Re: Data structure to keep things in memory

"Mike Schilling" <>
Sun, 28 Nov 2010 12:43:31 -0800
"Steven Simpson" <ss@domain.invalid> wrote in message

On 28/11/10 18:18, Mike Schilling wrote:

"Steven Simpson" <ss@domain.invalid> wrote in message

class RTSUser extends WeakReference<RTSHandle> implements Runnable {
 final RTSImpl impl;

 RTSUser(RTSHandle handle,
         ReferenceQueue<? super RTSHandle> queue,
         RTSImpl impl) {
   super(handle, queue);
   this.impl = impl;
  RTSUser user = new RTSUser(handle, queue, impl);

How do you keep the RTSUser's from being GC'd before they are
delivered to the queue?

Hmm, I was under the impression that the ReferenceQueue kept track of
References, but I see it's the other way around (looking at the source).

So you need a container of RTSUsers. That was served by the
Map<Reference<RTSHandle>, RTSImpl> in ClassCastException's original
suggestion, and a Collection<RTSUser> will suffice here.

If you have to keep all your RTSImpls anyway, you could make each one
point to its RTSUser, so the container of RTSImpls indirectly hangs on
to the RTSUsers. I was originally thinking of a case where getRTS()
took some sort of key, and mapped it to an RTSImpl, which referenced its
(multiple) RTSUsers, so that map did the job implicitly.

Maybe you can get away with a ConcurrentMap<Key, RTSUser>, if you want
to avoid synchronization:

ConcurrentMap is what I'm using. The consensus seems to be that it's the
best choice.

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