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387 lines
11 KiB
C++
387 lines
11 KiB
C++
/*
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* Copyright (c) 2005, Eric Crahen
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is furnished
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* to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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#ifndef __ZTBOUNDEDQUEUE_H__
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#define __ZTBOUNDEDQUEUE_H__
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#include "zthread/Condition.h"
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#include "zthread/Guard.h"
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#include "zthread/Queue.h"
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#include <deque>
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namespace ZThread {
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/**
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* @class BoundedQueue
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*
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* @author Eric Crahen <http://www.code-foo.com>
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* @date <2003-07-16T13:54:04-0400>
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* @version 2.3.0
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*
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* A BoundedQueue provides serialized access to a set of values. It differs from other
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* Queues by adding a maximum capacity, giving it the following properties:
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*
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* - Threads calling the empty() methods will be blocked until the BoundedQueue becomes empty.
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* - Threads calling the next() methods will be blocked until the BoundedQueue has a value to
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* return.
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* - Threads calling the add() methods will be blocked until the number of values in the
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* Queue drops below the maximum capacity.
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*
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* @see Queue
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*/
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template <class T, class LockType, typename StorageType=std::deque<T> >
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class BoundedQueue : public Queue<T>, public Lockable {
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//! Maximum capacity for the Queue
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size_t _capacity;
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//! Serialize access
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LockType _lock;
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//! Signaled if not full
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Condition _notFull;
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//! Signaled if not empty
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Condition _notEmpty;
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//! Signaled if empty
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Condition _isEmpty;
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//! Storage backing the queue
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StorageType _queue;
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//! Cancellation flag
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volatile bool _canceled;
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public:
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/**
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* Create a BoundedQueue with the given capacity.
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*
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* @param capacity maximum number of values to allow in the Queue at
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* at any time
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*/
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BoundedQueue(size_t capacity)
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: _notFull(_lock), _notEmpty(_lock), _isEmpty(_lock),
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_capacity(capacity), _canceled(false) {}
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//! Destroy this Queue
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virtual ~BoundedQueue() { }
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/**
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* Get the maximum capacity of this Queue.
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*
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* @return <i>size_t</i> maximum capacity
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*/
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size_t capacity() {
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return _capacity;
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}
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/**
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* Add a value to this Queue.
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*
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* If the number of values in the queue matches the value returned by <i>capacity</i>()
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* then the calling thread will be blocked until at least one value is removed from
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* the Queue.
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*
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* @param item value to be added to the Queue
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*
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* @exception Cancellation_Exception thrown if this Queue has been canceled.
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* @exception Interrupted_Exception thrown if the thread was interrupted while waiting
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* to add a value
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*
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* @pre The Queue should not have been canceled prior to the invocation of this function.
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* @post If no exception is thrown, a copy of <i>item</i> will have been added to the Queue.
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*
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* @see Queue::add(const T& item)
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*/
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virtual void add(const T& item) {
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Guard<LockType> g(_lock);
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// Wait for the capacity of the Queue to drop
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while ((_queue.size() == _capacity) && !_canceled)
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_notFull.wait();
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if(_canceled)
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throw Cancellation_Exception();
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_queue.push_back(item);
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_notEmpty.signal(); // Wake any waiters
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}
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/**
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* Add a value to this Queue.
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*
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* If the number of values in the queue matches the value returned by <i>capacity</i>()
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* then the calling thread will be blocked until at least one value is removed from
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* the Queue.
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*
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* @param item value to be added to the Queue
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* @param timeout maximum amount of time (milliseconds) this method may block
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* the calling thread.
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*
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* @return
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* - <em>true</em> if a copy of <i>item</i> can be added before <i>timeout</i>
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* milliseconds elapse.
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* - <em>false</em> otherwise.
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*
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* @exception Cancellation_Exception thrown if this Queue has been canceled.
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* @exception Interrupted_Exception thrown if the thread was interrupted while waiting
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* to add a value
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*
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* @pre The Queue should not have been canceled prior to the invocation of this function.
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* @post If no exception is thrown, a copy of <i>item</i> will have been added to the Queue.
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*
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* @see Queue::add(const T& item, unsigned long timeout)
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*/
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virtual bool add(const T& item, unsigned long timeout) {
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try {
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Guard<LockType> g(_lock, timeout);
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// Wait for the capacity of the Queue to drop
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while ((_queue.size() == _capacity) && !_canceled)
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if(!_notFull.wait(timeout))
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return false;
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if(_canceled)
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throw Cancellation_Exception();
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_queue.push_back(item);
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_notEmpty.signal(); // Wake any waiters
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} catch(Timeout_Exception&) { return false; }
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return true;
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}
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/**
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* Retrieve and remove a value from this Queue.
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*
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* If invoked when there are no values present to return then the calling thread
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* will be blocked until a value arrives in the Queue.
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*
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* @return <em>T</em> next available value
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*
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* @exception Cancellation_Exception thrown if this Queue has been canceled.
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* @exception Interrupted_Exception thrown if the thread was interrupted while waiting
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* to retrieve a value
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*
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* @pre The Queue should not have been canceled prior to the invocation of this function.
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* @post The value returned will have been removed from the Queue.
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*/
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virtual T next() {
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Guard<LockType> g(_lock);
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while ( _queue.empty() && !_canceled)
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_notEmpty.wait();
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if( _queue.empty()) // Queue canceled
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throw Cancellation_Exception();
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T item = _queue.front();
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_queue.pop_front();
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_notFull.signal(); // Wake any thread trying to add
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if(_queue.empty()) // Wake empty waiters
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_isEmpty.broadcast();
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return item;
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}
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/**
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* Retrieve and remove a value from this Queue.
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*
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* If invoked when there are no values present to return then the calling thread
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* will be blocked until a value arrives in the Queue.
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*
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* @param timeout maximum amount of time (milliseconds) this method may block
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* the calling thread.
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*
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* @return <em>T</em> next available value
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*
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* @exception Cancellation_Exception thrown if this Queue has been canceled.
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* @exception Timeout_Exception thrown if the timeout expires before a value
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* can be retrieved.
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*
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* @pre The Queue should not have been canceled prior to the invocation of this function.
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* @post The value returned will have been removed from the Queue.
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*/
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virtual T next(unsigned long timeout) {
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Guard<LockType> g(_lock, timeout);
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// Wait for items to be added
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while (_queue.empty() && !_canceled) {
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if(!_notEmpty.wait(timeout))
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throw Timeout_Exception();
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}
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if(_queue.empty()) // Queue canceled
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throw Cancellation_Exception();
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T item = _queue.front();
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_queue.pop_front();
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_notFull.signal(); // Wake add() waiters
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if(_queue.empty()) // Wake empty() waiters
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_isEmpty.broadcast();
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return item;
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}
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/**
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* Cancel this queue.
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*
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* @post Any threads blocked by an add() function will throw a Cancellation_Exception.
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* @post Any threads blocked by a next() function will throw a Cancellation_Exception.
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*
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* @see Queue::cancel()
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*/
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virtual void cancel() {
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Guard<LockType> g(_lock);
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_canceled = true;
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_notEmpty.broadcast(); // Wake next() waiters
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}
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/**
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* @see Queue::isCanceled()
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*/
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virtual bool isCanceled() {
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// Faster check since the Queue will not become un-canceled
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if(_canceled)
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return true;
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Guard<LockType> g(_lock);
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return _canceled;
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}
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/**
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* @see Queue::size()
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*/
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virtual size_t size() {
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Guard<LockType> g(_lock);
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return _queue.size();
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}
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/**
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* @see Queue::size(unsigned long timeout)
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*/
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virtual size_t size(unsigned long timeout) {
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Guard<LockType> g(_lock, timeout);
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return _queue.size();
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}
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/**
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* Test whether any values are available in this Queue.
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*
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* The calling thread is blocked until there are no values present
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* in the Queue.
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*
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* @return
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* - <em>true</em> if there are no values available.
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* - <em>false</em> if there <i>are</i> values available.
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*
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* @see Queue::empty()
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*/
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virtual bool empty() {
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Guard<LockType> g(_lock);
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while(!_queue.empty()) // Wait for an empty signal
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_isEmpty.wait();
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return true;
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}
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/**
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* Test whether any values are available in this Queue.
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*
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* The calling thread is blocked until there are no values present
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* in the Queue.
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*
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* @param timeout maximum amount of time (milliseconds) this method may block
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* the calling thread.
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*
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* @return
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* - <em>true</em> if there are no values available.
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* - <em>false</em> if there <i>are</i> values available.
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*
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* @exception Timeout_Exception thrown if <i>timeout</i> milliseconds
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* expire before a value becomes available
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*
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* @see Queue::empty()
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*/
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virtual bool empty(unsigned long timeout) {
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Guard<LockType> g(_lock, timeout);
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while(!_queue.empty()) // Wait for an empty signal
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_isEmpty.wait(timeout);
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return true;
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}
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public:
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virtual void acquire() {
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_lock.acquire();
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}
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virtual bool tryAcquire(unsigned long timeout) {
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return _lock.tryAcquire(timeout);
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}
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virtual void release() {
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_lock.release();
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}
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}; /* BoundedQueue */
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} // namespace ZThread
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#endif // __ZTBOUNDEDQUEUE_H__
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