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/**
* @file llthreadsafequeue.h
* @brief Base classes for thread, mutex and condition handling.
*
* $LicenseInfo:firstyear=2004&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#ifndef LL_LLTHREADSAFEQUEUE_H
#define LL_LLTHREADSAFEQUEUE_H
#include <string>
#include <stdexcept>
#include "llaprpool.h"
class LLThreadSafeQueueImplementation; // See below.
//
// A general queue exception.
//
class LL_COMMON_API LLThreadSafeQueueError:
public std::runtime_error
{
public:
LLThreadSafeQueueError(std::string const & message):
std::runtime_error(message)
{
; // No op.
}
};
//
// An exception raised when blocking operations are interrupted.
//
class LL_COMMON_API LLThreadSafeQueueInterrupt:
public LLThreadSafeQueueError
{
public:
LLThreadSafeQueueInterrupt(void):
LLThreadSafeQueueError("queue operation interrupted")
{
; // No op.
}
};
struct apr_queue_t; // From apr_queue.h
//
// Implementation details.
//
class LL_COMMON_API LLThreadSafeQueueImplementation
{
public:
LLThreadSafeQueueImplementation(unsigned int capacity);
~LLThreadSafeQueueImplementation();
void pushFront(void * element);
bool tryPushFront(void * element);
void * popBack(void);
bool tryPopBack(void *& element);
size_t size();
private:
LLAPRPool mPool; // The pool used for mQueue.
apr_queue_t * mQueue;
};
//
// Implements a thread safe FIFO.
//
template<typename ElementT>
class LLThreadSafeQueue
{
public:
typedef ElementT value_type;
// Constructor.
LLThreadSafeQueue(unsigned int capacity = 1024);
// Add an element to the front of queue (will block if the queue has
// reached capacity).
//
// This call will raise an interrupt error if the queue is deleted while
// the caller is blocked.
void pushFront(ElementT const & element);
// Try to add an element to the front ofqueue without blocking. Returns
// true only if the element was actually added.
bool tryPushFront(ElementT const & element);
// Pop the element at the end of the queue (will block if the queue is
// empty).
//
// This call will raise an interrupt error if the queue is deleted while
// the caller is blocked.
ElementT popBack(void);
// Pop an element from the end of the queue if there is one available.
// Returns true only if an element was popped.
bool tryPopBack(ElementT & element);
// Returns the size of the queue.
size_t size();
private:
LLThreadSafeQueueImplementation mImplementation;
};
// LLThreadSafeQueue
//-----------------------------------------------------------------------------
template<typename ElementT>
LLThreadSafeQueue<ElementT>::LLThreadSafeQueue(unsigned int capacity) :
mImplementation(capacity)
{
; // No op.
}
template<typename ElementT>
void LLThreadSafeQueue<ElementT>::pushFront(ElementT const & element)
{
ElementT * elementCopy = new ElementT(element);
try {
mImplementation.pushFront(elementCopy);
} catch (LLThreadSafeQueueInterrupt) {
delete elementCopy;
throw;
}
}
template<typename ElementT>
bool LLThreadSafeQueue<ElementT>::tryPushFront(ElementT const & element)
{
ElementT * elementCopy = new ElementT(element);
bool result = mImplementation.tryPushFront(elementCopy);
if(!result) delete elementCopy;
return result;
}
template<typename ElementT>
ElementT LLThreadSafeQueue<ElementT>::popBack(void)
{
ElementT * element = reinterpret_cast<ElementT *> (mImplementation.popBack());
ElementT result(*element);
delete element;
return result;
}
template<typename ElementT>
bool LLThreadSafeQueue<ElementT>::tryPopBack(ElementT & element)
{
void * storedElement;
bool result = mImplementation.tryPopBack(storedElement);
if(result) {
ElementT * elementPtr = reinterpret_cast<ElementT *>(storedElement);
element = *elementPtr;
delete elementPtr;
} else {
; // No op.
}
return result;
}
template<typename ElementT>
size_t LLThreadSafeQueue<ElementT>::size(void)
{
return mImplementation.size();
}
#endif
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