ui/app: add Lock/Unlock to Context for macOS

Without locking, asynchronous OpenGL rendering crashes on macOS.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

ui/app/egl.go

@@ -114,6 +114,10 @@ func (c *context) Functions() *gl.Functions {
 	return c.c
 }
 
+func (c *context) Lock() {}
+
+func (c *context) Unlock() {}
+
 func (c *context) MakeCurrent() error {
 	w, width, height := c.driver.nativeWindow(int(c.eglCtx.visualID))
 	win := _EGLNativeWindowType(w)

ui/app/gl_ios.go

@@ -83,6 +83,10 @@ func (c *context) Present() error {
 	return nil
 }
 
+func (c *context) Lock() {}
+
+func (c *context) Unlock() {}
+
 func (c *context) MakeCurrent() error {
 	if C.gio_makeCurrent(c.ctx) == 0 {
 		C.CFRelease(c.ctx)

ui/app/gl_js.go

@@ -62,6 +62,10 @@ func (c *context) Present() error {
 	return nil
 }
 
+func (c *context) Lock() {}
+
+func (c *context) Unlock() {}
+
 func (c *context) MakeCurrent() error {
 	if c.srgbFBO == nil {
 		var err error

ui/app/gl_macos.go

@@ -44,17 +44,30 @@ func (c *context) Functions() *gl.Functions {
 }
 
 func (c *context) Release() {
+	c.Lock()
+	defer c.Unlock()
 	C.gio_clearCurrentContext()
 	C.CFRelease(c.ctx)
 	c.ctx = 0
 }
 
 func (c *context) Present() error {
+	// Assume the caller already locked the context.
 	C.glFlush()
 	return nil
 }
 
+func (c *context) Lock() {
+	C.gio_lockContext(c.ctx)
+}
+
+func (c *context) Unlock() {
+	C.gio_unlockContext(c.ctx)
+}
+
 func (c *context) MakeCurrent() error {
+	c.Lock()
+	defer c.Unlock()
 	C.gio_makeCurrentContext(c.ctx)
 	return nil
 }

ui/app/gl_macos.h

@@ -5,3 +5,5 @@ __attribute__ ((visibility ("hidden"))) CFTypeRef gio_contextForView(CFTypeRef v
 __attribute__ ((visibility ("hidden"))) void gio_makeCurrentContext(CFTypeRef ctx);
 __attribute__ ((visibility ("hidden"))) void gio_flushContextBuffer(CFTypeRef ctx);
 __attribute__ ((visibility ("hidden"))) void gio_clearCurrentContext();
+__attribute__ ((visibility ("hidden"))) void gio_lockContext(CFTypeRef ctxRef);
+__attribute__ ((visibility ("hidden"))) void gio_unlockContext(CFTypeRef ctxRef);

ui/app/gl_macos.m

@@ -151,3 +151,13 @@ void gio_makeCurrentContext(CFTypeRef ctxRef) {
 	NSOpenGLContext *ctx = (__bridge NSOpenGLContext *)ctxRef;
 	return [ctx makeCurrentContext];
 }
+
+void gio_lockContext(CFTypeRef ctxRef) {
+	NSOpenGLContext *ctx = (__bridge NSOpenGLContext *)ctxRef;
+	CGLLockContext([ctx CGLContextObj]);
+}
+
+void gio_unlockContext(CFTypeRef ctxRef) {
+	NSOpenGLContext *ctx = (__bridge NSOpenGLContext *)ctxRef;
+	CGLUnlockContext([ctx CGLContextObj]);
+}

ui/app/internal/gl/gl.go

@@ -12,6 +12,8 @@ type Context interface {
 	Present() error
 	MakeCurrent() error
 	Release()
+	Lock()
+	Unlock()
 }
 
 const (

ui/app/internal/gpu/gpu.go

@@ -202,6 +202,7 @@ func (g *GPU) renderLoop(glctx gl.Context) error {
 			case <-g.refresh:
 				g.refreshErr <- glctx.MakeCurrent()
 			case frame := <-g.frames:
+				glctx.Lock()
 				if frame.collectStats && timers == nil && ctx.caps.EXT_disjoint_timer_query {
 					timers = newTimers(ctx)
 					zopsTimer = timers.newTimer()
@@ -253,6 +254,7 @@ func (g *GPU) renderLoop(glctx gl.Context) error {
 					res.summary = fmt.Sprintf("f:%7s zt:%7s st:%7s cov:%7s", ft, zt, st, covt)
 				}
 				res.err = err
+				glctx.Unlock()
 				g.results <- res
 			case <-g.stop:
 				break loop