Mercurial > hg > blitz_condensed
diff src/EDU/oswego/cs/dl/util/concurrent/misc/CVBuffer.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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--- /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; + } + } + +} +