Add beast_basics module

modules/beast_basics/threads/beast_Semaphore.cpp

@@ -0,0 +1,130 @@
+/*============================================================================*/
+/*
+  VFLib: https://github.com/vinniefalco/VFLib
+
+  Copyright (C) 2008 by Vinnie Falco <vinnie.falco@gmail.com>
+
+  This library contains portions of other open source products covered by
+  separate licenses. Please see the corresponding source files for specific
+  terms.
+
+  VFLib is provided under the terms of The MIT License (MIT):
+
+  Permission is hereby granted, free of charge, to any person obtaining a copy
+  of this software and associated documentation files (the "Software"), to deal
+  in the Software without restriction, including without limitation the rights
+  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+  copies of the Software, and to permit persons to whom the Software is
+  furnished to do so, subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be included in
+  all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+  IN THE SOFTWARE.
+*/
+/*============================================================================*/
+
+Semaphore::WaitingThread::WaitingThread ()
+    : m_event (false) // auto-reset
+{
+}
+
+void Semaphore::WaitingThread::wait ()
+{
+    m_event.wait ();
+}
+
+void Semaphore::WaitingThread::signal ()
+{
+    m_event.signal ();
+}
+
+//==============================================================================
+
+Semaphore::Semaphore (int initialCount)
+    : m_counter (initialCount)
+{
+}
+
+Semaphore::~Semaphore ()
+{
+    // Can't delete the semaphore while threads are waiting on it!!
+    bassert (m_waitingThreads.pop_front () == nullptr);
+
+    for (;;)
+    {
+        WaitingThread* waitingThread = m_deleteList.pop_front ();
+
+        if (waitingThread != nullptr)
+            delete waitingThread;
+        else
+            break;
+    }
+}
+
+void Semaphore::signal (int amount)
+{
+    bassert (amount > 0);
+
+    while (amount--)
+    {
+        // Make counter and list operations atomic.
+        LockType::ScopedLockType lock (m_mutex);
+
+        if (++m_counter <= 0)
+        {
+            WaitingThread* waitingThread = m_waitingThreads.pop_front ();
+
+            bassert (waitingThread != nullptr);
+
+            waitingThread->signal ();
+        }
+    }
+}
+
+void Semaphore::wait ()
+{
+    // Always prepare the WaitingThread object first, either
+    // from the delete list or through a new allocation.
+    //
+    WaitingThread* waitingThread = m_deleteList.pop_front ();
+
+    if (waitingThread == nullptr)
+        waitingThread = new WaitingThread;
+
+    {
+        // Make counter and list operations atomic.
+        LockType::ScopedLockType lock (m_mutex);
+
+        if (--m_counter >= 0)
+        {
+            // Acquired the resource so put waitingThread back.
+            m_deleteList.push_front (waitingThread);
+
+            waitingThread = nullptr;
+        }
+        else
+        {
+            // Out of resources, go on to the waiting list.
+            m_waitingThreads.push_front (waitingThread);
+        }
+    }
+
+    // Do we need to wait?
+    if (waitingThread != nullptr)
+    {
+        // Yes so do it.
+        waitingThread->wait ();
+
+        // If the wait is satisfied, then we've been taken off the
+        // waiting list so put waitingThread back in the delete list.
+        //
+        m_deleteList.push_front (waitingThread);
+    }
+}