Adding PushFront to ConcurrentQueue.h

Change-Id: I4b4410ab6209e265436e3bff381fba7989729b98

MITLib/Utility/ConcurrentQueue.h

@@ -66,6 +66,50 @@ public:
 		return true;
 	}
 
+	// Pushes object T when space is available
+	// Throws std::exception on timeout or when interrupted
+	bool PushFront(T item, int milliSeconds = INFINITE) {
+		bool bPushedItem = false;
+		CSingleLock lock(&m_mutex);
+		while(!bPushedItem) {
+			try
+			{
+				// Wait for space to be available
+				m_spaceAvailableEvent.WaitEvtEx(milliSeconds);
+			} catch(std::exception &e) {
+				printf("Push failed: %s\n", e.what());
+				throw;
+			}
+
+			// wait for critical section to become available
+			lock.Lock();
+
+			// inside critical section
+			{
+				size_t size = m_queue.size();
+				// Make sure that nobody else that was waiting pushed first
+				if( size < m_capacity) {
+					m_queue.push_front(item);
+					bPushedItem = true;
+
+					if (size == 0)
+					{
+						// Queue was empty, now there is one item
+						m_dataAvailableEvent.Set();
+					}
+
+					size++;
+					if (size >= m_capacity) {
+						// Queue is now full
+						m_spaceAvailableEvent.Reset();
+					}
+				}
+			}
+			lock.Unlock();
+		}
+		return true;
+	}
+
 	// Returns object T when available
 	// Throws std::exception on timeout or when interrupted
 	T Pop(int milliSeconds = INFINITE)
@@ -114,9 +158,9 @@ private:
 			// wait for event to be signaled that there is data
 			if (bThrowException)
 			{
-				m_dataAvailableEvent.WaitEvtEx(milliSeconds);
+				m_dataAvailableEvent.WaitEvtEx(remaining);
 			}
-			else if (!m_dataAvailableEvent.WaitEvt(milliSeconds))
+			else if (!m_dataAvailableEvent.WaitEvt(remaining))
 			{
 				return false;
 			}