Finalizable object usage in software transactions

• US 20080147757A1
• Filed: 12/14/2006
• Published: 06/19/2008
• Est. Priority Date: 12/14/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Duffy, John Joseph, Detlefs, David, Magruder, Michael M.
• Granted Patent: US 7,650,371 B2
• Time in Patent Office: Days
• US Class Current: 707/205
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 16/289 Object oriented databases
• CPC Class Codes: G06F 8/24 Object-oriented

Abstract

Various technologies and techniques are disclosed for providing a software transactional memory system that supports allocation and use of finalizable objects inside transactions. By supporting such finalizable object usage inside a software transactional memory system, correct behavior is maintained when a garbage collector must determine when a particular one or more of the objects are eligible for finalization. A to-be-finalized set is provided for a transaction. An object is placed into the to-be-finalized set for the transaction whenever a finalizable object is allocated within the transaction. A finalize indicator is set for each object in the to-be-finalized set at an appropriate time to indicate that the objects are eligible for finalization. For example, if the transaction is ready to commit and the transaction is an open transaction, then the to-be-finalized set is traversed and a finalize indicator is set for each object to indicate they are eligible for finalization.

Claims

1. A method for using finalizable objects in transactions in a software transactional memory system comprising the steps of:

providing a software transactional memory system; and

providing a feature in the software transactional memory system that supports allocation of finalizable objects inside a transaction so a garbage collector knows when a particular one or more of the objects are eligible for finalization.

2. The method of claim 1, wherein the feature that supports finalization of objects inside the transaction comprises maintaining a to-be-finalized set for the transaction.

3. The method of claim 2, wherein whenever a finalizable object is allocated while the transaction is active, the finalizable object is placed into the to-be-finalized set for the transaction.

4. The method of claim 1, wherein an indicator is set in the to-be-finalized set to indicate the finalizable object is eligible for finalization.

5. The method of claim 4, wherein the indicator is set when an open or non-nested transaction commits.

6. The method of claim 1, wherein if a request is made from the transaction to suppress a finalization operation for a particular object created within the transaction, the particular object is removed from the to-be-finalized set for the transaction.

7. The method of claim 1, wherein if a request is made from the transaction to re-register for a finalize operation for a particular object created within the transaction, the particular object is added to the to-be-finalized set for the transaction.

8. The method of claim 1, wherein if a request is made from the transaction to suppress a finalization operation for a particular object that was not created within the transaction, then a REDO action results.

9. The method of claim 1, wherein if a request is made from the transaction to re-register for a finalize operation for a particular object that was not created within the transaction, then a REDO action results.

10. A computer-readable medium having computer-executable instructions for causing a computer to perform the steps recited in claim 1.

11. A computer-readable medium having computer-executable instructions for causing a computer to perform steps comprising:

provide a software transactional memory system that supports allocation of finalizable objects inside a transaction;

provide a to-be-finalized set for a transaction;

place an object into the to-be-finalized set for the transaction whenever a finalizable object is allocated within the transaction; and

set a finalize indicator for each object in the to-be-finalized set at an appropriate time to indicate that the objects are eligible for finalization.

12. The computer-readable medium of claim 11, wherein the finalize indicator is set by assigning the finalize indicator a value of True.

13. The computer-readable medium of claim 11, wherein the appropriate time when the finalize indicator is set is when the open nested or non-nested transaction commits.

14. A method for using finalizable objects in transactions in a software transactional memory system comprising the steps of:

creating a to-be-finalized set for a transaction;

whenever a finalizable object is allocated while a transaction is alive, placing the finalizable object into the to-be-finalized set for the transaction; and

if the transaction is ready to commit and the transaction is an open nested or non-nested transaction, then traversing the to-be-finalized set and setting a finalize indicator for each object so a garbage collector will know that each object is eligible to finalize.

15. The method of claim 14, further comprising:

if the transaction is not an open nested or non-nested transaction, then copying the contents of the to-be-finalized set to a parent to-be-finalized set of the parent transaction.

16. The method of claim 14, further comprising:

if the transaction is ready to commit, performing at least one other task associated with the commit.

17. The method of claim 14, further comprising:

if the transaction is ready to rollback, then discarding the to-be-finalized set for the transaction.

18. The method of claim 17, further comprising:

if the transaction is ready to rollback, performing at least one other task associated with the rollback.

19. The method of claim 14, wherein the finalize indicator is set to a value of True for each object in the to-be-finalized set to indicate when each object is ready to be finalized.

20. A computer-readable medium having computer-executable instructions for causing a computer to perform the steps recited in claim 14.