( $keyedIds as $key => $id ) { // preserve order
$values[$key] = $this->getWithSetCallback( $key, $ttl, $func, $opts );
}
}
/**
- * @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
+ * Hash a possibly long string into a suitable component for makeKey()/makeGlobalKey()
+ *
+ * @param string $component A raw component used in building a cache key
+ * @return string 64 character HMAC using a stable secret for public collision resistance
+ * @since 1.34
+ */
+ public function hash256( $component ) {
+ return hash_hmac( 'sha256', $component, $this->secret );
+ }
+
+ /**
+ * Get an iterator of (cache key => entity ID) for a list of entity IDs
+ *
+ * The callback takes an ID string and returns a key via makeKey()/makeGlobalKey().
+ * There should be no network nor filesystem I/O used in the callback. The entity
+ * ID/key mapping must be 1:1 or an exception will be thrown. If hashing is needed,
+ * then use the hash256() method.
+ *
+ * Example usage for the default keyspace:
+ * @code
+ * $keyedIds = $cache->makeMultiKeys(
+ * $modules,
+ * function ( $module ) use ( $cache ) {
+ * return $cache->makeKey( 'module-info', $module );
+ * }
+ * );
+ * @endcode
+ *
+ * Example usage for mixed default and global keyspace:
+ * @code
+ * $keyedIds = $cache->makeMultiKeys(
+ * $filters,
+ * function ( $filter ) use ( $cache ) {
+ * return ( strpos( $filter, 'central:' ) === 0 )
+ * ? $cache->makeGlobalKey( 'regex-filter', $filter )
+ * : $cache->makeKey( 'regex-filter', $filter )
+ * }
+ * );
+ * @endcode
+ *
+ * Example usage with hashing:
+ * @code
+ * $keyedIds = $cache->makeMultiKeys(
+ * $urls,
+ * function ( $url ) use ( $cache ) {
+ * return $cache->makeKey( 'url-info', $cache->hash256( $url ) );
+ * }
+ * );
+ * @endcode
+ *
+ * @see WANObjectCache::makeKey()
+ * @see WANObjectCache::makeGlobalKey()
+ * @see WANObjectCache::hash256()
+ *
+ * @param string[]|int[] $ids List of entity IDs
+ * @param callable $keyCallback Function returning makeKey()/makeGlobalKey() on the input ID
+ * @return ArrayIterator Iterator of (cache key => ID); order of $ids is preserved
+ * @throws UnexpectedValueException
* @since 1.28
*/
- final public function makeMultiKeys( array $entities, callable $keyFunc ) {
- $map = [];
- foreach ( $entities as $entity ) {
- $map[$keyFunc( $entity, $this )] = $entity;
+ final public function makeMultiKeys( array $ids, $keyCallback ) {
+ $idByKey = [];
+ foreach ( $ids as $id ) {
+ // Discourage triggering of automatic makeKey() hashing in some backends
+ if ( strlen( $id ) > 64 ) {
+ $this->logger->warning( __METHOD__ . ": long ID '$id'; use hash256()" );
+ }
+ $key = $keyCallback( $id, $this );
+ // Edge case: ignore key collisions due to duplicate $ids like "42" and 42
+ if ( !isset( $idByKey[$key] ) ) {
+ $idByKey[$key] = $id;
+ } elseif ( (string)$id !== (string)$idByKey[$key] ) {
+ throw new UnexpectedValueException(
+ "Cache key collision; IDs ('$id','{$idByKey[$key]}') map to '$key'"
+ );
+ }
+ }
+
+ return new ArrayIterator( $idByKey );
+ }
+
+ /**
+ * Get an (ID => value) map from (i) a non-unique list of entity IDs, and (ii) the list
+ * of corresponding entity values by first appearance of each ID in the entity ID list
+ *
+ * For use with getMultiWithSetCallback() and getMultiWithUnionSetCallback().
+ *
+ * *Only* use this method if the entity ID/key mapping is trivially 1:1 without exception.
+ * Key generation method must utitilize the *full* entity ID in the key (not a hash of it).
+ *
+ * Example usage:
+ * @code
+ * $poems = $cache->getMultiWithSetCallback(
+ * $cache->makeMultiKeys(
+ * $uuids,
+ * function ( $uuid ) use ( $cache ) {
+ * return $cache->makeKey( 'poem', $uuid );
+ * }
+ * ),
+ * $cache::TTL_DAY,
+ * function ( $uuid ) use ( $url ) {
+ * return $this->http->run( [ 'method' => 'GET', 'url' => "$url/$uuid" ] );
+ * }
+ * );
+ * $poemsByUUID = $cache->multiRemap( $uuids, $poems );
+ * @endcode
+ *
+ * @see WANObjectCache::makeMultiKeys()
+ * @see WANObjectCache::getMultiWithSetCallback()
+ * @see WANObjectCache::getMultiWithUnionSetCallback()
+ *
+ * @param string[]|int[] $ids Entity ID list makeMultiKeys()
+ * @param mixed[] $res Result of getMultiWithSetCallback()/getMultiWithUnionSetCallback()
+ * @return mixed[] Map of (ID => value); order of $ids is preserved
+ * @since 1.34
+ */
+ final public function multiRemap( array $ids, array $res ) {
+ if ( count( $ids ) !== count( $res ) ) {
+ // If makeMultiKeys() is called on a list of non-unique IDs, then the resulting
+ // ArrayIterator will have less entries due to "first appearance" de-duplication
+ $ids = array_keys( array_flip( $ids ) );
+ if ( count( $ids ) !== count( $res ) ) {
+ throw new UnexpectedValueException( "Multi-key result does not match ID list" );
+ }
}
- return new ArrayIterator( $map );
+ return array_combine( $ids, $res );
}
/**
}
/**
- * @param array $keys
+ * @param string[] $keys
* @param string $prefix
- * @return string[]
+ * @return string[] Prefix keys; the order of $keys is preserved
*/
protected static function prefixCacheKeys( array $keys, $prefix ) {
$res = [];
}
/**
- * @param array $keys
+ * @param ArrayIterator $keys
* @param array $opts
- * @return string[] List of keys
+ * @return string[] Map of (ID => cache key)
*/
- private function getNonProcessCachedKeys( array $keys, array $opts ) {
+ private function getNonProcessCachedMultiKeys( ArrayIterator $keys, array $opts ) {
$pcTTL = $opts['pcTTL'] ?? self::TTL_UNCACHEABLE;
- $keysFound = [];
+ $keysMissing = [];
if ( $pcTTL > 0 && $this->callbackDepth == 0 ) {
$version = $opts['version'] ?? null;
$pCache = $this->getProcessCache( $opts['pcGroup'] ?? self::PC_PRIMARY );
- foreach ( $keys as $key ) {
- if ( $pCache->has( $this->getProcessCacheKey( $key, $version ), $pcTTL ) ) {
- $keysFound[] = $key;
+ foreach ( $keys as $key => $id ) {
+ if ( !$pCache->has( $this->getProcessCacheKey( $key, $version ), $pcTTL ) ) {
+ $keysMissing[$id] = $key;
}
}
}
- return array_diff( $keys, $keysFound );
+ return $keysMissing;
}
/**
- * @param array $keys
- * @param array $checkKeys
- * @return array Map of (cache key => mixed)
+ * @param string[] $keys
+ * @param string[]|string[][] $checkKeys
+ * @return string[] List of cache keys
*/
private function getRawKeysForWarmup( array $keys, array $checkKeys ) {
if ( !$keys ) {
dépôts / lhc / web / wiklou.git / blobdiff