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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 __ZTMONITOREDQUEUE_H__
+#define __ZTMONITOREDQUEUE_H__
+
+#include "zthread/Condition.h"
+#include "zthread/Guard.h"
+#include "zthread/Queue.h"
+
+#include <deque>
+
+namespace ZThread {
+
+ /**
+ * @class MonitoredQueue
+ * @author Eric Crahen <http://www.code-foo.com>
+ * @date <2003-07-16T20:23:28-0400>
+ * @version 2.3.0
+ *
+ * A MonitoredQueue is a Queue implementation that provides serialized access to the
+ * items added to it.
+ *
+ * - Threads calling the empty() methods will be blocked until the BoundedQueue becomes empty.
+ * - Threads calling the next() methods will be blocked until the BoundedQueue has a value to
+ * return.
+ *
+ * @see Queue
+ */
+ template <class T, class LockType, typename StorageType=std::deque<T> >
+ class MonitoredQueue : public Queue<T>, public Lockable {
+
+ //! Serialize access
+ LockType _lock;
+
+ //! Signaled on not empty
+ Condition _notEmpty;
+
+ //! Signaled on empty
+ Condition _isEmpty;
+
+ //! Storage backing the queue
+ StorageType _queue;
+
+ //! Cancellation flag
+ volatile bool _canceled;
+
+ public:
+
+ //! Create a new MonitoredQueue
+ MonitoredQueue()
+ : _notEmpty(_lock), _isEmpty(_lock), _canceled(false) {}
+
+ //! Destroy a MonitoredQueue, delete remaining items
+ virtual ~MonitoredQueue() { }
+
+ /**
+ * Add a value to this Queue.
+ *
+ * @param item value to be added to the Queue
+ *
+ * @exception Cancellation_Exception thrown if this Queue has been canceled.
+ * @exception Interrupted_Exception thrown if the thread was interrupted while waiting
+ * to add a value
+ *
+ * @pre The Queue should not have been canceled prior to the invocation of this function.
+ * @post If no exception is thrown, a copy of <i>item</i> will have been added to the Queue.
+ *
+ * @see Queue::add(const T& item)
+ */
+ virtual void add(const T& item) {
+
+ Guard<LockType> g(_lock);
+
+ // Allow no further additions in the canceled state
+ if(_canceled)
+ throw Cancellation_Exception();
+
+ _queue.push_back( item );
+
+ _notEmpty.signal(); // Wake one waiter
+
+ }
+
+ /**
+ * Add a value to this Queue.
+ *
+ * @param item value to be added to the Queue
+ * @param timeout maximum amount of time (milliseconds) this method may block
+ * the calling thread.
+ *
+ * @return
+ * - <em>true</em> if a copy of <i>item</i> can be added before <i>timeout</i>
+ * milliseconds elapse.
+ * - <em>false</em> otherwise.
+ *
+ * @exception Cancellation_Exception thrown if this Queue has been canceled.
+ * @exception Interrupted_Exception thrown if the thread was interrupted while waiting
+ * to add a value
+ *
+ * @pre The Queue should not have been canceled prior to the invocation of this function.
+ * @post If no exception is thrown, a copy of <i>item</i> will have been added to the Queue.
+ *
+ * @see Queue::add(const T& item, unsigned long timeout)
+ */
+ virtual bool add(const 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;
+
+ }
+
+ /**
+ * Retrieve and remove a value from this Queue.
+ *
+ * If invoked when there are no values present to return then the calling thread
+ * will be blocked until a value arrives in the Queue.
+ *
+ * @return <em>T</em> next available value
+ *
+ * @exception Cancellation_Exception thrown if this Queue has been canceled.
+ * @exception Interrupted_Exception thrown if the thread was interrupted while waiting
+ * to retrieve a value
+ *
+ * @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.
+ */
+ virtual T next() {
+
+ Guard<LockType> g(_lock);
+
+ while (_queue.empty() && !_canceled)
+ _notEmpty.wait();
+
+ if(_queue.empty()) // Queue canceled
+ throw Cancellation_Exception();
+
+ T item = _queue.front();
+ _queue.pop_front();
+
+ if(_queue.empty()) // Wake empty waiters
+ _isEmpty.broadcast();
+
+ return item;
+
+ }
+
+ /**
+ * Retrieve and remove a value from this Queue.
+ *
+ * If invoked when there are no values present to return then the calling thread
+ * will be blocked until a value arrives in the Queue.
+ *
+ * @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.
+ *
+ * @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.
+ */
+ 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()) // Queue canceled
+ throw Cancellation_Exception();
+
+ T item = _queue.front();
+ _queue.pop_front();
+
+ if(_queue.empty()) // Wake empty waiters
+ _isEmpty.broadcast();
+
+ return item;
+
+ }
+
+
+ /**
+ * Cancel this queue.
+ *
+ * @post Any threads blocked by a next() function will throw a Cancellation_Exception.
+ *
+ * @see Queue::cancel()
+ */
+ virtual void cancel() {
+
+ Guard<LockType> g(_lock);
+
+ _canceled = true;
+ _notEmpty.broadcast(); // Wake next() waiters
+
+ }
+
+ /**
+ * @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();
+
+ }
+
+ /**
+ * Test whether any values are available in this Queue.
+ *
+ * The calling thread is blocked until there are no values present
+ * in the Queue.
+ *
+ * @return
+ * - <em>true</em> if there are no values available.
+ * - <em>false</em> if there <i>are</i> values available.
+ *
+ * @see Queue::empty()
+ */
+ virtual bool empty() {
+
+ Guard<LockType> g(_lock);
+
+ while(!_queue.empty()) // Wait for an empty signal
+ _isEmpty.wait();
+
+ return true;
+
+ }
+
+ /**
+ * Test whether any values are available in this Queue.
+ *
+ * The calling thread is blocked until there are no values present
+ * in the Queue.
+ *
+ * @param timeout maximum amount of time (milliseconds) this method may block
+ * the calling thread.
+ *
+ * @return
+ * - <em>true</em> if there are no values available.
+ * - <em>false</em> if there <i>are</i> values available.
+ *
+ * @exception Timeout_Exception thrown if <i>timeout</i> milliseconds
+ * expire before a value becomes available
+ *
+ * @see Queue::empty()
+ */
+ virtual bool empty(unsigned long timeout) {
+
+ Guard<LockType> g(_lock, timeout);
+
+ while(!_queue.empty()) // Wait for an empty signal
+ _isEmpty.wait(timeout);
+
+ return true;
+
+ }
+
+ public:
+
+ virtual void acquire() {
+ _lock.acquire();
+ }
+
+ virtual bool tryAcquire(unsigned long timeout) {
+ return _lock.tryAcquire(timeout);
+ }
+
+ virtual void release() {
+ _lock.release();
+ }
+
+
+ }; /* MonitoredQueue */
+
+
+} // namespace ZThread
+
+#endif // __ZTMONITOREDQUEUE_H__
+