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Diffstat (limited to 'indra/llcommon/llthreadsafequeue.h')
| -rw-r--r-- | indra/llcommon/llthreadsafequeue.h | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/indra/llcommon/llthreadsafequeue.h b/indra/llcommon/llthreadsafequeue.h new file mode 100644 index 0000000000..46c8b91932 --- /dev/null +++ b/indra/llcommon/llthreadsafequeue.h @@ -0,0 +1,205 @@ +/** + * @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> + + +struct apr_pool_t; // From apr_pools.h +class LLThreadSafeQueueImplementation; // See below. + + +// +// A general queue exception. +// +class 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 LLThreadSafeQueueInterrupt: + public LLThreadSafeQueueError +{ +public: + LLThreadSafeQueueInterrupt(void): + LLThreadSafeQueueError("queue operation interrupted") + { + ; // No op. + } +}; + + +struct apr_queue_t; // From apr_queue.h + + +// +// Implementation details. +// +class LLThreadSafeQueueImplementation +{ +public: + LLThreadSafeQueueImplementation(apr_pool_t * pool, unsigned int capacity); + ~LLThreadSafeQueueImplementation(); + void pushFront(void * element); + bool tryPushFront(void * element); + void * popBack(void); + bool tryPopBack(void *& element); + size_t size(); + +private: + bool mOwnsPool; + apr_pool_t * mPool; + apr_queue_t * mQueue; +}; + + +// +// Implements a thread safe FIFO. +// +template<typename ElementT> +class LLThreadSafeQueue +{ +public: + typedef ElementT value_type; + + // If the pool is set to NULL one will be allocated and managed by this + // queue. + LLThreadSafeQueue(apr_pool_t * pool = 0, 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(apr_pool_t * pool, unsigned int capacity): + mImplementation(pool, 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 |