Function InitializeCollectionsHash

pg_documentdb/src/metadata/collection.c:172–219

* InitializeCollectionsHash (re)creates the collections hashes if they are * not valid. * * At the end of this function, either CollectionCacheIsValid is true or * an OOM was thrown. In the latter case, we will try again on the next * call. */

 * call.
 */
static void
InitializeCollectionsHash(void)
{
	/* make sure the metadata cache is initalized */
	InitializeDocumentDBApiExtensionCache();

	/* should not call this function if extension does not exist */
	Assert(IsDocumentDBApiExtensionActive());

	if (CollectionCacheIsValid)
	{
		/* already built the hashes */
		return;
	}

	if (CollectionsCacheContext == NULL)
	{
		CollectionsCacheContext = AllocSetContextCreate(CacheMemoryContext,
														"Cache context for collection",
														ALLOCSET_DEFAULT_SIZES);
	}

	/* reset any previously allocated memory */
	MemoryContextReset(CollectionsCacheContext);

	int hashFlags = HASH_ELEM | HASH_BLOBS | HASH_CONTEXT;

	/* create the (database name, collection name) -> collection hash */
	HASHCTL info;
	memset(&info, 0, sizeof(info));
	info.keysize = sizeof(MongoCollectionName);
	info.entrysize = sizeof(NameToCollectionCacheEntry);
	info.hcxt = CollectionsCacheContext;

	NameToCollectionHash = hash_create("Name to Collection ID Hash", 32,
									   &info, hashFlags);

	/* create the (relation OID) -> collection hash */
	memset(&info, 0, sizeof(info));
	info.keysize = sizeof(Oid);
	info.entrysize = sizeof(RelationIdToCollectionCacheEntry);
	info.hcxt = CollectionsCacheContext;

	RelationIdToCollectionHash = hash_create("Relation ID to Collection ID Hash", 32,
											 &info, hashFlags);

	CollectionCacheIsValid = true;
}


/*