From 5b452a9d75b24db2dc2f5b2f5b4f31d710384d2a Mon Sep 17 00:00:00 2001
From: Davide Beatrici <git@davidebeatrici.dev>
Date: Sun, 24 Mar 2024 00:15:12 +0100
Subject: [PATCH] OSS: Use std::atomic_flag instead of PauseFlag

We couldn't do it before because the functions we need were introduced in C++20.
---
 src/backends/OSS/CMakeLists.txt |  1 -
 src/backends/OSS/OSS.cpp        | 19 +++++++++++------
 src/backends/OSS/OSS.hpp        |  3 +--
 src/backends/OSS/PauseFlag.hpp  | 36 ---------------------------------
 4 files changed, 14 insertions(+), 45 deletions(-)
 delete mode 100644 src/backends/OSS/PauseFlag.hpp

diff --git a/src/backends/OSS/CMakeLists.txt b/src/backends/OSS/CMakeLists.txt
index ad53981..34b2df0 100644
--- a/src/backends/OSS/CMakeLists.txt
+++ b/src/backends/OSS/CMakeLists.txt
@@ -41,7 +41,6 @@ target_sources(be_oss
 		"FileDescriptor.hpp"
 		"OSS.cpp"
 		"OSS.hpp"
-		"PauseFlag.hpp"
 )
 
 target_link_libraries(be_oss
diff --git a/src/backends/OSS/OSS.cpp b/src/backends/OSS/OSS.cpp
index 6d84bbf..94657df 100644
--- a/src/backends/OSS/OSS.cpp
+++ b/src/backends/OSS/OSS.cpp
@@ -367,7 +367,8 @@ ErrorCode Flux::start(FluxConfig &config, const FluxFeedback &feedback) {
 
 ErrorCode Flux::stop() {
 	m_halt = true;
-	m_pause.set(false);
+	m_pause.clear();
+	m_pause.notify_all();
 
 	if (m_thread) {
 		m_thread->join();
@@ -380,7 +381,13 @@ ErrorCode Flux::stop() {
 }
 
 ErrorCode Flux::pause(const bool on) {
-	m_pause.set(on);
+	if (on) {
+		m_pause.test_and_set();
+	} else {
+		m_pause.clear();
+	}
+
+	m_pause.notify_all();
 
 	return CROSSAUDIO_EC_OK;
 }
@@ -409,8 +416,8 @@ void Flux::processInput() {
 		FluxData fluxData = { buffer.data(), static_cast< uint32_t >(bytes / frameSize) };
 		m_feedback.process(m_feedback.userData, &fluxData);
 
-		if (m_pause) {
-			m_pause.wait(false);
+		if (m_pause.test()) {
+			m_pause.wait(true);
 		}
 	}
 
@@ -431,9 +438,9 @@ void Flux::processOutput() {
 			break;
 		}
 
-		if (m_pause) {
+		if (m_pause.test()) {
 			ioctl(m_fd.get(), SNDCTL_DSP_SILENCE, 0);
-			m_pause.wait(false);
+			m_pause.wait(true);
 			ioctl(m_fd.get(), SNDCTL_DSP_SKIP, 0);
 		}
 	}
diff --git a/src/backends/OSS/OSS.hpp b/src/backends/OSS/OSS.hpp
index 578c99d..21dabce 100644
--- a/src/backends/OSS/OSS.hpp
+++ b/src/backends/OSS/OSS.hpp
@@ -7,7 +7,6 @@
 #define CROSSAUDIO_SRC_BACKENDS_OSS_OSS_HPP
 
 #include "FileDescriptor.hpp"
-#include "PauseFlag.hpp"
 
 #include "crossaudio/ErrorCode.h"
 #include "crossaudio/Flux.h"
@@ -86,8 +85,8 @@ class Flux {
 
 	FileDescriptor m_fd;
 
-	PauseFlag m_pause;
 	std::atomic_bool m_halt;
+	std::atomic_flag m_pause;
 	std::unique_ptr< std::thread > m_thread;
 };
 } // namespace oss
diff --git a/src/backends/OSS/PauseFlag.hpp b/src/backends/OSS/PauseFlag.hpp
deleted file mode 100644
index 000aff5..0000000
--- a/src/backends/OSS/PauseFlag.hpp
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright 2024 The Mumble Developers. All rights reserved.
-// Use of this source code is governed by a BSD-style license
-// that can be found in the LICENSE file at the root of the
-// Mumble source tree or at <https://www.mumble.info/LICENSE>.
-
-#ifndef CROSSAUDIO_SRC_BACKENDS_OSS_PAUSEFLAG_HPP
-#define CROSSAUDIO_SRC_BACKENDS_OSS_PAUSEFLAG_HPP
-
-#include <atomic>
-#include <condition_variable>
-#include <mutex>
-
-class PauseFlag {
-public:
-	PauseFlag() : m_paused(false) {}
-	~PauseFlag() {}
-
-	explicit operator bool() const { return m_paused; }
-
-	void set(const bool value) {
-		m_paused = value;
-		m_change.notify_all();
-	}
-
-	void wait(const bool value) {
-		std::mutex mutex;
-		std::unique_lock lock(mutex);
-		m_change.wait(lock, [this, value] { return m_paused == value; });
-	}
-
-private:
-	std::atomic_bool m_paused;
-	std::condition_variable m_change;
-};
-
-#endif