--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/EDU/oswego/cs/dl/util/concurrent/misc/CVBuffer.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,123 @@
+
+package EDU.oswego.cs.dl.util.concurrent.misc;
+import  EDU.oswego.cs.dl.util.concurrent.*;
+
+
+public class CVBuffer implements BoundedChannel {
+  private final Mutex mutex;
+  private final CondVar notFull;
+  private final CondVar notEmpty;
+  private int count = 0;
+  private int takePtr = 0;     
+  private int putPtr = 0;
+  private final Object[] array;
+
+  public CVBuffer(int cap) { 
+    array = new Object[cap];
+    mutex = new Mutex();
+    notFull = new CondVar(mutex);
+    notEmpty = new CondVar(mutex);
+  }
+
+  public CVBuffer() { 
+    this(DefaultChannelCapacity.get()); 
+  }
+
+  public int capacity() { return array.length; }
+
+  public void put(Object x) throws InterruptedException {
+    mutex.acquire();
+    try {
+      while (count == array.length) {
+        notFull.await();
+      }
+      array[putPtr] = x;
+      putPtr = (putPtr + 1) % array.length;
+      ++count;
+      notEmpty.signal();
+    }
+    finally {
+      mutex.release();
+    }
+  }
+
+  public Object take() throws InterruptedException {
+    Object x = null;
+    mutex.acquire();
+    try {
+      while (count == 0) {
+        notEmpty.await();
+      }
+      x = array[takePtr];
+      array[takePtr] = null;
+      takePtr = (takePtr + 1) % array.length;
+      --count;
+      notFull.signal();
+    }
+    finally {
+      mutex.release();
+    }
+    return x;
+  }
+    
+  public boolean offer(Object x, long msecs) throws InterruptedException {
+    mutex.acquire();
+    try {
+      if (count == array.length) {
+        notFull.timedwait(msecs);
+        if (count == array.length)
+          return false;
+      }
+      array[putPtr] = x;
+      putPtr = (putPtr + 1) % array.length;
+      ++count;
+      notEmpty.signal();
+      return true;
+    }
+    finally {
+      mutex.release();
+    }
+  }
+  
+  public Object poll(long msecs) throws InterruptedException {
+    Object x = null;
+    mutex.acquire();
+    try {
+      if (count == 0) {
+        notEmpty.timedwait(msecs);
+        if (count == 0)
+          return null;
+      }
+      x = array[takePtr];
+      array[takePtr] = null;
+      takePtr = (takePtr + 1) % array.length;
+      --count;
+      notFull.signal();
+    }
+    finally {
+      mutex.release();
+    }
+    return x;
+  }
+
+  public Object peek() {
+    try {
+      mutex.acquire();
+      try {
+        if (count == 0) 
+          return null;
+        else
+          return array[takePtr];
+      }
+      finally {
+        mutex.release();
+      }
+    }
+    catch (InterruptedException ex) {
+      Thread.currentThread().interrupt();
+      return null;
+    }
+  }
+
+}
+