Java7 WatchService - How to detect rename/move of the actual watched directory

Question

I'm using WatchService for synchronization data files with the application workbench. When I rename/move the watched directory I don't get any event nor the WatchKey won't become invalid. I still get events from the renamed directory but as far as I know there no way to find out the actual Path for the WatchKey besides WatchKey.watchable() which however still returns original directory path. I would like to avoid need of locking the watched directory against changes since I want to keep the application as lightweight as possible.

I have experienced this problem with JDK 7u10 on Windows 7

Do you know any workaround for this issue without locking the directory or watching all directories to the root?

UPDATE

On Linux I have observed the same behavior.

So far it seems I have three options now.

1) Rely on user's discipline that he/she won't move the data directories. I don't really like this options since it might lead to undefined behavior.

2) Use more extensive non-standard native library

3) Create hierarchy of watchdogs on superior directories. These would accept only ENTRY_DELETE events since this event (or OVERFLOW ) must appear at the moment the actual watched directory is moved or deleted and thus invalid.

Answer 1

My understanding is that renaming a directory will generate file system events on the old and new parent directories, not on the directory that is renamed. According to the answer to Can iNotify tell me where a monitored file is moved? , the OS cannot tell you where something was moved to unless you are monitoring the destination directory. (And besides, in Java 7/8 MOVE events aren't handled by the watch service implementation.)

UPDATE

You could try the jpathwatch project that adds support for ( platform specific ) extended events using the standard Java7 WatchService APIs.

References:

• documentation - http://jpathwatch.wordpress.com/
• javadoc - http://jpathwatch.sourceforge.net/