From Tanguy Fautre (Aris Technologies), ffmpeg plugin

src/osgPlugins/ffmpeg/MessageQueue.hpp

@@ -0,0 +1,156 @@
+
+#ifndef HEADER_GUARD_OSGFFMPEG_MESSAGE_QUEUE_H
+#define HEADER_GUARD_OSGFFMPEG_MESSAGE_QUEUE_H
+
+#include <OpenThreads/Condition>
+#include <OpenThreads/Mutex>
+#include <OpenThreads/ScopedLock>
+
+#include <deque>
+
+
+
+namespace osgFFmpeg {
+
+
+
+template <class T>
+class MessageQueue
+{
+public:
+
+    typedef T value_type;
+    typedef size_t size_type;
+
+    MessageQueue();
+    ~MessageQueue();
+
+    void clear();
+
+    void push(const T & value);
+
+    value_type pop();
+    value_type tryPop(bool & is_empty);
+    value_type timedPop(bool & is_empty, unsigned long ms);
+
+private:
+
+    MessageQueue(const MessageQueue &);
+    MessageQueue & operator = (const MessageQueue &);
+
+    typedef std::deque<T> Queue;
+    typedef OpenThreads::Condition Condition;
+    typedef OpenThreads::Mutex Mutex;
+    typedef OpenThreads::ScopedLock<Mutex> ScopedLock;
+
+    Mutex        m_mutex;
+    Condition    m_not_empty;
+    Queue        m_queue;
+};
+
+
+
+
+
+template <class T>
+MessageQueue<T>::MessageQueue()
+{
+
+}
+
+
+
+template <class T>
+MessageQueue<T>::~MessageQueue()
+{
+
+}
+
+
+
+template <class T>
+void MessageQueue<T>::clear()
+{
+    ScopedLock lock(m_mutex);
+
+    m_queue.clear();
+}
+
+
+
+template <class T>
+void MessageQueue<T>::push(const T & value)
+{
+    {
+        ScopedLock lock(m_mutex);
+        m_queue.push_back(value);
+    }
+
+    m_not_empty.signal();
+}
+
+
+
+template <class T>
+typename MessageQueue<T>::value_type MessageQueue<T>::pop()
+{
+    ScopedLock lock(m_mutex);
+
+    while (m_queue.empty())
+        m_not_empty.wait(&m_mutex);
+
+    const value_type value = m_queue.front();
+    m_queue.pop_front();
+
+    return value;
+}
+
+
+
+template <class T>
+typename MessageQueue<T>::value_type MessageQueue<T>::tryPop(bool & is_empty)
+{
+    ScopedLock lock(m_mutex);
+
+    is_empty = m_queue.empty();
+
+    if (is_empty)
+        return value_type();
+
+    const value_type value = m_queue.front();
+    m_queue.pop_front();
+
+    return value;
+}
+
+
+
+template <class T>
+typename MessageQueue<T>::value_type MessageQueue<T>::timedPop(bool & is_empty, const unsigned long ms)
+{
+    ScopedLock lock(m_mutex);
+
+    // We don't wait in a loop to avoid an infinite loop (as the ms timeout would not be decremented).
+    // This means that timedPop() could return with (is_empty = true) before the timeout has been hit.
+
+    if (m_queue.empty())
+        m_not_empty.wait(&m_mutex, ms);
+
+    is_empty = m_queue.empty();
+
+    if (is_empty)
+        return value_type();
+
+    const value_type value = m_queue.front();
+    m_queue.pop_front();
+
+    return value;
+}
+
+
+
+} // namespace osgFFmpeg
+
+
+
+#endif // HEADER_GUARD_OSGFFMPEG_MESSAGE_QUEUE_H