Cache coherence protocol

• US 20060248285A1
• Filed: 04/29/2005
• Published: 11/02/2006
• Est. Priority Date: 04/29/2005
• Status: Abandoned Application

• Current Assignee: SAP AG (SAP SE)
• Original Assignee: SAP AG (SAP SE)
• Inventors: Petev, Petio G.
• Application Number:
  US11/118,902
• Publication Number:
  US 20060248285A1
• Time in Patent Office: Days
• US Class Current: 711/141
• CPC Class Codes: G06F 12/084 with a shared cache

Abstract

One embodiment of the invention employs techniques for using a message server to route shared object management messages between virtual machines and/or worker nodes to maintain cache coherence. In one embodiment, shared locks and messaging service between worker nodes and/or virtual machines helps to provide this coherency. These messages utilize a message protocol. The protocol includes a hashable object key, a region identifier, and message type.

Claims

1. A method, comprising:

maintaining coherence of a cache using a shared lock construct and messages, the messages to utilize a message protocol and the shared lock construct to prevent simultaneous access to a shared object.

2. The method as in claim 1, wherein a message utilizing the message protocol comprises:

an object key, the object key hashable to obtain a storage location in the cache;

a region identification, the region identification to indicate which region of the cache a message concerns; and

a message type.

3. The method as in claim 2, wherein the message type is selected from the group consisting of:

internal, remove, and modify.

4. The method as in claim 2, wherein a message utilizing the message protocol further comprises:

a transportable object.

5. The method as in claim 2, wherein a message utilizing the message protocol further comprises:

a queue of messages, the queue of messages being a linked list.

6. A system, comprising:

a messaging service, the messaging service to employ a messaging protocol; and

a plurality of worker nodes communicatively coupled through the messaging service.

7. The system as in claim 6, wherein the message protocol comprises:

an object key, the object key hashable to obtain a storage location in cache;

a region identification, the region identification to indicate which region of cache a message concerns; and

a message type.

8. The system as in claim 7, wherein the message type is selected from the group consisting of:

internal, remove, and modify.

9. The system as in claim 8, wherein a message utilizing the message protocol further comprises:

a transportable object.

10. The system as in claim 7, wherein a message utilizing the message protocol further comprises:

a queue of messages, the queue of messages being a linked list.

11. The system as in claim 6, further comprising:

a shared memory, the shared memory accessible by the plurality of worker nodes; and

a shared object in the shared memory.

12. The system as in claim 11, wherein a worker node comprises:

a cache manager to manage the cache of the worker node;

at least one application that accesses the shared object, the at least one application further including an external listener to receive invalidation notices from the cache manager and at least one thread;

an internal listener to receive notifications from the messaging service; and

a registration table to store the addresses of listeners of the system that do not belong to the worker node.

13. The system as in claim 12, wherein each application thread includes a shared lock construct.

14. The system as in claim 13, wherein the shared locker is provided by a locker class.

15. An article of manufacture including program code which, when executed by a machine, causes the machine to perform the operations of:

maintaining cache coherence using a shared lock construct and messages, the messages to utilize a message protocol and the shared lock construct to prevent simultaneous access to a shared object.

16. The article of manufacture as in claim 15 comprising additional program code to cause said machine to perform the operations of:

an object key, the object key hashable to obtain a storage location in cache;

a region identification, the region identification to indicate which region of cache a message concerns; and

a message type.

17. The article of manufacture as in claim 16, wherein the message type is selected from the group consisting of:

internal, remove, and modify.

18. The article of manufacture as in claim 15, wherein a message utilizing the message protocol further comprises:

a transportable object.

19. The article of manufacture as in claim 15, wherein a message utilizing the message protocol further comprises:

a queue of messages, the queue of messages being a linked list.