Method, system, and apparatus for managing access to a data object

• US 20060004760A1
• Filed: 06/21/2004
• Published: 01/05/2006
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Marinescu, Adrian, Clift, Neill M.
• Granted Patent: US 7,428,539 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure

Abstract

In accordance with an embodiment of this invention, a mechanism for managing a plurality of access requests for a data object is provided. The mechanism includes a lock control identifying whether a requested data object is in use and a waiter control identifying whether at least one of the plurality of access requests have been denied immediate access to the data object and is currently waiting for access to the data object. Additionally, the mechanism maintains a list optimize control identifying whether one of the plurality of access requests is currently optimizing a waiters list of access requests waiting to access to the data object.

Claims

1. A mechanism for managing a plurality of access requests for a data object, comprising:

a lock control identifying whether a requested data object is in use;

a waiter control identifying whether at least one of the plurality of access requests have been denied immediate access to the data object and is currently waiting for access to the data object; and

a list optimize control identifying whether one of the plurality of access requests is currently optimizing a waiters list of access requests waiting to access to the data object.

2. The locking mechanism of claim 1, further comprising:

a share count identifying a number of access requests that are currently sharing access to the data object.

3. The locking mechanism of claim 2, wherein the share count equals zero if the data object is being accessed by an exclusive access request.

4. The locking mechanism of claim 2, wherein the share count is greater than zero if the data object is being accessed by at least one shared access request.

5. The locking mechanism of claim 1, wherein the lock control identifies that the data object is in use if at least one of the plurality of access requests obtains access to the data object.

6. The locking mechanism of claim 5, wherein the at least one of the plurality of access requests is an exclusive access request.

7. The locking mechanism of claim 5, wherein the at least one of the plurality of access requests is a shared access request.

8. The locking mechanism of claim 1, wherein the waiter control identifies that at least one of the plurality of access requests is currently waiting for access to the data object.

9. The locking mechanism of claim 1, further comprising:

a multiple share control identifying if more than one of the plurality of access requests are currently sharing access to the data object.

10. The locking mechanism of claim 1, wherein each of the access requests that are denied immediate access to the data object attempt to optimize the waiters list by setting the list optimize control.

11. A computer readable medium having computer-executable components for managing access to a data object, the components comprising:

a waiters list component, wherein the waiters list component maintains a respective wait block representative of each access request that have been denied immediate access to the data object and are waiting to access the data object; and

a locking mechanism component controlling access to the data object, the locking mechanism comprising;

a reference to the waiters list; and

an optimization control for the waiters list.

12. The computer system of claim 11, wherein the optimization control identifies whether the waiters list is currently being optimized by one of the plurality of access requests that are waiting to access the data object.

13. The computer system of claim 11, wherein at least one of the wait blocks in the waiters list identifies an end wait block of the waiters list.

14. The computer system of claim 11, wherein at least one of the wait blocks in the waiters list identifies a previous wait block.

15. The computer system of claim 11, wherein at least one of the wait blocks in the waiters list identifies a subsequent wait block.

16. The computer system of claim 11, wherein at least one of the wait blocks in the waiters list identifies a number of access requests that were currently accessing the data object prior to its addition to the waiters list.

17. The computer system of claim 11, wherein at least one of the wait blocks in the waiters list identifies an end wait block of the waiters list, a previous wait block, and a subsequent wait block.

18. The computer system of claim 11, wherein locking mechanism includes an indication of a number of the plurality of access requests currently waiting to access the data object.

19. A method for maintaining a waiters list of access requests that are waiting to access a data object that is locked, the method comprising:

receiving an access request for the data object;

generating a wait block representative of the access request;

adding the wait block to the front of the waiters list;

determining if the waiters list is currently being optimized;

if it is determined that the waiters list is not currently being optimized, optimizing the waiters list;

determining if the lock on the data object has been released; and

if it is determined that the lock in the data object has been released, allowing at least one of the access requests identified by a wait block to attempt to access the data object.

20. The method of claim 19, wherein allowing at least one of the access requests identified by a wait block to attempt to access the data object includes allowing all of the access requests identified by a wait block to attempt to access the data object.

21. The method of claim 19, wherein allowing at least one of the access requests identified by a wait block to attempt to access the data object includes allowing the first access request identified by a wait block added to the waiters list to attempt to access the data object.

22. The method of claim 19, wherein optimizing the waiters list includes:

adding a reference to at least one of the wait blocks identifying the first wait block added to the waiters list.

23. The method of claim 19, wherein optimizing the waiters list includes:

adding a reference to at least one of the wait blocks identifying the wait block preceding the wait block to which the reference is added.

24. The method of claim 19, wherein optimizing the waiters list includes:

adding a reference to at least one of the wait blocks identifying the wait block subsequent to the wait block to which the reference is added.

25. The method of claim 19, wherein optimizing the waiters list includes:

adding a reference to at least one of the wait blocks identifying the first wait block added to the waiters list;

adding a reference to at least one of the wait blocks identifying the wait block preceding the wait block to which the reference is added; and

adding a reference to at least one of the wait blocks identifying the wait block subsequent to the wait block to which the reference is added.

26. A computer-readable medium having computer-executable instructions for performing the method recited in claim 19.

27. The computer system having a processor, a memory and an operating environment, the computer system operable to perform the method recited claim 19.

28. A method for controlling access to a data object, the method comprising:

receiving a first exclusive access request for the data object;

placing an exclusive lock on the data object;

receiving a second access request for the data object;

creating a wait block representative of the second access request;

adding the wait block to a waiters list;

determining whether the waiters list is currently being optimized; and

if it is determined that the waiters list is not currently being optimized, allowing the second access request to optimize the waiters list.

29. The method of claim 28, further comprising:

including an indication in the lock that an access request is currently waiting to access the data object.

30. The method of claim 28, further comprising:

generating a pointer to the waiters list in response to adding the wait block to the waiters list.

31. A computer-readable medium having computer-executable instructions for performing the method recited in claim 28.

32. The computer system having a processor, a memory and an operating environment, the computer system operable to perform the method recited claim 28.