/**
* This method is called each time a Being acquires a Palantir. Since each Being is a Java Thread,
* it will be called concurrently from different threads. This method increments the number of
* threads gazing and checks that the number of threads gazing does not exceed the number of
* Palantiri in the simulation using an AtomicLong object instantiated above (mGazingThreads). If
* the number of gazing threads exceeds the number of Palantiri, this thread will call shutdown
* and return false.
*
* @return false if the number of gazing threads is greater than the number of Palantiri,
* otherwise true.
*/
private boolean incrementGazingCountAndCheck(PalantiriPresenter presenter) {
final long numberOfGazingThreads = presenter.mGazingTasks.incrementAndGet();
if (numberOfGazingThreads > Options.instance().numberOfPalantiri()) {
presenter.shutdown();
return false;
} else return true;
}
/** Perform the Being gazing logic. */
@Override
public Void doInBackground(PalantiriPresenter... presenters) {
// Don't start the threads immediately.
Utils.pauseThread(500);
// Initialize local variables.
int i = 0;
Palantir palantir = null;
final PalantiriPresenter presenter = presenters[0];
// Try to gaze at a palantir the designated number of times.
for (; i < Options.instance().gazingIterations(); ++i)
try {
// Break out of the loop if the BeingAsyncTask has
// been cancelled.
// you fill in here by replacing "false" with
// the appropriate method call to an AsyncTask method.
if (isCancelled()) {
// If we've been instructed to stop gazing, notify
// the UI and exit gracefully.
presenter.mView.get().threadShutdown(mIndex);
break;
}
// Show that we're waiting on the screen.
// you fill in here with the appropriate
// call to an AsyncTask method.
publishProgress(presenter.mView.get().markWaiting(mIndex));
// Get a Palantir - this call blocks if there are no
// available Palantiri.
palantir = presenter.getModel().acquirePalantir();
if (palantir == null)
Log.d(
TAG,
"Received a null palantir in "
+ Thread.currentThread().getId()
+ " for Being "
+ mIndex);
// Make sure we were supposed to get a Palantir.
if (!incrementGazingCountAndCheck(presenter)) break;
// Mark it as used on the screen.
// you fill in here with the appropriate
// call to an AsyncTask method.
publishProgress(presenter.mView.get().markUsed(palantir.getId()));
// Show that we're gazing on the screen.
// you fill in here with the appropriate
// call to an AsyncTask method.
publishProgress(presenter.mView.get().markGazing(mIndex));
// Gaze at my Palantir for the alloted time.
palantir.gaze();
// Show that we're no longer gazing.
// you fill in here with the appropriate
// call to an AsyncTask method.
publishProgress(presenter.mView.get().markIdle(mIndex));
Utils.pauseThread(500);
// Mark the Palantir as being free.
// you fill in here with the appropriate call
// to an AsyncTask method.
publishProgress(presenter.mView.get().markFree(palantir.getId()));
Utils.pauseThread(500);
// Tell the double-checker that we're about to
// give up a Palantir.
decrementGazingCount(presenter);
} catch (Exception e) {
Log.d(TAG, "Exception caught in index " + mIndex);
// If we're interrupted by an exception, notify the UI and
// exit gracefully.
presenter.mView.get().threadShutdown(mIndex);
} finally {
// Give it back to the manager.
presenter.getModel().releasePalantir(palantir);
}
Log.d(
TAG,
"Thread "
+ mIndex
+ " has finished "
+ i
+ " of its "
+ Options.instance().gazingIterations()
+ " gazing iterations");
return (Void) null;
}