Fully implements application shutdown procedure that is invoked when the

user closes the the main gui window or invokes exit from the file menu.

src/main/java/io/github/dsheirer/controller/channel/ChannelProcessingManager.java

@@ -363,6 +363,22 @@ public class ChannelProcessingManager implements ChannelEventListener
         }
     }
 
+    /**
+     * Stops all currently processing channels to prepare for shutdown.
+     */
+    public void shutdown()
+    {
+        mLog.debug("Stopping Channels ...");
+        for(Channel channel: mChannelModel.getChannels())
+        {
+            if(channel.isProcessing())
+            {
+                mLog.debug("Stopping channel: " + channel.toString());
+                stopProcessing(channel, true);
+            }
+        }
+    }
+
     /**
      * Adds a message listener that will be added to all channels to receive
      * any messages.

src/main/java/io/github/dsheirer/gui/SDRTrunk.java

@@ -69,6 +69,8 @@ import java.awt.Robot;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.KeyEvent;
+import java.awt.event.WindowAdapter;
+import java.awt.event.WindowEvent;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 import java.nio.file.FileSystems;
@@ -88,6 +90,7 @@ public class SDRTrunk implements Listener<TunerEvent>
     private ControllerPanel mControllerPanel;
     private ChannelModel mChannelModel;
     private ChannelProcessingManager mChannelProcessingManager;
+    private SourceManager mSourceManager;
     private SettingsManager mSettingsManager;
     private SpectralDisplayPanel mSpectralPanel;
     private JFrame mMainGui = new JFrame();
@@ -141,10 +144,10 @@ public class SDRTrunk implements Listener<TunerEvent>
 
         RecorderManager recorderManager = new RecorderManager();
 
-        SourceManager sourceManager = new SourceManager(tunerModel, mSettingsManager);
+        mSourceManager = new SourceManager(tunerModel, mSettingsManager);
 
         mChannelProcessingManager = new ChannelProcessingManager(mChannelModel, channelMapModel, aliasModel,
-            eventLogManager, recorderManager, sourceManager);
+            eventLogManager, recorderManager, mSourceManager);
         mChannelProcessingManager.addAudioPacketListener(recorderManager);
 
         mChannelModel.addListener(mChannelProcessingManager);
@@ -156,7 +159,7 @@ public class SDRTrunk implements Listener<TunerEvent>
         AliasActionManager aliasActionManager = new AliasActionManager();
         mChannelProcessingManager.addMessageListener(aliasActionManager);
 
-        AudioManager audioManager = new AudioManager(sourceManager.getMixerManager());
+        AudioManager audioManager = new AudioManager(mSourceManager.getMixerManager());
         mChannelProcessingManager.addAudioPacketListener(audioManager);
 
         mBroadcastModel = new BroadcastModel(mIconManager);
@@ -168,13 +171,13 @@ public class SDRTrunk implements Listener<TunerEvent>
 
         mControllerPanel = new ControllerPanel(audioManager, aliasModel, mBroadcastModel,
             mChannelModel, channelMapModel, mChannelProcessingManager, mIconManager,
-            mapService, mSettingsManager, sourceManager, tunerModel);
+            mapService, mSettingsManager, mSourceManager, tunerModel);
 
         mSpectralPanel = new SpectralDisplayPanel(mChannelModel,
             mChannelProcessingManager, mSettingsManager);
 
         TunerSpectralDisplayManager tunerSpectralDisplayManager = new TunerSpectralDisplayManager(mSpectralPanel,
-                mChannelModel, mChannelProcessingManager, mSettingsManager);
+            mChannelModel, mChannelProcessingManager, mSettingsManager);
         tunerModel.addListener(tunerSpectralDisplayManager);
         tunerModel.addListener(this);
 
@@ -223,14 +226,6 @@ public class SDRTrunk implements Listener<TunerEvent>
         }
     }
 
-    /**
-     * Launch the application.
-     */
-    public static void main(String[] args)
-    {
-        new SDRTrunk();
-    }
-
     /**
      * Initialize the contents of the frame.
      */
@@ -243,9 +238,10 @@ public class SDRTrunk implements Listener<TunerEvent>
          */
         mTitle = SystemProperties.getInstance().getApplicationName();
         mMainGui.setTitle(mTitle);
-        mMainGui.setSize(new Dimension(1280,800));
+        mMainGui.setSize(new Dimension(1280, 800));
         mMainGui.setLocationRelativeTo(null);
         mMainGui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        mMainGui.addWindowListener(new ShutdownMonitor());
 
         //Set preferred sizes to influence the split
         mSpectralPanel.setPreferredSize(new Dimension(1280, 300));
@@ -318,6 +314,7 @@ public class SDRTrunk implements Listener<TunerEvent>
             {
                 public void actionPerformed(ActionEvent event)
                 {
+                    processShutdown();
                     System.exit(0);
                 }
             }
@@ -400,6 +397,21 @@ public class SDRTrunk implements Listener<TunerEvent>
         menuBar.add(screenCaptureItem);
     }
 
+    /**
+     * Performs shutdown operations
+     */
+    private void processShutdown()
+    {
+        mLog.debug("Application shutdown started ...");
+        mLog.debug("Stopping channels ...");
+        mChannelProcessingManager.shutdown();
+        mLog.debug("Stopping spectral display ...");
+        mSpectralPanel.clearTuner();
+        mLog.debug("Releasing tuners ...");
+        mSourceManager.shutdown();
+        mLog.debug("Shutdown complete.");
+    }
+
     /**
      * Lazy constructor for broadcast status panel
      */
@@ -520,6 +532,15 @@ public class SDRTrunk implements Listener<TunerEvent>
         }
     }
 
+    public class ShutdownMonitor extends WindowAdapter
+    {
+        @Override
+        public void windowClosing(WindowEvent e)
+        {
+            processShutdown();
+        }
+    }
+
     public class BroadcastStatusVisibleMenuItem extends JCheckBoxMenuItem
     {
         private ControllerPanel mControllerPanel;
@@ -543,4 +564,12 @@ public class SDRTrunk implements Listener<TunerEvent>
             });
         }
     }
+
+    /**
+     * Launch the application.
+     */
+    public static void main(String[] args)
+    {
+        new SDRTrunk();
+    }
 }

src/main/java/io/github/dsheirer/source/SourceManager.java

@@ -44,6 +44,15 @@ public class SourceManager
         //in via the constructor.  Perform loading outside of this class.
     }
 
+    /**
+     * Prepare for shutdown and release all tuners
+     */
+    public void shutdown()
+    {
+        mTunerManager.releaseTuners();
+        mTunerManager.dispose();
+    }
+
     public MixerManager getMixerManager()
     {
         return mMixerManager;

src/main/java/io/github/dsheirer/source/tuner/Tuner.java

@@ -98,8 +98,12 @@ public abstract class Tuner implements ISourceEventProcessor
         return mName;
     }
 
+    /**
+     * Dispose and prepare for shutdown
+     */
     public void dispose()
     {
+        getTunerController().dispose();
     }
 
     /**

src/main/java/io/github/dsheirer/source/tuner/TunerController.java

@@ -61,6 +61,11 @@ public abstract class TunerController implements Tunable, ISourceEventProcessor,
         mSourceEventListener = new SourceEventListenerToProcessorAdapter(this);
     }
 
+    /**
+     * Dispose of this tuner controller and prepare for shutdown.
+     */
+    public abstract void dispose();
+
     /**
      * Implements the ISourceEventListener interface to receive requests from sample consumers
      */

src/main/java/io/github/dsheirer/source/tuner/TunerManager.java

@@ -1,19 +1,16 @@
 /*******************************************************************************
- * sdrtrunk
+ * sdr-trunk
- * Copyright (C) 2014-2017 Dennis Sheirer
+ * Copyright (C) 2014-2018 Dennis Sheirer
  *
- * This program is free software: you can redistribute it and/or modify
+ * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public
- * it under the terms of the GNU General Public License as published by
+ * License as published by  the Free Software Foundation, either version 3 of the License, or  (at your option) any
- * the Free Software Foundation, either version 3 of the License, or
+ * later version.
- * (at your option) any later version.
  *
- * This program is distributed in the hope that it will be useful,
+ * This program is distributed in the hope that it will be useful,  but WITHOUT ANY WARRANTY; without even the implied
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * warranty of  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
- * 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
+ * You should have received a copy of the GNU General Public License  along with this program.
- * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * If not, see <http://www.gnu.org/licenses/>
  *
  ******************************************************************************/
 package io.github.dsheirer.source.tuner;
@@ -74,7 +71,15 @@ public class TunerManager
      */
     public void dispose()
     {
-        LibUsb.exit(null);
+        mLog.info("Shutting down LibUsb ...");
+        try
+        {
+            LibUsb.exit(null);
+        }
+        catch(Exception e)
+        {
+            mLog.error("Error shutting down LibUsb", e);
+        }
     }
 
     /**
@@ -217,6 +222,22 @@ public class TunerManager
         return new TunerInitStatus(null, "Unknown Device");
     }
 
+    /**
+     * Releases all tuners in preparation for shutdown
+     */
+    public void releaseTuners()
+    {
+        mLog.info("Releasing [" + mTunerModel.getTuners().size() + "] tuner(s) ...");
+        Tuner tuner = mTunerModel.getTuner(0);
+
+        while(tuner != null)
+        {
+            mTunerModel.removeTuner(tuner);
+            tuner.dispose();
+            tuner = mTunerModel.getTuner(0);
+        }
+    }
+
     private TunerInitStatus initAirspyTuner(Device device,
                                             DeviceDescriptor descriptor)
     {

src/main/java/io/github/dsheirer/source/tuner/airspy/AirspyTunerController.java

@@ -180,6 +180,24 @@ public class AirspyTunerController extends USBTunerController
             USB_TRANSFER_BUFFER_SIZE);
     }
 
+    @Override
+    public void dispose()
+    {
+        if(mDeviceHandle != null)
+        {
+            mLog.info("Releasing Airspy Tuner - " + getDeviceInfo().getSerialNumber());
+            try
+            {
+                LibUsb.close(mDeviceHandle);
+            }
+            catch(Exception e)
+            {
+                mLog.error("error while closing device handle", e);
+            }
+
+            mDeviceHandle = null;
+        }
+    }
 
     @Override
     protected USBTransferProcessor getUSBTransferProcessor()

src/main/java/io/github/dsheirer/source/tuner/hackrf/HackRFTuner.java

@@ -37,10 +37,6 @@ public class HackRFTuner extends Tuner
         return (HackRFTunerController)getTunerController();
     }
 
-    public void dispose()
-    {
-    }
-
     @Override
     public TunerClass getTunerClass()
     {

src/main/java/io/github/dsheirer/source/tuner/hackrf/HackRFTunerController.java

@@ -157,6 +157,25 @@ public class HackRFTunerController extends USBTunerController
         mUSBTransferProcessor = new USBTransferProcessor(name, mDeviceHandle, mNativeBufferConverter, USB_TRANSFER_BUFFER_SIZE);
     }
 
+    @Override
+    public void dispose()
+    {
+        if(mDeviceHandle != null)
+        {
+            mLog.info("Releasing HackRF Tuner");
+            try
+            {
+                LibUsb.close(mDeviceHandle);
+            }
+            catch(Exception e)
+            {
+                mLog.error("error while closing device handle", e);
+            }
+
+            mDeviceHandle = null;
+        }
+    }
+
     @Override
     protected USBTransferProcessor getUSBTransferProcessor()
     {

src/main/java/io/github/dsheirer/source/tuner/rtl/RTL2832Tuner.java

@@ -38,10 +38,6 @@ public class RTL2832Tuner extends Tuner
         mTunerClass = tunerClass;
     }
 
-    public void dispose()
-    {
-    }
-
     public RTL2832TunerController getController()
     {
         return (RTL2832TunerController)getTunerController();

src/main/java/io/github/dsheirer/source/tuner/rtl/e4k/E4KTunerController.java

@@ -256,6 +256,26 @@ public class E4KTunerController extends RTL2832TunerController
             USB_TRANSFER_BUFFER_SIZE);
     }
 
+    @Override
+    public void dispose()
+    {
+        if(mDeviceHandle != null)
+        {
+            mLog.info("Releasing E4000 Tuner");
+
+            try
+            {
+                LibUsb.close(mDeviceHandle);
+            }
+            catch(Exception e)
+            {
+                mLog.error("error while closing device handle", e);
+            }
+
+            mDeviceHandle = null;
+        }
+    }
+
     /**
      * Sets the IF filters (mixer, channel and RC) to the correct filter setting
      * for the selected bandwidth/sample rate

src/main/java/io/github/dsheirer/source/tuner/rtl/r820t/R820TTunerController.java

@@ -30,6 +30,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.usb4java.Device;
 import org.usb4java.DeviceDescriptor;
+import org.usb4java.LibUsb;
 import org.usb4java.LibUsbException;
 
 import javax.swing.JPanel;
@@ -260,6 +261,26 @@ public class R820TTunerController extends RTL2832TunerController
         }
     }
 
+    @Override
+    public void dispose()
+    {
+        mLog.info("Releasing R820T Tuner");
+
+        if(mDeviceHandle != null)
+        {
+            try
+            {
+                LibUsb.close(mDeviceHandle);
+            }
+            catch(Exception e)
+            {
+                mLog.error("error while closing device handle", e);
+            }
+
+            mDeviceHandle = null;
+        }
+    }
+
     /**
      * Initializes the tuner section.
      */

src/main/java/io/github/dsheirer/source/tuner/test/TestTunerController.java

@@ -65,6 +65,12 @@ public class TestTunerController extends TunerController
         }
     }
 
+    @Override
+    public void dispose()
+    {
+        //no-op
+    }
+
     @Override
     public void addBufferListener(Listener<ReusableComplexBuffer> listener)
     {