use atomic wait instead of semaphore

src/main.cpp

@@ -25,7 +25,6 @@
 #include "sdlwindow.hpp"
 #include "wlserver.hpp"
 #include "gpuvis_trace_utils.h"
-#include "steamcompmgr_shared.hpp"
 
 #if HAVE_OPENVR
 #include "vr_session.hpp"
@@ -763,8 +762,8 @@ int main(int argc, char **argv)
 		{
 			fprintf( stderr, "Failed to initialize OpenVR runtime\n" );
 			if ( BIsSDLSession() ) {
-				sdl_latch = -1;
-				sdlLatchSem.signal();
+				g_sdlLatch = 1;
+				g_sdlLatch.notify_one();
 			}
 			return 1;
 		}
@@ -775,8 +774,8 @@ int main(int argc, char **argv)
 	{
 		fprintf( stderr, "Failed to initialize output\n" );
 		if ( BIsSDLSession() ) {
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 		}
 		return 1;
 	}
@@ -786,8 +785,8 @@ int main(int argc, char **argv)
 		if ( !SDL_Vulkan_CreateSurface( g_SDLWindow, instance, &surface ) )
 		{
 			fprintf(stderr, "SDL_Vulkan_CreateSurface failed: %s", SDL_GetError() );
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 			return 1;
 		}
 	}
@@ -798,8 +797,8 @@ int main(int argc, char **argv)
 	{
 		fprintf( stderr, "Failed to initialize Vulkan\n" );
 		if ( BIsSDLSession() ) {
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 		}
 		return 1;
 	}
@@ -808,8 +807,8 @@ int main(int argc, char **argv)
 	{
 		fprintf( stderr, "vulkan_init_formats failed\n" );
 		if ( BIsSDLSession() ) {
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 		}
 		return 1;
 	}
@@ -818,8 +817,8 @@ int main(int argc, char **argv)
 	{
 		fprintf( stderr, "vulkan_make_output failed\n" );
 		if ( BIsSDLSession() ) {
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 		}
 		return 1;
 	}
@@ -851,8 +850,8 @@ int main(int argc, char **argv)
 		{
 			fprintf( stderr, "Cannot specify -w without -h\n" );
 			if ( BIsSDLSession() ) {
-				sdl_latch = -1;
-				sdlLatchSem.signal();
+				g_sdlLatch = 1;
+				g_sdlLatch.notify_one();
 			}
 			return 1;
 		}
@@ -865,16 +864,16 @@ int main(int argc, char **argv)
 	{
 		if ( !wlserver_init() )
 		{
-			sdl_latch = -1;
-			sdlLatchSem.signal();
+			g_sdlLatch = 1;
+			g_sdlLatch.notify_one();
 
 			fprintf( stderr, "Failed to initialize wlserver\n" );
 			return 1;
 		}
 		else
-			sdl_latch |= 1;
+			g_sdlLatch = 1;
 
-		sdlLatchSem.signal();
+		g_sdlLatch.notify_one();
 	}
 
 #if HAVE_OPENVR

src/sdlwindow.cpp

@@ -108,8 +108,7 @@ extern bool g_bForceRelativeMouse;
 
 static std::string gamescope_str = DEFAULT_TITLE;
 
-std::atomic<int64_t> sdl_latch = {0}; //sdl_latch to notify sdl thread when wl-server is fully initialized
-sem sdlLatchSem;
+std::atomic<bool> g_sdlLatch = {0}; //g_sdlLatch to notify sdl thread when wl-server is fully initialized
 
 void inputSDLThreadRun( void )
 {
@@ -184,28 +183,23 @@ void inputSDLThreadRun( void )
 	SDL_Surface *icon_surface = nullptr;
 	SDL_Cursor *cursor = nullptr;
 
-	bool latch_cleared_successfully = true;
 
 	{
-		int64_t sdl_latch_cached = sdl_latch.load(std::memory_order_relaxed);
+		bool sdlLatch_cached = g_sdlLatch.load(std::memory_order_relaxed);
 
 		bool loop_done = false;
 		while (!loop_done)
 		{
-			if ( sdl_latch_cached == 0 && (sdl_latch_cached=sdl_latch.load()) == 0)
-				sdlLatchSem.wait();
+			if ( sdlLatch_cached == 0 && (sdlLatch_cached=g_sdlLatch.load(std::memory_order_acq_rel)) == 0)
+				g_sdlLatch.wait(0);
 
 
-			if ( (sdl_latch_cached = sdl_latch.load(std::memory_order_relaxed)) < 0 ) {
-				latch_cleared_successfully = false;
-				loop_done=true;
-			}
-			if ( sdl_latch_cached != 0 && sdl_latch.load() > 0)
+			if ( sdlLatch_cached != 0)
 				loop_done=true;
 		}
 	}
 
-	while( latch_cleared_successfully && SDL_WaitEvent( &event ) )
+	while( SDL_WaitEvent( &event ) )
 	{
 		fake_timestamp++;
 

src/sdlwindow.hpp

@@ -22,5 +22,4 @@ void sdlwindow_cursor(std::shared_ptr<std::vector<uint32_t>> pixels, uint32_t wi
 
 extern SDL_Window *g_SDLWindow;
 
-extern std::atomic<int64_t> sdl_latch; //sdl_latch to notify sdl thread when wl-server is fully initialized
-extern sem sdlLatchSem;
+extern std::atomic<bool> g_sdlLatch; //sdl_latch to notify sdl thread when wl-server is fully initialized

src/steamcompmgr.cpp

@@ -1106,7 +1106,32 @@ static std::atomic<bool> g_bForceRepaint{false};
 
 static int g_nCursorScaleHeight = -1;
 
+// poor man's semaphore
+class sem
+{
+public:
+	void wait( void )
+	{
+		std::unique_lock<std::mutex> lock(mtx);
+
+		while(count == 0){
+			cv.wait(lock);
+		}
+		count--;
+	}
 
+	void signal( void )
+	{
+		std::unique_lock<std::mutex> lock(mtx);
+		count++;
+		cv.notify_one();
+	}
+
+private:
+	std::mutex mtx;
+	std::condition_variable cv;
+	int count = 0;
+};
 
 sem statsThreadSem;
 std::mutex statsEventQueueLock;

src/steamcompmgr_shared.hpp

@@ -4,39 +4,10 @@
 #include <variant>
 #include <string>
 #include "gamescope-control-protocol.h"
-#include <condition_variable>
-#include <mutex>
 
 struct commit_t;
 struct wlserver_vk_swapchain_feedback;
 
-// poor man's semaphore
-class sem
-{
-public:
-	void wait( void )
-	{
-		std::unique_lock<std::mutex> lock(mtx);
-
-		while(count == 0){
-			cv.wait(lock);
-		}
-		count--;
-	}
-
-	void signal( void )
-	{
-		std::unique_lock<std::mutex> lock(mtx);
-		count++;
-		cv.notify_one();
-	}
-
-private:
-	std::mutex mtx;
-	std::condition_variable cv;
-	int count = 0;
-};
-
 struct motif_hints_t
 {
 	unsigned long flags;