Fix tape realtime play (#265)

Author: prybicki

src/api/apiCore.cpp

@@ -1258,7 +1258,7 @@ RGL_API rgl_status_t rgl_tape_play(const char* path)
 			throw RecordError("rgl_tape_play: recording active");
 		} else {
 			TapePlayer player(path);
-			player.playRealtime();
+			player.playApproximatelyRealtime();
 		}
 	});
 #endif //_WIN32

src/tape/TapePlayer.cpp

@@ -15,6 +15,7 @@
 #include <filesystem>
 #include <fstream>
 #include <cassert>
+#include <thread>
 
 #include <tape/TapePlayer.hpp>
 #include <tape/tapeDefinitions.hpp>
@@ -23,14 +24,11 @@
 
 namespace fs = std::filesystem;
 
-TapePlayer::TapePlayer(const char* path)
+TapePlayer::TapePlayer(const char* path) : path(path)
 {
-	std::string pathYaml = fs::path(path).concat(YAML_EXTENSION).string();
-	std::string pathBin = fs::path(path).concat(BIN_EXTENSION).string();
-
-	playbackState = std::make_unique<PlaybackState>(pathBin.c_str());
+	playbackState = std::make_unique<PlaybackState>(getBinPath().c_str());
 
-	yamlRoot = YAML::LoadFile(pathYaml);
+	yamlRoot = YAML::LoadFile(getYamlPath());
 	if (yamlRoot.IsNull()) {
 		throw RecordError("Invalid Tape: Empty YAML file detected");
 	}
@@ -43,6 +41,10 @@ TapePlayer::TapePlayer(const char* path)
 	nextCallIdx = 0;
 }
 
+std::string TapePlayer::getBinPath() const { return fs::path(path).concat(BIN_EXTENSION).string(); }
+
+std::string TapePlayer::getYamlPath() const { return fs::path(path).concat(YAML_EXTENSION).string(); }
+
 void TapePlayer::checkTapeVersion()
 {
 	auto versionCallIdx = findFirst({RGL_VERSION});
@@ -110,8 +112,6 @@ void TapePlayer::playUntil(std::optional<APICallIdx> breakpoint)
 	}
 }
 
-void TapePlayer::rewindTo(APICallIdx nextCall) { this->nextCallIdx = nextCall; }
-
 void TapePlayer::playThis(APICallIdx idx)
 {
 	const TapeCall& call = getTapeCall(idx);
@@ -121,15 +121,30 @@ void TapePlayer::playThis(APICallIdx idx)
 	tapeFunctions[call.getFnName()](call.getArgsNode(), *playbackState);
 }
 
-#include <thread>
-void TapePlayer::playRealtime()
+
+void TapePlayer::playApproximatelyRealtime()
 {
+	// Approximation comes from the fact that we don't account for the time it takes to execute the function
+	// This could be fixed by moving TAPE_HOOK to the beginning of the API call
+	// It might be a good idea to do so, because it would record failed calls.
 	auto beginTimestamp = std::chrono::steady_clock::now();
-	TapeCall nextCall = getTapeCall(nextCallIdx);
 	for (; nextCallIdx < yamlRoot.size(); ++nextCallIdx) {
+		TapeCall nextCall = getTapeCall(nextCallIdx);
 		auto nextCallNs = std::chrono::nanoseconds(nextCall.getTimestamp().asNanoseconds());
 		auto elapsed = std::chrono::steady_clock::now() - beginTimestamp;
 		std::this_thread::sleep_for(nextCallNs - elapsed);
 		playThis(nextCallIdx);
 	}
 }
+
+void TapePlayer::reset()
+{
+	auto status = rgl_cleanup();
+	if (status != RGL_SUCCESS) {
+		const char* error = nullptr;
+		rgl_get_last_error_string(&error);
+		throw RecordError(fmt::format("Failed to reset playback state: {}", error));
+	}
+	nextCallIdx = 0;
+	playbackState = std::make_unique<PlaybackState>(getBinPath().c_str());
+}

src/tape/TapePlayer.hpp

@@ -46,15 +46,18 @@ struct TapePlayer
 	void playThis(APICallIdx idx);
 	void playThrough(APICallIdx last);
 	void playUntil(std::optional<APICallIdx> breakpoint = std::nullopt);
-	void playRealtime();
-	void rewindTo(APICallIdx nextCall = 0);
+	void playApproximatelyRealtime();
+	void reset();
 
 	rgl_node_t getNodeHandle(TapeAPIObjectID key) { return playbackState->nodes.at(key); }
 
 private:
 	YAML::Node yamlRoot{};
 	APICallIdx nextCallIdx{};
 	std::unique_ptr<PlaybackState> playbackState;
+	std::string path;
 
 	static inline std::map<std::string, TapeFunction> tapeFunctions = {};
+	std::string getBinPath() const;
+	std::string getYamlPath() const;
 };

tools/tapePlayer.cpp

@@ -22,6 +22,9 @@ int main(int argc, char** argv)
 		return 1;
 	}
 	TapePlayer player{argv[1]};
-	player.playUntil();
+	while (true) {
+		player.playApproximatelyRealtime();
+		player.reset();
+	}
 	return 0;
 }