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126 lines
3.5 KiB
C++
126 lines
3.5 KiB
C++
//------------------------------------------------------------------------------
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/*
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This file is part of Beast: https://github.com/vinniefalco/Beast
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Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>
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Permission to use, copy, modify, and/or distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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//==============================================================================
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Semaphore::Semaphore (int initialCount)
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: m_counter (initialCount)
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{
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}
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Semaphore::~Semaphore ()
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{
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// Can't delete the semaphore while threads are waiting on it!!
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bassert (m_waitingThreads.pop_front () == nullptr);
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for (;;)
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{
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WaitingThread* waitingThread = m_deleteList.pop_front ();
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if (waitingThread != nullptr)
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delete waitingThread;
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else
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break;
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}
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}
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void Semaphore::signal (int amount)
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{
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bassert (amount > 0);
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while (amount--)
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{
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// Make counter and list operations atomic.
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LockType::ScopedLockType lock (m_mutex);
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if (++m_counter <= 0)
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{
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WaitingThread* waitingThread = m_waitingThreads.pop_front ();
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bassert (waitingThread != nullptr);
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waitingThread->signal ();
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}
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}
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}
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bool Semaphore::wait (int timeOutMilliseconds)
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{
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bool signaled = true;
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// Always prepare the WaitingThread object first, either
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// from the delete list or through a new allocation.
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//
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WaitingThread* waitingThread = m_deleteList.pop_front ();
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if (waitingThread == nullptr)
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waitingThread = new WaitingThread;
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{
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// Make counter and list operations atomic.
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LockType::ScopedLockType lock (m_mutex);
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if (--m_counter >= 0)
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{
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// Acquired the resource so put waitingThread back.
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m_deleteList.push_front (waitingThread);
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waitingThread = nullptr;
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}
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else
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{
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// Out of resources, go on to the waiting list.
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m_waitingThreads.push_front (waitingThread);
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}
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}
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// Do we need to wait?
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if (waitingThread != nullptr)
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{
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// Yes so do it.
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signaled = waitingThread->wait (timeOutMilliseconds);
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// If the wait is satisfied, then we've been taken off the
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// waiting list so put waitingThread back in the delete list.
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//
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m_deleteList.push_front (waitingThread);
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}
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return signaled;
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}
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//------------------------------------------------------------------------------
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Semaphore::WaitingThread::WaitingThread ()
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: m_event (false) // auto-reset
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{
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}
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bool Semaphore::WaitingThread::wait (int timeOutMilliseconds)
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{
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return m_event.wait (timeOutMilliseconds);
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}
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void Semaphore::WaitingThread::signal ()
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{
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m_event.signal ();
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}
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//------------------------------------------------------------------------------
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// VFALCO TODO Unit Tests!
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