src/plugins/emulator/src/com/motorola/studio/android/emulator/logic/stop/AndroidEmulatorStopper.java

/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.motorola.studio.android.emulator.logic.stop;

import static com.motorola.studio.android.common.log.StudioLogger.error;
import static com.motorola.studio.android.common.log.StudioLogger.info;
import static com.motorola.studio.android.common.log.StudioLogger.warn;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.osgi.util.NLS;
import org.eclipse.sequoyah.vnc.protocol.PluginProtocolActionDelegate;
import org.eclipse.sequoyah.vnc.protocol.lib.ProtocolHandle;
import org.eclipse.sequoyah.vnc.vncviewer.registry.VNCProtocolRegistry;

import com.motorola.studio.android.common.utilities.EclipseUtils;
import com.motorola.studio.android.emulator.i18n.EmulatorNLS;
import com.motorola.studio.android.emulator.logic.AndroidLogicUtils;
import com.motorola.studio.android.emulator.logic.IAndroidLogicInstance;

/**
 * DESCRIPTION:
 * This class contains the business layer of the Android 
 * Emulator stop procedure 
 *
 * RESPONSIBILITY:
 * Stop any Android Emulator
 *
 * COLABORATORS:
 * None. 
 *
 * USAGE:
 * Use the public method to stop a Android Emulator
 */
public class AndroidEmulatorStopper
{
    private static Lock lock = new ReentrantReadWriteLock().writeLock();

    private static final int MAX_LOCK_ATTEMPTS = 20;

    /**
     * Stops this instance, removing its viewer from Android Emulator View
     *
     * @param instance The device instance
     * @param force If true do not ask the user if he/she wants to proceed
     * @param monitor A progress monitor that will show the disposal
     *                action progress at UI
     *                
     * @return True if the instance was stopped; false if the user chose not to stop it              
     */
    public static boolean stopInstance(final IAndroidLogicInstance instance, boolean force,
            boolean kill, IProgressMonitor monitor)
    {

        if (instance == null)
        {
            error("Could not stop the protocol because the provided instance is null");
            return false;
        }

        boolean canProceed = true;

        // decision whether to actually stop or not comes from user
        if (!force)
        {

            canProceed =
                    EclipseUtils.showQuestionDialog(EmulatorNLS.GEN_Question, NLS.bind(
                            EmulatorNLS.QUESTION_AndroidEmulatorStopper_StopEmulatorQuestion,
                            instance.getName()));

        }

        if (canProceed)
        {
            int attempts = 0;
            boolean locked = lock.tryLock();
            while (!locked && (attempts < MAX_LOCK_ATTEMPTS))
            {
                try
                {
                    Thread.sleep(125);
                }
                catch (InterruptedException e)
                {
                    //Do nothing!
                }
                locked = lock.tryLock();
                attempts++;
            }

            if (locked)
            {
                if (monitor == null)
                {
                    monitor = new NullProgressMonitor();
                }

                try
                {
                    info("Stopping the Android Emulator instance");

                    monitor
                            .beginTask(EmulatorNLS.MON_AndroidEmulatorStopper_DisposingInstance,
                                    200);
                    monitor.setTaskName(EmulatorNLS.MON_AndroidEmulatorStopper_DisposingInstance);

                    // Try to stop the protocol.
                    //
                    // This is not critical to the stop instance procedure, but it is 
                    // desirable because the TmL's methods may do some cleanup
                    // before returning. The loop below tries to stop for some time (and 
                    // give enough time for cleanup as well), but if TmL does not finish
                    // in an acceptable time, the stop instance procedure continues

                    try
                    {
                        info("Trying to stop the protocol");
                        // Try to implement a TmL independent code
                        ProtocolHandle handle = instance.getProtocolHandle();
                        if (handle != null)
                        {
                            PluginProtocolActionDelegate.requestStopProtocol(handle);

                            while (PluginProtocolActionDelegate.isProtocolRunning(handle))
                            {
                                Thread.sleep(250);
                            }
                            VNCProtocolRegistry.getInstance().unregister(handle);
                            info("Protocol stopped");
                        }
                    }
                    catch (Exception e)
                    {
                        error("There was an error while trying to stop the protocol");
                    }

                    // Try to implement a TmL independent code
                    instance.setProtocolHandle(null);

                    monitor.worked(100);
                    monitor.setTaskName(EmulatorNLS.MON_AndroidEmulatorStopper_StopVm);

                    if (kill)
                    {
                        AndroidLogicUtils.kill(instance);
                    }

                    info("Stopped the Android Emulator instance");
                }
                finally
                {
                    monitor.done();
                    try
                    {
                        lock.unlock();
                    }
                    catch (Exception e)
                    {
                        warn("The thread that is releasing the lock is not the one which has it.");
                    }
                }
            }
            else
            {
                canProceed = false;
            }
        }

        return canProceed;
    }
}