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authorNeo2003 <none@none>2008-10-02 16:23:55 -0500
committerNeo2003 <none@none>2008-10-02 16:23:55 -0500
commit9b1c0e006f20091f28f3f468cfcab1feb51286bd (patch)
treeb5d1ba94a656e6679f8737f9ea6bed1239b73b14 /dep/include/zthread/BlockingQueue.h
[svn] * Proper SVN structureinit
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+/*
+ * Copyright (c) 2005, Eric Crahen
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is furnished
+ * to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+
+#ifndef __ZTBLOCKINGQUEUE_H__
+#define __ZTBLOCKINGQUEUE_H__
+
+#include "zthread/Guard.h"
+#include "zthread/Condition.h"
+#include "zthread/Queue.h"
+
+#include <deque>
+
+namespace ZThread {
+
+ /**
+ * @class BlockingQueue
+ * @author Eric Crahen <http://www.code-foo.com>
+ * @date <2003-07-16T12:01:43-0400>
+ * @version 2.3.0
+ *
+ * Like a LockedQueue, a BlockingQueue is a Queue implementation that provides
+ * serialized access to the items added to it. It differs by causing threads
+ * accessing the next() methods to block until a value becomes available.
+ */
+ template <class T, class LockType, typename StorageType = std::deque<T> >
+ class BlockingQueue : public Queue<T>, public Lockable {
+
+ //! Serialize access
+ LockType _lock;
+
+ //! Signaled when empty
+ Condition _notEmpty;
+
+ //! Storage backing the queue
+ StorageType _queue;
+
+ //! Cancellation flag
+ volatile bool _canceled;
+
+ public:
+
+ //! Create a new BlockingQueue
+ BlockingQueue() : _notEmpty(_lock), _canceled(false) {}
+
+ //! Destroy this BlockingQueue
+ virtual ~BlockingQueue() { }
+
+ /**
+ * @see Queue::add(const T& item)
+ */
+ virtual void add(const T& item) {
+
+ Guard<LockType> g(_lock);
+
+ if(_canceled)
+ throw Cancellation_Exception();
+
+ _queue.push_back(item);
+
+ _notEmpty.signal();
+
+ }
+
+ /**
+ * @see Queue::add(const T& item, unsigned long timeout)
+ */
+ virtual bool add(T item, unsigned long timeout) {
+
+ try {
+
+ Guard<LockType> g(_lock, timeout);
+
+ if(_canceled)
+ throw Cancellation_Exception();
+
+ _queue.push_back(item);
+
+ _notEmpty.signal();
+
+ } catch(Timeout_Exception&) { return false; }
+
+ return true;
+
+ }
+
+ /**
+ * Get a value from this Queue. The calling thread may block indefinitely.
+ *
+ * @return <em>T</em> next available value
+ *
+ * @exception Cancellation_Exception thrown if this Queue has been canceled.
+ *
+ * @exception Interrupted_Exception thrown if the calling thread is interrupted
+ * before a value becomes available.
+ *
+ * @pre The Queue should not have been canceled prior to the invocation of this function.
+ * @post The value returned will have been removed from the Queue.
+ *
+ * @see Queue::next()
+ */
+ virtual T next() {
+
+ Guard<LockType> g(_lock);
+
+ while(_queue.empty() && !_canceled)
+ _notEmpty.wait();
+
+ if( _queue.empty() )
+ throw Cancellation_Exception();
+
+ T item = _queue.front();
+ _queue.pop_front();
+
+ return item;
+
+ }
+
+
+ /**
+ * Get a value from this Queue. The calling thread may block indefinitely.
+ *
+ * @param timeout maximum amount of time (milliseconds) this method may block
+ * the calling thread.
+ *
+ * @return <em>T</em> next available value
+ *
+ * @exception Cancellation_Exception thrown if this Queue has been canceled.
+ * @exception Timeout_Exception thrown if the timeout expires before a value
+ * can be retrieved.
+ * @exception Interrupted_Exception thrown if the calling thread is interrupted
+ * before a value becomes available.
+ *
+ * @pre The Queue should not have been canceled prior to the invocation of this function.
+ * @post The value returned will have been removed from the Queue.
+ *
+ * @see Queue::next(unsigned long timeout)
+ */
+ virtual T next(unsigned long timeout) {
+
+ Guard<LockType> g(_lock, timeout);
+
+ while(_queue.empty() && !_canceled) {
+ if(!_notEmpty.wait(timeout))
+ throw Timeout_Exception();
+ }
+
+ if(_queue.empty() )
+ throw Cancellation_Exception();
+
+ T item = _queue.front();
+ _queue.pop_front();
+
+ return item;
+
+ }
+
+
+ /**
+ * @see Queue::cancel()
+ *
+ * @post If threads are blocked on one of the next() functions then
+ * they will be awakened with a Cancellation_Exception.
+ */
+ virtual void cancel() {
+
+ Guard<LockType> g(_lock);
+
+ _notEmpty.broadcast();
+ _canceled = true;
+
+ }
+
+ /**
+ * @see Queue::isCanceled()
+ */
+ virtual bool isCanceled() {
+
+ // Faster check since the queue will not become un-canceled
+ if(_canceled)
+ return true;
+
+ Guard<LockType> g(_lock);
+
+ return _canceled;
+
+ }
+
+ /**
+ * @see Queue::size()
+ */
+ virtual size_t size() {
+
+ Guard<LockType> g(_lock);
+ return _queue.size();
+
+ }
+
+ /**
+ * @see Queue::size(unsigned long timeout)
+ */
+ virtual size_t size(unsigned long timeout) {
+
+ Guard<LockType> g(_lock, timeout);
+ return _queue.size();
+
+ }
+
+ public:
+
+ virtual void acquire() {
+ _lock.acquire();
+ }
+
+ virtual bool tryAcquire(unsigned long timeout) {
+ return _lock.tryAcquire(timeout);
+ }
+
+ virtual void release() {
+ _lock.release();
+ }
+
+ }; /* BlockingQueue */
+
+} // namespace ZThread
+
+#endif // __ZTBLOCKINGQUEUE_H__