* - 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
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 integer $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 = iterator_to_array( $keyedIds, true );
+ $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
*