1 files changed, 212 insertions, 0 deletions
diff --git a/src/zencore/logging/asyncsink.cpp b/src/zencore/logging/asyncsink.cpp
new file mode 100644
index 000000000..02bf9f3ba
--- /dev/null
+++ b/src/zencore/logging/asyncsink.cpp
@@ -0,0 +1,212 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zencore/logging/asyncsink.h>
+
+#include <zencore/blockingqueue.h>
+#include <zencore/logging/logmsg.h>
+#include <zencore/thread.h>
+
+#include <future>
+#include <string>
+#include <thread>
+
+namespace zen::logging {
+
+struct AsyncLogMessage
+{
+	enum class Type : uint8_t
+	{
+		Log,
+		Flush,
+		Shutdown
+	};
+
+	Type MsgType = Type::Log;
+
+	// Points to the LogPoint from upstream logging code. LogMessage guarantees
+	// this is always valid (either a static LogPoint from ZEN_LOG macros or one
+	// of the per-level default LogPoints).
+	const LogPoint* Point = nullptr;
+
+	int									  ThreadId = 0;
+	std::string							  OwnedPayload;
+	std::string							  OwnedLoggerName;
+	std::chrono::system_clock::time_point Time;
+
+	std::shared_ptr<std::promise<void>> FlushPromise;
+};
+
+struct AsyncSink::Impl
+{
+	explicit Impl(std::vector<SinkPtr> InSinks) : m_Sinks(std::move(InSinks))
+	{
+		m_WorkerThread = std::thread([this]() {
+			zen::SetCurrentThreadName("AsyncLog");
+			WorkerLoop();
+		});
+	}
+
+	~Impl()
+	{
+		AsyncLogMessage ShutdownMsg;
+		ShutdownMsg.MsgType = AsyncLogMessage::Type::Shutdown;
+		m_Queue.Enqueue(std::move(ShutdownMsg));
+
+		if (m_WorkerThread.joinable())
+		{
+			m_WorkerThread.join();
+		}
+	}
+
+	void Log(const LogMessage& Msg)
+	{
+		AsyncLogMessage AsyncMsg;
+		AsyncMsg.OwnedPayload	 = std::string(Msg.GetPayload());
+		AsyncMsg.OwnedLoggerName = std::string(Msg.GetLoggerName());
+		AsyncMsg.ThreadId		 = Msg.GetThreadId();
+		AsyncMsg.Time			 = Msg.GetTime();
+		AsyncMsg.Point			 = &Msg.GetLogPoint();
+		AsyncMsg.MsgType		 = AsyncLogMessage::Type::Log;
+
+		m_Queue.Enqueue(std::move(AsyncMsg));
+	}
+
+	void Flush()
+	{
+		auto Promise = std::make_shared<std::promise<void>>();
+		auto Future	 = Promise->get_future();
+
+		AsyncLogMessage FlushMsg;
+		FlushMsg.MsgType	  = AsyncLogMessage::Type::Flush;
+		FlushMsg.FlushPromise = std::move(Promise);
+
+		m_Queue.Enqueue(std::move(FlushMsg));
+
+		Future.get();
+	}
+
+	void SetFormatter(std::unique_ptr<Formatter> InFormatter)
+	{
+		for (auto& CurrentSink : m_Sinks)
+		{
+			CurrentSink->SetFormatter(InFormatter->Clone());
+		}
+	}
+
+private:
+	void ForwardLogToSinks(const AsyncLogMessage& AsyncMsg)
+	{
+		LogMessage Reconstructed(*AsyncMsg.Point, AsyncMsg.OwnedLoggerName, AsyncMsg.OwnedPayload);
+		Reconstructed.SetTime(AsyncMsg.Time);
+		Reconstructed.SetThreadId(AsyncMsg.ThreadId);
+
+		for (auto& CurrentSink : m_Sinks)
+		{
+			if (CurrentSink->ShouldLog(Reconstructed.GetLevel()))
+			{
+				try
+				{
+					CurrentSink->Log(Reconstructed);
+				}
+				catch (const std::exception&)
+				{
+				}
+			}
+		}
+	}
+
+	void FlushSinks()
+	{
+		for (auto& CurrentSink : m_Sinks)
+		{
+			try
+			{
+				CurrentSink->Flush();
+			}
+			catch (const std::exception&)
+			{
+			}
+		}
+	}
+
+	void WorkerLoop()
+	{
+		AsyncLogMessage Msg;
+		while (m_Queue.WaitAndDequeue(Msg))
+		{
+			switch (Msg.MsgType)
+			{
+				case AsyncLogMessage::Type::Log:
+					{
+						ForwardLogToSinks(Msg);
+						break;
+					}
+
+				case AsyncLogMessage::Type::Flush:
+					{
+						FlushSinks();
+						if (Msg.FlushPromise)
+						{
+							Msg.FlushPromise->set_value();
+						}
+						break;
+					}
+
+				case AsyncLogMessage::Type::Shutdown:
+					{
+						m_Queue.CompleteAdding();
+
+						AsyncLogMessage Remaining;
+						while (m_Queue.WaitAndDequeue(Remaining))
+						{
+							if (Remaining.MsgType == AsyncLogMessage::Type::Log)
+							{
+								ForwardLogToSinks(Remaining);
+							}
+							else if (Remaining.MsgType == AsyncLogMessage::Type::Flush)
+							{
+								FlushSinks();
+								if (Remaining.FlushPromise)
+								{
+									Remaining.FlushPromise->set_value();
+								}
+							}
+						}
+
+						FlushSinks();
+						return;
+					}
+			}
+		}
+	}
+
+	std::vector<SinkPtr>		   m_Sinks;
+	BlockingQueue<AsyncLogMessage> m_Queue;
+	std::thread					   m_WorkerThread;
+};
+
+AsyncSink::AsyncSink(std::vector<SinkPtr> InSinks) : m_Impl(std::make_unique<Impl>(std::move(InSinks)))
+{
+}
+
+AsyncSink::~AsyncSink() = default;
+
+void
+AsyncSink::Log(const LogMessage& Msg)
+{
+	m_Impl->Log(Msg);
+}
+
+void
+AsyncSink::Flush()
+{
+	m_Impl->Flush();
+}
+
+void
+AsyncSink::SetFormatter(std::unique_ptr<Formatter> InFormatter)
+{
+	m_Impl->SetFormatter(std::move(InFormatter));
+}
+
+}  // namespace zen::logging