Function GetMongoCollectionByColId

pg_documentdb/src/metadata/collection.c:315–428

* GetMongoCollectionByColId() gets the MongoCollection metadata by collectionId. */

 * GetMongoCollectionByColId() gets the MongoCollection metadata by collectionId.
 */
MongoCollection *
GetMongoCollectionByColId(uint64 collectionId, LOCKMODE lockMode)
{
	/* make sure hashes exist */
	InitializeCollectionsHash();

	Oid documentsTableOid = GetRelationIdForCollectionId(collectionId, lockMode);

	if (!OidIsValid(documentsTableOid))
	{
		/* table was dropped */
		return NULL;
	}

	bool foundInCache = false;

	RelationIdToCollectionCacheEntry *entryByRelId =
		hash_search(RelationIdToCollectionHash, &documentsTableOid, HASH_FIND,
					&foundInCache);

	if (foundInCache)
	{
		/* now that we have a lock, check for invalidations */
		AcceptInvalidationMessages();

		/*
		 * After acquiring the lock on the table, we may have received an invalidation
		 * that could indicate a rename. In that case, CollectionCacheIsValid or
		 * entry->isValid is set to false and we treat this as a cache miss by
		 * continuing below.
		 */
		if (!CollectionCacheIsValid)
		{
			InitializeCollectionsHash();
		}
		else if (entryByRelId->isValid)
		{
			return CopyMongoCollection(&(entryByRelId->collection));
		}
	}

	MongoCollection collection;
	memset(&collection, 0, sizeof(collection));

	/*
	 * Temporarily disable unimportant logs related to collection catalog lookup
	 * so that regression test outputs don't become flaky (e.g.: due to commands
	 * being executed by Citus locally).
	 */
	int savedGUCLevel = NewGUCNestLevel();
	SetGUCLocally("client_min_messages", "WARNING");

	/* Read the collection metadata from ApiCatalogSchemaName.collections */
	bool collectionExists =
		GetMongoCollectionFromCatalogById(collectionId, documentsTableOid,
										  &collection);

	/* rollback the GUC change that we made for client_min_messages */