cocoa: move to a simpler threading model

Unfortunately using dispatch_sync for synchronization turned out to be really
bad for us. It caused a wide array of race conditions, deadlocks, etc.

Moving to a very simple mutex. It's not clear to me how to do liveresizing
with this, for now it just flickers with is unacceptable (maybe I'll draw
black instead).

This should fix all the threading cocoa bugs. Reopen if it's not the case!

Fixes #751
Fixes #1129

7 files changed, 37 insertions, 114 deletions

diff --git a/video/out/cocoa/mpvadapter.h b/video/out/cocoa/mpvadapter.h
index af536d2f56..205b2b1443 100644
--- a/video/out/cocoa/mpvadapter.h
+++ b/video/out/cocoa/mpvadapter.h
@@ -19,12 +19,13 @@
 #include "video/out/vo.h"
 
 @interface MpvCocoaAdapter : NSObject
+- (void)lock;
+- (void)unlock;
 - (void)setNeedsResize;
 - (void)signalMouseMovement:(NSPoint)point;
 - (void)putKey:(int)mpkey withModifiers:(int)modifiers;
 - (void)putAxis:(int)mpkey delta:(float)delta;
 - (void)putCommand:(char*)cmd;
-- (void)performAsyncResize:(NSSize)size;
 - (void)handleFilesArray:(NSArray *)files;
 - (void)didChangeWindowedScreenProfile:(NSScreen *)screen;
 
diff --git a/video/out/cocoa/view.m b/video/out/cocoa/view.m
index f5b69a7fbc..0c5a92123e 100644
--- a/video/out/cocoa/view.m
+++ b/video/out/cocoa/view.m
@@ -229,8 +229,9 @@
 
 - (void)drawRect:(NSRect)rect
 {
-    [self.adapter performAsyncResize:[self frameInPixels].size];
+    [self.adapter lock];
     [self.adapter setNeedsResize];
+    [self.adapter unlock];
 }
 
 - (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
diff --git a/video/out/cocoa_common.m b/video/out/cocoa_common.m
index dc7a195442..cbfcaa1359 100644
--- a/video/out/cocoa_common.m
+++ b/video/out/cocoa_common.m
@@ -27,6 +27,7 @@
 #include "video/out/cocoa/view.h"
 #import "video/out/cocoa/mpvadapter.h"
 
+#include "osdep/threads.h"
 #include "osdep/macosx_compat.h"
 #include "osdep/macosx_events_objc.h"
 
@@ -47,6 +48,8 @@
 #include "common/msg.h"
 
 #define CF_RELEASE(a) if ((a) != NULL) CFRelease(a)
+#define cocoa_lock(s)    pthread_mutex_lock(&s->mutex)
+#define cocoa_unlock(s)  pthread_mutex_unlock(&s->mutex)
 
 static void vo_cocoa_fullscreen(struct vo *vo);
 static void vo_cocoa_ontop(struct vo *vo);
@@ -64,16 +67,12 @@ struct vo_cocoa_state {
     NSInteger window_level;
 
     bool did_resize;
-    bool skip_next_swap_buffer;
-    bool inside_sync_section;
 
     IOPMAssertionID power_mgmt_assertion;
 
-    NSLock *lock;
-    bool enable_resize_redraw;
+    pthread_mutex_t mutex;
     void *ctx;
     void (*gl_clear)(void *ctx);
-    void (*resize_redraw)(struct vo *vo, int w, int h);
 
     struct mp_log *log;
 
@@ -86,18 +85,19 @@ struct vo_cocoa_state {
     id   fs_icc_changed_ns_observer;
 };
 
-static void dispatch_on_main_thread(struct vo *vo, void(^block)(void))
+static void with_cocoa_lock(struct vo *vo, void(^block)(void))
 {
     struct vo_cocoa_state *s = vo->cocoa;
-    if (!s->inside_sync_section) {
-        dispatch_sync(dispatch_get_main_queue(), ^{
-            s->inside_sync_section = true;
-            block();
-            s->inside_sync_section = false;
-        });
-    } else {
-        block();
-    }
+    cocoa_lock(s);
+    block();
+    cocoa_unlock(s);
+}
+
+static void with_cocoa_lock_on_main_thread(struct vo *vo, void(^block)(void))
+{
+    dispatch_async(dispatch_get_main_queue(), ^{
+        with_cocoa_lock(vo, block);
+    });
 }
 
 void *vo_cocoa_glgetaddr(const char *s)
@@ -137,14 +137,11 @@ int vo_cocoa_init(struct vo *vo)
     struct vo_cocoa_state *s = talloc_zero(vo, struct vo_cocoa_state);
     *s = (struct vo_cocoa_state){
         .did_resize = false,
-        .skip_next_swap_buffer = false,
-        .inside_sync_section = false,
         .power_mgmt_assertion = kIOPMNullAssertionID,
-        .lock = [[NSLock alloc] init],
-        .enable_resize_redraw = NO,
         .log = mp_log_new(s, vo->log, "cocoa"),
         .icc_profile_path_changed = false,
     };
+    mpthread_mutex_init_recursive(&s->mutex);
     vo->cocoa = s;
     return 1;
 }
@@ -164,7 +161,7 @@ static void vo_cocoa_set_cursor_visibility(struct vo *vo, bool *visible)
 
 void vo_cocoa_uninit(struct vo *vo)
 {
-    dispatch_sync(dispatch_get_main_queue(), ^{
+    with_cocoa_lock(vo, ^{
         struct vo_cocoa_state *s = vo->cocoa;
         enable_power_management(vo);
         cocoa_rm_fs_screen_profile_observer(vo);
@@ -179,19 +176,9 @@ void vo_cocoa_uninit(struct vo *vo)
 
         [s->window release];
         s->window = nil;
-
-        [s->lock release];
-        s->lock = nil;
     });
 }
 
-void vo_cocoa_register_resize_callback(struct vo *vo,
-                                       void (*cb)(struct vo *vo, int w, int h))
-{
-    struct vo_cocoa_state *s = vo->cocoa;
-    s->resize_redraw = cb;
-}
-
 void vo_cocoa_register_gl_clear_callback(struct vo *vo, void *ctx,
                                          void (*cb)(void *ctx))
 {
@@ -343,31 +330,6 @@ static void cocoa_set_window_title(struct vo *vo, const char *title)
     talloc_free(talloc_ctx);
 }
 
-static void vo_cocoa_resize_redraw(struct vo *vo, int width, int height)
-{
-    struct vo_cocoa_state *s = vo->cocoa;
-
-    if (!s->resize_redraw)
-        return;
-
-    if (!s->gl_ctx)
-        return;
-
-    vo_cocoa_set_current_context(vo, true);
-
-    [s->gl_ctx update];
-
-    if (s->enable_resize_redraw) {
-        s->resize_redraw(vo, width, height);
-        s->skip_next_swap_buffer = true;
-    } else {
-        s->gl_clear(s->ctx);
-    }
-
-    [s->gl_ctx flushBuffer];
-    vo_cocoa_set_current_context(vo, false);
-}
-
 static void cocoa_rm_fs_screen_profile_observer(struct vo *vo)
 {
     struct vo_cocoa_state *s = vo->cocoa;
@@ -416,9 +378,7 @@ int vo_cocoa_config_window(struct vo *vo, uint32_t flags, void *gl_ctx)
     struct vo_cocoa_state *s = vo->cocoa;
     __block int ctxok = 0;
 
-    dispatch_on_main_thread(vo, ^{
-        s->enable_resize_redraw = false;
-
+    with_cocoa_lock(vo, ^{
         struct mp_rect screenrc;
         vo_cocoa_update_screen_info(vo, &screenrc);
 
@@ -443,8 +403,6 @@ int vo_cocoa_config_window(struct vo *vo, uint32_t flags, void *gl_ctx)
             vo_cocoa_fullscreen(vo);
             cocoa_add_fs_screen_profile_observer(vo);
         }
-
-        s->enable_resize_redraw = true;
     });
 
     if (ctxok < 0)
@@ -460,31 +418,18 @@ void vo_cocoa_set_current_context(struct vo *vo, bool current)
     struct vo_cocoa_state *s = vo->cocoa;
 
     if (current) {
-        if (!s->inside_sync_section)
-            [s->lock lock];
-
-        if (s->gl_ctx)
-            [s->gl_ctx makeCurrentContext];
+        cocoa_lock(s);
+        if (s->gl_ctx) [s->gl_ctx makeCurrentContext];
     } else {
         [NSOpenGLContext clearCurrentContext];
-
-        if (!s->inside_sync_section)
-            [s->lock unlock];
+        cocoa_unlock(s);
     }
 }
 
 void vo_cocoa_swap_buffers(struct vo *vo)
 {
     struct vo_cocoa_state *s = vo->cocoa;
-    if (s->skip_next_swap_buffer) {
-        // When in live resize the GL view asynchronously updates itself from
-        // it's drawRect: implementation and calls flushBuffer. This means the
-        // backbuffer is probably in an inconsistent state, so we skip one
-        // flushBuffer call here on the playloop thread.
-        s->skip_next_swap_buffer = false;
-    } else {
-        [s->gl_ctx flushBuffer];
-    }
+    [s->gl_ctx flushBuffer];
 }
 
 int vo_cocoa_check_events(struct vo *vo)
@@ -507,10 +452,8 @@ int vo_cocoa_check_events(struct vo *vo)
 
 static void vo_cocoa_fullscreen_sync(struct vo *vo)
 {
-    dispatch_on_main_thread(vo, ^{
-        vo->cocoa->enable_resize_redraw = false;
+    with_cocoa_lock_on_main_thread(vo, ^{
         vo_cocoa_fullscreen(vo);
-        vo->cocoa->enable_resize_redraw = true;
     });
 }
 
@@ -651,14 +594,13 @@ int vo_cocoa_control(struct vo *vo, int *events, int request, void *arg)
         return VO_TRUE;
     case VOCTRL_FULLSCREEN:
         vo_cocoa_fullscreen_sync(vo);
-        *events |= VO_EVENT_RESIZE;
         return VO_TRUE;
     case VOCTRL_ONTOP:
         vo_cocoa_ontop(vo);
         return VO_TRUE;
     case VOCTRL_GET_UNFS_WINDOW_SIZE: {
         int *s = arg;
-        dispatch_on_main_thread(vo, ^{
+        with_cocoa_lock(vo, ^{
             NSSize size = [vo->cocoa->view frame].size;
             s[0] = size.width;
             s[1] = size.height;
@@ -666,7 +608,7 @@ int vo_cocoa_control(struct vo *vo, int *events, int request, void *arg)
         return VO_TRUE;
     }
     case VOCTRL_SET_UNFS_WINDOW_SIZE: {
-        dispatch_on_main_thread(vo, ^{
+        with_cocoa_lock(vo, ^{
             int *s = arg;
             [vo->cocoa->window queueNewVideoSize:NSMakeSize(s[0], s[1])];
         });
@@ -705,6 +647,14 @@ void *vo_cocoa_cgl_pixel_format(struct vo *vo)
 @implementation MpvCocoaAdapter
 @synthesize vout = _video_output;
 
+- (void)lock {
+    vo_cocoa_set_current_context(self.vout, true);
+}
+
+- (void)unlock {
+    vo_cocoa_set_current_context(self.vout, false);
+}
+
 - (void)setNeedsResize {
     struct vo_cocoa_state *s = self.vout->cocoa;
     s->did_resize = true;
@@ -743,10 +693,6 @@ void *vo_cocoa_cgl_pixel_format(struct vo *vo)
     ta_free(cmd_);
 }
 
-- (void)performAsyncResize:(NSSize)size {
-    vo_cocoa_resize_redraw(self.vout, size.width, size.height);
-}
-
 - (BOOL)isInFullScreenMode {
     return self.vout->opts->fullscreen;
 }
diff --git a/video/out/gl_cocoa.c b/video/out/gl_cocoa.c
index 9df1eec4cc..428dce2e0e 100644
--- a/video/out/gl_cocoa.c
+++ b/video/out/gl_cocoa.c
@@ -157,7 +157,6 @@ void mpgl_set_backend_cocoa(MPGLContext *ctx)
     ctx->releaseGlContext = releaseGlContext_cocoa;
     ctx->swapGlBuffers = swapGlBuffers_cocoa;
     ctx->vo_init = vo_cocoa_init;
-    ctx->register_resize_callback = vo_cocoa_register_resize_callback;
     ctx->vo_uninit = vo_cocoa_uninit;
     ctx->vo_control = vo_cocoa_control;
     ctx->set_current = set_current_cocoa;
diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index 5923a697e9..5608b48938 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -2388,18 +2388,6 @@ static int validate_scaler_opt(struct mp_log *log, const m_option_t *opt,
     return handle_scaler_opt(s) ? 1 : M_OPT_INVALID;
 }
 
-// Resize and redraw the contents of the window without further configuration.
-// Intended to be used in situations where the frontend can't really be
-// involved with reconfiguring the VO properly.
-// gl_video_resize() should be called when user interaction is done.
-void gl_video_resize_redraw(struct gl_video *p, int w, int h)
-{
-    p->gl->Viewport(p->vp_x, p->vp_y, w, h);
-    p->vp_w = w;
-    p->vp_h = h;
-    gl_video_render_frame(p);
-}
-
 void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec)
 {
     p->hwdec = hwdec;
diff --git a/video/out/gl_video.h b/video/out/gl_video.h
index 8ea5d3420f..47d09d7f57 100644
--- a/video/out/gl_video.h
+++ b/video/out/gl_video.h
@@ -74,7 +74,6 @@ bool gl_video_set_equalizer(struct gl_video *p, const char *name, int val);
 bool gl_video_get_equalizer(struct gl_video *p, const char *name, int *val);
 
 void gl_video_set_debug(struct gl_video *p, bool enable);
-void gl_video_resize_redraw(struct gl_video *p, int w, int h);
 
 struct gl_hwdec;
 void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec);
diff --git a/video/out/vo_opengl.c b/video/out/vo_opengl.c
index 3b6e3a2e43..1acd6ef466 100644
--- a/video/out/vo_opengl.c
+++ b/video/out/vo_opengl.c
@@ -203,13 +203,6 @@ static bool config_window(struct gl_priv *p, int flags)
     return mpgl_config_window(p->glctx, mpgl_caps, flags);
 }
 
-static void video_resize_redraw_callback(struct vo *vo, int w, int h)
-{
-    struct gl_priv *p = vo->priv;
-    gl_video_resize_redraw(p->renderer, w, h);
-
-}
-
 static int reconfig(struct vo *vo, struct mp_image_params *params, int flags)
 {
     struct gl_priv *p = vo->priv;
@@ -221,10 +214,6 @@ static int reconfig(struct vo *vo, struct mp_image_params *params, int flags)
         return -1;
     }
 
-    if (p->glctx->register_resize_callback) {
-        p->glctx->register_resize_callback(vo, video_resize_redraw_callback);
-    }
-
     gl_video_config(p->renderer, params);
 
     p->vo_flipped = !!(flags & VOFLAG_FLIPPING);