Fixed updating the Local Repository caches

[vrubezhny]

Local Repository caches are made to be updated:

• (only temporary lemminx-maven build repository) when a MavenProject is built and cached
• (all cached) every 30 minutes

Also, Diagnostic is made to be re-calculated on finishing of Maven Lemminx Extension initialization

[mickaelistria]

Wasn't the local repository searcher already placing a file listener to properly update its cache whenever something changes?

[angelozerr]

@mickaelistria we removed the thread wich created a watchservice which updated the cache because the original code tracked only the root .m2/repository. I have fixed that to create a watchservice for children folders but we had a problem which created too many watchservice. To avoid this problem we removed this watchservice.

[mickaelistria]

OK, got it. And what is used now to detect new content in the Maven repo? I just read about FileAlterationMonitor ( https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/monitor/FileAlterationObserver.html ), would it be capable of being notified recursively?

[angelozerr]

For the moment we have no find a solution to evict the cache.

Just for your information we have 2 local repo now. The user local repo which is not polluated when user is typing in the editor and à .lemminx-maven repo which is polluated

[mickaelistria]

For the moment we have no find a solution to evict the cache.

OK, please make sure there is an issue, and ideally a test case to demo it, tracking it. This can be an important feature (although not a regression).

Just for your information we have 2 local repo now. The user local repo which is not polluated when user is typing in the editor and à .lemminx-maven repo which is polluated

OK, sounds good.

[angelozerr]

If it is based on watchservice we will have the same problem, because in short watchservice must never used with a lot of directories

One idea that we had with @vrubezhny is to provide a thread which evicts the cache per 1 hour

[mickaelistria]

FileAlterationMonitor does some polling with a given interval. It can be once per hour or every 3 minutes. Polling a file system isn't too heavy.

[mickaelistria]

Here is the code: https://github.com/apache/commons-io/blob/master/src/main/java/org/apache/commons/io/monitor/FileAlterationMonitor.java

[angelozerr]

We need indeed try it. Thanks @mickaelistria for your suggestion!

[vrubezhny]

I have created #507 to track this.