diff --git a/indra/llcommon/llthreadsafequeue.h b/indra/llcommon/llthreadsafequeue.h index 04f51816d7..c57520c01f 100644 --- a/indra/llcommon/llthreadsafequeue.h +++ b/indra/llcommon/llthreadsafequeue.h @@ -37,6 +37,9 @@ #include #include +/***************************************************************************** +* LLThreadSafeQueue +*****************************************************************************/ // // A general queue exception. // @@ -77,8 +80,8 @@ class LLThreadSafeQueue public: typedef ElementT value_type; - // If the pool is set to NULL one will be allocated and managed by this - // queue. + // Limiting the number of pending items prevents unbounded growth of the + // underlying queue. LLThreadSafeQueue(U32 capacity = 1024); // Add an element to the queue (will block if the queue has @@ -86,13 +89,15 @@ public: // // This call will raise an interrupt error if the queue is closed while // the caller is blocked. - void push(ElementT const& element); + template + void push(T&& element); // legacy name void pushFront(ElementT const & element) { return push(element); } // Try to add an element to the queue without blocking. Returns // true only if the element was actually added. - bool tryPush(ElementT const& element); + template + bool tryPush(T&& element); // legacy name bool tryPushFront(ElementT const & element) { return tryPush(element); } @@ -102,9 +107,9 @@ public: // to lock the mutex, versus how long to wait for the queue to stop being // full. Careful settings for each timeout might be orders of magnitude // apart. However, this method conflates them. - template + template bool tryPushFor(const std::chrono::duration& timeout, - ElementT const & element); + T&& element); // legacy name template bool tryPushFrontFor(const std::chrono::duration& timeout, @@ -112,9 +117,9 @@ public: // Try to add an element to the queue, blocking if full but with // timeout at specified time_point. Returns true if the element was added. - template - bool tryPushUntil(const std::chrono::time_point& timeout, - ElementT const& element); + template + bool tryPushUntil(const std::chrono::time_point& until, + T&& element); // no legacy name because this is a newer method // Pop the element at the head of the queue (will block if the queue is @@ -141,7 +146,7 @@ public: // Pop the element at the head of the queue, blocking if empty, with // timeout at specified time_point. Returns true if an element was popped. template - bool tryPopUntil(const std::chrono::time_point& timeout, + bool tryPopUntil(const std::chrono::time_point& until, ElementT& element); // no legacy name because this is a newer method @@ -172,11 +177,74 @@ protected: typedef std::unique_lock lock_t; boost::fibers::condition_variable_any mCapacityCond; boost::fibers::condition_variable_any mEmptyCond; + + // if we're able to lock immediately, do so and run the passed callable, + // which must accept lock_t& and return bool + template + bool tryLock(CALLABLE&& callable); + // if we're able to lock before the passed time_point, do so and run the + // passed callable, which must accept lock_t& and return bool + template + bool tryLockUntil(const std::chrono::time_point& until, + CALLABLE&& callable); + // while lock is locked, really push the passed element, if we can + template + bool push_(lock_t& lock, T&& element); + // while lock is locked, really pop the head element, if we can + template + bool pop_(lock_t& lock, ElementT& element, + PRED&& pred=[](const ElementT&){ return true; }); }; -// LLThreadSafeQueue -//----------------------------------------------------------------------------- +/***************************************************************************** +* PriorityQueueAdapter +*****************************************************************************/ +namespace LL +{ + /** + * std::priority_queue's API is almost like std::queue, intentionally of + * course, but you must access the element about to pop() as top() rather + * than as front(). Make an adapter for use with LLThreadSafeQueue. + */ + template , + typename Compare=std::less> + class PriorityQueueAdapter + { + public: + // publish all the same types + typedef std::priority_queue queue_type; + typedef typename queue_type::container_type container_type; + typedef typename queue_type::value_compare value_compare; + typedef typename queue_type::value_type value_type; + typedef typename queue_type::size_type size_type; + typedef typename queue_type::reference reference; + typedef typename queue_type::const_reference const_reference; + // Although std::queue defines both const and non-const front() + // methods, std::priority_queue defines only const top(). + const_reference front() const { return mQ.top(); } + // std::priority_queue has no equivalent to back(), so it's good that + // LLThreadSafeQueue doesn't use it. + + // All the rest of these merely forward to the corresponding + // queue_type methods. + bool empty() const { return mQ.empty(); } + size_type size() const { return mQ.size(); } + void push(const value_type& value) { mQ.push(value); } + void push(value_type&& value) { mQ.push(std::move(value)); } + template + void emplace(Args&&... args) { mQ.emplace(std::forward(args)...); } + void pop() { mQ.pop(); } + + private: + queue_type mQ; + }; +} // namespace LL + + +/***************************************************************************** +* LLThreadSafeQueue implementation +*****************************************************************************/ template LLThreadSafeQueue::LLThreadSafeQueue(U32 capacity) : mCapacity(capacity), @@ -185,24 +253,69 @@ LLThreadSafeQueue::LLThreadSafeQueue(U32 capacity) : } -template -void LLThreadSafeQueue::push(ElementT const & element) +// if we're able to lock immediately, do so and run the passed callable, which +// must accept lock_t& and return bool +template +template +bool LLThreadSafeQueue::tryLock(CALLABLE&& callable) +{ + lock_t lock1(mLock, std::defer_lock); + if (!lock1.try_lock()) + return false; + + return std::forward(callable)(lock1); +} + + +// if we're able to lock before the passed time_point, do so and run the +// passed callable, which must accept lock_t& and return bool +template +template +bool LLThreadSafeQueue::tryLockUntil( + const std::chrono::time_point& until, + CALLABLE&& callable) +{ + lock_t lock1(mLock, std::defer_lock); + if (!lock1.try_lock_until(until)) + return false; + + return std::forward(callable)(lock1); +} + + +// while lock is locked, really push the passed element, if we can +template +template +bool LLThreadSafeQueue::push_(lock_t& lock, T&& element) +{ + if (mStorage.size() >= mCapacity) + return false; + + mStorage.push(std::forward(element)); + lock.unlock(); + // now that we've pushed, if somebody's been waiting to pop, signal them + mEmptyCond.notify_one(); + return true; +} + + +template +template +void LLThreadSafeQueue::push(T&& element) { lock_t lock1(mLock); while (true) { + // On the producer side, it doesn't matter whether the queue has been + // drained or not: the moment either end calls close(), further push() + // operations will fail. if (mClosed) { LLTHROW(LLThreadSafeQueueInterrupt()); } - if (mStorage.size() < mCapacity) - { - mStorage.push(element); - lock1.unlock(); - mEmptyCond.notify_one(); + if (push_(lock1, std::forward(element))) return; - } // Storage Full. Wait for signal. mCapacityCond.wait(lock1); @@ -210,71 +323,85 @@ void LLThreadSafeQueue::push(ElementT const & element) } +template +template +bool LLThreadSafeQueue::tryPush(T&& element) +{ + return tryLock( + [this, element=std::move(element)](lock_t& lock) + { + if (mClosed) + return false; + return push_(lock, std::move(element)); + }); +} + + template -template +template bool LLThreadSafeQueue::tryPushFor( const std::chrono::duration& timeout, - ElementT const & element) + T&& element) { // Convert duration to time_point: passing the same timeout duration to // each of multiple calls is wrong. - return tryPushUntil(std::chrono::steady_clock::now() + timeout, element); + return tryPushUntil(std::chrono::steady_clock::now() + timeout, + std::forward(element)); } template -template +template bool LLThreadSafeQueue::tryPushUntil( - const std::chrono::time_point& endpoint, - ElementT const& element) + const std::chrono::time_point& until, + T&& element) { - lock_t lock1(mLock, std::defer_lock); - if (!lock1.try_lock_until(endpoint)) - return false; - - while (true) - { - if (mClosed) + return tryLockUntil( + until, + [this, until, element=std::move(element)](lock_t& lock) { - return false; - } + while (true) + { + if (mClosed) + { + return false; + } - if (mStorage.size() < mCapacity) - { - mStorage.push(element); - lock1.unlock(); - mEmptyCond.notify_one(); - return true; - } + if (push_(lock, std::move(element))) + return true; - // Storage Full. Wait for signal. - if (LLCoros::cv_status::timeout == mCapacityCond.wait_until(lock1, endpoint)) - { - // timed out -- formally we might recheck both conditions above - return false; - } - // If we didn't time out, we were notified for some reason. Loop back - // to check. - } + // Storage Full. Wait for signal. + if (LLCoros::cv_status::timeout == mCapacityCond.wait_until(lock, until)) + { + // timed out -- formally we might recheck both conditions above + return false; + } + // If we didn't time out, we were notified for some reason. Loop back + // to check. + } + }); } -template -bool LLThreadSafeQueue::tryPush(ElementT const & element) +// while lock is locked, really pop the head element, if we can +template +template +bool LLThreadSafeQueue::pop_( + lock_t& lock, ElementT& element, PRED&& pred) { - lock_t lock1(mLock, std::defer_lock); - if (!lock1.try_lock()) + // If mStorage is empty, there's no head element. + // If there's a head element, pass it to the predicate to see if caller + // considers it ready to pop. + // Unless both are satisfied, no point in continuing. + if (mStorage.empty() || ! std::forward(pred)(mStorage.front())) return false; - if (mClosed) - return false; - - if (mStorage.size() >= mCapacity) - return false; - - mStorage.push(element); - lock1.unlock(); - mEmptyCond.notify_one(); + // std::queue::front() is the element about to pop() + element = mStorage.front(); + mStorage.pop(); + lock.unlock(); + // now that we've popped, if somebody's been waiting to push, signal them + mCapacityCond.notify_one(); return true; } @@ -285,22 +412,20 @@ ElementT LLThreadSafeQueue::pop(void) lock_t lock1(mLock); while (true) { - if (!mStorage.empty()) - { - // std::queue::front() is the element about to pop() - ElementT value = mStorage.front(); - mStorage.pop(); - lock1.unlock(); - mCapacityCond.notify_one(); - return value; - } + // On the consumer side, we always try to pop before checking mClosed + // so we can finish draining the queue. + ElementT value; + if (pop_(lock1, value)) + return std::move(value); + // Once the queue is empty, mClosed lets us know if there will ever be + // any more coming. if (mClosed) { LLTHROW(LLThreadSafeQueueInterrupt()); } - // Storage empty. Wait for signal. + // Storage empty, queue still open. Wait for signal. mEmptyCond.wait(lock1); } } @@ -309,21 +434,14 @@ ElementT LLThreadSafeQueue::pop(void) template bool LLThreadSafeQueue::tryPop(ElementT & element) { - lock_t lock1(mLock, std::defer_lock); - if (!lock1.try_lock()) - return false; - - // no need to check mClosed: tryPop() behavior when the queue is - // closed is implemented by simple inability to push any new elements - if (mStorage.empty()) - return false; - - // std::queue::front() is the element about to pop() - element = mStorage.front(); - mStorage.pop(); - lock1.unlock(); - mCapacityCond.notify_one(); - return true; + return tryLock( + [this, &element](lock_t& lock) + { + // no need to check mClosed: tryPop() behavior when the queue is + // closed is implemented by simple inability to push any new + // elements + return pop_(lock, element); + }); } @@ -342,39 +460,33 @@ bool LLThreadSafeQueue::tryPopFor( template template bool LLThreadSafeQueue::tryPopUntil( - const std::chrono::time_point& endpoint, + const std::chrono::time_point& until, ElementT& element) { - lock_t lock1(mLock, std::defer_lock); - if (!lock1.try_lock_until(endpoint)) - return false; - - while (true) - { - if (!mStorage.empty()) + return tryLockUntil( + until, + [this, until, &element](lock_t& lock) { - // std::queue::front() is the element about to pop() - element = mStorage.front(); - mStorage.pop(); - lock1.unlock(); - mCapacityCond.notify_one(); - return true; - } + while (true) + { + if (pop_(lock, element)) + return true; - if (mClosed) - { - return false; - } + if (mClosed) + { + return false; + } - // Storage empty. Wait for signal. - if (LLCoros::cv_status::timeout == mEmptyCond.wait_until(lock1, endpoint)) - { - // timed out -- formally we might recheck both conditions above - return false; - } - // If we didn't time out, we were notified for some reason. Loop back - // to check. - } + // Storage empty. Wait for signal. + if (LLCoros::cv_status::timeout == mEmptyCond.wait_until(lock, until)) + { + // timed out -- formally we might recheck both conditions above + return false; + } + // If we didn't time out, we were notified for some reason. Loop back + // to check. + } + }); }