Method and apparatus for sharing resource locks amongst applications

• US 8,566,298 B1
• Filed: 07/28/2005
• Issued: 10/22/2013
• Est. Priority Date: 07/28/2005
• Status: Expired due to Fees

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Operating Corporation (Gen Digital Inc.)
• Inventors: Nagaralu, Sree Hari, Borate, Milind, Nagaraj, Murali
• Primary Examiner(s): Beausoliel, Jr., Robert
• Assistant Examiner(s): Arjomandi, Noosha
• Application Number:
  US11/191,500
• Time in Patent Office: 3,008 Days
• Field of Search: 707/704
• US Class Current: 707/704
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A method and apparatus for sharing an exclusive lock for a resource amongst a defined plurality of applications. A first application to lock a resource is given a key. The first application may provide the key to other applications to allow those applications to simultaneously access the locked resource. Generally, the first application will only provide keys to applications that are compatible with the first application such that the applications having keys to a resource will be able to simultaneously access the resource without conflict.

Claims

1. A method for sharing resource locks amongst applications comprising:

receiving a lock request, wherein

the lock request is received from a first application, and

the lock request specifies that a resource be locked;

locking the resource using a key and lock combination for the locked resource;

supplying the key to the first application;

creating an exclusive lock mode key and a shared lock mode key;

detecting whether the locked resource is locked according to a shared lock mode or an exclusive lock mode;

sharing the shared lock mode key with at least one second application to enable the at least one second application to simultaneously access the resource, or sharing the exclusive lock mode key with the at least one second application to enable the at least one second application to have exclusive access to the resource, wherein the sharing comprises sending the key from the first application to the at least one second application; and

enabling the at least one second application to simultaneously access the resource with the first application.

2. The method of claim 1, wherein

the locking the resource is performed based on a locking policy.

3. The method of claim 1, wherein

the first application and the at least one second application form a group of compatible applications that simultaneously access the resource without conflict.

4. The method of claim 1, further comprising:

selecting the at least one second application from a list of known applications that are compatible with the first application, wherein

each known application of the known applications is configured to access the resource simultaneously with the first application without conflicting with the first application.

5. The method of claim 1, wherein

the first application is executed by a first node of a computer network, and

at least one of the at least one second applications is executed by the first node, by a second node of the computer network, or by both the first node and the second node.

6. The method of claim 1, wherein the locking further comprises:

receiving the key from the first application; and

creating a lock for the resource that matches the key.

7. The method of claim 1, further comprising:

incrementing a lock count for each application that accesses the resource using the key;

decrementing the lock count for each application that ceases accessing the resource using the key; and

dissolving the lock on the resource when the lock count reaches a specific value.

8. The method of claim 1, wherein the creating further comprises:

creating a plurality of keys for a plurality of colored locks; and

sharing the plurality of keys with a plurality of second applications, wherein

each color represents a different lock mode that can be utilized by a matching colored key.

9. The method of claim 1, wherein

the first application creates a list of authorized compatible applications, and

the authorized compatible applications are configured to simultaneously access the resource without conflict.

10. A non-transitory computer readable storage medium storing instructions executable by a processor to:

receive a lock request, wherein

the lock request is received from a first application, and

the lock request specifies that a resource be locked;

lock the resource using a key and lock combination for the locked resource;

supply the key to the first application;

create an exclusive lock mode key and a shared lock mode key;

detect whether the locked resource is locked according to a shared lock mode or an exclusive lock mode;

share the shared lock mode key with at least one second application to enable the at least one second application to simultaneously access the resource, or share the exclusive lock mode key with the at least one second application to enable the at least one second application to have exclusive access to the resource, wherein sharing comprises sending the key from the first application to at least one second application; and

enable the at least one second application to simultaneously access the resource with the first application.

11. The non-transitory computer readable storage medium of claim 10, wherein the instructions are further executable to:

select the at least one second application from a list of known applications that are compatible with the first application, wherein

each known application of the known applications is configured to access the resource simultaneously with the first application without conflicting with the first application.

12. An apparatus for sharing resource locks amongst applications comprising:

means for providing a lock manager, wherein the lock manager is configured for

receiving a lock request from a first application to lock a resource,

locking the resource using a key and lock combination,

supplying the key to the first application, and

creating an exclusive lock mode key and a shared lock mode key;

means for detecting whether the locked resource is locked according to a shared lock mode or an exclusive lock mode; and

means for providing a lock Application Programming Interface (API), operating with said first application, wherein

the lock API is configured for

sharing the shared lock mode key with at least one second application to enable the at least one second application to simultaneously access the resource, or sharing the exclusive lock mode key with the at least one second application to enable the at least one second application to have exclusive access to the resource, wherein the sharing comprises sending the key to the at least one second application, and

enabling the at least one second application to simultaneously access the resource with the first application.

13. The apparatus of claim 12, wherein

locking the resource occurs on a first come, first served basis.

14. The apparatus of claim 12, wherein

the first application and the at least one second application form a group of compatible applications that simultaneously access the resource without conflict.

15. The apparatus of claim 12, wherein

the first application is executed by a first node of a computer network, and

at least one of the at least one second applications is executed by the first node, by a second node of the computer network, or by both the first node and the second node.

16. The apparatus of claim 12, wherein

the lock manager receives they key from the first application and creates a lock for the resource that matches the key.

17. The apparatus of claim 12, wherein the lock manager further comprises:

a lock counter, wherein

the lock counter is incremented for each application that accesses the resource using the key,

the lock counter is decremented for each application that ceases accessing the resource using the key, and

the lock manager terminates the lock on the resource when the lock counter reaches a specific value.

18. The apparatus of claim 12, wherein

the lock manager creates a plurality of keys for a plurality of colored locks,

the lock Application Programming Interface (API) shares the plurality of keys with a plurality of applications, and

each color represents a different lock mode that can be utilized by a matching colored key.