Add Ringbuffer interface an 2 implementations, synchronized (locking) SyncedRingbuffer and lock-free LFRingbuffer.

SyncedRingbuffer is moved from JOGL to GlueGen, and generalized w/ common interface Ringbuffer
to allow testing diff. implementations.

- Added Ringbuffer.AllocEmptyArray factory interface, allowing to pass a constructor
  to construct the generic array.

- Added functionality is growBuffer(..), allowing to either grow a full or empty buffer,
  using Ringbuffer.AllocEmptyArray.

- Removed explicit 'clearRef' at get*(..), always clear the taken reference for better
  interface generalization.

- Added LFRingbuffer, exposing lock-free get*(..) and put*(..) methods
  using the 'Always Keep One Slot Open' pattern using the read/write index as barriers only.

- Ctor's copy an optional passed user array into the internal array,
  utilizing Ringbuffer.AllocEmptyArray.

- Added unit tests.

3 files changed, 996 insertions, 0 deletions

diff --git a/src/java/com/jogamp/common/util/LFRingbuffer.java b/src/java/com/jogamp/common/util/LFRingbuffer.java
new file mode 100644
index 0000000..a6b441a
--- /dev/null
+++ b/src/java/com/jogamp/common/util/LFRingbuffer.java
@@ -0,0 +1,401 @@
+/**
+ * Copyright 2013 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ * 
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ * 
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+
+package com.jogamp.common.util;
+
+import java.io.PrintStream;
+
+/** 
+ * Simple implementation of {@link Ringbuffer},
+ * exposing <i>lock-free</i>
+ * {@link #get() get*(..)} and {@link #put(Object) put*(..)} methods.
+ * <p>
+ * Implementation utilizes the <i>Always Keep One Slot Open</i>,
+ * hence implementation maintains an internal array of <code>capacity</code> <i>plus one</i>!
+ * </p>
+ * <p>
+ * Implementation is thread safe if:
+ * <ul>
+ *   <li>{@link #get() get*(..)} operations are performed from one thread only.</li>
+ *   <li>{@link #put(Object) put*(..)} operations are performed from one thread only.</li>
+ *   <li>{@link #get() get*(..)} and {@link #put(Object) put*(..)} thread may be the same.</li>
+ * </ul>
+ * </p>
+ * <p>
+ * Following methods utilize global synchronization:
+ * <ul>
+ *  <li>{@link #resetFull(Object[])}</li>
+ *  <li>{@link #clear()}</li>
+ *  <li>{@link #growBuffer(Object[], int, AllocEmptyArray)}</li>
+ * </ul>
+ * User needs to synchronize above methods w/ the lock-free
+ * w/ {@link #get() get*(..)} and {@link #put(Object) put*(..)} methods,
+ * e.g. by controlling their threads before invoking the above.
+ * </p>
+ * <p>
+ * Characteristics:
+ * <ul>
+ *   <li>Read position points to the last read element.</li>
+ *   <li>Write position points to the last written element.</li>
+ * </ul>
+ * <table border="1">
+ *   <tr><td>Empty</td><td>writePos == readPos</td><td>size == 0</td></tr>
+ *   <tr><td>Full</td><td>writePos == readPos - 1</td><td>size == capacity</td></tr>
+ * </table>
+ * </p>
+ */
+public class LFRingbuffer<T> implements Ringbuffer<T> {
+
+    private final Object syncRead = new Object();
+    private final Object syncWrite = new Object();
+    private final Object syncGlobal = new Object();
+    private /* final */ volatile T[] array;     // not final due to grow
+    private /* final */ volatile int capacityPlusOne;  // not final due to grow
+    private volatile int readPos;
+    private volatile int writePos;
+    private volatile int size;
+    
+    public final String toString() {
+        return "LFRingbuffer<?>[filled "+size+" / "+(capacityPlusOne-1)+", writePos "+writePos+", readPos "+readPos+"]";
+    }
+    
+    public final void dump(PrintStream stream, String prefix) {
+        stream.println(prefix+" "+toString()+" {");
+        for(int i=0; i<capacityPlusOne; i++) {
+            stream.println("\t["+i+"]: "+array[i]);
+        }
+        stream.println("}");
+    }
+    
+    /** 
+     * Create a full ring buffer instance w/ the given array's net capacity and content.
+     * <p> 
+     * Example for a 10 element Integer array:
+     * <pre>
+     *  Integer[] source = new Integer[10];
+     *  // fill source with content ..
+     *  Ringbuffer<Integer> rb = new LFRingbuffer<Integer>(source, new Ringbuffer.AllocEmptyArray<Integer>() {
+     *      public Integer[] newArray(int size) {
+     *          return new Integer[size];
+     *      } } );
+     * </pre>
+     * </p>
+     * <p>
+     * {@link #isFull()} returns true on the newly created full ring buffer.
+     * </p>
+     * <p>
+     * Implementation will allocate an internal array with size of array <code>copyFrom</code> <i>plus one</i>,
+     * and copy all elements from array <code>copyFrom</code> into the internal array.
+     * </p>
+     * @param copyFrom mandatory source array determining ring buffer's net {@link #capacity()} and initial content.
+     * @param allocEmptyArray implementation hook to allocate a new empty array of generic type T
+     * @throws IllegalArgumentException if <code>copyFrom</code> is <code>null</code>   
+     */
+    public LFRingbuffer(T[] copyFrom, AllocEmptyArray<T> allocEmptyArray) throws IllegalArgumentException {
+        capacityPlusOne = copyFrom.length + 1;
+        array = allocEmptyArray.newArray(capacityPlusOne);
+        resetImpl(true, copyFrom);
+    }
+    
+    /** 
+     * Create an empty ring buffer instance w/ the given net <code>capacity</code>.
+     * <p> 
+     * Example for a 10 element Integer array:
+     * <pre>
+     *  Ringbuffer<Integer> rb = new LFRingbuffer<Integer>(10, new Ringbuffer.AllocEmptyArray<Integer>() {
+     *      public Integer[] newArray(int size) {
+     *          return new Integer[size];
+     *      } } );
+     * </pre>
+     * </p>
+     * <p>
+     * {@link #isEmpty()} returns true on the newly created empty ring buffer.
+     * </p>
+     * <p>
+     * Implementation will allocate an internal array of size <code>capacity</code> <i>plus one</i>.
+     * </p>
+     * @param capacity the initial net capacity of the ring buffer
+     * @param allocEmptyArray implementation hook to allocate a new empty array of generic type T
+     */
+    public LFRingbuffer(int capacity, AllocEmptyArray<T> allocEmptyArray) {
+        capacityPlusOne = capacity+1;
+        array = allocEmptyArray.newArray(capacityPlusOne);
+        resetImpl(false, null);
+    }
+        
+    @Override
+    public final T[] getInternalArray() { return array; }
+    
+    @Override
+    public final int capacity() { return capacityPlusOne-1; }
+    
+    @Override
+    public final void clear() {
+        synchronized ( syncGlobal ) {
+            resetImpl(false, null);
+            for(int i=0; i<capacityPlusOne; i++) {
+                this.array[i] = null;
+            }
+        }
+    }
+    
+    @Override
+    public final void resetFull(T[] copyFrom) throws IllegalArgumentException {
+        resetImpl(true, copyFrom);
+    }
+    
+    private final void resetImpl(boolean full, T[] copyFrom) throws IllegalArgumentException {
+        synchronized ( syncGlobal ) {
+            if( null != copyFrom ) {
+                if( copyFrom.length != capacityPlusOne-1 ) {
+                    throw new IllegalArgumentException("copyFrom array length "+copyFrom.length+" != capacity "+this);
+                }
+                System.arraycopy(copyFrom, 0, array, 0, copyFrom.length);
+                array[capacityPlusOne-1] = null; // null 'plus-one' field!
+            } else if( full ) {
+                throw new IllegalArgumentException("copyFrom array is null");
+            }
+            readPos = capacityPlusOne - 1;
+            if( full ) {
+                writePos = readPos - 1;
+                size = capacityPlusOne - 1;
+            } else {
+                writePos = readPos;
+                size = 0;
+            }
+        }
+    }
+    
+    @Override
+    public final int size() { return size; }
+    
+    @Override
+    public final int getFreeSlots() { return capacityPlusOne - 1 - size; }
+
+    @Override
+    public final boolean isEmpty() { return 0 == size; }
+    
+    @Override
+    public final boolean isFull() { return capacityPlusOne - 1 == size; }
+    
+    /**
+     * {@inheritDoc} 
+     * <p>
+     * Implementation advances the read position and returns the element at it, if not empty.
+     * </p>
+     */
+    @Override
+    public final T get() {
+        try {
+            return getImpl(false, false);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+
+    /**
+     * {@inheritDoc} 
+     * <p>
+     * Implementation advances the read position and returns the element at it, if not empty.
+     * </p>
+     */
+    @Override
+    public final T getBlocking() throws InterruptedException {
+        return getImpl(true, false);
+    }
+    
+    @Override
+    public final T peek() {
+        try {
+            return getImpl(false, true);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+    @Override
+    public final T peekBlocking() throws InterruptedException {
+        return getImpl(true, true);
+    }
+    
+    private final T getImpl(boolean blocking, boolean peek) throws InterruptedException {
+        int localReadPos = readPos;
+        if( localReadPos == writePos ) {
+            if( blocking ) {
+                synchronized( syncRead ) {
+                    while( localReadPos == writePos ) {
+                        syncRead.wait();
+                    }
+                }
+            } else {
+                return null;
+            }
+        }
+        localReadPos = (localReadPos + 1) % capacityPlusOne;
+        final T r = array[localReadPos];
+        if( !peek ) {
+            array[localReadPos] = null;
+            synchronized ( syncWrite ) {
+                size--;
+                readPos = localReadPos;
+                syncWrite.notifyAll(); // notify waiting putter
+            }
+        }
+        return r;
+    }
+    
+    /**
+     * {@inheritDoc} 
+     * <p>
+     * Implementation advances the write position and stores the given element at it, if not full.
+     * </p>
+     */
+    @Override
+    public final boolean put(T e) {
+        try {
+            return putImpl(e, false, false);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+    
+    /** 
+     * {@inheritDoc} 
+     * <p>
+     * Implementation advances the write position and stores the given element at it, if not full.
+     * </p>
+     */
+    @Override
+    public final void putBlocking(T e) throws InterruptedException {
+        if( !putImpl(e, false, true) ) {
+            throw new InternalError("Blocking put failed: "+this);
+        }
+    }
+    
+    /**
+     * {@inheritDoc}
+     * <p> 
+     * Implementation advances the write position and keeps the element at it, if not full.
+     * </p>
+     */
+    @Override
+    public final boolean putSame(boolean blocking) throws InterruptedException {
+        return putImpl(null, true, blocking);
+    }
+    
+    private final boolean putImpl(T e, boolean sameRef, boolean blocking) throws InterruptedException {
+        int localWritePos = writePos;
+        localWritePos = (localWritePos + 1) % capacityPlusOne;
+        if( localWritePos == readPos ) {
+            if( blocking ) {
+                synchronized( syncWrite ) {
+                    while( localWritePos == readPos ) {
+                        syncWrite.wait();
+                    }
+                }
+            } else {
+                return false;
+            }
+        }
+        if( !sameRef ) {
+            array[localWritePos] = e;
+        }
+        synchronized ( syncRead ) {
+            size++;
+            writePos = localWritePos;
+            syncRead.notifyAll(); // notify waiting getter
+        }
+        return true;
+    }
+    
+     
+    @Override
+    public final void waitForFreeSlots(int count) throws InterruptedException {
+        synchronized ( syncRead ) {
+            if( capacityPlusOne - 1 - size < count ) {
+                while( capacityPlusOne - 1 - size < count ) {
+                    syncRead.wait();
+                }
+            }
+        }
+    }
+    
+    @Override
+    public void growBuffer(T[] newElements, int amount, AllocEmptyArray<T> allocEmptyArray) throws IllegalStateException, IllegalArgumentException {
+        synchronized( syncGlobal ) {        
+            final boolean isFull = capacityPlusOne - 1 == size;
+            final boolean isEmpty = 0 == size;
+            if( !isFull && !isEmpty ) {
+                throw new IllegalStateException("Buffer neither full nor empty: "+this);
+            }
+            if( isEmpty ) {
+                if( readPos != writePos ) {
+                    throw new InternalError("R/W pos not equal at empty: "+this);
+                }
+            } else /* isFull */ {
+                final int wp1 = ( writePos + 1 ) % capacityPlusOne;
+                if( wp1 != readPos ) {
+                    throw new InternalError("R != W+1 pos at full: "+this);
+                }
+            }
+            if( null != newElements && amount < newElements.length ) {
+                throw new IllegalArgumentException("amount "+amount+" < newElements "+newElements.length);
+            }
+            final int newCapacity = capacityPlusOne + amount;
+            final T[] oldArray = array;
+            final T[] newArray = allocEmptyArray.newArray(newCapacity);
+            
+            if( isFull ) {
+                // writePos == readPos - 1
+                readPos = ( writePos + 1 + amount ) % newCapacity; // warp readPos to the end of the new data location
+                
+                if(writePos >= 0) {
+                    System.arraycopy(oldArray,          0, newArray,          0, writePos+1);
+                }
+                if( null != newElements && newElements.length > 0 ) {
+                    System.arraycopy(newElements,       0, newArray, writePos+1, newElements.length);
+                }
+                final int tail = capacityPlusOne-1-writePos;
+                if( tail > 0 ) {
+                    System.arraycopy(oldArray, writePos+1, newArray,   readPos, tail);
+                }
+            } else /* if ( isEmpty ) */ {
+                // writePos == readPos
+                writePos += amount; // warp writePos to the end of the new data location
+                
+                if( readPos >= 0 ) {
+                    System.arraycopy(oldArray,         0, newArray,          0, readPos+1);
+                }
+                if( null != newElements && newElements.length > 0 ) {
+                    System.arraycopy(newElements,      0, newArray,  readPos+1, newElements.length);
+                }
+                final int tail = capacityPlusOne-1-readPos;
+                if( tail > 0 ) {
+                    System.arraycopy(oldArray, readPos+1, newArray,  writePos+1, tail);
+                }
+                size = amount;
+            }
+            
+            capacityPlusOne = newCapacity;
+            array = newArray;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/java/com/jogamp/common/util/Ringbuffer.java b/src/java/com/jogamp/common/util/Ringbuffer.java
new file mode 100644
index 0000000..733a235
--- /dev/null
+++ b/src/java/com/jogamp/common/util/Ringbuffer.java
@@ -0,0 +1,214 @@
+/**
+ * Copyright 2013 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ * 
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ * 
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+package com.jogamp.common.util;
+
+import java.io.PrintStream;
+
+/** 
+ * Ring buffer interface, a.k.a circular buffer.
+ * <p>
+ * Caller can chose whether to block until get / put is able to proceed or not.
+ * </p>
+ * <p>
+ * Caller can chose whether to pass an empty array and clear references at get,
+ * or using a preset array for circular access of same objects.
+ * </p>
+ * <p>
+ * Synchronization and hence thread safety details belong to the implementation. 
+ * </p>
+ */
+public interface Ringbuffer<T> {
+    
+    /** 
+     * Implementation hook for {@link #growBuffer(Object[], int, AllocEmptyArray)}
+     * to pass an implementation of {@link #newArray(int)}. 
+     * @param <T> type of array
+     */
+    public static interface AllocEmptyArray<T> {
+        /**
+         * Returns a new allocated empty array of generic type T with given size.
+         */
+        public T[] newArray(int size);
+    }
+    
+    /** Returns a short string representation incl. size/capacity and internal r/w index (impl. dependent). */ 
+    public String toString();
+
+    /** Debug functionality - Dumps the contents of the internal array. */
+    public void dump(PrintStream stream, String prefix);
+
+    /** 
+     * Returns the internal array as-is, i.e. w/o a copy.
+     * <p>
+     * The layout and size of the internal array is implementation dependent.
+     * </p> 
+     * <p>
+     * Users shall not modify or rely on the returned array.
+     * </p> 
+     * @deprecated This method should not be required 
+     */
+    public T[] getInternalArray();
+
+    /** Returns the net capacity of this ring buffer. */
+    public int capacity();
+
+    /**
+     * Resets the read and write position according to an empty ring buffer 
+     * and set all ring buffer slots to <code>null</code>.
+     * <p>
+     * {@link #isEmpty()} will return <code>true</code> after calling this method.
+     * </p>
+     */
+    public void clear();
+
+    /**
+     * Resets the read and write position according to a full ring buffer 
+     * and fill all slots w/ elements of array <code>copyFrom</code>.
+     * <p>
+     * Array's <code>copyFrom</code> elements will be copied into the internal array, 
+     * hence it's length must be equal to {@link #capacity()}.
+     * </p>
+     * @param copyFrom Mandatory array w/ length {@link #capacity()} to be copied into the internal array.
+     * @throws IllegalArgumentException if <code>copyFrom</code> is <code>null</code>.   
+     * @throws IllegalArgumentException if <code>copyFrom</code>'s length is different from {@link #capacity()}.
+     */
+    public void resetFull(T[] copyFrom) throws IllegalArgumentException;
+
+    /** Returns the number of elements in this ring buffer. */
+    public int size();
+
+    /** Returns the number of free slots available to put.  */
+    public int getFreeSlots();
+
+    /** Returns true if this ring buffer is empty, otherwise false. */
+    public boolean isEmpty();
+
+    /** Returns true if this ring buffer is full, otherwise false. */
+    public boolean isFull();
+
+    /**
+     * Dequeues the oldest enqueued element if available, otherwise null.
+     * <p>
+     * The returned ring buffer slot will be set to <code>null</code> to release the reference
+     * and move ownership to the caller.
+     * </p>
+     * <p>
+     * Method is non blocking and returns immediately;.
+     * </p>
+     * @return the oldest put element if available, otherwise null.  
+     */
+    public T get();
+
+    /**
+     * Dequeues the oldest enqueued element.
+     * <p>
+     * The returned ring buffer slot will be set to <code>null</code> to release the reference
+     * and move ownership to the caller.
+     * </p>
+     * <p>
+     * Methods blocks until an element becomes available via put.
+     * </p>
+     * @return the oldest put element  
+     * @throws InterruptedException 
+     */
+    public T getBlocking() throws InterruptedException;
+
+    /** 
+     * Peeks the next element at the read position w/o modifying pointer, nor blocking.
+     * @return <code>null</code> if empty, otherwise the element which would be read next.
+     */
+    public T peek();
+
+    /** 
+     * Peeks the next element at the read position w/o modifying pointer, but w/ blocking.
+     * @return <code>null</code> if empty, otherwise the element which would be read next.
+     */
+    public T peekBlocking() throws InterruptedException;
+
+    /** 
+     * Enqueues the given element.
+     * <p>
+     * Returns true if successful, otherwise false in case buffer is full.
+     * </p>
+     * <p>
+     * Method is non blocking and returns immediately;.
+     * </p>
+     */
+    public boolean put(T e);
+
+    /** 
+     * Enqueues the given element.
+     * <p>
+     * Method blocks until a free slot becomes available via get.
+     * </p>
+     * @throws InterruptedException 
+     */
+    public void putBlocking(T e) throws InterruptedException;
+
+    /** 
+     * Enqueues the same element at it's write position, if not full.
+     * <p>
+     * Returns true if successful, otherwise false in case buffer is full.
+     * </p>
+     * <p>
+     * If <code>blocking</code> is true, method blocks until a free slot becomes available via get.
+     * </p>
+     * @param blocking if true, wait until a free slot becomes available via get.
+     * @throws InterruptedException 
+     */
+    public boolean putSame(boolean blocking) throws InterruptedException;
+
+    /**
+     * Blocks until at least <code>count</code> free slots become available.
+     * @throws InterruptedException
+     */
+    public void waitForFreeSlots(int count) throws InterruptedException;
+
+    /**
+     * Grows a full or empty ring buffer, increasing it's capacity about the amount.
+     * <p>
+     * Growing an empty ring buffer increases it's size about the amount, i.e. renders it not empty.
+     * The new elements are inserted at the read position, able to be read out via {@link #get()} etc.
+     * </p>
+     * <p>
+     * Growing a full ring buffer leaves the size intact, i.e. renders it not full.
+     * The new elements are inserted at the write position, able to be written to via {@link #put(Object)} etc.
+     * </p>
+     * 
+     * @param newElements array of new empty elements the buffer shall grow about, maybe <code>null</code>.
+     *        If not <code>null</code>, array size must be <= <code>amount</code>
+     * @param amount the amount of elements the buffer shall grow about
+     * @param allocEmptyArray implementation hook to allocate a new empty array of generic type T
+     * @throws IllegalStateException if buffer is neither full nor empty
+     * @throws IllegalArgumentException if newElements is given but is > amount
+     */
+    public void growBuffer(T[] newElements, int amount,
+            AllocEmptyArray<T> allocEmptyArray) throws IllegalStateException,
+            IllegalArgumentException;
+
+}
\ No newline at end of file
diff --git a/src/java/com/jogamp/common/util/SyncedRingbuffer.java b/src/java/com/jogamp/common/util/SyncedRingbuffer.java
new file mode 100644
index 0000000..b8ddbd6
--- /dev/null
+++ b/src/java/com/jogamp/common/util/SyncedRingbuffer.java
@@ -0,0 +1,381 @@
+/**
+ * Copyright 2013 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ * 
+ *    1. Redistributions of source code must retain the above copyright notice, this list of
+ *       conditions and the following disclaimer.
+ * 
+ *    2. Redistributions in binary form must reproduce the above copyright notice, this list
+ *       of conditions and the following disclaimer in the documentation and/or other materials
+ *       provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ */
+
+package com.jogamp.common.util;
+
+import java.io.PrintStream;
+
+/** 
+ * Simple synchronized implementation of {@link Ringbuffer}.
+ * <p>
+ * All methods utilize global synchronization.
+ * </p>
+ * <p>
+ * Characteristics:
+ * <ul>
+ *   <li>Read position points to the next read element.</li>
+ *   <li>Write position points to the next write element.</li>
+ * </ul>
+ * <table border="1">
+ *   <tr><td>Empty</td><td>writePos == readPos</td><td>size == 0</td></tr>
+ *   <tr><td>Full</td><td>writePos == readPos</td><td>size == capacity</td></tr>
+ * </table>
+ * </p>
+ */
+public class SyncedRingbuffer<T> implements Ringbuffer<T> {
+
+    private final Object syncGlobal = new Object();
+    private /* final */ T[] array;     // not final due to grow
+    private /* final */ int capacity;  // not final due to grow
+    private int readPos;
+    private int writePos;
+    private int size;
+    
+    @Override
+    public final String toString() {
+        return "SyncedRingbuffer<?>[filled "+size+" / "+capacity+", writePos "+writePos+", readPos "+readPos+"]";
+    }
+    
+    @Override
+    public final void dump(PrintStream stream, String prefix) {
+        stream.println(prefix+" "+toString()+" {");
+        for(int i=0; i<capacity; i++) {
+            stream.println("\t["+i+"]: "+array[i]);
+        }
+        stream.println("}");
+    }
+    
+    /** 
+     * Create a full ring buffer instance w/ the given array's net capacity and content.
+     * <p> 
+     * Example for a 10 element Integer array:
+     * <pre>
+     *  Integer[] source = new Integer[10];
+     *  // fill source with content ..
+     *  Ringbuffer<Integer> rb = new SyncedRingbuffer<Integer>(source, new Ringbuffer.AllocEmptyArray<Integer>() {
+     *      public Integer[] newArray(int size) {
+     *          return new Integer[size];
+     *      } } );
+     * </pre>
+     * </p>
+     * <p>
+     * {@link #isFull()} returns true on the newly created full ring buffer.
+     * </p>
+     * <p>
+     * Implementation will allocate an internal array with size of array <code>copyFrom</code>
+     * and copy all elements from array <code>copyFrom</code> into the internal array.
+     * </p>
+     * @param copyFrom mandatory source array determining ring buffer's net {@link #capacity()} and initial content.
+     * @param allocEmptyArray implementation hook to allocate a new empty array of generic type T
+     * @throws IllegalArgumentException if <code>copyFrom</code> is <code>null</code>   
+     */
+    public SyncedRingbuffer(T[] copyFrom, AllocEmptyArray<T> allocEmptyArray) throws IllegalArgumentException {
+        capacity = copyFrom.length;
+        array = allocEmptyArray.newArray(capacity);
+        resetImpl(true, copyFrom);
+    }
+    
+    /** 
+     * Create an empty ring buffer instance w/ the given net <code>capacity</code>.
+     * <p> 
+     * Example for a 10 element Integer array:
+     * <pre>
+     *  Ringbuffer<Integer> rb = new SyncedRingbuffer<Integer>(10, new Ringbuffer.AllocEmptyArray<Integer>() {
+     *      public Integer[] newArray(int size) {
+     *          return new Integer[size];
+     *      } } );
+     * </pre>
+     * </p>
+     * <p>
+     * {@link #isEmpty()} returns true on the newly created empty ring buffer.
+     * </p>
+     * <p>
+     * Implementation will allocate an internal array of size <code>capacity</code>.
+     * </p>
+     * @param capacity the initial net capacity of the ring buffer
+     * @param allocEmptyArray implementation hook to allocate a new empty array of generic type T
+     */
+    public SyncedRingbuffer(int capacity, AllocEmptyArray<T> allocEmptyArray) {
+        this.capacity = capacity;
+        this.array = allocEmptyArray.newArray(capacity);
+        resetImpl(false, null);
+    }
+    
+    @Override
+    public final T[] getInternalArray() { return array; }
+    
+    @Override
+    public final int capacity() { return capacity; }
+    
+    /**
+     * {@inheritDoc}
+     * <p>
+     * Implementation sets read and write position to zero.
+     * </p>
+     */
+    @Override
+    public final void clear() {
+        synchronized ( syncGlobal ) {
+            resetImpl(false, null);
+            for(int i=0; i<capacity; i++) {
+                this.array[i] = null;
+            }
+        }
+    }
+    
+    @Override
+    public final void resetFull(T[] copyFrom) throws IllegalArgumentException {
+        resetImpl(true, copyFrom);
+    }
+    
+    private final void resetImpl(boolean full, T[] copyFrom) throws IllegalArgumentException {
+        synchronized ( syncGlobal ) {
+            if( null != copyFrom ) {
+                if( copyFrom.length != capacity() ) {
+                    throw new IllegalArgumentException("copyFrom array length "+copyFrom.length+" != capacity "+this);
+                }
+                System.arraycopy(copyFrom, 0, array, 0, copyFrom.length);
+            } else if( full ) {
+                throw new IllegalArgumentException("copyFrom array is null");
+            }
+            readPos = 0;
+            writePos = 0;
+            size = full ? capacity : 0;
+        }
+    }
+    
+    @Override
+    public final int size() {
+        synchronized ( syncGlobal ) {
+            return size;
+        }
+    }
+    
+    @Override
+    public final int getFreeSlots() {
+        synchronized ( syncGlobal ) {
+            return capacity - size;
+        }
+    }
+
+    @Override
+    public final boolean isEmpty() {
+        synchronized ( syncGlobal ) {
+            return 0 == size;
+        }
+    }
+    
+    @Override
+    public final boolean isFull() {
+        synchronized ( syncGlobal ) {
+            return capacity == size;
+        }
+    }
+    
+    /**
+     * {@inheritDoc}
+     * <p>
+     * Implementation returns the element at the current read position and advances it, if not empty.
+     * </p>
+     */
+    @Override
+    public final T get() {
+        try {
+            return getImpl(false, false);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+
+    /**
+     * {@inheritDoc}
+     * <p>
+     * Implementation returns the element at the current read position and advances it, if not empty.
+     * </p>
+     */
+    @Override
+    public final T getBlocking() throws InterruptedException {
+        return getImpl(true, false);
+    }
+    
+    @Override
+    public final T peek() {
+        try {
+            return getImpl(false, true);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+    @Override
+    public final T peekBlocking() throws InterruptedException {
+        return getImpl(true, true);
+    }
+    
+    private final T getImpl(boolean blocking, boolean peek) throws InterruptedException {
+        synchronized( syncGlobal ) {        
+            if( 0 == size ) {
+                if( blocking ) {
+                    while( 0 == size ) {
+                        syncGlobal.wait();
+                    }
+                } else {
+                    return null;
+                }
+            }
+            final int localReadPos = readPos;
+            final T r = array[localReadPos];
+            if( !peek ) {
+                array[localReadPos] = null;
+                size--;
+                readPos = (localReadPos + 1) % capacity;
+                syncGlobal.notifyAll(); // notify waiting putter
+            }
+            return r;
+        }
+    }
+    
+    /** 
+     * {@inheritDoc}
+     * <p>
+     * Implementation stores the element at the current write position and advances it, if not full.
+     * </p>
+     */
+    @Override
+    public final boolean put(T e) {
+        try {
+            return putImpl(e, false, false);
+        } catch (InterruptedException ie) { throw new RuntimeException(ie); }
+    }
+    
+    /** 
+     * {@inheritDoc}
+     * <p>
+     * Implementation stores the element at the current write position and advances it, if not full.
+     * </p>
+     */
+    @Override
+    public final void putBlocking(T e) throws InterruptedException {
+        if( !putImpl(e, false, true) ) {
+            throw new InternalError("Blocking put failed: "+this);
+        }
+    }
+    
+    /** 
+     * {@inheritDoc}
+     * <p>
+     * Implementation keeps the element at the current write position and advances it, if not full.
+     * </p>
+     */
+    @Override
+    public final boolean putSame(boolean blocking) throws InterruptedException {
+        return putImpl(null, true, blocking);
+    }
+    
+    private final boolean putImpl(T e, boolean sameRef, boolean blocking) throws InterruptedException {
+        synchronized( syncGlobal ) {        
+            if( capacity == size ) {
+                if( blocking ) {
+                    while( capacity == size ) {
+                        syncGlobal.wait();
+                    }
+                } else {
+                    return false;
+                }
+            }
+            final int localWritePos = writePos;
+            if( !sameRef ) {
+                array[localWritePos] = e;
+            }
+            size++;
+            writePos = (localWritePos + 1) % capacity;
+            syncGlobal.notifyAll(); // notify waiting getter
+            return true;
+        }
+    }
+    
+    @Override
+    public final void waitForFreeSlots(int count) throws InterruptedException {
+        synchronized ( syncGlobal ) {
+            if( capacity - size < count ) {
+                while( capacity - size < count ) {
+                    syncGlobal.wait();
+                }
+            }
+        }
+    }
+    
+    @Override
+    public void growBuffer(T[] newElements, int amount, AllocEmptyArray<T> allocEmptyArray) throws IllegalStateException, IllegalArgumentException {
+        synchronized ( syncGlobal ) {
+            final boolean isFull = capacity == size;
+            final boolean isEmpty = 0 == size;
+            if( !isFull && !isEmpty ) {
+                throw new IllegalStateException("Buffer neither full nor empty: "+this);
+            }
+            if( readPos != writePos ) {
+                throw new InternalError("R/W pos not equal: "+this);
+            }
+            if( null != newElements && amount < newElements.length ) {
+                throw new IllegalArgumentException("amount "+amount+" < newElements "+newElements.length);
+            }
+            final int newCapacity = capacity + amount;
+            final T[] oldArray = array;
+            final T[] newArray = allocEmptyArray.newArray(newCapacity);
+            
+            if( isFull ) {
+                // writePos == readPos
+                readPos += amount; // warp readPos to the end of the new data location
+                
+                if(writePos > 0) {
+                    System.arraycopy(oldArray,        0, newArray,        0, writePos);
+                }
+                if( null != newElements && newElements.length > 0 ) {
+                    System.arraycopy(newElements,     0, newArray, writePos, newElements.length);
+                }
+                final int tail = capacity-writePos;
+                if( tail > 0 ) {
+                    System.arraycopy(oldArray, writePos, newArray,  readPos, tail);
+                }
+            } else /* if ( isEmpty ) */ {
+                // writePos == readPos
+                writePos += amount; // warp writePos to the end of the new data location
+                
+                if( readPos > 0 ) {
+                    System.arraycopy(oldArray,        0, newArray,        0, readPos);
+                }
+                if( null != newElements && newElements.length > 0 ) {
+                    System.arraycopy(newElements,     0, newArray,  readPos, newElements.length);
+                }
+                final int tail = capacity-readPos;
+                if( tail > 0 ) {
+                    System.arraycopy(oldArray,  readPos, newArray, writePos, tail);
+                }
+                size = amount;
+            }
+            
+            capacity = newCapacity;
+            array = newArray;
+        }
+    }
+}