Opening a temporary object handle on a resource object

• US 9,063,784 B2
• Filed: 09/03/2010
• Issued: 06/23/2015
• Est. Priority Date: 09/03/2009
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Cullen, Paul, Hickson, Andrew, Reece, Stuart, Longerstaey, Gary
• Primary Examiner(s): Lee, Tammy
• Application Number:
  US12/875,650
• Publication Number:
  US 20110061052A1
• Time in Patent Office: 1,754 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 9/5011 the resources being hardware resources other than CPUs, Servers and Terminals

Abstract

A system is provided for using a temporary object handle. The system includes a resource manager: receiving an open temporary handle request from an application for a resource object, where a temporary handle can by asynchronously invalidated by the resource manager at any time; and creating a handle control block at the resource manager for the object, including an indication that the handle is a temporary handle. The system then includes the resource manager: responsive to receiving a request from an application to use a handle, which has been invalidated by the resource manager, sending a response to the application that the handle is invalidated.

Claims

1. A computer program product comprising:

a non-transitory computer readable storage device; and

program code stored on the non-transitory computer readable storage device that when executed by a processor performs the functions of;

providing, via a resource manager, a temporary handle to a first application managed by a first database that is requesting access to a resource object managed by a second database, wherein the temporary handle provides access to the resource object, wherein the temporary handle can be asynchronously invalidated or closed by the resource manager of the resource object at any time whilst the first application is active, wherein the temporary handle includes a priority attribute indicating that a resource manager should invalidate any other existing temporary handle on the resource object having a lower priority attribute to allow a higher priority request by the temporary handle;

receiving, at the resource manager, a conflicting request to access the resource object from a second application;

in response to receiving the conflicting request from the second application, the resource manager;

invalidating the temporary handle and any other existing temporary handles associated with the resource object that conflict with and have a lower priority than a priority of the second application; and

in response to receiving a request from the first application to close the temporary handle after the temporary handle has been invalidated by the resource manager, the resource manager deleting a handle control block associated with the temporary handle, wherein the resource manager comprises a plurality of handle control blocks, wherein each handle control block is allocated for a particular resource object.

2. The computer program product of claim 1, wherein the program code further comprises program code that when executed by the processor performs the functions of:

receiving an open temporary handle request from the first application for the resource object;

in response to receiving the open temporary handle request, allocating, at the resource manager, the handle control block for the resource object that includes an indication that the temporary handle is temporary;

receiving a request from the first application to use a handle which has been invalidated by the resource manager; and

in response to receiving the request from the first application to use a handle which has been invalidated, sending a response to the first application that indicates the handle has been invalidated.

3. The computer program product of claim 1, wherein the resource object is an open file, and wherein the first application and the second application are operating within a same operating system.

4. The computer program product of claim 1, wherein the second application has a plurality of temporary handles associated with a plurality of applications.

5. The computer program product of claim 1, wherein:

the temporary handle further comprises an open handle to a queue;

the temporary handle is an opaque reference.

6. The computer program product of claim 1, wherein the handle control block remains on the resource manager with a closed flag after the temporary handle is closed by the resource manager.

7. The computer program product of claim 1, wherein:

the temporary handle is a Unix file handle;

the temporary handle identifies whether the resource was opened for at least one of read and write access;

the resource object is stored within one or more blocks of memory that are managed by the second database;

the resource manager manages access to a plurality of resource objects, including the resource object; and

the temporary handle is not a lock.

8. The computer program product of claim 1, wherein the program code further comprises program code that when executed by the processor performs the functions of:

referencing the handle control block to an object control block, wherein the object control block represents an indirect reference to the resource object;

wherein invalidating the temporary handle further comprises;

asynchronously invalidating, via the resource manager, the temporary handle by including an indication in the handle control block that the temporary handle is invalid;

de-referencing the handle control block from the object control block; and

invalidating any other existing temporary handle on the resource object having a lower priority attribute than a priority attribute of a higher priority request to allow the higher priority request to access the resource object.

9. The computer program product of claim 1, wherein the temporary handle is chained to a control block representing the queue and a control block representing a connection associated with the temporary handle, the program code further comprising program code that when executed by the processor performs the functions of:

in response to invalidating the temporary handle;

flagging the temporary handle as closed; and

unchaining the temporary handle from the control block, wherein the temporary handle remains chained to the control block representing the connection associated with the temporary handle; and

in response to the first application explicitly closing the temporary handle, releasing the control block representing the temporary handle.

10. A data processing system for referencing a resource object, the system comprising:

a processor;

a memory coupled to the processor and having code that executed by the processor provides a resource manager for managing a resource object referenced by a first application, wherein the resource manager is configured to;

provide a temporary handle to a first application managed by a first database that is requesting access to a resource object managed by a second database, wherein the temporary handle provides access to the resource object, wherein the temporary handle can be asynchronously invalidated or closed by the resource manager of the resource object at any time whilst the first application is active, wherein the temporary handle includes a priority attribute indicating that a resource manager should invalidate any other existing temporary handle on the resource object having a lower priority attribute to allow a higher priority request by the temporary handle;

receive a conflicting request to access the resource object from a second application, wherein the conflicting request has an associated priority that is higher than the priority attribute of the temporary handle;

in response to receiving the conflicting request from the second application, invalidate the temporary handle and any other existing temporary handles to access the resource object that conflict with and have a lower priority than the priority associated with the conflicting request from the second application; and

in response to receiving a request from the first application to close the temporary handle after the temporary handle has been invalidated by the resource manager, delete a handle control block associated with the temporary handle, wherein the resource manager comprises a plurality of handle control blocks, wherein each handle control block is allocated for a particular resource object.

11. The data processing system as claimed in claim 10, wherein the resource manager further comprises a handle invalidated response mechanism, and wherein the resource manager is further configured to respond to the first application attempting to use an invalidated handle.

12. The data processing system as claimed in claim 10, wherein any application opening a temporary handle is able to cope with the resource object being made unavailable at any time.

13. The data processing system as claimed in claim 10, wherein the resource manager is further configured to:

set the handle control block of the temporary handle as one of closed and invalidated, wherein the handle control block includes an indication that the temporary handle is temporary; and

in response to flagging the handle control block as one of closed or invalidated, de-reference the handle control block from an object control block that represents as an indirect reference to the resource object.

14. The data processing system as claimed in claim 10, wherein the resource object is an open file, and wherein the first application and the second application are operating within a same operating system.

15. The data processing system of claim 10, wherein the second application has a plurality of temporary handles associated with a plurality of applications.

16. The data processing system of claim 10, wherein the resource manager further comprises:

an open handle request receiver; and

a handle manager that is configured to;

create the handle control block for the resource object that includes an indication that the temporary handle is temporary; and

reference the handle control block to an object control block, wherein the object control block represents an indirect reference to the resource object; and

a handle closing mechanism.

17. The data processing system of claim 16, wherein the resource manager is further configured to:

receive an open temporary handle request from the first application for the resource object;

in response to receiving the open temporary handle request, allocate, at the resource manager, the handle control block for the resource object;

receive a request from the first application to use a handle which has been invalidated by the resource manager;

in response to receiving the request from the first application to use a handle which has been invalidated, send a response to the first application that indicates the handle has been invalidated;

asynchronously invalidate, via the resource manager, the temporary handle by including an indication in the handle control block that the temporary handle is invalid;

de-reference the handle control block from the object control block; and

invalidate any other existing temporary handle on the resource object having a lower priority attribute than a priority attribute of a higher priority request to allow the higher priority request to access the resource object.

18. The data processing system as claimed in claim 10, wherein:

the temporary handle further comprises an open handle to a queue;

the temporary handle is an opaque reference;

the temporary handle is chained to a control block representing the queue and a control block representing a connection associated with the temporary handle; and

the resource manager is further configured to;

in response to invalidating the temporary handle;

flag the temporary handle as closed; and

unchain the temporary handle from the control block, wherein the temporary handle remains chained to the control block representing the connection associated with the temporary handle; and

in response to the first application explicitly closing the temporary handle, release the control block representing the temporary handle.

19. The data processing system as claimed in claim 10, wherein the handle control block remains on the resource manager with a closed flag after the temporary handle is closed by the resource manager.

20. The data processing system as claimed in claim 10, wherein:

the temporary handle is a Unix file handle;

the temporary handle identifies whether the resource was opened for at least one of read and write access;

the resource object is stored within one or more blocks of memory that are managed by the second database;

the resource manager manages access to a plurality of resource objects, including the resource object; and

the temporary handle is not a lock.