Systems and methods for managing semantic locks

• US 20080168458A1
• Filed: 01/05/2007
• Published: 07/10/2008
• Est. Priority Date: 01/05/2007
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Isilon Systems Incorporated (Dell Technologies Inc.)
• Inventors: Passey, Aaron J., Fachan, Neal T.
• Granted Patent: US 7,509,448 B2
• Time in Patent Office: Days
• US Class Current: 718/104
• CPC Class Codes: G06F 2209/523 Mode
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database

Abstract

In one embodiment, a system for managing semantic locks and semantic lock requests for a resource is provided. Access to the resource is controlled such that compatible lock requests can access the resource and incompatible lock requests are queued.

Claims

1. A system for managing semantic locks and semantic lock requests for a resource:

a resource;

a resource lock information indicating existing locks on said resource;

a first lock compatibility table stored in a memory including information on a plurality of lock types, said information relating to the compatibility among the plurality of lock types; and

a software module configured to;

receive a first lock request;

access said first lock compatibility table and said resource lock information to determine whether said first lock request is compatible with existing locks on said resource; and

transmit a response indicating that said first lock request could be granted if said first lock request is compatible with the existing locks on said resource.

2. The system of claim 1, wherein said software module is further configured to transmit the response indicating that said first lock request could be granted if said first lock request is compatible with a second pending lock request.

3. The system of claim 1, wherein said software module is associated with a second node, said second node assigned to said resource.

4. The system of claim 3, wherein said first lock request originates from a first node remote from said second node.

5. The system of claim 3, wherein said second node tracks said resource lock information.

6. The system of claim 1, wherein said resource lock information includes:

the types of locks on said resource; and

the types of locks that a third node should have on the resource in order to accommodate said first lock request.

7. The system of claim 3, wherein said second node is configured to grant or deny said first lock request.

8. The system of claim 7, wherein said second node permits said first node to obtain a lock on said resource of the type requested by said first lock request and subtypes associated with said requested lock type.

9. The system of claim 7, wherein said second node permits said first node to maintain one or more locks on said resource even after said first node has finished using said resource.

10. The system of claim 9, wherein said first node releases said one or more maintained locks in response to a request from a fourth node for at least one lock that is incompatible with said one or more maintained locks.

11. The system of claim 1, wherein said first lock compatibility table disallows equal lock types.

12. The system of claim 1, wherein said first lock compatibility table is asymmetric.

13. The system of claim 1, further comprising a second lock compatibility table that applies to only a portion of all possible said first lock requests indicated by said first lock compatibility table.

14. A method for managing semantic locks and semantic locks requests for a resource comprising:

receiving a first lock request for a resource;

accessing a first lock compatibility table and a resource lock information to determine whether said first lock request is compatible with existing locks on said resource, wherein;

the first lock compatibility table stores information relating to the compatibility among a plurality of lock types; and

the resource lock information indicates existing locks on said resource; and

transmitting a response indicating that said first lock request could be granted if said first lock request is compatible with the existing locks on said resource.

15. The method of claim 14, wherein the response is transmitted if said first lock request is compatible with a second pending lock request

16. The method of claim 14, wherein the first lock request is received at a second node, said second node assigned to said resource.

17. The method of claim 16, wherein said first lock request originates from a first node remote from said second node.

18. The method of claim 17, wherein said second node tracks said resource lock information.

19. The method of claim 14, wherein said resource lock information includes:

the types of locks on said resource; and

the types of locks that a third node should have on the resource in order to accommodate said first lock request.

20. The method of claim 17, wherein said second node is configured to grant or deny said first lock request.

21. The method of claim 20, wherein said second node permits said first node to obtain a lock on said resource of the type requested by said first lock request and subtypes associated with said requested lock type.

22. The method of claim 20, wherein said second node permits said first node to maintain one or more locks on said resource even after said first node has finished using said resource.

23. The method of claim 21, wherein said first node releases said one or more maintained locks in response to a request from a fourth node for at least one lock that is incompatible with said one or more maintained locks.

24. The method of claim 14, wherein said first lock compatibility table disallows equal lock types.

25. The method of claim 14, wherein said lock compatibility table is asymmetric.

26. The method of claim 14, further comprising receiving a second lock compatibility table that applies to only a portion of all possible said first lock requests indicated by said first lock compatibility table.