System and method for handling resource transaction requests

• US 7,069,366 B2
• Filed: 01/18/2003
• Issued: 06/27/2006
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: X Corp. (f/k/a Twitter, Inc.) (X Holdings Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Huras, Matthew A., Winer, Michael J., Goss, Jeffrey J., McArthur, Catherine S., Posner, Sarah, Zheng, Roger L. Q., Meadowcroft, Lorysa M., Flasza, Miroslaw A.
• Primary Examiner(s): Perveen, Rehana
• Assistant Examiner(s): DALEY, CHRISTOPHER ANTHONY
• Application Number:
  US10/346,214
• Publication Number:
  US 20030145146A1
• Time in Patent Office: 1,256 Days
• Field of Search: 710/200
• US Class Current: 710/200
• CPC Class Codes: G06F 16/24557 Efficient disk access during query execution
• CPC Class Codes: G06F 2209/522 Manager
• CPC Class Codes: G06F 2209/523 Mode
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A system and method handle resource transaction requests. The system marks a waiting transaction request, having an access mode which is incompatible with the access mode of the executing transaction, with an ignore bit, so that a transaction request with an access mode compatible with the access mode of the executing transaction may receive a lock in order to access the resource. The transaction request is then marked with a bypass indicator such that when the executing transactions are finished accessing the resource, the waiting transaction request may be notified that it may have access to the resource. The system includes the ignore bit so that each transaction request that arrives after the ignore bit has been set, does not suffer from a long waiting time before being provided access to the resource.

Claims

1. A method of handling a lock request from a requesting transaction request (transaction B) for additional access to a resource, comprising:

receiving a lock request for the additional access to the resource from the requesting transaction request (transaction B);

determining if a conflict exists between an access mode of the requesting transaction request (transaction B) and an access mode of all prior transaction requests (transaction A) with current access to the resource;

wherein if the conflict exists, determining if the requesting transaction request (transaction B) has been refused and is currently waiting for access to the resource;

wherein if the requesting transaction request (transaction B) is not waiting for access to the resource and is having current access to the resource, substantially concurrently with the prior transaction requests (transaction A), assigning an ignore indicator to the requesting transaction request (transaction B); and

wherein the ignore indicator allows a subsequent transaction request (transaction C), with an access mode that conflicts with the requesting transaction (transaction B), to be granted access to the resource, substantially concurrently with the prior transaction requests (transaction A) and the requesting transaction request (transaction B), if an access mode of the subsequent transaction requests (transaction C) does not conflict with the access mode of the prior transaction request (transition A), bypassing the conflicting requesting transaction request (transaction B).

2. The method of claim 1, further comprising setting an overall ignore bit if the ignore indicator is assigned to the requesting transaction request.

3. The method of claim 1, further comprising granting a bypass indicator to the subsequent transaction request.

4. The method of claim 3, further comprising:

monitoring the prior transaction requests to determine when a prior transaction request has been assigned the bypass indicator; and

granting the requesting transaction request access to the resource.

5. The method of claim 4, further comprising clearing the bypass indicator and the ignore indicator.

6. An apparatus for handling a lock request from a requesting transaction request (transaction B) for additional access to a resource, the apparatus comprising:

a lock manager for receiving the lock request for the additional access to the resource from the requesting transaction request (transaction B), and that compares an access mode of the requesting transaction request (transaction B) with an access mode of prior transaction requests (transaction A);

the requester further determining if a conflict exists between the access mode of the requesting transaction request (transaction B) and the access mode of the prior transaction requests (transaction A) with current access to the resource;

wherein if the conflict exists, the requester determining if the requesting transaction request (transaction B) has been refused and is currently waiting for access to the resource;

wherein if the requesting transaction request (transaction B) is not waiting for access to the resource and is having current access to the resource, substantially concurrently with the prior transaction requests (transaction A), the requester assigning an ignore indicator to the requesting transaction request (transaction B); and

wherein the ignore indicator allows a subsequent transaction request (transaction C), with an access mode that conflicts with the requesting transaction (transaction B), to be granted access to the resource, substantially concurrently with the prior transaction requests (transaction A) and the requesting transaction request (transaction B), if an access mode of the subsequent transaction requests (transaction C) does not conflict with the access mode of the prior transaction request (transaction A), bypassing the conflicting requesting transaction request (transaction B).

7. The apparatus of claim 6, wherein the requester further sets an overall ignore indicator if the ignore indicator is granted.

8. The apparatus of claim 7, wherein the lock manager assigns a bypass indicator to the subsequent transaction request.

9. The apparatus of claim 8, wherein when a prior transaction request is assigned the bypass indicator, the lock manager grants access to the resource for the requesting transaction request.

10. A computer program product having instruction codes for handling a lock request from a requesting transaction request (transaction B) for additional access to a resource comprising:

a first set of instruction codes for receiving a lock request for the additional access to the resource from the requesting transaction request (transaction B);

a second set of instruction codes for determining if a conflict exists between an access mode of the requesting transaction request (transaction B) and an access mode of all prior transaction requests (transaction A) with current access to the resource;

wherein if the conflict exists, the second set of instruction codes determines if the requesting transaction request (transaction B) has been refused and is currently waiting for access to the resource;

wherein if the requesting transaction request (transaction B) is not waiting for access to the resource and is having current access to the resource, substantially concurrently with the prior transaction requests (transaction A), the second set of instruction codes assigns an ignore indicator to the requesting transaction request (transaction B); and

wherein the ignore indicator allows a subsequent transaction request (transaction C), with an access mode that conflicts with the requesting transaction (transaction B), to be granted access to the resource, substantially concurrently with the prior transaction requests (transaction A) and the requesting transaction request (transaction B), if an access mode of the subsequent transaction request (transaction C) does not conflict with the access mode of the prior transaction requests (transaction A), bypassing the conflicting requesting transaction request (transaction B).

11. The computer program product of claim 10, further comprising a third set of instruction codes for setting an overall ignore bit if the ignore indicator is assigned to the requesting transaction request.

12. The computer program product of claim 10, further comprising a third set of instruction codes for granting a bypass indicator to the subsequent transaction request.

13. The computer program product of claim 12, further comprising a fourth set of instruction codes for monitoring a prior transaction request to determine when the prior transaction request has been assigned the bypass indicator and for granting the requesting transaction request access to the resource.

14. The computer program product of claim 13, further comprising a fifth set of instruction codes for clearing the bypass indicator and the ignore indicator.

15. A system for handling a lock request from a requesting transaction request (transaction B) for additional access to a resource, comprising:

means for receiving a lock request for the additional access to the resource from the requesting transaction request (transaction B);

means for determining if a conflict exists between an access mode of the requesting transaction request (transaction B) and an access mode of all prior transaction requests (transaction A) with current access to the resource;

means for determining if the requesting transaction requests (transaction B) has been refused and is currently waiting for access to the resource;

means for assigning an ignore indicator to the requesting transaction request (transaction B), if the requesting transaction requests (transaction B) is not waiting for access to the resource and is having current access to the resource, substantially concurrently with the prior transaction requests (transaction A); and

wherein the ignore indicator allows a subsequent transaction request (transaction C), with an access mode that conflicts with the requesting transaction (transaction B), to be granted access to the resource, substantially concurrently with the prior transaction requests (transaction A) and the requesting transaction request (transaction B), if an access mode of the subsequent transaction request (transaction C) does not conflict with the access mode of the prior transaction requests (transaction A), bypassing the conflicting requesting transaction request (transaction B).

16. The system of claim 15, further comprising means for setting an overall ignore bit if the ignore indicator is assigned to the requesting transaction request.

17. The system of claim 15, further comprising means for granting a bypass indicator to the subsequent transaction request.

18. The system of claim 17, further comprising means for monitoring a prior transaction request to determine when the prior transaction request has been assigned the bypass indicator and for granting the requesting transaction request access to the resource.

19. The system of claim 18, further comprising means for clearing the bypass indicator and the ignore indicator.