Suspension and reinstatement of reference handles

• US 20050071466A1
• Filed: 10/15/2004
• Published: 03/31/2005
• Est. Priority Date: 06/29/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Douceur, John R., Bernet, Yoram
• Granted Patent: US 7,305,468 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

A handle administration system is described in which software agents receive handles to various resources that they can use to obtain the resources. The described embodiments provide multiple states that can be assumed by the handles. An unassigned state is provided in which handles are not assigned to a particular resource, nor can they be dereferenced to obtain pointers to any resources. An assigned state is provided in which handles are assigned to a particular resource and can be dereferenced to obtain a pointer to the resource. A suspended state is provided in which the handles are assigned to a particular resource but cannot be dereferenced to obtain a pointer to that resource. Advantageously, a suspended handle can be reinstated to assume the assigned state. In one embodiment, the handle system is implemented by incorporating a suitable field in a handle database that is used to indicate that a handle is suspended. In another embodiment, no additional fields are necessary. Rather, handle values in the handle database are manipulated to indicate that a handle has been suspended. These manipulations can be easily undone to reinstate a handle. In the described embodiment, a three state handle system can be advantageously employed to implement a two-phase commit operation.

Claims

1. A method of managing resources comprising:

requesting one or more agents to suspend one or more handles; and

releasing the suspended handles.

2. The method of claim 1, wherein the handles are associated with one or more resources when they are suspended.

3. The method of claim 1, wherein the handles are associated with one or more resources when they are suspended but cannot be dereferenced into a pointer for those resources.

4. The method of claim 1, wherein the one or more agents comprise a plurality of agents, and handles are released only if all of the agents can suspend the handles.

5. The method of claim 1 further comprising reinstating the handle if one or more of the agents could not suspend the handle.

6. One or more computer-readable media having computer-readable instructions thereon which, when executed by one or more computers, cause the computers to implement the method of claim 1.

7. A method of managing resources comprising:

indicating that a handle is suspended in a handle database; and

reinstating a handle that is indicated as suspended in the handle database by having the handle assume an assigned state in which it can be validly dereferenced to obtain a pointer to a resource.

8. The method of claim 7, wherein said indicating comprises setting a flag to indicate that the handle is suspended.

9. The method of claim 7, wherein said indicating comprises manipulating a handle value in the handle database to indicate that the handle is suspended.

10. One or more computer-readable media having computer-readable instructions thereon which, when executed by one or more computers, cause the computers to implement the method of claim 7.

11. A system comprising:

one or more processors;

one or more computer-readable media;

computer-readable instructions on the one or more computer-readable media which, when executed, cause the one or more processors to implement a method comprising;

requesting one or more agents to suspend one or more handles; and

releasing the suspended handles.

12. The system of claim 11, wherein the handles are associated with one or more resources when they are suspended.

13. The system of claim 11, wherein the handles are associated with one or more resources when they are suspended but cannot be dereferenced into a pointer for those resources.

14. The system of claim 11, wherein the one or more agents comprise a plurality of agents, and handles are released only if all of the agents can suspend the handles.

15. The system of claim 11 further comprising reinstating the handle if one or more of the agents could not suspend the handle.

16. A system comprising:

means for requesting one or more agents to suspend one or more handles; and

means for releasing the suspended handles.

17. The system of claim 16, wherein the handles are associated with one or more resources when they are suspended.

18. The system of claim 16, wherein the handles are associated with one or more resources when they are suspended but cannot be dereferenced into a pointer for those resources.

19. The system of claim 16, wherein the one or more agents comprise a plurality of agents, and handles are released only if all of the agents can suspend the handles.

20. The system of claim 16 further comprising means for reinstating the handle if one or more of the agents could not suspend the handle.

21. A system comprising:

one or more processors;

one or more computer-readable media;

computer-readable instructions on the one or more computer-readable media which, when executed, cause the one or more processors to implement a method comprising;

indicating that a handle is suspended in a handle database; and

reinstating a handle that is indicated as suspended in the handle database by having the handle assume an assigned state in which it can be validly dereferenced to obtain a pointer to a resource.

22. The system of claim 21, wherein said indicating comprises setting a flag to indicate that the handle is suspended.

23. The system of claim 21, wherein said indicating comprises manipulating a handle value in the handle database to indicate that the handle is suspended.

24. A system comprising:

means for indicating that a handle is suspended in a handle database; and

means for reinstating a handle that is indicated as suspended in the handle database by having the handle assume an assigned state in which it can be validly dereferenced to obtain a pointer to a resource.

25. The system of claim 24, wherein said means for indicating comprises means for setting a flag to indicate that the handle is suspended.

26. The system of claim 24, wherein said means for indicating comprises means for manipulating a handle value in the handle database to indicate that the handle is suspended.