zencore: Added BlockingQueue (moved from upstreamcache.cpp)

1 files changed, 73 insertions, 0 deletions

diff --git a/zencore/include/zencore/blockingqueue.h b/zencore/include/zencore/blockingqueue.h
new file mode 100644
index 000000000..fbb4480a1
--- /dev/null
+++ b/zencore/include/zencore/blockingqueue.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <atomic>
+#include <deque>
+#include <mutex>
+
+namespace zen {
+
+template<typename T>
+class BlockingQueue
+{
+public:
+	BlockingQueue() = default;
+
+	~BlockingQueue() { CompleteAdding(); }
+
+	void Enqueue(T&& Item)
+	{
+		{
+			std::lock_guard Lock(m_Lock);
+			m_Queue.emplace_back(std::move(Item));
+			m_Size++;
+		}
+
+		m_NewItemSignal.notify_one();
+	}
+
+	bool WaitAndDequeue(T& Item)
+	{
+		if (m_CompleteAdding.load())
+		{
+			return false;
+		}
+
+		std::unique_lock Lock(m_Lock);
+		m_NewItemSignal.wait(Lock, [this]() { return !m_Queue.empty() || m_CompleteAdding.load(); });
+
+		if (!m_Queue.empty())
+		{
+			Item = std::move(m_Queue.front());
+			m_Queue.pop_front();
+			m_Size--;
+
+			return true;
+		}
+
+		return false;
+	}
+
+	void CompleteAdding()
+	{
+		if (!m_CompleteAdding.load())
+		{
+			m_CompleteAdding.store(true);
+			m_NewItemSignal.notify_all();
+		}
+	}
+
+	std::size_t Size() const
+	{
+		std::unique_lock Lock(m_Lock);
+		return m_Queue.size();
+	}
+
+private:
+	mutable std::mutex		m_Lock;
+	std::condition_variable m_NewItemSignal;
+	std::deque<T>			m_Queue;
+	std::atomic_bool		m_CompleteAdding{false};
+	std::atomic_uint32_t	m_Size;
+};
+
+}  // namespace zen