Mechanism for ensuring SCM database consistency on multi-part operation boundaries

• US 6,178,429 B1
• Filed: 11/26/1997
• Issued: 01/23/2001
• Est. Priority Date: 11/26/1997
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Cherf, Scott
• Primary Examiner(s): Amsbury, Wayne
• Assistant Examiner(s): PARDO, THUY N
• Application Number:
  US08/978,689
• Time in Patent Office: 1,154 Days
• Field of Search: 711/164, 395/677, 395/200.08, 705/36, 707/2, 707/8, 707/200, 707/201, 707/203, 707/204, 707/205, 707/202, 707/1, 707/100, 707/9, 709/104, 709/229, 709/13, 710/240, 714/1, 714/5
• US Class Current: 707/690
• CPC Class Codes: G06F 16/1774 Locking methods, e.g. locking methods for file systems allowing shared and concurrent access to files
• CPC Class Codes: Y10S 707/99939 Privileged access
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

A mechanism for guaranteeing a coherent repository, including a list of requested files that are to be committed to the repository or to be processed (e.g. read) by an operation, and a list of “protected” files that are currently being processed. Either all of or none of the requested files are committed or are processed. Therefore, if any one of the requested files is in the protected-files list, then the invention waits until none of the requested files is protected before committing the requested files to the repository or before processing the requested files. An abnormal operation may hold up the protected files in the protected-files list for an unreasonably-long period of time. The invention thus provides an alarm mechanism, which scans the protected-files list to detect whether an abnormal operation exists. If such an operation is found, then the invention alerts an alarm agent and replaces the inconsistent files caused by the abnormal operation. The invention uses an atomic operation to change the requested-files list to a prenatal-file list, then to the protected-files list, and finally to a deceased-files list.

Claims

1. A method for processing coherent files in a multi-part operation, comprising the steps of:

maintaining a protected-files list of the names of files that are currently being processed;

creating a requested-files list of the names of files to be processed in an operation;

comparing the requested-files list to the protected-files list;

adding the requested-files list to the protected-files list using an atomic operation when none of the names of the requested files is in the protected-files list;

performing the multi-part operation; and

removing the names of the requested files from the protected-files list when the operation is complete.

2. The method of claim 1 wherein the requested-files list is a directory containing the names of the requested files.

3. The method of claim 2 wherein the step of adding includes renaming the directory.

4. The method of claim 1 wherein the step of creating uses virtual pointers.

5. The method of claim 1 wherein the step of creating includes adding the name of a file and corresponding version information.

6. The method of claim 5 wherein the step of comparing compares the names and version information of the protected files and of the requested files.

7. The method of claim 1 wherein the step of comparing compares the names of the requested and the protected files.

8. The method of claim 1 wherein the step of creating uses the names of files in a change set.

9. The method of claim 1 wherein the step of removing is an atomic operation.

10. The method of claim 1 wherein the protected-files list is derived from a prenatal-files list.

11. The method of claim 1 wherein the protected-files list becomes a deceased-files list.

12. The method of claim 1 wherein the requested-files list becomes a prenatal-files list.

13. The method of claim 12 wherein the prenatal-files list becomes a protected-files list corresponding to the requested-files list.

14. The method of claim 13 wherein the protected-files list corresponding to the requested-files list becomes a deceased-files list.

15. A method for reading coherent files in a multi-part operation, comprising the steps of:

maintaining a protected-files list of the names of files that are currently being processed;

renaming the protected-files list to a deceased-files list after the protected files are no longer processed;

creating a requested-files list of the names of files to be read from a repository;

comparing the requested-files list to the protected-files list until none of the names of the requested files is in the protected-files list; and

allowing the requested files to be read from the repository.

16. The method of claim 15 wherein the step of creating includes adding the name of the file requested and corresponding version information.

17. The method of claim 15 wherein the step of comparing compares the file names of the requested-files list with the protected-files list.

18. The method of claim 17 wherein the step of comparing compares version information of the requested-files list with the protected-files list.

19. The method of claim 15 wherein the step of creating uses the names of files in a change set.

20. The method of claim 15 wherein the protected-files list is renamed by an atomic operation.

21. The method of claim 15 wherein the step of maintaining includes the step of renaming a prenatal-files list to the protected-files list.

22. The method of claim 21 wherein the step of renaming is an atomic operation.

23. The method of claim 21 wherein each one of the prenatal-files list, the protected-files list, and the deceased-files list is a file directory.

24. The method of claim 15 wherein the deceased-files list is retained as an audit file for providing a record of files requested.

25. A method for detecting and recovering from a repository inconsistency, comprising the steps of:

scanning a protected-files list and thereby detecting an abnormal operation associated with files in the protected-files list;

alerting a system agent if the abnormal operation is found;

replacing any inconsistent files caused by the abnormal operation; and

removing a list of files that includes the any inconsistent files from the protected-files list.

26. The method of claim 25 wherein the step of scanning includes scanning the times the files were initially placed on the protected-files list.

27. The method of claim 25 wherein the step of replacing includes restoring on the protected-files list the names of replaced files.

28. The method of claim 25 wherein the step of alerting includes sending information about the abnormal operation.

29. The method of claim 27 wherein the step of restoring includes getting confirmation from a user.

30. The method of claim 25 wherein the abnormal operation is selected from a group consisting of a failed operation, a stalled operations, and an operation that has exceeded its allotted time.

31. The method of claim 25 wherein the protected-files list is derived from a prenatal-files list.

32. The method of claim 25 wherein the protected-files list becomes a deceased-files list.

33. A processing system for multi-part operations, comprising:

a protected-files list of names of files currently being processed;

a requested-files list of names of files that will be processed in an operation;

means for comparing the requested-files list with the protected-files list;

means for adding the requested-files list to the protected-files list in an atomic operation; and

means for removing the requested-files list from the protected-files list when the multi-part operation is complete.

34. The system of claim 33 wherein the means for comparing is capable of comparing file names.

35. The system of claim 33 wherein the means for comparing is capable of comparing version numbers.

36. The system of claim 33 wherein the requested-files list is a change set.

37. The system of claim 33 wherein the requested-files list and the protected-files list are each a directory tree.

38. The system of claim 33 wherein the means for comparing is capable of comparing names and version numbers.

39. The system of claim 33 wherein the requested-files list contains a version number of each of the requested files.

40. A computer-based storage medium storing code for causing a computer to perform the steps of:

receiving an operation request including a requested-files list of the names of requested files to be operated upon;

comparing the requested-files list to a protected-files list;

adding the requested-files list to the protected-files list when none of the requested files is in the protected-files list;

processing the operation; and

removing names of files from the protected-files list once the operation is complete.

41. The method of claim 40 wherein the requested-files list constitutes a directory.

42. The method of claim 41 wherein the step of adding includes renaming said directory.

43. The method of claim 40 wherein the step of receiving receives virtual pointers referencing the requested-files list.

44. The method of claim 40 further comprising the step of adding the names of the requested files and corresponding version information to a previously existing requested-files list.

45. The method of claim 40 further comprising the step of adding names of the requested files from a predefined change set.

46. The method of claim 40 wherein the step of comparing compares the file names and version information of the requested-files list with the protected-files list.

47. The method of claim 40 wherein the step of removing is an atomic operation.