[WIP] Implements reusable sample buffers across all components. This

produces a significant reduction in memory usage, especially for tuners
like the airspy and hackrf that produce 10/20 MSPS sample rates.  This
is observed to be around 66% reduction in peak memory usage and provides
a more stable memory utilization across time reducing stress on the
garbage collector.

Use of these reusable memory buffers will be pushed further down into
the processing chain modules to ensure we keep new object creation
to the lowest levels possible.

src/main/java/io/github/dsheirer/module/demodulate/am/AMDemodulatorModule.java

@@ -1,19 +1,17 @@
 /*******************************************************************************
- *     SDR Trunk 
- *     Copyright (C) 2014,2015 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/>
+ * sdr-trunk
+ * Copyright (C) 2014-2018 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.module.demodulate.am;
 
@@ -26,12 +24,12 @@ import io.github.dsheirer.dsp.gain.AutomaticGainControl_RB;
 import io.github.dsheirer.module.Module;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.sample.complex.ComplexBuffer;
-import io.github.dsheirer.sample.complex.IComplexBufferListener;
+import io.github.dsheirer.sample.complex.reusable.IReusableComplexBufferListener;
+import io.github.dsheirer.sample.complex.reusable.ReusableComplexBuffer;
 import io.github.dsheirer.sample.real.IFilteredRealBufferProvider;
 import io.github.dsheirer.sample.real.RealBuffer;
 
-public class AMDemodulatorModule extends Module
-    implements IComplexBufferListener, IFilteredRealBufferProvider
+public class AMDemodulatorModule extends Module implements IReusableComplexBufferListener, IFilteredRealBufferProvider
 {
     private static final int SAMPLE_RATE = 48000;
 
@@ -39,6 +37,7 @@ public class AMDemodulatorModule extends Module
     private AMDemodulator_CB mDemodulator;
     private RealFIRFilter_RB_RB mLowPassFilter;
     private AutomaticGainControl_RB mAGC;
+    private ReusableBufferListener mReusableBufferListener = new ReusableBufferListener();
 
     /**
      * AM Demodulator Module
@@ -60,9 +59,9 @@ public class AMDemodulatorModule extends Module
     }
 
     @Override
-    public Listener<ComplexBuffer> getComplexBufferListener()
+    public Listener<ReusableComplexBuffer> getReusableComplexBufferListener()
     {
-        return mIQFilter;
+        return mReusableBufferListener;
     }
 
     @Override
@@ -107,4 +106,19 @@ public class AMDemodulatorModule extends Module
     public void stop()
     {
     }
+
+
+    public class ReusableBufferListener implements Listener<ReusableComplexBuffer>
+    {
+        @Override
+        public void receive(ReusableComplexBuffer reusableComplexBuffer)
+        {
+            float[] samples = reusableComplexBuffer.getCopyOfSamples();
+
+            //TODO: redesign the filter chain so that we can simply pass a float array ...
+
+            mIQFilter.receive(new ComplexBuffer(samples));
+            reusableComplexBuffer.decrementUserCount();
+        }
+    }
 }

src/main/java/io/github/dsheirer/module/demodulate/fm/FMDemodulatorModule.java

@@ -24,13 +24,14 @@ import io.github.dsheirer.dsp.fm.FMDemodulator_CB;
 import io.github.dsheirer.module.Module;
 import io.github.dsheirer.sample.Listener;
 import io.github.dsheirer.sample.complex.ComplexBuffer;
-import io.github.dsheirer.sample.complex.IComplexBufferListener;
+import io.github.dsheirer.sample.complex.reusable.IReusableComplexBufferListener;
+import io.github.dsheirer.sample.complex.reusable.ReusableComplexBuffer;
 import io.github.dsheirer.sample.real.IUnFilteredRealBufferProvider;
 import io.github.dsheirer.sample.real.RealBuffer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class FMDemodulatorModule extends Module implements IComplexBufferListener, IUnFilteredRealBufferProvider
+public class FMDemodulatorModule extends Module implements IReusableComplexBufferListener, IUnFilteredRealBufferProvider
 {
     private final static Logger mLog = LoggerFactory.getLogger(FMDemodulatorModule.class);
 
@@ -38,6 +39,7 @@ public class FMDemodulatorModule extends Module implements IComplexBufferListene
 
     private ComplexFIRFilter_CB_CB mIQFilter;
     private FMDemodulator_CB mDemodulator;
+    private ReusableBufferListener mReusableBufferListener = new ReusableBufferListener();
 
     /**
      * FM Demodulator with I/Q filter.  Demodulated output is unfiltered and
@@ -68,9 +70,9 @@ public class FMDemodulatorModule extends Module implements IComplexBufferListene
     }
 
     @Override
-    public Listener<ComplexBuffer> getComplexBufferListener()
+    public Listener<ReusableComplexBuffer> getReusableComplexBufferListener()
     {
-        return mIQFilter;
+        return mReusableBufferListener;
     }
 
     @Override
@@ -110,4 +112,18 @@ public class FMDemodulatorModule extends Module implements IComplexBufferListene
     public void stop()
     {
     }
+
+    public class ReusableBufferListener implements Listener<ReusableComplexBuffer>
+    {
+        @Override
+        public void receive(ReusableComplexBuffer reusableComplexBuffer)
+        {
+            float[] samples = reusableComplexBuffer.getCopyOfSamples();
+
+            //TODO: redesign the filter chain so that we can simply pass a float array ...
+
+            mIQFilter.receive(new ComplexBuffer(samples));
+            reusableComplexBuffer.decrementUserCount();
+        }
+    }
 }