Replaced the Disposer

src/org/adblockplus/libadblockplus/Disposer.java

+/*
+ * This file is part of Adblock Plus <http://adblockplus.org/>,
+ * Copyright (C) 2006-2014 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.adblockplus.libadblockplus;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.HashSet;
+
+public final class Disposer extends WeakReference<Disposable>
+{
+  final static ReferenceQueue<Disposable> referenceQueue = new ReferenceQueue<Disposable>();
+  final static HashSet<Disposer> disposerSet = new HashSet<Disposer>();

[Felix Dahlke, 2014/04/30 15:34:08]

Should be "static final".

[René Jeschke, 2014/04/30 15:43:16]

Done.

+  private final Disposable disposable;
+  private volatile boolean isDisposed = false;

[Felix Dahlke, 2014/04/30 15:34:08]

Should be "disposed" according to the bean convention IMO. "isDisposed" would be
the name of the getter.

[René Jeschke, 2014/04/30 15:43:16]

Done.

+
+  static
+  {
+    final Thread thread = new Thread(new Cleaner());
+    thread.setName(Cleaner.class.getCanonicalName());
+    thread.setDaemon(true);
+    thread.start();
+  }
+
+  public Disposer(final Disposable referent, final Disposable disposable)

[Felix Dahlke, 2014/04/30 15:34:08]

How about renaming "disposable" to "reference"? That'd be a bit more clear IMO.

[René Jeschke, 2014/04/30 15:43:16]

'referent' is the reference that get stored in the ReferenceQueue to track when
'referent' is only weakly reachable.

'disposable' is the object that actually does the disposing.

So, IMO: both names are correct.

[Felix Dahlke, 2014/04/30 15:50:43]

Isn't disposable the object that _gets_ disposed once the referent is GCed?
Anyway, yeah, "reference" is probably too ambiguous here. We could call
"referent" "reference" and it'd still make sense.

+  {
+    super(referent, referenceQueue);

[Felix Dahlke, 2014/04/30 15:34:08]

Shouldn't it be the referentQueue if it stores the referents?

[René Jeschke, 2014/04/30 15:43:16]

It stores the value from a local variable called 'referent', yep, but it stores
and manages 'WeakReference's, that's why it's a 'ReferenceQueue' and that's also
why the member is called 'referenceQueue'.

+    this.disposable = disposable;
+
+    synchronized (disposerSet)
+    {
+      disposerSet.add(this);
+    }
+  }
+
+  public synchronized void dispose()
+  {
+    if (!this.isDisposed)
+    {
+      try
+      {
+        this.disposable.dispose();
+      }
+      catch (final Throwable t)
+      {
+        // catch to set state to 'disposed' on all circumstances
+      }
+
+      this.isDisposed = true;
+      synchronized (disposerSet)
+      {
+        disposerSet.remove(this);
+      }
+    }
+  }
+
+  private static final class Cleaner implements Runnable
+  {
+    public Cleaner()
+    {
+      //
+    }
+
+    @Override
+    public void run()
+    {
+      for (;;)
+      {
+        try
+        {
+          ((Disposer) Disposer.referenceQueue.remove()).dispose();
+        }
+        catch (final Throwable t)
+        {
+          // ignored
+        }
+      }
+    }
+  }
+}