1 files changed, 432 insertions, 0 deletions
diff --git a/trunk/qpid/java/common/src/main/java/org/apache/qpid/pool/ReadWriteJobQueue.java b/trunk/qpid/java/common/src/main/java/org/apache/qpid/pool/ReadWriteJobQueue.java
new file mode 100644
index 0000000000..8de0f93ce9
--- /dev/null
+++ b/trunk/qpid/java/common/src/main/java/org/apache/qpid/pool/ReadWriteJobQueue.java
@@ -0,0 +1,432 @@
+package org.apache.qpid.pool;
+
+import java.util.AbstractQueue;
+import java.util.Iterator;
+import java.util.Collection;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/*
+*
+* Licensed to the Apache Software Foundation (ASF) under one
+* or more contributor license agreements.  See the NOTICE file
+* distributed with this work for additional information
+* regarding copyright ownership.  The ASF licenses this file
+* to you 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.
+*
+*/
+public class ReadWriteJobQueue extends AbstractQueue<Runnable> implements BlockingQueue<Runnable>
+{
+
+    private final AtomicInteger _count = new AtomicInteger(0);
+
+    private final ReentrantLock _takeLock = new ReentrantLock();
+
+    private final Condition _notEmpty = _takeLock.newCondition();
+
+    private final ReentrantLock _putLock = new ReentrantLock();
+
+    private final ConcurrentLinkedQueue<ReadWriteRunnable> _readJobQueue = new ConcurrentLinkedQueue<ReadWriteRunnable>();
+
+    private final ConcurrentLinkedQueue<ReadWriteRunnable> _writeJobQueue = new ConcurrentLinkedQueue<ReadWriteRunnable>();
+
+
+    private class ReadWriteJobIterator implements Iterator<Runnable>
+    {
+
+        private boolean _onReads;
+        private Iterator<ReadWriteRunnable> _iter = _writeJobQueue.iterator();
+
+        public boolean hasNext()
+        {
+            if(!_iter.hasNext())
+            {
+                if(_onReads)
+                {
+                    _iter = _readJobQueue.iterator();
+                    _onReads = true;
+                    return _iter.hasNext();
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            else
+            {
+                return true;
+            }
+        }
+
+        public Runnable next()
+        {
+            if(_iter.hasNext())
+            {
+                return _iter.next();
+            }
+            else
+            {
+                return null;
+            }
+        }
+
+        public void remove()
+        {
+            _takeLock.lock();
+            try
+            {
+                _iter.remove();
+                _count.decrementAndGet();
+            }
+            finally
+            {
+                _takeLock.unlock();
+            }
+        }
+    }
+
+    public Iterator<Runnable> iterator()
+    {
+        return new ReadWriteJobIterator();
+    }
+
+    public int size()
+    {
+        return _count.get();
+    }
+
+    public boolean offer(final Runnable runnable)
+    {
+        final ReadWriteRunnable job = (ReadWriteRunnable) runnable;
+        final ReentrantLock putLock = _putLock;
+        putLock.lock();
+        try
+        {
+            if(job.isRead())
+            {
+                _readJobQueue.offer(job);
+            }
+            else
+            {
+                _writeJobQueue.offer(job);
+            }
+            if(_count.getAndIncrement() == 0)
+            {
+                _takeLock.lock();
+                try
+                {
+                    _notEmpty.signal();
+                }
+                finally
+                {
+                    _takeLock.unlock();
+                }
+            }
+            return true;
+        }
+        finally
+        {
+            putLock.unlock();
+        }
+    }
+
+    public void put(final Runnable runnable) throws InterruptedException
+    {
+        final ReadWriteRunnable job = (ReadWriteRunnable) runnable;
+        final ReentrantLock putLock = _putLock;
+        putLock.lock();
+
+        try
+        {
+            if(job.isRead())
+            {
+                _readJobQueue.offer(job);
+            }
+            else
+            {
+                _writeJobQueue.offer(job);
+            }
+            if(_count.getAndIncrement() == 0)
+            {
+                                _takeLock.lock();
+                try
+                {
+                    _notEmpty.signal();
+                }
+                finally
+                {
+                    _takeLock.unlock();
+                }
+            }
+
+        }
+        finally
+        {
+            putLock.unlock();
+        }
+    }
+
+
+
+    public boolean offer(final Runnable runnable, final long timeout, final TimeUnit unit) throws InterruptedException
+    {
+        final ReadWriteRunnable job = (ReadWriteRunnable) runnable;
+        final ReentrantLock putLock = _putLock;
+        putLock.lock();
+
+        try
+        {
+            if(job.isRead())
+            {
+                _readJobQueue.offer(job);
+            }
+            else
+            {
+                _writeJobQueue.offer(job);
+            }
+            if(_count.getAndIncrement() == 0)
+            {
+                _takeLock.lock();
+                try
+                {
+                    _notEmpty.signal();
+                }
+                finally
+                {
+                    _takeLock.unlock();
+                }
+            }
+
+            return true;
+        }
+        finally
+        {
+            putLock.unlock();
+        }
+
+    }
+
+    public Runnable take() throws InterruptedException
+    {
+        final ReentrantLock takeLock = _takeLock;
+        takeLock.lockInterruptibly();
+        try
+        {
+            try
+            {
+                while (_count.get() == 0)
+                {
+                    _notEmpty.await();
+                }
+            }
+            catch (InterruptedException ie)
+            {
+                _notEmpty.signal();
+                throw ie;
+            }
+
+            ReadWriteRunnable job = _writeJobQueue.poll();
+            if(job == null)
+            {
+                job = _readJobQueue.poll();
+            }
+            int c = _count.getAndDecrement();
+            if (c > 1)
+            {
+                _notEmpty.signal();
+            }
+            return job;
+        }
+        finally
+        {
+            takeLock.unlock();
+        }
+
+
+    }
+
+    public Runnable poll(final long timeout, final TimeUnit unit) throws InterruptedException
+    {
+        final ReentrantLock takeLock = _takeLock;
+        final AtomicInteger count = _count;
+        long nanos = unit.toNanos(timeout);
+        takeLock.lockInterruptibly();
+        ReadWriteRunnable job = null;
+        try
+        {
+
+            for (;;)
+            {
+                if (count.get() > 0)
+                {
+                    job = _writeJobQueue.poll();
+                    if(job == null)
+                    {
+                        job = _readJobQueue.poll();
+                    }
+                    int c = count.getAndDecrement();
+                    if (c > 1)
+                    {
+                        _notEmpty.signal();
+                    }
+                    break;
+                }
+                if (nanos <= 0)
+                {
+                    return null;
+                }
+                try
+                {
+                    nanos = _notEmpty.awaitNanos(nanos);
+                }
+                catch (InterruptedException ie)
+                {
+                    _notEmpty.signal();
+                    throw ie;
+                }
+            }
+        }
+        finally
+        {
+            takeLock.unlock();
+        }
+
+        return job;
+    }
+
+    public int remainingCapacity()
+    {
+        return Integer.MAX_VALUE;
+    }
+
+    public int drainTo(final Collection<? super Runnable> c)
+    {
+        int total = 0;
+
+        _putLock.lock();
+        _takeLock.lock();
+        try
+        {
+            ReadWriteRunnable job;
+            while((job = _writeJobQueue.peek())!= null)
+            {
+                c.add(job);
+                _writeJobQueue.poll();
+                _count.decrementAndGet();
+                total++;
+            }
+
+            while((job = _readJobQueue.peek())!= null)
+            {
+                c.add(job);
+                _readJobQueue.poll();
+                _count.decrementAndGet();
+                total++;
+            }
+
+        }
+        finally
+        {
+            _takeLock.unlock();
+            _putLock.unlock();
+        }
+        return total;
+    }
+
+    public int drainTo(final Collection<? super Runnable> c, final int maxElements)
+    {
+        int total = 0;
+
+        _putLock.lock();
+        _takeLock.lock();
+        try
+        {
+            ReadWriteRunnable job;
+            while(total<=maxElements && (job = _writeJobQueue.peek())!= null)
+            {
+                c.add(job);
+                _writeJobQueue.poll();
+                _count.decrementAndGet();
+                total++;
+            }
+
+            while(total<=maxElements && (job = _readJobQueue.peek())!= null)
+            {
+                c.add(job);
+                _readJobQueue.poll();
+                _count.decrementAndGet();
+                total++;
+            }
+
+        }
+        finally
+        {
+            _takeLock.unlock();
+            _putLock.unlock();
+        }
+        return total;
+
+    }
+
+    public Runnable poll()
+    {
+        final ReentrantLock takeLock = _takeLock;
+        takeLock.lock();
+        try
+        {
+            if(_count.get() > 0)
+            {
+                ReadWriteRunnable job = _writeJobQueue.poll();
+                if(job == null)
+                {
+                    job = _readJobQueue.poll();
+                }
+                _count.decrementAndGet();
+                return job;
+            }
+            else
+            {
+                return null;
+            }
+        }
+        finally
+        {
+            takeLock.unlock();
+        }
+
+    }
+
+    public Runnable peek()
+    {
+        final ReentrantLock takeLock = _takeLock;
+        takeLock.lock();
+        try
+        {
+            ReadWriteRunnable job = _writeJobQueue.peek();
+            if(job == null)
+            {
+                job = _readJobQueue.peek();
+            }
+            return job;
+        }
+        finally
+        {
+            takeLock.unlock();
+        }
+    }
+}