Systems and methods for notifying listeners of events

• US 20070233710A1
• Filed: 03/31/2006
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Fachan, Neal, Passey, Aaron
• Granted Patent: US 7,756,898 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1734 Details of monitoring file system events, e.g. by the use of hooks, filter drivers, logs
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications

Abstract

In one embodiment, systems and methods are provided for tracking events wherein an event system monitors certain areas of a system. When an event occurs in one area of the system, the event system notifies the processes listening to that area of the system of the event.

Claims

1. An event listening system, the event listening system comprising:

a file system including a plurality of files, the plurality of files logically stored in a tree;

for each of the plurality of files, a first data structure configured to track a set of listening files that are listening for events that affect the corresponding file;

a plurality of processes that each listen for events that affect at least one of the plurality of files;

a second data structure configured to track, for each of the plurality of files, which of the plurality of processes are listening to each of the files;

a listening module configured to receive an identifier for a first file of the plurality of files and to determine whether the first file is relevant to any of the plurality of processes using the first data structure and the second data structure;

a traverse module configured to traverse a first set of first data structures that correspond to a subset of the plurality of files that represent one branch of the tree; and

an update module configured to update at least one of the corresponding first data structures of the file in at least one traversed level by reviewing a scope of at least one of the listening files of the first data structure that corresponds to the file'"'"'s parent.

2. The event listening system of claim 1, wherein the file system is a distributed file system.

3. The event listening system of claim 1, wherein the files include files and directories.

4. The event listening system of claim 1, wherein the second data structure comprises:

for each of the plurality of files, a set of processes listening to the corresponding file.

5. The event listening system of claim 4, wherein the second data structure further comprises:

for each of the processes, a scope of files related to the corresponding file for which the corresponding process is listening.

6. The event listening system of claim 5, wherein the listening module is further configured to determine whether the processes listening to the file include a scope that encompasses the first file.

7. The event listening system of claim 4, wherein the second data structure further comprises:

for each of the processes, a set of events for which the corresponding process is listening.

8. The event listening system of claim 1, wherein the listening module is further configured to review the first data structure corresponding to the first file;

for each listening file in the set of listening files, to use the second data structure to determine whether there are any processes listening to the file.

9. The event listening system of claim 1 further comprising:

an event message module configured to send an event message to the plurality of processes that are relevant to the first file.

10. The event listening system of claim 1 further comprising:

a plurality of message queues corresponding to the plurality of processes configured to receive and queue the event messages.

11. A method for listening for events, the method comprising:

logically storing a plurality of files in a tree;

for each of the plurality of files, tracking a set of listening files that are listening for events that affect the corresponding file;

storing a plurality of processes that each listen for events that affect at least one of the plurality of files;

for each of the plurality of files, tracking which of the plurality of processes are listening to each of the files;

receiving an identifier for a first file of the plurality of files;

determining whether the first file is relevant to any of the plurality of processes using the first data structure and the second data structure;

traversing a first set of first data structures that correspond to a subset of the plurality of files that represent one branch of the tree; and

updating at least one of the corresponding first data structures of the file in at least one traversed level, wherein updating includes reviewing a scope of at least one of the listening files of the first data structure that corresponds to the file'"'"'s parent.

12. The method of claim 11, wherein the file system is a distributed file system.

13. The method of claim 11, wherein the files include files and directories.

14. A system for listening for events, the system comprising:

a file structure comprising a plurality of files that are logically stored in a tree;

for each of the plurality of files, a data structure corresponding to each files, the data structure comprising;

a set of identifiers of the plurality of files that are listening for events that affect the corresponding file; and

an indication of the currentness of the data structure.

15. The system of claim 14 wherein the indication of the currentness of the data structure is a generation number.

16. The system of claim 14, further comprising:

an update module configured to update the data structures that correspond to a subset of the plurality of files that represent one branch of the tree.

17. The system of claim 16, wherein the update module is configured:

to begin with the data structure that corresponds to the leaf node file of the one branch;

to climb the one branch, reviewing the corresponding data structure of the file at each climbed level in the one branch, until reaching a data structure whose indication indicates that the data structure is current; and

from that level, to traverse down the one branch to the leaf node file updating the corresponding data structure of the file at each traversed level in the one branch.

18. The system of claim 17, wherein the update module is further configured:

update the corresponding data structure of the file at each traversed level in the one branch using the corresponding data structure of the file'"'"'s parent.

19. A method for listening for events, the method comprising:

logically storing a plurality of files in a tree; and

for each of the plurality of files, storing a data structure corresponding to each files, the data structure comprising a set of identifiers of the plurality of files that are listening for events that affect the corresponding file and an indication of the currentness of the data structure.

20. The method of claim 19, further comprising:

updating the data structures that correspond to a subset of the plurality of files that represent one branch of the tree.

21. The method of claim 20, further comprising

starting with the data structure that corresponds to the leaf node file of the one branch;

climbing the one branch;

reviewing the corresponding data structure of the file at each climbed level in the one branch, until reaching a data structure whose indication indicates that the data structure is current; and

from that level, traversing down the one branch to the leaf node file and updating the corresponding data structure of the file at each traversed level in the one branch.

22. The event listening method of claim 21 further comprising:

updating the corresponding data structure of the file at each traversed level in the one branch using the corresponding data structure of the file'"'"'s parent.

23. A storage medium having a computer program stored thereon for causing a suitably programmed system to process the computer program by performing the method of claim 19 when such computer program is executed on the system.

24. A system for queuing event messages in a file system, the system comprising:

a plurality of processes that each listen for events that affect at least one of a plurality of files

a first data structure configured to determine, for each of the plurality of processes, a set of listening files to which each of the plurality of processes is listening; and

a message module configured;

to receive an event message related to a first file of the plurality of files, the event message including an indication of a minimum scope that would have generated the event message;

to search the first data structure to determine a first subset of the plurality of processes that that listen for files that are affected by the event using the sets of listening files;

to determine a second subset of the first subset by removing from the first subset, processes whose scope is less than the minimum scope of the event message; and

to inform the second subset of the event message.

25. The system of claim 24 wherein each of the plurality of processes including an event queue and the message module is further configured to send the event message to the event queues of the second subset.

26. The system of claim 24, wherein the minimum scope is determined by a scope module configured to:

receive a first identifier corresponding to the first file;

receive a second identifier corresponding to a second file;

determine whether the first file matches the second file;

if the first file matches the second file, returning a minimum scope of single; and

if the first file does not match the second file,

determining if the first file is the immediate child of the second file;

if the first file is the immediate child of the second file, returning a minimum scope of children; and

if the first file is not the immediate child of the second file, returning a minimum scope of recursive.