Reference count propagation

摘要

Methods and systems are provided for tracking object instances stored on a plurality of network nodes, which tracking enables a global determination of when an object has no references across the networked nodes and can be safely de-allocated. According to one aspect of the invention, each node has a local object store for tracking and optionally storing objects on the node, and the local object stores collectively share the locally stored instances of the objects across the network. One or more applications, e.g., a file system and/or a storage system, use the local object stores for storing all persistent data of the application as objects.

主权项

1. A non-transitory computer-readable medium containing executable program instructions for performing a method comprising:
in a plurality of networked nodes wherein each node has a local object store, the local object stores storing objects and sharing one or more objects, the objects having globally unique names across the networked nodes and wherein the object names do not change based upon where the objects are stored on the nodes; maintaining, at each node, a Local Reference Count LRC of local references to object names, independent of any object instance stored in the local store, the LRC being maintained as a signed integer, wherein adjustments are made to the LRC for each local new reference and dereference, wherein a de-referencing of an object name can generate a negative LRC value; wherein ownership of object names are assigned to different nodes, each object name being assigned to a single owner node, and wherein the one node assigned ownership initiates an instance reconciliation for the object comprising:
the owner node receiving messages from all of the local nodes concerning the number of instances of the object at each respective node;the owner node calculating a desired number and location of instances of the object across the networked nodes; andthe owner node instructing the other nodes to add or delete instances of the object according to the calculated number and location.