[RFC][Icedtea-Web]: Fix bug where you can clear cache while plugin is in use.

[Denis Lila]

> It does get called every time it is about to launch an
> applet/application.

Yeah, that's what I meant when I said it's called rarely -
markRunning will be called once per applet, and the number
of function calls in any one applet will vastly outnumber
the number of applet creations. Still, it's a good idea
to return early on null.

> Ah yes, I missed that. It is ok if we don't release the lock from
> okToClearCache since these calls should only happen when either the
> jvm is shuttingdown or when we call to clear cache which will return
> after it does its check + clear if allowed.

Just to make sure we're on the same page: do we agree that the lock
should be released only after the cache is actually cleared?


> In the event that we can only get exclusive locks, this means we can
> only have 1 plugin, or 1 javaws running at a time.

That's right. Isn't that a huge problem?

> This can be solved by having essentially a semaphore kind of
> structure. (Don't like this...JVM can be killed via kill -9 and it
> won't decrement the count).
> Another way to do this is give them all their own unique cache
> directory, no more worries...But this defeats the purpose of a cache..

What about what I suggested (with the two locks (actually, we could just
use locks on disjoint regions of the same file - we don't have to
introduce a new file))?
Then again, this problem only needs to be solved if the platform we're
running on doesn't support shared locks. If they all do support shared
locks, then we can just replace tryLock with lock in mark_running
and forget about these complicated solutions.

Regards,
Denis.

----- Original Message -----
> Hello Denis,
> 
> ----- Original Message -----
> > Hi.
> >
...