Method and system for optimizing resources for cache management

• US 6,687,793 B1
• Filed: 12/28/2001
• Issued: 02/03/2004
• Est. Priority Date: 12/28/2001
• Status: Active Grant

• Current Assignee: Ip Ot Sub Ulc
• Original Assignee: Vignette Corporation (Open Text Corporation)
• Inventors: Thomas, David, Wells, Scott
• Primary Examiner(s): Thai, Tuan V
• Application Number:
  US10/034,712
• Time in Patent Office: 767 Days
• Field of Search: 711/100, 711/118, 711/133, 711/136, 711/154, 711/167
• US Class Current: 711/133
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: G06F 2212/264 Remote server
• CPC Class Codes: G06F 2212/465 Structured object, e.g. database record
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

The present invention provides a system and method for optimizing a cache that substantially eliminates reduces the disadvantages of previously developed cache management systems. More particularly, embodiments of the present invention provide a system of optimizing a cache by polling cached assets with a frequency dependent of the relative activity of a cached asset. An embodiment of the method of the system includes the steps of: (i) polling a cached asset according to a first schedule to determine if the cached asset has been active within a first predefined period of time; (ii) if the cached asset has not been active, polling the cached asset according to a second schedule to determine if the cached asset has been inactive for at least a second predefined period of time; (iii) demoting the cached asset to less active status; and (iv) if the cached asset has been inactive for at least within the second predefined period of time, demoting the cached asset to inactive status. In one embodiment of the present invention, if the cached asset has been active within the second predefined period of time, the cached asset can again be polled according to the first frequency. The frequency with which the cached asset can be polled according to the first and second schedule can be a matter of optimization. Polling according to the first schedule can occur at a greater frequency than polling according to the second schedule. Thus, more active assets can be polled more often than less active assets.

Claims

1. A method for managing a cache comprising:

polling a cached asset according to a first schedule to determine if said cached asset has been active within a first predefined period of time;

if said cached asset has not been active within said first predefined period of time;

demoting said cached asset to less-active status;

polling said cached asset according to a second schedule to determine if said cached asset has been active within a second predefined period of time;

if said cached asset has not been active within said second predefined period of time, demoting said cached asset to inactive status.

2. The method of claim 1, wherein in the step of polling said cached asset according to said first schedule further comprises processing a timestamp associated with said cached asset.

3. The method of claim 2, wherein said timestamp further comprises a last accessed time stamp.

4. The method of claim 2, wherein said timestamp further comprises a last modified time stamp.

5. The method of claim 1, further comprising if said cached asset has been active within said second predetermined period of time, promoting said cached asset to an active status;

and polling said cached asset according to said second schedule to determine if said cached asset has been active since a last polling interval; and

polling said cached asset according to said first schedule.

6. The method of claim 1, further comprising removing said cached asset from said cache.

7. The method of claim 6, further comprising removing said cached asset from said cache when said cached asset has been inactive for at least third predetermined period of time.

8. The method of claim 6, further comprising removing said cached asset from said cache if a set of inactive cached assets becomes larger than a predefined limit.

9. The method of claim 6, further comprising notifying a user prior to removing said cached asset from said cache.

10. The method of claim 1 wherein polling according to said first schedule occurs at a greater frequency than polling according to said second schedule.

11. The method of claim 1, wherein said second predefined period of time is longer than said first predefined period of time.

12. A method of managing a cache comprising:

maintaining an active file list of recently active cached files stored in said cache;

maintaining a less active file list of less active cached files stored in said cache;

polling a cached file represented in said active file list according to a first schedule to determine if said file has been active within a first predefined period;

if said cached file has been active within said first predefined period, maintaining a file entry associated with said cached file in said active file list;

if said cached file has not been active for at least said first predefined period of time;

demoting said file entry to said less active file list;

polling said cached file according to a second schedule to determine if said cached file has been active within a second predefined period of time; and

if said cached file has been active within said second predefined period of time, promoting said file entry to said active file list; and

if said cached file has not been active for at least a second predefined period of time, removing said file entry from said less active file list.

13. The method of claim 12, further wherein removing said file entry from said less active file list comprises:

demoting said file entry to a non-active file list, and wherein said method further comprises maintaining said non-active file list; and

removing said cached file from said non-active file list upon a triggering event.

14. The method of claim 13, wherein the triggering event is the cached file remaining non-active for greater than a third predefined period of time.

15. The method of claim 13, wherein the triggering event is a set of non-active files represented in said non-active file list exceeding a predetermined size.

16. The method of claim 13, further comprising notifying a user prior to removing said cached file from said cache.

17. The method of claim 12, wherein polling according to said first schedule occurs at a greater frequency than polling according to said second schedule.

18. The method of claim 12, further comprising receiving a notification at a cache manager from a file management system that said cached file has been active within the second predefined period of time.

19. The method of claim 12, wherein an attribute for said cached file includes a file time stamp.

20. The method of claim 19, wherein the step of polling said cached file according to said first schedule further comprises comparing said time stamp to a previous time stamp.

21. The method of claim 20, wherein said file time stamp is either a last modified time stamp or a last accessed time stamp.

22. The method of claim 12, wherein the step of polling said cached file according to said second schedule to determine if said cached file has been active within said second predefined period further comprises comparing said file time stamp to a previous time stamp.

23. The method of claim 22, wherein said file time stamp is either a last modified time stamp or a last accessed time stamp.

24. A system of managing a cache comprising a computer readable medium containing a software program executable by a computer processor to:

maintain a list of cached files;

poll a cached file associated with the list of cached files according to a first schedule to determine if said cached file has been active for at least a first predefined period of time; and

if said cached file has not been active within said first predefined period of time;

demote said cached file to a less-active status;

poll said cached file according to a second schedule to determine if said cached file has been active within a second predefined period of time; and

if said cached file has not been active for at least said second predefined period of time, demote said cached file to inactive status.

25. The system of claim 24, wherein said software program is further executable to:

if said cached file has been active within the second predetermined period of time, poll said cached file according to said first schedule to determine if said cached file has been active within said first predetermined period of time.

26. The system of claim 24, wherein said software program is further executable to remove said cached file from said cache.

27. The system of claim 26, wherein said software program is further executable to notify a user prior to removing said associated file from said cache.

28. The system of claim 24, wherein polling said file entry according said first schedule occurs at a greater frequency than polling according to said second schedule.

29. The system of claim 24, wherein said software program is further executable to receive a notification from a file management system that said cached file has been active.

30. The system of claim 24, wherein a file attribute for said cached file includes a file time stamp.

31. The system of claim 30, wherein the step of polling said cached file according to said first schedule to determine if said cached file has been active within said first predefined period further comprises comparing said file time stamp to a previous time stamp.

32. The system of claim 31, wherein said file time stamp is either a last modified time stamp or a last accessed time stamp.

33. The system of claim 32, wherein the step of polling said file entry according to said second schedule to determine if said associated file has been active within said second predefined period further comprises comparing said file time stamp to a previous time stamp.

34. The system of claim 24, wherein said software program is further executable to:

determine if said cached file has been active within said second predetermined period of time;

if said cached file has been active within said predetermined period of time, polling said cached file according to said first schedule.

35. A method for managing a cache comprising:

polling a cached file according to a first schedule to determine if said cached file has been active within a first predefined period of time;

if said cached file has not been active within said first predefined period of time;

demoting said cached file to less-active status;

polling said cached file according to a second schedule to determine if said cached file has been active within a second predefined period of time;

if said cached file has not been active within said second predefined period of time, demoting said cached file to inactive status.

36. The method of claim 35, wherein in the step of polling said cached file according to said first schedule further comprises processing a timestamp associated with said cached file.

37. The method of claim 36, wherein said timestamp further comprises a last accessed time stamp.

38. The method of claim 36, wherein said timestamp further comprises a last modified time stamp.

39. The method of claim 35, further comprising if said cached file has been active within said second predetermined period of time, promoting said cached file to an active status;

and polling said cached file according to said second schedule to determine if said cached file has been active since a last polling interval; and

polling said cached file according to said first schedule.

40. The method of claim 35, further comprising removing said cached file from said cache.

41. The method of claim 40, further comprising removing said cached file from said cache when said cached file has been inactive for at least third predetermined period of time.

42. The method of claim 40, further comprising removing said cached file from said cache if a set of inactive cached files becomes larger than a predefined limit.

43. The method of claim 40, further comprising notifying a user prior to removing said cached file from said cache.

44. The method of claim 35 wherein polling according to said first schedule occurs at a greater frequency than polling according to said second schedule.

45. The method of claim 35, wherein said second predefined period of time is longer than said first predefined period of time.