#1243 Updates USB tuner error handling to prevent stack overflow when tuner error occurs while streaming. (#1247)

Co-authored-by: Dennis Sheirer <dsheirer@github.com>

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

@@ -25,6 +25,7 @@ import io.github.dsheirer.channel.metadata.ChannelAndMetadata;
 import io.github.dsheirer.channel.metadata.ChannelMetadata;
 import io.github.dsheirer.channel.metadata.ChannelMetadataModel;
 import io.github.dsheirer.controller.channel.event.ChannelStartProcessingRequest;
+import io.github.dsheirer.controller.channel.event.ChannelStopProcessingRequest;
 import io.github.dsheirer.controller.channel.event.PreloadDataContent;
 import io.github.dsheirer.controller.channel.map.ChannelMapModel;
 import io.github.dsheirer.identifier.Form;
@@ -46,12 +47,9 @@ import io.github.dsheirer.source.SourceEvent;
 import io.github.dsheirer.source.SourceException;
 import io.github.dsheirer.source.config.SourceConfigTuner;
 import io.github.dsheirer.source.config.SourceConfigTunerMultipleFrequency;
+import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
 import io.github.dsheirer.source.tuner.manager.TunerManager;
 import io.github.dsheirer.util.ThreadPool;
-import javafx.application.Platform;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.awt.GraphicsEnvironment;
 import java.util.ArrayList;
 import java.util.List;
@@ -62,6 +60,9 @@ import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import javafx.application.Platform;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Channel processing manager handles all starting and stopping of channel decoding.  A processing chain is created
@@ -124,7 +125,20 @@ public class ChannelProcessingManager implements Listener<ChannelEvent>
      */
     private boolean isProcessing(Channel channel)
     {
-        return mProcessingChains.containsKey(channel) && mProcessingChains.get(channel).isProcessing();
+        boolean isProcessing = false;
+
+        mLock.lock();
+
+        try
+        {
+            isProcessing = mProcessingChains.containsKey(channel) && mProcessingChains.get(channel).isProcessing();
+        }
+        finally
+        {
+            mLock.unlock();
+        }
+
+        return isProcessing;
     }
 
     /**
@@ -153,18 +167,60 @@ public class ChannelProcessingManager implements Listener<ChannelEvent>
      */
     public Channel getChannel(ProcessingChain processingChain)
     {
+        Channel channel = null;
+
         if(processingChain != null)
         {
-            for(Map.Entry<Channel,ProcessingChain> entry : mProcessingChains.entrySet())
+            mLock.lock();
+
+            try
             {
-                if(entry.getValue() == processingChain)
+                for(Map.Entry<Channel,ProcessingChain> entry : mProcessingChains.entrySet())
                 {
-                    return entry.getKey();
+                    if(entry.getValue() == processingChain)
+                    {
+                        channel = entry.getKey();
+                        break;
+                    }
                 }
             }
+            finally
+            {
+                mLock.unlock();
+            }
         }
 
-        return null;
+        return channel;
+    }
+
+    /**
+     * Retrieves the channel associated with the processing chain that is consuming from the tuner channel source
+     * @param tunerChannelSource to find the channel
+     * @return channel
+     */
+    private Channel getChannel(TunerChannelSource tunerChannelSource)
+    {
+        Channel channel = null;
+
+        mLock.lock();
+
+        try
+        {
+            for(Map.Entry<Channel,ProcessingChain> entry : mProcessingChains.entrySet())
+            {
+                if(entry.getValue().hasSource(tunerChannelSource))
+                {
+                    channel = entry.getKey();
+                    break;
+                }
+            }
+        }
+        finally
+        {
+            mLock.unlock();
+        }
+
+        return channel;
     }
 
     /**
@@ -273,6 +329,28 @@ public class ChannelProcessingManager implements Listener<ChannelEvent>
         }
     }
 
+    /**
+     * Request to stop a channel that is currently processing
+     * @param request with the tuner channel source feeding the channel to be stopped.
+     */
+    @Subscribe
+    public void stopChannelRequest(ChannelStopProcessingRequest request)
+    {
+        Channel channel = getChannel(request.getTunerChannelSource());
+
+        if(channel != null)
+        {
+            try
+            {
+                stop(channel);
+            }
+            catch(ChannelException ce)
+            {
+                mLog.error("Error stopping channel [" + channel + "]", ce);
+            }
+        }
+    }
+
     /**
      * Stops the specified channel
      * @param channel to stop
@@ -720,9 +798,7 @@ public class ChannelProcessingManager implements Listener<ChannelEvent>
     {
         @Override public void receive(SourceEvent sourceEvent)
         {
-            if((sourceEvent.getEvent() == SourceEvent.Event.NOTIFICATION_ERROR_STATE ||
-                sourceEvent.getEvent() == SourceEvent.Event.NOTIFICATION_TUNER_SHUTDOWN) &&
-                    sourceEvent.getSource() != null)
+            if(sourceEvent.getEvent() == SourceEvent.Event.NOTIFICATION_ERROR_STATE && sourceEvent.getSource() != null)
             {
                 Channel toShutdown = null;
 
@@ -750,10 +826,6 @@ public class ChannelProcessingManager implements Listener<ChannelEvent>
                     {
                         mLog.warn("Channel source error detected - stopping channel [" + toShutdown.getName() + "]");
                     }
-                    else if(sourceEvent.getEvent() == SourceEvent.Event.NOTIFICATION_TUNER_SHUTDOWN)
-                    {
-                        mLog.warn("Tuner removal detected - stopping channel [" + toShutdown.getName() + "]");
-                    }
                     else
                     {
                         mLog.warn("Source event error - stopping channel [" + toShutdown.getName() + "]");

src/main/java/io/github/dsheirer/controller/channel/event/ChannelStopProcessingRequest.java

@@ -0,0 +1,44 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2022 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.controller.channel.event;
+
+import io.github.dsheirer.module.ModuleEventBusMessage;
+import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
+
+/**
+ * Request to stop processing a channel for a specific tuner channel source
+ */
+public class ChannelStopProcessingRequest extends ModuleEventBusMessage
+{
+    private TunerChannelSource mTunerChannelSource;
+    /**
+     * Constructs an instance
+     * @param tunerChannelSource for the channel to stop
+     */
+    public ChannelStopProcessingRequest(TunerChannelSource tunerChannelSource)
+    {
+        mTunerChannelSource = tunerChannelSource;
+    }
+
+    public TunerChannelSource getTunerChannelSource()
+    {
+        return mTunerChannelSource;
+    }
+}

src/main/java/io/github/dsheirer/dsp/filter/channelizer/PolyphaseChannelManager.java

@@ -21,11 +21,13 @@ package io.github.dsheirer.dsp.filter.channelizer;
 import io.github.dsheirer.buffer.INativeBuffer;
 import io.github.dsheirer.buffer.INativeBufferProvider;
 import io.github.dsheirer.buffer.NativeBufferPoisonPill;
+import io.github.dsheirer.controller.channel.event.ChannelStopProcessingRequest;
 import io.github.dsheirer.dsp.filter.FilterFactory;
 import io.github.dsheirer.dsp.filter.channelizer.output.IPolyphaseChannelOutputProcessor;
 import io.github.dsheirer.dsp.filter.channelizer.output.OneChannelOutputProcessor;
 import io.github.dsheirer.dsp.filter.channelizer.output.TwoChannelOutputProcessor;
 import io.github.dsheirer.dsp.filter.design.FilterDesignException;
+import io.github.dsheirer.eventbus.MyEventBus;
 import io.github.dsheirer.sample.Broadcaster;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.sample.complex.InterleavedComplexSamples;
@@ -37,10 +39,6 @@ import io.github.dsheirer.source.tuner.TunerController;
 import io.github.dsheirer.source.tuner.channel.TunerChannel;
 import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
 import io.github.dsheirer.util.Dispatcher;
-import org.apache.commons.math3.util.FastMath;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -51,6 +49,9 @@ import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.CopyOnWriteArrayList;
+import org.apache.commons.math3.util.FastMath;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Polyphase Channel Manager is a DDC channel manager and complex buffer queue/processor for a tuner.  This class
@@ -136,14 +137,7 @@ public class PolyphaseChannelManager implements ISourceEventProcessor
 
         for(TunerChannelSource tunerChannelSource: toStop)
         {
-            try
-            {
-                tunerChannelSource.process(SourceEvent.tunerShutdown(tunerChannelSource));
-            }
-            catch(SourceException se)
-            {
-                mLog.error("Error stopping tuner channel source for tuner shutdown");
-            }
+            MyEventBus.getGlobalEventBus().post(new ChannelStopProcessingRequest(tunerChannelSource));
         }
     }
 

src/main/java/io/github/dsheirer/playlist/PlaylistManager.java

@@ -32,6 +32,7 @@ import io.github.dsheirer.controller.channel.ChannelModel;
 import io.github.dsheirer.controller.channel.ChannelProcessingManager;
 import io.github.dsheirer.controller.channel.map.ChannelMap;
 import io.github.dsheirer.controller.channel.map.ChannelMapModel;
+import io.github.dsheirer.eventbus.MyEventBus;
 import io.github.dsheirer.icon.IconModel;
 import io.github.dsheirer.module.log.EventLogManager;
 import io.github.dsheirer.preference.UserPreferences;
@@ -40,10 +41,6 @@ import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.service.radioreference.RadioReference;
 import io.github.dsheirer.source.tuner.manager.TunerManager;
 import io.github.dsheirer.util.ThreadPool;
-import javafx.collections.ListChangeListener;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -54,6 +51,9 @@ import java.util.ArrayList;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+import javafx.collections.ListChangeListener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Manages all aspects of playlists and related models
@@ -104,6 +104,11 @@ public class PlaylistManager implements Listener<ChannelEvent>
         mChannelModel = new ChannelModel(mAliasModel);
         mChannelProcessingManager = new ChannelProcessingManager(mChannelMapModel, eventLogManager, mTunerManager,
             mAliasModel, mUserPreferences);
+
+        //Register the channel processing manager to receive global channel stop processing requests so that it can
+        //respond to tuner shutdown (ie error) events
+        MyEventBus.getGlobalEventBus().register(mChannelProcessingManager);
+
         mChannelModel.addListener(mChannelProcessingManager);
         mChannelProcessingManager.addChannelEventListener(mChannelModel);
 

src/main/java/io/github/dsheirer/sample/Broadcaster.java

@@ -1,7 +1,6 @@
 /*
- * ******************************************************************************
- * sdrtrunk
- * Copyright (C) 2014-2019 Dennis Sheirer
+ * *****************************************************************************
+ * Copyright (C) 2014-2022 Dennis Sheirer
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,17 +14,16 @@
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>
- * *****************************************************************************
+ * ****************************************************************************
  */
 package io.github.dsheirer.sample;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.locks.ReentrantLock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Broadcasts an item to multiple listeners
@@ -33,7 +31,6 @@ import java.util.concurrent.locks.ReentrantLock;
 public class Broadcaster<T> implements Listener<T>
 {
     private final static Logger mLog = LoggerFactory.getLogger(Broadcaster.class);
-    private boolean mDebug;
     private ReentrantLock mLock = new ReentrantLock();
     private List<Listener<T>> mListeners = new ArrayList<>();
 
@@ -41,14 +38,6 @@ public class Broadcaster<T> implements Listener<T>
     {
     }
 
-    /**
-     * Turns on/off debugging to troubleshoot and log which listeners are receiving an item.
-     */
-    public void setDebug(boolean debug)
-    {
-        mDebug = debug;
-    }
-
     /**
      * Implements the Listener<T> interface to receive an element and broadcast that element to all registered
      * listeners.
@@ -66,16 +55,7 @@ public class Broadcaster<T> implements Listener<T>
      */
     public void dispose()
     {
-        mLock.lock();
-
-        try
-        {
-            mListeners.clear();
-        }
-        finally
-        {
-            mLock.unlock();
-        }
+        clear();
     }
 
     /**
@@ -152,16 +132,7 @@ public class Broadcaster<T> implements Listener<T>
      */
     public void clear()
     {
-        mLock.lock();
-
-        try
-        {
-            mListeners.clear();
-        }
-        finally
-        {
-            mLock.unlock();
-        }
+        mListeners.clear();
     }
 
     /**
@@ -173,21 +144,11 @@ public class Broadcaster<T> implements Listener<T>
 
         try
         {
-            if(mDebug)
+            List<Listener<T>> listeners = new ArrayList<>(mListeners);
+
+            for(Listener listener: listeners)
             {
-                for(Listener<T> listener : mListeners)
-                {
-                    mLog.debug("Sending [" + t + "] to listener [" + listener.getClass() + "]");
-                    listener.receive(t);
-                    mLog.debug("Finished sending to listener [" + listener.getClass() + "]");
-                }
-            }
-            else
-            {
-                for(Listener<T> listener : mListeners)
-                {
-                    listener.receive(t);
-                }
+                listener.receive(t);
             }
         }
         finally

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

@@ -28,6 +28,7 @@ import io.github.dsheirer.source.tuner.TunerEvent.Event;
 import io.github.dsheirer.source.tuner.manager.ChannelSourceManager;
 import io.github.dsheirer.source.tuner.manager.HeterodyneChannelSourceManager;
 import io.github.dsheirer.source.tuner.manager.PolyphaseChannelSourceManager;
+import java.util.concurrent.atomic.AtomicBoolean;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -44,6 +45,7 @@ public abstract class Tuner implements ISourceEventProcessor, ITunerErrorListene
     private TunerController mTunerController;
     private TunerFrequencyErrorMonitor mTunerFrequencyErrorMonitor;
     private ITunerErrorListener mTunerErrorListener;
+    private AtomicBoolean mRunning = new AtomicBoolean();
 
     public Tuner(TunerController tunerController, ITunerErrorListener tunerErrorListener)
     {
@@ -85,20 +87,25 @@ public abstract class Tuner implements ISourceEventProcessor, ITunerErrorListene
      */
     public void start() throws SourceException
     {
-        try
+        if(mRunning.compareAndSet(false, true))
         {
-            getTunerController().start();
-        }
-        catch(SourceException se)
-        {
-            //Rethrow the source exception
-            throw se;
-        }
-        catch(Exception e)
-        {
-            //Wrap any other exceptions in a new source exception
-            mLog.error("Error starting " + getTunerClass() + " tuner", e);
-            throw new SourceException("Unable to start " + getTunerClass() + " tuner", e);
+            try
+            {
+                getTunerController().start();
+            }
+            catch(SourceException se)
+            {
+                mRunning.set(false);
+                //Rethrow the source exception
+                throw se;
+            }
+            catch(Exception e)
+            {
+                mRunning.set(false);
+                //Wrap any other exceptions in a new source exception
+                mLog.error("Error starting " + getTunerClass() + " tuner", e);
+                throw new SourceException("Unable to start " + getTunerClass() + " tuner", e);
+            }
         }
     }
 
@@ -107,20 +114,24 @@ public abstract class Tuner implements ISourceEventProcessor, ITunerErrorListene
      */
     public void stop()
     {
-        if(getChannelSourceManager() != null)
+        if(mRunning.compareAndSet(true, false))
         {
-            getChannelSourceManager().stopAllChannels();
-            getChannelSourceManager().dispose();
-            mChannelSourceManager = null;
+            broadcast(new TunerEvent(this, Event.NOTIFICATION_SHUTTING_DOWN));
+
+            if(getChannelSourceManager() != null)
+            {
+                getChannelSourceManager().stopAllChannels();
+                getChannelSourceManager().dispose();
+                mChannelSourceManager = null;
+            }
+
+            getTunerController().stop();
+            getTunerController().dispose();
+
+            mTunerEventBroadcaster.clear();
+            mTunerFrequencyErrorMonitor = null;
+            mTunerErrorListener = null;
         }
-
-        broadcast(new TunerEvent(this, Event.NOTIFICATION_SHUTTING_DOWN));
-        getTunerController().stop();
-        getTunerController().dispose();
-
-        mTunerEventBroadcaster.clear();
-        mTunerFrequencyErrorMonitor = null;
-        mTunerErrorListener = null;
     }
 
     /**

src/main/java/io/github/dsheirer/source/tuner/channel/TunerChannelSource.java

@@ -172,10 +172,6 @@ public abstract class TunerChannelSource extends ComplexSource implements ISourc
                 sourceEvent.setSource(this);
                 broadcastProducerSourceEvent(sourceEvent);
                 break;
-            case NOTIFICATION_TUNER_SHUTDOWN:
-                //Rebroadcast this event so the channel processing manager receives it and shuts down the channel
-                broadcastConsumerSourceEvent(sourceEvent);
-                break;
             //Request events from the consumer
             case REQUEST_CHANNEL_FREQUENCY_CORRECTION_CHANGE:
                 setChannelFrequencyCorrection(sourceEvent.getValue().longValue());

src/main/java/io/github/dsheirer/source/tuner/manager/ChannelSourceManager.java

@@ -25,8 +25,9 @@ import io.github.dsheirer.source.SourceEvent;
 import io.github.dsheirer.source.tuner.channel.ChannelSpecification;
 import io.github.dsheirer.source.tuner.channel.TunerChannel;
 import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
-
 import java.util.SortedSet;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Interface to define the functionality of a channel source manager for handling tuner channel management and source
@@ -34,6 +35,8 @@ import java.util.SortedSet;
  */
 public abstract class ChannelSourceManager implements ISourceEventProcessor
 {
+    private Logger mLogger = LoggerFactory.getLogger(ChannelSourceManager.class);
+
     private Broadcaster<SourceEvent> mSourceEventBroadcaster = new Broadcaster<>();
 
     /**

src/main/java/io/github/dsheirer/source/tuner/manager/HeterodyneChannelSourceManager.java

@@ -19,7 +19,9 @@
 package io.github.dsheirer.source.tuner.manager;
 
 import io.github.dsheirer.buffer.NativeSampleDelayBuffer;
+import io.github.dsheirer.controller.channel.event.ChannelStopProcessingRequest;
 import io.github.dsheirer.dsp.filter.design.FilterDesignException;
+import io.github.dsheirer.eventbus.MyEventBus;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.source.SourceEvent;
 import io.github.dsheirer.source.SourceException;
@@ -28,14 +30,13 @@ import io.github.dsheirer.source.tuner.channel.ChannelSpecification;
 import io.github.dsheirer.source.tuner.channel.HalfBandTunerChannelSource;
 import io.github.dsheirer.source.tuner.channel.TunerChannel;
 import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.List;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.CopyOnWriteArrayList;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Channel provider for heterodyne and decimate method of channel provisioning.
@@ -68,14 +69,7 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
 
         for(TunerChannelSource tunerChannelSource: toStop)
         {
-            try
-            {
-                tunerChannelSource.process(SourceEvent.tunerShutdown(tunerChannelSource));
-            }
-            catch(SourceException se)
-            {
-                mLog.error("Error stopping tuner channel source for tuner shutdown");
-            }
+            MyEventBus.getGlobalEventBus().post(new ChannelStopProcessingRequest(tunerChannelSource));
         }
     }
 
@@ -278,8 +272,6 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
                         //The start sample stream request contains a start timestamp and the delay buffer
                         //will preload the channel with delayed sample buffers that either contain the
                         //timestamp or occur later/newer than the timestamp.
-//                        mSampleDelayBuffer.addListener((CICTunerChannelSource)sourceEvent.getSource(),
-//                                sourceEvent.getValue().longValue());
                         mSampleDelayBuffer.addListener((HalfBandTunerChannelSource)sourceEvent.getSource(),
                                 sourceEvent.getValue().longValue());
                     }
@@ -287,7 +279,6 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
                 case REQUEST_STOP_SAMPLE_STREAM:
                     if(sourceEvent.getSource() instanceof HalfBandTunerChannelSource)
                     {
-//                        mSampleDelayBuffer.removeListener((CICTunerChannelSource)sourceEvent.getSource());
                         mSampleDelayBuffer.removeListener((HalfBandTunerChannelSource)sourceEvent.getSource());
                         stopDelayBuffer();
                     }
@@ -295,7 +286,6 @@ public class HeterodyneChannelSourceManager extends ChannelSourceManager
                 case REQUEST_SOURCE_DISPOSE:
                     if(sourceEvent.getSource() instanceof HalfBandTunerChannelSource)
                     {
-//                        CICTunerChannelSource channelSource = (CICTunerChannelSource)sourceEvent.getSource();
                         HalfBandTunerChannelSource channelSource = (HalfBandTunerChannelSource) sourceEvent.getSource();
                         mChannelSources.remove(channelSource);
                         mTunerChannels.remove(channelSource.getTunerChannel());

src/main/java/io/github/dsheirer/source/tuner/manager/PassThroughSourceManager.java

@@ -19,6 +19,8 @@
 
 package io.github.dsheirer.source.tuner.manager;
 
+import io.github.dsheirer.controller.channel.event.ChannelStopProcessingRequest;
+import io.github.dsheirer.eventbus.MyEventBus;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.source.SourceEvent;
 import io.github.dsheirer.source.SourceException;
@@ -27,14 +29,13 @@ import io.github.dsheirer.source.tuner.channel.ChannelSpecification;
 import io.github.dsheirer.source.tuner.channel.PassThroughChannelSource;
 import io.github.dsheirer.source.tuner.channel.TunerChannel;
 import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.util.ArrayList;
 import java.util.List;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.CopyOnWriteArrayList;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Pass through source manager for relatively small bandwidth complex streams that don't warrant the overhead of
@@ -62,14 +63,7 @@ public class PassThroughSourceManager extends ChannelSourceManager
 
         for(TunerChannelSource tunerChannelSource: toStop)
         {
-            try
-            {
-                tunerChannelSource.process(SourceEvent.tunerShutdown(tunerChannelSource));
-            }
-            catch(SourceException se)
-            {
-                mLog.error("Error stopping tuner channel source for tuner shutdown");
-            }
+            MyEventBus.getGlobalEventBus().post(new ChannelStopProcessingRequest(tunerChannelSource));
         }
     }
 

src/main/java/io/github/dsheirer/source/tuner/ui/TunerSpectralDisplayManager.java

@@ -31,14 +31,28 @@ import io.github.dsheirer.util.SwingUtils;
 import io.github.dsheirer.util.ThreadPool;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+/**
+ * Spectral display manager for displaying tuner spectral content.
+ */
 public class TunerSpectralDisplayManager implements Listener<TunerEvent>
 {
+    private Logger mLog = LoggerFactory.getLogger(TunerSpectralDisplayManager.class);
+
     private SpectralDisplayPanel mSpectralDisplayPanel;
     private PlaylistManager mPlaylistManager;
     private SettingsManager mSettingsManager;
     private DiscoveredTunerModel mDiscoveredTunerModel;
 
+    /**
+     * Constructs an instance
+     * @param panel to manage
+     * @param playlistManager for channel updates
+     * @param settingsManager for settings
+     * @param discoveredTunerModel to access tuners
+     */
     public TunerSpectralDisplayManager(SpectralDisplayPanel panel, PlaylistManager playlistManager,
                                        SettingsManager settingsManager, DiscoveredTunerModel discoveredTunerModel)
     {