Fixes #4937: Metadata cache is purged when entity cache item removed

diff --git a/engine/lib/entities.php b/engine/lib/entities.php
index a1c1c2997ece48dfc2bb4bda7e755193fb21200f..e9c96a59665312d4c27d105341df9a2dfc0298e9 100644 (file)
--- a/engine/lib/entities.php
+++ b/engine/lib/entities.php
@@ -68,7 +68,15 @@ function cache_entity(ElggEntity $entity) {
        // Don't store too many or we'll have memory problems
        // TODO(evan): Pick a less arbitrary limit
        if (count($ENTITY_CACHE) > 256) {
-               unset($ENTITY_CACHE[array_rand($ENTITY_CACHE)]);
+               $random_guid = array_rand($ENTITY_CACHE);
+
+               unset($ENTITY_CACHE[$random_guid]);
+
+               // Purge separate metadata cache. Original idea was to do in entity destructor, but that would
+               // have caused a bunch of unnecessary purges at every shutdown. Doing it this way we have no way
+               // to know that the expunged entity will be GCed (might be another reference living), but that's
+               // OK; the metadata will reload if necessary.
+               elgg_get_metadata_cache()->clear($random_guid);
        }
 
        $ENTITY_CACHE[$entity->guid] = $entity;