Revert "Unblock ASIOStart() before calling bufferSwitch()."

This reverts commit 1262460. We don't need this workaround anymore since PortAudio/portaudio@2d8c7eb fixed the root cause of #60.
dechamps · Jan 2, 2021 · 53e395e · 53e395e
1 parent ce20994
commit 53e395e
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Showing 4 changed files with 16 additions and 109 deletions.
diff --git a/src/flexasio/FlexASIO/flexasio.cpp b/src/flexasio/FlexASIO/flexasio.cpp
@@ -779,7 +779,7 @@ namespace flexasio {
 		return result;
 	}()),
 		hostSupportsOutputReady(preparedState.flexASIO.hostSupportsOutputReady),
-		activeStream(preparedState.openStreamResult.stream.get()) {}
+		activeStream(StartStream(preparedState.openStreamResult.stream.get())) {}
 
 	void FlexASIO::Stop() {
 		if (!preparedState.has_value()) throw ASIOException(ASE_InvalidMode, "stop() called before createBuffers()");
@@ -861,14 +861,6 @@ namespace flexasio {
 				memset(output_samples[output_channel_index], 0, frameCount * outputSampleSizeInBytes);
 		}
 
-		// Some backends (e.g. WASAPI) issue the first stream callback from within Pa_StartStream().
-		// This is problematic because some host applications (e.g. foo_out_asio) wait for Start() to finish
-		// before returning from bufferSwitch(), resulting in a deadlock. See: https://github.com/dechamps/FlexASIO/issues/60
-		// To work around this problem, unblock Start() if it is still running by the time we reach this point.
-		// One possible downside of this approach is that we might not report Start() errors properly if they occur
-		// after the first stream callback fires.
-		if (state == InitialState()) activeStream.EndWaitForStartOutcome();
-
 		// See dechamps_ASIOUtil/BUFFERS.md for the gory details of how ASIO buffer management works.
 
 		if (state != State::PRIMING) {

diff --git a/src/flexasio/FlexASIO/flexasio.h b/src/flexasio/FlexASIO/flexasio.h
@@ -158,8 +158,7 @@ namespace flexasio {
 				PreparedState& preparedState;
 				const bool host_supports_timeinfo;
 				const bool hostSupportsOutputReady;
-				State InitialState() const { return hostSupportsOutputReady ? State::PRIMING : State::PRIMED; }
-				State state = InitialState();
+				State state = hostSupportsOutputReady ? State::PRIMING : State::PRIMED;
 				// The index of the "unlocked" buffer (or "half-buffer", i.e. 0 or 1) that contains data not currently being processed by the ASIO host.
 				long driverBufferIndex = state == State::PRIMING ? 1 : 0;
 				std::atomic<SamplePosition> samplePosition;
@@ -170,7 +169,7 @@ namespace flexasio {
 
 				Win32HighResolutionTimer win32HighResolutionTimer;
 				Registration registration{ preparedState.runningState, *this };
-				ActiveStream activeStream;
+				const ActiveStream activeStream;
 			};
 
 			static int StreamCallback(const void *input, void *output, unsigned long frameCount, const PaStreamCallbackTimeInfo *timeInfo, PaStreamCallbackFlags statusFlags, void *userData) throw();

diff --git a/src/flexasio/FlexASIO/portaudio.cpp b/src/flexasio/FlexASIO/portaudio.cpp
@@ -3,27 +3,8 @@
 #include "log.h"
 #include "../FlexASIOUtil/portaudio.h"
 
-#include <Objbase.h>
-
 namespace flexasio {
 
-	namespace {
-
-		class COMInitializer {
-		public:
-			COMInitializer() {
-				Log() << "Initializing COM";
-				const auto hresult = CoInitializeEx(NULL, COINIT_MULTITHREADED);
-				if (FAILED(hresult)) throw std::system_error(hresult, std::system_category(), "CoInitializeEx() failed");
-			}
-			~COMInitializer() {
-				Log() << "Uninitializing COM";
-				CoUninitialize();
-			}
-		};
-
-	}
-
 	void StreamDeleter::operator()(PaStream* stream) throw() {
 		Log() << "Closing PortAudio stream " << stream;
 		const auto error = Pa_CloseStream(stream);
@@ -47,65 +28,19 @@ namespace flexasio {
 		return Stream(stream);
 	}
 
-	ActiveStream::ActiveStream(PaStream* stream) : stream(stream), startThread([this] {
-		std::exception_ptr exception;
-		try {
-			Log() << "Starting PortAudio stream " << this->stream;
-			{
-				COMInitializer comInitializer;  // Required because WASAPI Pa_StartStream() calls into the COM library
-				const auto error = Pa_StartStream(this->stream);
-				if (error != paNoError) throw std::runtime_error(std::string("unable to start PortAudio stream: ") + Pa_GetErrorText(error));
-			}
-			Log() << "PortAudio stream started";
-		}
-		catch (...) {
-		  exception = std::current_exception();
-		}
-		Log() << "Setting start outcome";
-		try {
-			if (exception)
-				promisedOutcome.set_exception(exception);
-			else
-				promisedOutcome.set_value();
-		}
-		catch (const std::future_error& future_error) {
-			if (future_error.code() != std::future_errc::promise_already_satisfied) throw;
-			Log() << "Start outcome already set";
-			return;
-		}
-		Log() << "Start outcome set";
-		}) {
-		Log() << "Waiting for start outcome";
-		promisedOutcome.get_future().get();
-		Log() << "Start outcome is OK";
-	}
-
-	ActiveStream::StartThread::~StartThread() {
-		if (thread.joinable()) {
-			Log() << "Waiting for start thread to finish";
-			thread.join();
-			Log() << "Start thread finished";
-		}
-	}
-
-	void ActiveStream::EndWaitForStartOutcome() {
-		Log() << "Ending wait for outcome";
-		try {
-			promisedOutcome.set_value();
-		}
-		catch (const std::future_error& future_error) {
-			if (future_error.code() != std::future_errc::promise_already_satisfied) throw;
-			Log() << "Start outcome already set";
-			return;
-		}
-		Log() << "Outcome wait ended";
-	}
-
-	ActiveStream::~ActiveStream() {
+	void StreamStopper::operator()(PaStream* stream) throw() {
 		Log() << "Stopping PortAudio stream " << stream;
 		const auto error = Pa_StopStream(stream);
 		if (error != paNoError)
 			Log() << "Unable to stop PortAudio stream: " << Pa_GetErrorText(error);
 	}
 
+	ActiveStream StartStream(PaStream* const stream) {
+		Log() << "Starting PortAudio stream " << stream;
+		const auto error = Pa_StartStream(stream);
+		if (error != paNoError) throw std::runtime_error(std::string("unable to start PortAudio stream: ") + Pa_GetErrorText(error));
+		Log() << "PortAudio stream started";
+		return ActiveStream(stream);
+	}
+
 }
diff --git a/src/flexasio/FlexASIO/portaudio.h b/src/flexasio/FlexASIO/portaudio.h
@@ -3,8 +3,6 @@
 #include <portaudio.h>
 
 #include <memory>
-#include <future>
-#include <thread>
 
 namespace flexasio {
 
@@ -14,27 +12,10 @@ namespace flexasio {
 	using Stream = std::unique_ptr<PaStream, StreamDeleter>;
 	Stream OpenStream(const PaStreamParameters *inputParameters, const PaStreamParameters *outputParameters, double sampleRate, unsigned long framesPerBuffer, PaStreamFlags streamFlags, PaStreamCallback *streamCallback, void *userData);
 
-	class ActiveStream {
-	public:
-		ActiveStream(PaStream*);
-		~ActiveStream();
-
-		void EndWaitForStartOutcome();
-
-	private:
-		class StartThread {
-		public:
-			template <typename... Args> StartThread(Args&&... args) : thread(std::forward<Args>(args)...) {}
-			~StartThread();
-
-		private:
-			std::thread thread;
-		};
-
-		PaStream* const stream;
-
-		std::promise<void> promisedOutcome;
-		StartThread startThread;
+	struct StreamStopper {
+		void operator()(PaStream*) throw();
 	};
+	using ActiveStream = std::unique_ptr<PaStream, StreamStopper>;
+	ActiveStream StartStream(PaStream*);
 
 }