> On Mar 23, 2016, at 10:02 AM, Peter Levart <peter.lev...@gmail.com> wrote:
> ...so I checked what it would be needed if there was such
> getPendingReferences() native method. It turns out that a single native
> method would not be enough to support the precise direct ByteBuffer
> allocation. Here's a refactored webrev that introduces a
> getPendingReferences() method which could be turned into a native equivalent
> one day. There is another native method needed - int awaitEnqueuePhaseStart():
>
> http://cr.openjdk.java.net/~plevart/jdk9-dev/removeInternalCleaner/webrev.09.part2/
I don't think the Reference.awaitEnqueuePhaseStart thing is needed.
Rather, I think the Direct-X-Buffer allocation should conspire with
the the Direct-X-Buffer cleanups directly to manage that sort of
thing, and not add anything to Reference and the reference processing
thread. E.g. the phase and signal/wait are purely part of
Direct-X-Buffer. (I also think something like that could/should have
been done instead of providing Direct-X-Buffer with access to
Reference.tryHandlePending, but that's likely water under the bridge
now.)
Something very roughly like this:
allocating thread, after allocation failed
bool waitForCleanups() {
int epoch = DXB.getCleanupCounter();
long start = startTime();
long timeout = calcTimeout(start)
synchronized (DXB.getCleanupMonitor()) {
while (epoch == DBX.getCleanupCounter()) {
wait(timeout);
timeout = calcTimeout(start);
if (timeout <= 0) break;
}
return epoch != DBX.getCleanupCounter();
}
}
cleanup function, after freeing memory
synchronized (DBX.getCleanupMonitor()) {
DBX.incCleanupCounter();
DBX.getCleanupMonitor().notify_all();
}
Actually, epoch should probably have been obtained *before* the failed
allocation attempt, and should be an argument to waitForCleanups.
That's all quite sketchy, but I need to do other things today.
Peter, care to try filling this in?
