LeakCanary.install(this);

private final Application.ActivityLifecycleCallbacks lifecycleCallbacks =
      new Application.ActivityLifecycleCallbacks() {

        /// blahblah...

        @Override public void onActivityDestroyed(Activity activity) {
          ActivityRefWatcher.this.onActivityDestroyed(activity);
        }
      };

void onActivityDestroyed(Activity activity) {
    refWatcher.watch(activity);
}

/**
   * Watches the provided references and checks if it can be GCed. This method is non blocking,
   * the check is done on the {@link Executor} this {@link RefWatcher} has been constructed with.
   *
   * @param referenceName An logical identifier for the watched object.
   */
  public void watch(Object watchedReference, String referenceName) {
    checkNotNull(watchedReference, "watchedReference");
    checkNotNull(referenceName, "referenceName");
    if (debuggerControl.isDebuggerAttached()) {
      return;
    }
    final long watchStartNanoTime = System.nanoTime();
    String key = UUID.randomUUID().toString();
    retainedKeys.add(key);
    final KeyedWeakReference reference =
        new KeyedWeakReference(watchedReference, key, referenceName, queue);


    watchExecutor.execute(new Runnable() {
      @Override public void run() {
        ensureGone(reference, watchStartNanoTime);
      }
    });
  }

final KeyedWeakReference reference =
        new KeyedWeakReference(watchedReference, key, referenceName, queue);

watchExecutor.execute(new Runnable() {
      @Override public void run() {
        ensureGone(reference, watchStartNanoTime);
      }
});

void ensureGone(KeyedWeakReference reference, long watchStartNanoTime) {
    long gcStartNanoTime = System.nanoTime();


    long watchDurationMs = NANOSECONDS.toMillis(gcStartNanoTime - watchStartNanoTime);
    removeWeaklyReachableReferences();
    if (gone(reference) || debuggerControl.isDebuggerAttached()) {
      return;
    }
    gcTrigger.runGc();
    removeWeaklyReachableReferences();
    if (!gone(reference)) {
      long startDumpHeap = System.nanoTime();
      long gcDurationMs = NANOSECONDS.toMillis(startDumpHeap - gcStartNanoTime);


      File heapDumpFile = heapDumper.dumpHeap();


      if (heapDumpFile == HeapDumper.NO_DUMP) {
        // Could not dump the heap, abort.
        return;
      }
      long heapDumpDurationMs = NANOSECONDS.toMillis(System.nanoTime() - startDumpHeap);
      heapdumpListener.analyze(
          new HeapDump(heapDumpFile, reference.key, reference.name, excludedRefs, watchDurationMs,
              gcDurationMs, heapDumpDurationMs));
    }
  }


  private boolean gone(KeyedWeakReference reference) {
    return !retainedKeys.contains(reference.key);
  }


  private void removeWeaklyReachableReferences() {
    // WeakReferences are enqueued as soon as the object to which they point to becomes weakly
    // reachable. This is before finalization or garbage collection has actually happened.
    KeyedWeakReference ref;
    while ((ref = (KeyedWeakReference) queue.poll()) != null) {
      retainedKeys.remove(ref.key);
    }
  }

while ((ref = (KeyedWeakReference) queue.poll()) != null) {
      retainedKeys.remove(ref.key);
}