[vlc-commits] vout: ios: fix previousEaglContext being overridden

[Thomas Guillem]

vlc | branch: master | Thomas Guillem <thomas at gllm.fr> | Tue Mar  6 09:21:30 2018 +0100| [d5b6c4d8e01c3ceddd4efafee9e84b4688a8e0a3] | committer: Thomas Guillem

vout: ios: fix previousEaglContext being overridden

This commit fixes the previousEaglContext variable being overridden when the
glESView is locked from the main thread and from the vout thread. This variable
should only by read/write from a same thread.

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=d5b6c4d8e01c3ceddd4efafee9e84b4688a8e0a3
---

 modules/video_output/ios.m | 64 +++++++++++++++++++++++++++-------------------
 1 file changed, 38 insertions(+), 26 deletions(-)

diff --git a/modules/video_output/ios.m b/modules/video_output/ios.m
index a298bad621..92cf920720 100644
--- a/modules/video_output/ios.m
+++ b/modules/video_output/ios.m
@@ -88,7 +88,6 @@ vlc_module_end ()
 @interface VLCOpenGLES2VideoView : UIView {
     vout_display_t *_voutDisplay;
     EAGLContext *_eaglContext;
-    EAGLContext *_previousEaglContext;
     GLuint _renderBuffer;
     GLuint _frameBuffer;
 
@@ -97,20 +96,20 @@ vlc_module_end ()
     BOOL _bufferNeedReset;
     BOOL _appActive;
 
+    /* Written from MT, read locked from vout */
     vout_display_place_t _place;
 }
 @property (readonly) GLuint renderBuffer;
 @property (readonly) GLuint frameBuffer;
 @property (readwrite) vout_display_t* voutDisplay;
 @property (readonly) EAGLContext* eaglContext;
- at property (readonly) BOOL isAppActive;
 @property GLuint shaderProgram;
 
 - (void)createBuffers;
 - (void)destroyBuffers;
 - (void)resetBuffers;
-- (void)makeCurrent;
-- (void)releaseCurrent;
+- (BOOL)makeCurrent:(EAGLContext **)previousEaglContext;
+- (void)releaseCurrent:(EAGLContext *)previousEaglContext;
 
 - (void)setPlace:(const vout_display_place_t *)place;
 - (void)reshape;
@@ -133,6 +132,7 @@ struct vout_display_sys_t
 struct gl_sys
 {
     VLCOpenGLES2VideoView *glESView;
+    EAGLContext *previousEaglContext;
 };
 
 static void *OurGetProcAddress(vlc_gl_t *gl, const char *name)
@@ -396,10 +396,9 @@ static int GLESMakeCurrent(vlc_gl_t *gl)
 {
     struct gl_sys *sys = gl->sys;
 
-    if (unlikely(![sys->glESView isAppActive]))
+    if (![sys->glESView makeCurrent:&sys->previousEaglContext])
         return VLC_EGENERIC;
 
-    [sys->glESView makeCurrent];
     [sys->glESView resetBuffers];
     return VLC_SUCCESS;
 }
@@ -408,15 +407,14 @@ static void GLESReleaseCurrent(vlc_gl_t *gl)
 {
     struct gl_sys *sys = gl->sys;
 
-    [sys->glESView releaseCurrent];
+    [sys->glESView releaseCurrent:sys->previousEaglContext];
 }
 
 static void GLESSwap(vlc_gl_t *gl)
 {
     struct gl_sys *sys = gl->sys;
 
-    if (likely([sys->glESView isAppActive]))
-        [[sys->glESView eaglContext] presentRenderbuffer:GL_RENDERBUFFER];
+    [[sys->glESView eaglContext] presentRenderbuffer:GL_RENDERBUFFER];
 }
 
 
@@ -424,7 +422,7 @@ static void GLESSwap(vlc_gl_t *gl)
  * Our UIView object
  *****************************************************************************/
 @implementation VLCOpenGLES2VideoView
- at synthesize voutDisplay = _voutDisplay, eaglContext = _eaglContext, isAppActive = _appActive;
+ at synthesize voutDisplay = _voutDisplay, eaglContext = _eaglContext;
 
 + (Class)layerClass
 {
@@ -454,7 +452,7 @@ static void GLESSwap(vlc_gl_t *gl)
      * need if there is already an active context created by another OpenGL
      * provider we cache it and restore analog to the
      * makeCurrent/releaseCurrent pattern used through-out the class */
-    _previousEaglContext = [EAGLContext currentContext];
+    EAGLContext *previousEaglContext = [EAGLContext currentContext];
 
     _eaglContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
 
@@ -471,7 +469,7 @@ static void GLESSwap(vlc_gl_t *gl)
 
     self.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
 
-    [self releaseCurrent];
+    [self releaseCurrent:previousEaglContext];
 
     return self;
 }
@@ -568,11 +566,9 @@ static void GLESSwap(vlc_gl_t *gl)
         return;
     }
 
-    if (unlikely(!_appActive)) {
+    EAGLContext *previousEaglContext;
+    if (![self makeCurrent:&previousEaglContext])
         return;
-    }
-
-    [self makeCurrent];
 
     glDisable(GL_DEPTH_TEST);
 
@@ -590,7 +586,7 @@ static void GLESSwap(vlc_gl_t *gl)
             msg_Err(_voutDisplay, "Failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
     }
 
-    [self releaseCurrent];
+    [self releaseCurrent:previousEaglContext];
 }
 
 - (void)destroyBuffers
@@ -603,7 +599,9 @@ static void GLESSwap(vlc_gl_t *gl)
         return;
     }
 
-    [self makeCurrent];
+    EAGLContext *previousEaglContext;
+    if (![self makeCurrent:&previousEaglContext])
+        return;
 
     /* clear frame buffer */
     glDeleteFramebuffers(1, &_frameBuffer);
@@ -613,7 +611,7 @@ static void GLESSwap(vlc_gl_t *gl)
     glDeleteRenderbuffers(1, &_renderBuffer);
     _renderBuffer = 0;
 
-    [self releaseCurrent];
+    [self releaseCurrent:previousEaglContext];
 }
 
 - (void)resetBuffers
@@ -625,15 +623,27 @@ static void GLESSwap(vlc_gl_t *gl)
     }
 }
 
-- (void)makeCurrent
+- (BOOL)makeCurrent:(EAGLContext **)previousEaglContext
 {
-    _previousEaglContext = [EAGLContext currentContext];
-    [EAGLContext setCurrentContext:_eaglContext];
+    vlc_mutex_lock(&_mutex);
+
+    if (unlikely(!_appActive))
+    {
+        vlc_mutex_unlock(&_mutex);
+        return NO;
+    }
+
+    *previousEaglContext = [EAGLContext currentContext];
+
+    BOOL success = [EAGLContext setCurrentContext:_eaglContext];
+
+    vlc_mutex_unlock(&_mutex);
+    return success;
 }
 
-- (void)releaseCurrent
+- (void)releaseCurrent:(EAGLContext *)previousEaglContext
 {
-    [EAGLContext setCurrentContext:_previousEaglContext];
+    [EAGLContext setCurrentContext:previousEaglContext];
 }
 
 - (void)layoutSubviews
@@ -653,7 +663,9 @@ static void GLESSwap(vlc_gl_t *gl)
         return;
     }
 
-    [self makeCurrent];
+    EAGLContext *previousEaglContext;
+    if (![self makeCurrent:&previousEaglContext])
+        return;
 
     CGSize viewSize = [self bounds].size;
     CGFloat scaleFactor = self.contentScaleFactor;
@@ -673,7 +685,7 @@ static void GLESSwap(vlc_gl_t *gl)
 
     // x / y are top left corner, but we need the lower left one
     glViewport(place.x, place.y, place.width, place.height);
-    [self releaseCurrent];
+    [self releaseCurrent:previousEaglContext];
 }
 
 - (void)tapRecognized:(UITapGestureRecognizer *)tapRecognizer