MAINTAINING AND UPDATING FILE SYSTEM SHADOWS ON A LOCAL DEVICE BY A SYNCHRONIZATION CLIENT OF A CLOUD-BASED PLATFORM

• US 20140379647A1
• Filed: 06/23/2014
• Published: 12/25/2014
• Est. Priority Date: 06/21/2013
• Status: Active Grant

• Current Assignee: Box Incorporated
• Original Assignee: Box Incorporated
• Inventors: Smith, Benjamin Campbell, Mackenzie, David, Lu, Yiming, Potrebic, Peter, Jourda, Florian, Parmar, Kunal
• Granted Patent: US 9,805,050 B2
• Time in Patent Office: Days
• US Class Current: 707/624
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems

Abstract

Systems and methods for maintaining and updating file system shadows by a synchronization client of a cloud-based platform. In some embodiments, an executor of the synchronization client can execute an action on an item in the local file system which changes the state of the item from an old state to a new state. The synchronization client updates the file system shadows with the new state of the item via an interface to facilitate generation of a synchronization event for the change to the item, that would otherwise go undetected if the change to the item was immediately reversed. In some embodiments, methods for providing shadow consistency and enhancing concurrent access to shadows are implemented by the synchronization client in maintaining and updating the file system shadows.

Claims

1. A method of updating one or more shadows of a local file system by a synchronization client, comprising:

executing an action on an item in the local file system by the synchronization client, wherein the action changes the state of the item from an old state to a new state;

providing an interface for updating the one or more shadows of the local file system; and

updating the one or more shadows of the local file system with the new state of the item using the interface to facilitate generation of a synchronization event for the change to the item.

2. The method of claim 1, wherein the synchronization client is installed on a client device and is associated with a cloud-based collaboration and storage platform.

3. The method of claim 1, further comprising:

immediately following execution of the action, executing another action on the item by the synchronization client, wherein the another action reverses the change to the item so that a current state of the local file system retains the old state of the item;

determining a difference between the current state of the local file system and a state of the one or more shadows, wherein the state of the one or more shadows have the new state of the item; and

generating the synchronization event for the change to the item that is immediately reversed based on the difference to bring a remote file system in synchronization with the local file system.

4. The method of claim 3, wherein without updating the one or more shadows of the local file system with the new state of the item, the change to the item that is immediately reversed goes undetected and causes the remote file system and the local file system to go out of synchronization.

5. The method of claim 3, wherein the one or more shadows of the local file system provide the synchronization client with the last known state of the local file system to compare against the current state of the local file system to determine the difference and detect the change to the local file system.

6. The method of claim 3, wherein the one or more shadows of the local file system allow the synchronization client to order changes detected on the local file system by comparing each change against the last known state of the local file system to determine if applying the change to the local file system causes the local file system to be in an inconsistent state.

7. The method of claim 6, wherein if applying the change to the local file system causes the local file system to be in an inconsistent state, the change is buffered until other changes cause the change to be consistent with the last known state of the local file system.

8. The method of claim 1, wherein the one or more shadows allow the synchronization client to perform path look ups for items for performing any operations on the local file system.

9. The method of claim 3, wherein the synchronization event is generated by a component monitoring the local file system and the execution of the actions on the item is performed by a component that handles execution of synchronization events generated by the component monitoring the local file system.

10. The method of claim 1, further comprising enhancing concurrency in the local file system by:

scanning the local file system to determine the current state of the file system, wherein the scanning is in response to a local file system notification;

acquiring a monitor lock to prevent concurrent access to the one or more shadows;

verifying that the one or more shadows have not been updated in between completion of the scan of the local file system and acquiring the monitor lock before determining the difference between the current state of the local file system and the state of the one or more shadows.

11. The method of claim 10, wherein the verifying includes checking if a flag is set, wherein:

in response to detecting that the flag is set, clearing the flag, releasing the monitor lock and re-initiating the scan of the local file system; and

in response to detecting that the flag is clear, determining the difference between the current state of the local file system and the state of the one or more shadows.

12. A synchronization client for updating one or more shadows of a local file system, comprising:

a local file system monitor comprising one or more shadows of the local file system, and configured to;

scan the local file system to determine the current state of the local file system;

determine any difference between the current state and the last known state of the local file system provided by the one or more shadows of the local file system

identify, based on the difference, items for which synchronization events are to be generated, wherein the synchronization events synchronize the local file system with a remote file system; and

a synchronization executor configured to;

execute an action on an item in the local file system that changes the state of the item from an old state to a new state; and

provide the new state of the item via an interface to the local file system monitor to update the one or more shadows of the local file system.

13. The system of claim 12, wherein the synchronization client is installed on a client device and is associated with a cloud-based collaboration and storage platform.

14. The system of claim 12, wherein without updating the one or more shadows of the local file system with the new state of the item, the change to the item, if immediately reversed, goes undetected and causes the remote file system and the local file system to be unsynchronized.

15. The system of claim 12, wherein the one or more shadows of the local file system allow the synchronization client to order changes detected on the local file system by comparing each change against the last known state of the local file system to determine if applying the change to the local file system causes the local file system to be in an inconsistent state.

16. The system of claim 15, wherein if applying the change to the local file system causes the local file system to be in an inconsistent state, the change is buffered until other changes cause the change to be consistent with the last known state of the local file system.

17. The system of claim 12, wherein the one or more shadows allow the synchronization client to perform path look ups for items for performing any operations on the local file system.

18. The system of claim 12, wherein the local file system monitor is multi-threaded and a monitor lock is provided for thread safety, wherein the monitor lock prevents the local file system monitor and the synchronization executor from being executed simultaneously.

19. The system of claim 18, wherein the local file system monitor improves concurrency of the local file system monitor by acquiring the monitor lock after completing a scan but before determining any difference between the current and last known states of the local file system.

20. A method for updating one or more shadows of a local file system by a synchronization client, comprising:

executing an action on an item in the local file system that changes the state of the item from an old state to a new state;

updating the one or more shadows of the local file system using the new state of the item;

scanning the local file system to determine the current state of the local file system;

determining any difference between the current state and the last known state of the local file system provided by one or more shadows of the local file system; and

identifying, based on the difference, items for which synchronization events are to be generated, wherein the synchronization events synchronize the local file system with a remote file system.

21. The method of claim 20, wherein the synchronization client is installed on a client device and is associated with a cloud-based collaboration and storage platform.

22. The method of claim 20, wherein without updating the one or more shadows of the local file system with the new state of the item, the change to the item, if immediately reversed, goes undetected and causes the remote file system and the local file system to be unsynchronized.

23. The method of claim 20, wherein the one or more shadows allow the synchronization client to perform path look ups for items for performing any operations on the local file system.