Transaction-Aware Caching for Access Control Metadata

• US 20080162485A1
• Filed: 03/14/2008
• Published: 07/03/2008
• Est. Priority Date: 05/12/2000
• Status: Active Grant

• Current Assignee: David B. Pitfield, David J. Long
• Original Assignee: David B. Pitfield, David J. Long
• Inventors: Pitfield, David B., Long, David J.
• Granted Patent: US 8,745,017 B2
• Time in Patent Office: Days
• US Class Current: 707/9
• CPC Class Codes: H04L 63/10 for controlling access to devices or network resources
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

Techniques are provided for performing transaction-aware caching of metadata in an electronic file system. A mechanism is described for providing transaction-aware caching that uses a cache hierarchy, where the cache hierarchy includes uncommitted caches associated with sessions in an application and a committed cache that is shared among the sessions in that application. Techniques are described for caching document metadata, access control metadata and folder path metadata. Also described is a technique for using negative cache entries to avoid unnecessary communications with a server when applications repeatedly request non-existent data.

Claims

1. A method for determining authorization to operate on a file, the method comprising the computer-implemented steps of:

receiving a request, associated with a session, for an operation on the file;

looking in one or more session caches that are associated with said session for an entry that contains permissions metadata for said file;

if said entry is not in said one or more session caches, then

looking for said entry in one or more shared caches whose entries are accessible to multiple sessions; and

if said entry is not in said one or more shared caches, then obtaining said permissions metadata from a source other than said one or more session caches and said one or more shared caches; and

using said permission data to determine whether said operation may be performed on said file.

2. The method of claim 1 wherein said permissions metadata is modified directly.

3. The method of claim 1 wherein said permissions metadata is modified indirectly.

4. The method of claim 1 wherein said permissions metadata is for one or more users and said one or more users are associated with one or more groups.

5. The method of claim 1, wherein said permissions metadata is for one or more users and said one or more users are associated with one or more groups, wherein a particular user of said one or more users are associated with more than one group, and wherein the method further comprises the computer-implemented step of:

merging together all permissions metadata for said particular user from said more than one group.

6. The method of claim 1 wherein said entry for said one or more shared caches is populated when said permissions metadata is referenced.

7. The method of claim 1 wherein said entry has an ID column identifying said file and a metadata column containing said permissions metadata.

8. The method of claim 7 wherein said metadata column of said entry in said one or more session caches is populated with modified permissions metadata that was modified by said session.

9. The method of claim 7 wherein said ID column for said one or more session caches is populated when said permissions metadata is modified.

10. The method of claim 7 wherein said ID column for said one or more session caches is populated when said file is modified.

11. The method of claim 7 wherein said metadata column for said one or more session caches is populated when said file is referenced subsequent to said file being modified.

12. The method of claim 7 wherein said metadata column for said one or more session caches is populated when said permissions metadata is referenced subsequent to said permissions metadata being modified.

13. The method of claim 7 wherein said metadata column for said one or more session caches is populated when said file is referenced subsequent to said permissions metadata being modified.

14. The method of claim 7 wherein said metadata column for said one or more session caches is populated when said permissions metadata is referenced subsequent to said file being modified.

15. The method of claim 1, wherein said session is associated with a transaction, and wherein the method further comprises the computer-implemented step of:

invalidating said entries in said one or more shared caches when said transaction successfully terminates wherein said entries in said one or more shared caches are duplicates of entries in said one or more session caches.

16. A computer-readable storage medium storing one or more sequences of instructions for determining authorization to operate on a file, which instructions, when executed by one or more processors, cause the one or more processors to perform the steps of:

receiving a request, associated with a session, for an operation on the file;

looking in one or more session caches that are associated with said session for an entry that contains permissions metadata for said file;

if said entry is not in said one or more session caches, then

looking for said entry in one or more shared caches whose entries are accessible to multiple sessions; and

if said entry is not in said one or more shared caches, then obtaining said permissions metadata from a source other than said one or more session caches and said one or more shared caches; and

using said permission data to determine whether said operation may be performed on said file.

17. The computer-readable storage medium of claim 16 wherein said permissions metadata is modified directly.

18. The computer-readable storage medium of claim 16 wherein said permissions metadata is modified indirectly.

19. The computer-readable storage medium of claim 16 wherein said permissions metadata is for one or more users and said one or more users are associated with one or more groups.

20. The computer-readable storage medium of claim 16, wherein said permissions metadata is for one or more users and said one or more users are associated with one or more groups, wherein a particular user of said one or more users are associated with more than one group, and wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to perform the step of:

merging together all permissions metadata for said particular user from said more than one group.

21. The computer-readable storage medium of claim 16 wherein said entry for said one or more shared caches is populated when said permissions metadata is referenced.

22. The computer-readable storage medium of claim 16 wherein said entry has an ID column identifying said file and a metadata column containing said permissions metadata.

23. The computer-readable storage medium of claim 22 wherein said metadata column of said entry in said one or more session caches is populated with modified permissions metadata that was modified by said session.

24. The computer-readable storage medium of claim 22 wherein said ID column for said one or more session caches is populated when said permissions metadata is modified.

25. The computer-readable storage medium of claim 22 wherein said ID column for said one or more session caches is populated when said file is modified.

26. The computer-readable storage medium of claim 22 wherein said metadata column for said one or more session caches is populated when said file is referenced subsequent to said file being modified.

27. The computer-readable storage medium of claim 22 wherein said metadata column for said one or more session caches is populated when said permissions metadata is referenced subsequent to said permissions metadata being modified.

28. The computer-readable storage medium of claim 22 wherein said metadata column for said one or more session caches is populated when said file is referenced subsequent to said permissions metadata being modified.

29. The computer-readable storage medium of claim 22 wherein said metadata column for said one or more session caches is populated when said permissions metadata is referenced subsequent to said file being modified.

30. The computer-readable storage medium of claim 16, wherein said session is associated with a transaction, and wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to perform the step of:

invalidating said entries in said one or more shared caches when said transaction successfully terminates wherein said entries in said one or more shared caches are duplicates of entries in said one or more session caches.