1 files changed, 178 insertions, 0 deletions
diff --git a/src/OSSupport/Queue.h b/src/OSSupport/Queue.h
new file mode 100644
index 000000000..6c3d58295
--- /dev/null
+++ b/src/OSSupport/Queue.h
@@ -0,0 +1,178 @@
+
+// Queue.h
+
+// Implements the cQueue class representing a thread safe queue
+
+#pragma once
+
+/*
+Items can be added multiple times to a queue, there are two functions for
+adding, EnqueueItem() and EnqueueItemIfNotPresent(). The first one always
+enqueues the specified item, the second one checks if the item is already
+present and only queues it if it isn't.
+
+Usage:
+To create a queue of type T, instantiate a cQueue<T> object. You can also
+modify the behavior of the queue when deleting items and when adding items
+that are already in the queue by providing a second parameter, a class that
+implements the functions Delete() and Combine(). An example is given in
+cQueueFuncs and is used as the default behavior.
+*/
+
+/// This empty struct allows for the callback functions to be inlined
+template<class T>
+struct cQueueFuncs 
+{
+public:
+
+	/// Called when an Item is deleted from the queue without being returned
+	static void Delete(T) {};
+	
+	/// Called when an Item is inserted with EnqueueItemIfNotPresent and there is another equal value already inserted
+	static void Combine(T & a_existing, const T & a_new) {};
+};
+
+
+
+
+
+template <class ItemType, class Funcs = cQueueFuncs<ItemType> >
+class cQueue
+{
+	// The actual storage type for the queue
+	typedef typename std::list<ItemType> QueueType;
+	
+	// Make iterator an alias for the QueueType's iterator
+	typedef typename QueueType::iterator iterator;
+	
+public:
+	cQueue() {}
+	~cQueue() {}
+
+
+	/// Enqueues an item to the queue, may block if other threads are accessing the queue.
+	void EnqueueItem(ItemType a_Item)
+	{
+		cCSLock Lock(m_CS);
+		m_Contents.push_back(a_Item);
+		m_evtAdded.Set();
+	}
+
+
+	/// Enqueues an item in the queue if not already present (as determined by operator ==). Blocks other threads from accessing the queue.
+	void EnqueueItemIfNotPresent(ItemType a_Item)
+	{
+		cCSLock Lock(m_CS);
+
+		for (iterator itr = m_Contents.begin(); itr != m_Contents.end(); ++itr)
+		{
+			if ((*itr) == a_Item)
+			{
+				Funcs::Combine(*itr, a_Item);
+				return;
+			}
+		}
+		m_Contents.push_back(a_Item);
+		m_evtAdded.Set();
+	}
+
+
+	/// Dequeues an item from the queue if any are present.
+	/// Returns true if successful. Value of item is undefined if dequeuing was unsuccessful.
+	bool TryDequeueItem(ItemType & item)
+	{
+		cCSLock Lock(m_CS);
+		if (m_Contents.size() == 0)
+		{
+			return false; 
+		}
+		item = m_Contents.front();
+		m_Contents.pop_front();
+		m_evtRemoved.Set();
+		return true;
+	}
+
+
+	/// Dequeues an item from the queue, blocking until an item is available.
+	ItemType DequeueItem(void)
+	{
+		cCSLock Lock(m_CS);
+		while (m_Contents.size() == 0)
+		{
+			cCSUnlock Unlock(Lock);
+			m_evtAdded.Wait();
+		}
+		ItemType item = m_Contents.front();
+		m_Contents.pop_front();
+		m_evtRemoved.Set();
+		return item;
+	}
+
+
+	/// Blocks until the queue is empty.
+	void BlockTillEmpty(void)
+	{
+		cCSLock Lock(m_CS);
+		while (!m_Contents.empty())
+		{
+			cCSUnlock Unlock(Lock);
+			m_evtRemoved.Wait();
+		}
+	}
+
+
+	/// Removes all Items from the Queue, calling Delete on each of them.
+	void Clear(void)
+	{
+		cCSLock Lock(m_CS);
+		while (!m_Contents.empty())
+		{
+			Funcs::Delete(m_Contents.front());
+			m_Contents.pop_front();
+		}
+	}
+
+
+	/// Returns the size at time of being called.
+	/// Do not use to determine whether to call DequeueItem(), use TryDequeueItem() instead
+	size_t Size(void)
+	{
+		cCSLock Lock(m_CS);
+		return m_Contents.size();
+	}
+
+
+	/// Removes the item from the queue. If there are multiple such items, only the first one is removed.
+	/// Returns true if the item has been removed, false if no such item found.
+	bool Remove(ItemType a_Item)
+	{
+		cCSLock Lock(m_CS);
+		for (iterator itr = m_Contents.begin(); itr != m_Contents.end(); ++itr)
+		{
+			if ((*itr) == a_Item)
+			{
+				m_Contents.erase(itr);
+				m_evtRemoved.Set();
+				return true;
+			}
+		}
+		return false;
+	}
+
+private:
+	/// The contents of the queue
+	QueueType m_Contents;
+	
+	/// Mutex that protects access to the queue contents
+	cCriticalSection m_CS;
+	
+	/// Event that is signalled when an item is added
+	cEvent m_evtAdded;
+	
+	/// Event that is signalled when an item is removed (both dequeued or erased)
+	cEvent m_evtRemoved;
+};
+
+
+
+