Suspension and reinstatement of reference handles

• US 20050060683A1
• Filed: 10/15/2004
• Published: 03/17/2005
• 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 7,395,331 B2
• Time in Patent Office: Days
• US Class Current: 717/100
• 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 resource management system comprising:

at least one computer readable media; and

one or more handle records resident on the media, each record having fields, one of the fields being configured to provide indicia of whether a handle is in a state other than an assigned state and an unassigned state.

2. The resource management system of claim 1, wherein the other state comprises a suspended state in which a handle can be associated with a particular resource, but cannot be dereferenced to obtain a pointer to that resource.

3. A data structure embodied on a computer-readable medium for use in managing resources, the data structure comprising:

a first portion that is associated with a pointer to a resource; and

a second portion that is associated with a suspended handle state.

4. The data structure of claim 3, wherein the suspended handle state indicates a handle that is associated with a particular resource but which cannot be dereferenced to obtain a pointer to that resource.

5. The data structure of claim 3, wherein the second portion is configured to hold a value that indicates that a handle is suspended.

6. The data structure of claim 3 further comprising a handle administrator that is configured to use said data structure to manage handles for the resources, the handle administrator being configured to dereference handles into pointers to resources with which the handles are associated.

7. The data structure of claim 6, wherein the handle administrator is configured to receive a handle and determine whether the handle is valid and not suspended before dereferencing it into a pointer.

8. A computing device comprising:

one or more processors;

at least one computer readable media;

one or more handle records resident on the media, each record having fields, one of the fields being configured to provide indicia of whether a handle is in a state other than an assigned state and an unassigned state;

computer-readable instructions on the computer-readable media which, when executed by the one or more processors, cause the one or more processors to utilize the one or more handle records to manage handle-associated resources.

9. The computing device of claim 8, wherein the other state comprises a suspended state in which a handle can be associated with a particular resource, but cannot be dereferenced to obtain a pointer to that resource.

10. A computing device comprising:

one or more processors;

at least one computer readable media;

a data structure embodied on the computer readable media, the data structure comprising;

a first portion that is associated with a pointer to a resource; and

a second portion that is associated with a suspended handle state;

computer-readable instructions on the computer-readable media which, when executed by the one or more processors, cause the one or more processors to utilize the data structure to manage resources.

11. The computing device of claim 10, wherein the suspended handle state indicates a handle that is associated with a particular resource but which cannot be dereferenced to obtain a pointer to that resource.

12. The computing device of claim 10, wherein the second portion is configured to hold a value that indicates that a handle is suspended.

13. The computing device of claim 10 further comprising a handle administrator that is configured to use said data structure to manage handles for the resources, the handle administrator being configured to dereference handles into pointers to resources with which the handles are associated.

14. The computing device of claim 13, wherein the handle administrator is configured to receive a handle and determine whether the handle is valid and not suspended before dereferencing it into a pointer.