Event driven transaction state management with single cache for persistant framework

• US 20040148283A1
• Filed: 01/27/2003
• Published: 07/29/2004
• Est. Priority Date: 01/27/2003
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Harris, Jason, Li, Chia-Hsin
• Granted Patent: US 7,111,001 B2
• Time in Patent Office: Days
• US Class Current: 707/5
• CPC Class Codes: G06F 16/2336 Pessimistic concurrency control approaches, e.g. locking or multiple versions without time stamps
• CPC Class Codes: G06F 9/466 Transaction processing
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99935 Query augmenting and refining, e.g. inexact access
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method for managing transactions associated with a persistent framework in a multi-thread environment is provided. The method initiates with associating each individual thread with an event queue. Then an event is added to a first event queue associated with a respective thread. The event is associated with a persistent object. Next, write access to the persistent object is prevented to all threads except the respective thread. Then, the event in the first event queue associated with the persistent object is executed. A computer readable media and a system capable of maintaining transaction states of persistent objects are also provided.

Claims

1. A method for managing transactions associated with a persistent framework in a multi-thread environment, comprising:

associating each individual thread with an event queue;

adding an event to a first event queue associated with a respective thread, the event associated with a persistent object;

preventing write access to the persistent object to all threads except the respective thread; and

executing the event in the first event queue associated with the persistent object.

2. The method of claim 1, wherein the event is selected from the group consisting of a deletion of the persistent object, a change of the persistent object or an addition of a new persistent object.

3. The method of claim 1, wherein the method operation of adding an event to a first event queue associated with a respective thread, the event associated with a persistent object includes,

preserving an order of the event in the first event queue.

4. The method of claim 1, wherein the method operation of preventing write access to the persistent object to all threads except the respective thread includes,

associating a lock with the persistent object in a cache associated with each event queue.

5. The method of claim 1, further comprising:

adding a plurality of events to the first event queue; and

executing a portion of the plurality of events.

6. A method for maintaining transaction states of persistent objects in a multi-user environment, comprising:

receiving a request to modify a persistent object stored in a main cache;

copying the persistent object from the main cache to an event queue associated with the request;

storing a modified persistent object and a corresponding transaction state with the persistent object in the event queue;

writing the modified persistent object to the main cache and a persistent storage; and

removing the persistent object from the main cache and the persistent storage.

7. The method of claim 6, further comprising:

preventing write accessibility to the persistent object stored in the main cache when the persistent object is copied from the main cache to the event queue;

8. The method of claim 6, wherein each user of the multi-user environment is associated with a separate event queue.

9. The method of claim 6, further comprising:

preserving an order of receipt for the request to modify the persistent object by adding each successive request associated with the event queue to a bottom of the event queue.

10. The method of claim 6, wherein the event queue corresponds to a single user of the multi-user environment.

11. A method for maintaining transaction states of persistent objects capable of being accessed by a plurality of clients, comprising:

associating each one of a plurality of clients with an event queue, each event queue associated with a single cache of a persistent framework;

receiving a request to modify a persistent object to a modified persistent object, the persistent object stored in the single cache;

storing the modified persistent object, a transaction state indicator and a copy of the persistent object in a respective event queue in a manner to preserve an order of successive modifications of additional persistent objects stored in the respective event queue;

preventing write access to the persistent object stored in the single cache for a remainder of the plurality of clients; and

committing the modified persistent object in the respective event queue to the single cache.

12. The method of claim 11, wherein a portion of the successive modifications of the additional persistent objects stored in the respective event queue are committed to the single cache along with the modified persistent object.

13. The method of claim 12, wherein the portion is identified through a common transaction state indicator.

14. The method of claim 11, further comprising:

preventing the modified persistent object in the respective event queue from being stored in any other event queue.

15. The method of claim 11, further comprising:

after committing the modified persistent object, removing the modified persistent object and the persistent object from the respective event queue; and

replacing the persistent object in the single cache with the modified persistent object, the modified persistent object enabled for write and read access by the plurality of clients.

16. A computer program product configured to be executed on a computer system, comprising:

program instructions for associating each individual thread with an event queue;

program instructions for adding an event to a first event queue associated with a respective thread, the event associated with a persistent object;

program instructions for preventing write access to the persistent object for all threads except the respective thread; and

program instructions for executing the event in the first event queue associated with the persistent object.

17. The computer program product of claim 16, wherein the event is selected from the group consisting of a deletion of the persistent object, a change of the persistent object or an addition of a new persistent object.

18. The computer program product of claim 16, wherein the program instructions for adding an event to a first event queue associated with a respective thread, the event associated with a persistent object includes, program instructions for preserving an order of the event in the first event queue.

19. The computer program product of claim 16, wherein the program instructions for preventing write access to the persistent object for all threads except the respective thread includes,

program instructions for associating a lock with the persistent object in a cache associated with each event queue.

20. The computer program product of claim 16, further comprising:

program instructions for adding a plurality of events to the first event queue; and

program instructions for executing a portion of the plurality of events.

21. A computer readable media having program instructions for maintaining transaction states of persistent objects capable of being accessed by a plurality of clients, comprising:

program instructions for associating each one of a plurality of clients with an event queue, each event queue associated with a single cache of a persistent framework;

program instructions for requesting modification of a persistent object to a modified persistent object, the persistent object stored in the single cache;

program instructions for storing the modified persistent object, a transaction state indicator and a copy of the persistent object in a respective event queue in a manner to preserve an order of successive modifications of additional persistent objects stored in the respective event queue;

program instructions for preventing write access to the persistent object stored in the single cache; and

program instructions for committing the modified persistent object in the respective event queue to the single cache.

22. The computer readable media of claim 21, further including,

program instructions for committing a portion of the successive modifications of the additional persistent objects stored in the respective event queue to the single cache along with the modified persistent object.

23. The computer readable media of claim 22, wherein the portion is identified through a common transaction state indicator.

24. The computer readable media of claim 21, further comprising:

program instructions for preventing the modified persistent object in the respective event queue from being stored in any other event queue.

25. The computer readable media of claim 21, further comprising:

program instructions for removing the modified persistent object and the persistent object from the respective event queue after committing the modified persistent object; and

program instructions for replacing the persistent object in the single cache with the modified persistent object, the modified persistent object enabled for write and read access by the plurality of clients.

26. A system capable of maintaining transaction states of persistent objects, comprising:

a persistent storage unit;

a server in communication with the persistent storage unit, the server including at least one central processing unit (CPU), the at least one CPU including a main cache configured to store persistent objects, the main cache associated with a plurality of event queues, each of the plurality of event queues associated with a separate thread, each of the plurality of event queues further configured to store data, the data including copies of each of the persistent objects from the main cache, modifications corresponding to respective copies of the persistent objects, and transaction states corresponding to each of the copies of the persistent objects, wherein a single event queue is enabled to allow execution of at least a subset of the modifications stored therein.

27. The system of claim 26, wherein each separate thread is associated with a client.

28. The system of claim 26, wherein the persistent storage unit is a database selected from the group consisting of a relational database, a hierarchical database, and an object database.

29. The system of claim 26, wherein the main cache is configured to prevent write access to one of the persistent objects when the one of the persistent objects is copied to one of the plurality of event queues.

30. The system of claim 26, wherein a lock is placed on the one of the persistent objects to prevent write access.

31. The system of claim 26, wherein execution of at least the subset of the modifications stored within the event queue is based on one of a transaction state and a particular persistent object.