PROCESS-SAFE READ/WRITE LOCKS

• US 20120151110A1
• Filed: 12/14/2010
• Published: 06/14/2012
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: Ivanti, Inc. (Ivanti Software, Inc.)
• Original Assignee: Appsense Incorporated
• Inventors: Pointon, Richard, Somerfield, Richard James
• Granted Patent: US 9,542,235 B2
• Time in Patent Office: Days
• US Class Current: 710/200
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

In one embodiment, a non-transitory processor-readable medium stores code representing instructions that when executed cause a processor to obtain a first mutual exclusion object. The first mutual exclusion object can be a write mutual exclusion object associated with a shared resource. The code can further represent instructions that when executed cause the processor to obtain a second mutual exclusion object associated with an object manager module and define a read event object with a name conforming to a predetermined format. The code can further represent instructions that when executed cause the processor to release the second mutual exclusion object, release the first mutual exclusion object, read at least a portion of the shared resource, obtain the second mutual exclusion object, destroy the read event object and release the second mutual exclusion object.

Claims

1. A non-transitory processor-readable medium storing code representing instructions that when executed cause a processor to:

obtain a first mutual exclusion object, the first mutual exclusion object being a write mutual exclusion object associated with a shared resource;

obtain a second mutual exclusion object, the second mutual exclusion object being associated with an object manager module;

define a read event object with a name conforming to a predetermined format;

release the second mutual exclusion object;

release the first mutual exclusion object;

read at least a portion of the shared resource;

obtain the second mutual exclusion object;

destroy the read event object; and

release the second mutual exclusion object.

2. The non-transitory processor-readable medium of claim 1, wherein the read event object is a kernel object.

3. The non-transitory processor-readable medium of claim 1, further comprising code representing instructions that when executed cause a processor to:

set an indicator based on the destroying.

4. The non-transitory processor-readable medium of claim 1, wherein the shared resource is a data file.

5. The non-transitory processor-readable medium of claim 1, wherein the object manager module is a Windows kernel object manager module.

6. The non-transitory processor-readable medium of claim 1, wherein the reading of the at least a portion of the shared resource is performed by an operating system process.

7. A non-transitory processor-readable medium storing code representing instructions that when executed cause a processor to:

obtain a first mutual exclusion object, the first mutual exclusion object being associated with a shared resource;

obtain a second mutual exclusion object, the second mutual exclusion object being associated with an object manager module;

receive, from the object manager module, a count value, the count value being based at least in part on a number of read event objects that have a name conforming to a predetermined format;

release the second mutual exclusion object;

determine that the count value is zero, the count value being zero based at least in part on an abnormal reader process termination;

write one or more bits to the shared resource; and

release the first mutual exclusion object.

8. The non-transitory processor-readable medium of claim 7, wherein each read event object having the name conforming to the predetermined format is a kernel object.

9. The non-transitory processor-readable medium of claim 7, further comprising code representing instructions that when executed cause a processor to:

determine that the count value is not zero;

obtain the second mutual exclusion object in response to a termination of a read event object;

receive, from the object manager module, the count value;

determine that the count value is zero;

write the one or more bits to the shared resource; and

release the second mutual exclusion object.

10. The non-transitory processor-readable medium of claim 9, further comprising code representing instructions that when executed cause a processor to:

remain in an idle state until an indication of the read event object termination is received.

11. The non-transitory processor-readable medium of claim 9, further comprising code representing instructions that when executed cause a processor to:

remain in an idle state for a predetermined period of time; and

upon expiration of the predetermined period of time;

obtain the second mutual exclusion object;

receive, from the object manager module, the count value;

determine that the count value is zero;

write the one or more bits to the shared resource; and

release the second mutual exclusion object.

12. The non-transitory processor-readable medium of claim 7, wherein the shared resource is a database record.

13. An apparatus, comprising:

a processor;

a memory;

a shared resource;

a library module, the library module including;

a read module, the read module configured to;

obtain a write mutual exclusion object, the write mutual exclusion object being associated with the shared resource;

obtain an object manager mutual exclusion object, the object manager mutual exclusion object being associated with an object manager module;

define a read event object, the read event object having a name conforming to a predetermined format;

release the object manager mutual exclusion object;

release the write mutual exclusion object;

access an indicated portion of the shared resource;

obtain the object manager mutual exclusion object;

destroy the read event object;

set a read event indicator; and

release the object manager mutual exclusion object; and

a write module, the write module configured to;

obtain the write mutual exclusion object;

obtain the object manager mutual exclusion object;

receive a count value from the object manager mutual exclusion object, the count value being based at least in part on a quantity of read event objects named according to the predetermined format;

release the object manager mutual exclusion object;

determine that the count value is zero, the count value being zero based at least in part on an abnormal process termination;

write one or more bits to the shared resource; and

release the write mutual exclusion object;

a first application, the first application configured to access the indicated portion of the shared resource using at least an instance of the read module; and

a second application, the second application configured to write to the shared resource using at least an instance of the write module.

14. The apparatus of claim 13, wherein the read event object is a kernel object.

15. The apparatus of claim 13, wherein the write module is further configured to:

determine that the count value does not have the zero value;

obtain the object manager mutual exclusion object in response to a termination of a read event object;

receive, from the object manager module, the count value;

determine that the count value is zero;

write the one or more bits to the shared resource;

release the object manager mutual exclusion object; and

release the write mutual exclusion object.

16. The apparatus of claim 13, wherein the write module is further configured to:

remain in an idle state until an indication of the termination of the read event object is received.

17. The apparatus of claim 13, wherein the library module is a dynamic link library (DLL).

18. The apparatus of claim 13, wherein the shared resource is a buffer.

19. The apparatus of claim 13, wherein the library module is included in two or more processes, each of the two or more processes being executed by the processor.