Function GraphContext_FindOrAddAttribute

src/graph/graphcontext.c:449–499

}

Attribute_ID GraphContext_FindOrAddAttribute
(
	GraphContext *gc,
	const char *attribute,
	bool *created
) {
	ASSERT(gc);

	bool created_flag = false;
	unsigned char *attr = (unsigned char*)attribute;
	uint l = strlen(attribute);

	// acquire a read lock for looking up the attribute
	pthread_rwlock_rdlock(&gc->_attribute_rwlock);

	// see if attribute already exists
	void *attribute_id = raxFind(gc->attributes, attr, l);

	if(attribute_id == raxNotFound) {
		// we are writing to the shared GraphContext
		// release the held lock and re-acquire as a writer
		pthread_rwlock_unlock(&gc->_attribute_rwlock);
		pthread_rwlock_wrlock(&gc->_attribute_rwlock);

		// lookup the attribute again now that we are in a critical region
		attribute_id = raxFind(gc->attributes, attr, l);

		// if set by another thread, use the retrieved value
		if(attribute_id == raxNotFound) {
			// otherwise, it will be assigned an ID
			// equal to the current mapping size
			attribute_id = (void *)raxSize(gc->attributes);
			// insert the new attribute key and ID
			raxInsert(gc->attributes, attr, l, attribute_id, NULL);
			array_append(gc->string_mapping, rm_strdup(attribute));
			created_flag = true;

			// new attribute been added, update graph version
			_GraphContext_UpdateVersion(gc, attribute);
		}
	}

	// release the lock
	pthread_rwlock_unlock(&gc->_attribute_rwlock);

	if(created) {
		*created = created_flag;
	}

	return (uintptr_t)attribute_id;
}

const char *GraphContext_GetAttributeString
(