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-rw-r--r--engine/classes/ElggVolatileMetadataCache.php347
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+<?php
+/**
+ * ElggVolatileMetadataCache
+ * In memory cache of known metadata values stored by entity.
+ *
+ * @package Elgg.Core
+ * @subpackage Cache
+ *
+ * @access private
+ */
+class ElggVolatileMetadataCache {
+
+ /**
+ * The cached values (or null for known to be empty). If the portion of the cache
+ * is synchronized, missing values are assumed to indicate that values do not
+ * exist in storage, otherwise, we don't know what's there.
+ *
+ * @var array
+ */
+ protected $values = array();
+
+ /**
+ * Does the cache know that it contains all names fetch-able from storage?
+ * The keys are entity GUIDs and either the value exists (true) or it's not set.
+ *
+ * @var array
+ */
+ protected $isSynchronized = array();
+
+ /**
+ * @var null|bool
+ */
+ protected $ignoreAccess = null;
+
+ /**
+ * @param int $entity_guid
+ *
+ * @param array $values
+ */
+ public function saveAll($entity_guid, array $values) {
+ if (!$this->getIgnoreAccess()) {
+ $this->values[$entity_guid] = $values;
+ $this->isSynchronized[$entity_guid] = true;
+ }
+ }
+
+ /**
+ * @param int $entity_guid
+ *
+ * @return array
+ */
+ public function loadAll($entity_guid) {
+ if (isset($this->values[$entity_guid])) {
+ return $this->values[$entity_guid];
+ } else {
+ return array();
+ }
+ }
+
+ /**
+ * Declare that there may be fetch-able metadata names in storage that this
+ * cache doesn't know about
+ *
+ * @param int $entity_guid
+ */
+ public function markOutOfSync($entity_guid) {
+ unset($this->isSynchronized[$entity_guid]);
+ }
+
+ /**
+ * @param $entity_guid
+ *
+ * @return bool
+ */
+ public function isSynchronized($entity_guid) {
+ return isset($this->isSynchronized[$entity_guid]);
+ }
+
+ /**
+ * @param int $entity_guid
+ *
+ * @param string $name
+ *
+ * @param array|int|string|null $value null means it is known that there is no
+ * fetch-able metadata under this name
+ * @param bool $allow_multiple
+ */
+ public function save($entity_guid, $name, $value, $allow_multiple = false) {
+ if ($this->getIgnoreAccess()) {
+ // we don't know if what gets saves here will be available to user once
+ // access control returns, hence it's best to forget :/
+ $this->markUnknown($entity_guid, $name);
+ } else {
+ if ($allow_multiple) {
+ if ($this->isKnown($entity_guid, $name)) {
+ $existing = $this->load($entity_guid, $name);
+ if ($existing !== null) {
+ $existing = (array) $existing;
+ $existing[] = $value;
+ $value = $existing;
+ }
+ } else {
+ // we don't know whether there are unknown values, so it's
+ // safest to leave that assumption
+ $this->markUnknown($entity_guid, $name);
+ return;
+ }
+ }
+ $this->values[$entity_guid][$name] = $value;
+ }
+ }
+
+ /**
+ * Warning: You should always call isKnown() beforehand to verify that this
+ * function's return value should be trusted (otherwise a null return value
+ * is ambiguous).
+ *
+ * @param int $entity_guid
+ *
+ * @param string $name
+ *
+ * @return array|string|int|null null = value does not exist
+ */
+ public function load($entity_guid, $name) {
+ if (isset($this->values[$entity_guid]) && array_key_exists($name, $this->values[$entity_guid])) {
+ return $this->values[$entity_guid][$name];
+ } else {
+ return null;
+ }
+ }
+
+ /**
+ * Forget about this metadata entry. We don't want to try to guess what the
+ * next fetch from storage will return
+ *
+ * @param int $entity_guid
+ *
+ * @param string $name
+ */
+ public function markUnknown($entity_guid, $name) {
+ unset($this->values[$entity_guid][$name]);
+ $this->markOutOfSync($entity_guid);
+ }
+
+ /**
+ * If true, load() will return an accurate value for this name
+ *
+ * @param int $entity_guid
+ *
+ * @param string $name
+ *
+ * @return bool
+ */
+ public function isKnown($entity_guid, $name) {
+ if (isset($this->isSynchronized[$entity_guid])) {
+ return true;
+ } else {
+ return (isset($this->values[$entity_guid]) && array_key_exists($name, $this->values[$entity_guid]));
+ }
+
+ }
+
+ /**
+ * Declare that metadata under this name is known to be not fetch-able from storage
+ *
+ * @param int $entity_guid
+ *
+ * @param string $name
+ *
+ * @return array
+ */
+ public function markEmpty($entity_guid, $name) {
+ $this->values[$entity_guid][$name] = null;
+ }
+
+ /**
+ * Forget about all metadata for an entity
+ *
+ * @param int $entity_guid
+ */
+ public function clear($entity_guid) {
+ $this->values[$entity_guid] = array();
+ $this->markOutOfSync($entity_guid);
+ }
+
+ /**
+ * Clear entire cache and mark all entities as out of sync
+ */
+ public function flush() {
+ $this->values = array();
+ $this->isSynchronized = array();
+ }
+
+ /**
+ * Use this value instead of calling elgg_get_ignore_access(). By default that
+ * function will be called.
+ *
+ * This setting makes this component a little more loosely-coupled.
+ *
+ * @param bool $ignore
+ */
+ public function setIgnoreAccess($ignore) {
+ $this->ignoreAccess = (bool) $ignore;
+ }
+
+ /**
+ * Tell the cache to call elgg_get_ignore_access() to determing access status.
+ */
+ public function unsetIgnoreAccess() {
+ $this->ignoreAccess = null;
+ }
+
+ /**
+ * @return bool
+ */
+ protected function getIgnoreAccess() {
+ if (null === $this->ignoreAccess) {
+ return elgg_get_ignore_access();
+ } else {
+ return $this->ignoreAccess;
+ }
+ }
+
+ /**
+ * Invalidate based on options passed to the global *_metadata functions
+ *
+ * @param string $action Action performed on metadata. "delete", "disable", or "enable"
+ *
+ * @param array $options Options passed to elgg_(delete|disable|enable)_metadata
+ *
+ * "guid" if given, invalidation will be limited to this entity
+ *
+ * "metadata_name" if given, invalidation will be limited to metadata with this name
+ */
+ public function invalidateByOptions($action, array $options) {
+ // remove as little as possible, optimizing for common cases
+ if (empty($options['guid'])) {
+ // safest to clear everything unless we want to make this even more complex :(
+ $this->flush();
+ } else {
+ if (empty($options['metadata_name'])) {
+ // safest to clear the whole entity
+ $this->clear($options['guid']);
+ } else {
+ switch ($action) {
+ case 'delete':
+ $this->markEmpty($options['guid'], $options['metadata_name']);
+ break;
+ default:
+ $this->markUnknown($options['guid'], $options['metadata_name']);
+ }
+ }
+ }
+ }
+
+ /**
+ * @param int|array $guids
+ */
+ public function populateFromEntities($guids) {
+ if (empty($guids)) {
+ return;
+ }
+ if (!is_array($guids)) {
+ $guids = array($guids);
+ }
+ $guids = array_unique($guids);
+
+ // could be useful at some point in future
+ //$guids = $this->filterMetadataHeavyEntities($guids);
+
+ $db_prefix = elgg_get_config('dbprefix');
+ $options = array(
+ 'guids' => $guids,
+ 'limit' => 0,
+ 'callback' => false,
+ 'joins' => array(
+ "JOIN {$db_prefix}metastrings v ON n_table.value_id = v.id",
+ "JOIN {$db_prefix}metastrings n ON n_table.name_id = n.id",
+ ),
+ 'selects' => array('n.string AS name', 'v.string AS value'),
+ 'order_by' => 'n_table.entity_guid, n_table.time_created ASC',
+
+ // @todo don't know why this is necessary
+ 'wheres' => array(get_access_sql_suffix('n_table')),
+ );
+ $data = elgg_get_metadata($options);
+
+ // build up metadata for each entity, save when GUID changes (or data ends)
+ $last_guid = null;
+ $metadata = array();
+ $last_row_idx = count($data) - 1;
+ foreach ($data as $i => $row) {
+ $name = $row->name;
+ $value = ($row->value_type === 'text') ? $row->value : (int) $row->value;
+ $guid = $row->entity_guid;
+ if ($guid !== $last_guid) {
+ if ($last_guid) {
+ $this->saveAll($last_guid, $metadata);
+ }
+ $metadata = array();
+ }
+ if (isset($metadata[$name])) {
+ $metadata[$name] = (array) $metadata[$name];
+ $metadata[$name][] = $value;
+ } else {
+ $metadata[$name] = $value;
+ }
+ if (($i == $last_row_idx)) {
+ $this->saveAll($guid, $metadata);
+ }
+ $last_guid = $guid;
+ }
+ }
+
+ /**
+ * Filter out entities whose concatenated metadata values (INTs casted as string)
+ * exceed a threshold in characters. This could be used to avoid overpopulating the
+ * cache if RAM usage becomes an issue.
+ *
+ * @param array $guids GUIDs of entities to examine
+ *
+ * @param int $limit Limit in characters of all metadata (with ints casted to strings)
+ *
+ * @return array
+ */
+ public function filterMetadataHeavyEntities(array $guids, $limit = 1024000) {
+ $db_prefix = elgg_get_config('dbprefix');
+
+ $options = array(
+ 'guids' => $guids,
+ 'limit' => 0,
+ 'callback' => false,
+ 'joins' => "JOIN {$db_prefix}metastrings v ON n_table.value_id = v.id",
+ 'selects' => array('SUM(LENGTH(v.string)) AS bytes'),
+ 'order_by' => 'n_table.entity_guid, n_table.time_created ASC',
+ 'group_by' => 'n_table.entity_guid',
+ );
+ $data = elgg_get_metadata($options);
+ // don't cache if metadata for entity is over 10MB (or rolled INT)
+ foreach ($data as $row) {
+ if ($row->bytes > $limit || $row->bytes < 0) {
+ array_splice($guids, array_search($row->entity_guid, $guids), 1);
+ }
+ }
+ return $guids;
+ }
+}
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