[GStreamer] GL/DMABuf logging improvements

https://bugs.webkit.org/show_bug.cgi?id=274146

Reviewed by Xabier Rodriguez-Calvar.

The webkitdisplay GST_DEBUG category can be used to diagnose WebKit/GL errors now. The DMABuf
rendering code path was also instrumented with logs in order to help diagnosing issues.

* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp:
(WebCore::MediaPlayerPrivateGStreamer::pushDMABufToCompositor):
* Source/WebCore/platform/graphics/gstreamer/PlatformDisplayGStreamer.cpp:
(WebCore::ensureDebugCategoryInitialized):
(WebCore::PlatformDisplay::gstGLContext const):

Canonical link: https://commits.webkit.org/278802@main

Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp

@@ -3448,8 +3448,10 @@ void MediaPlayerPrivateGStreamer::pushDMABufToCompositor()
     ASSERT(is<TextureMapperPlatformLayerProxyDMABuf>(proxy));
 
     Locker locker { proxy.lock() };
-    if (!proxy.isActive())
+    if (!proxy.isActive()) {
+        GST_ERROR_OBJECT(pipeline(), "TextureMapperPlatformLayerProxyDMABuf is inactive");
         return;
+    }
 
     // Currently we have to cover two ways of detecting a DMABuf memory. The most reliable is by detecting
     // the memory:DMABuf feature on the GstCaps object. All sensible decoders yielding DMABufs specify this.
@@ -3544,12 +3546,16 @@ void MediaPlayerPrivateGStreamer::pushDMABufToCompositor()
         .height = static_cast<uint32_t>GST_VIDEO_INFO_HEIGHT(&videoInfo),
         .flags = GBMBufferSwapchain::BufferDescription::LinearStorage,
     };
-    if (bufferDescription.format.fourcc == DMABufFormat::FourCC::Invalid)
+    if (bufferDescription.format.fourcc == DMABufFormat::FourCC::Invalid) {
+        GST_ERROR_OBJECT(pipeline(), "Invalid DMABuf fourcc for GStreamer video format %s", gst_video_format_to_string(GST_VIDEO_INFO_FORMAT(&videoInfo)));
         return;
+    }
 
     auto swapchainBuffer = m_swapchain->getBuffer(bufferDescription);
-    if (!swapchainBuffer)
+    if (!swapchainBuffer) {
+        GST_ERROR_OBJECT(pipeline(), "Swap chain has no available buffer");
         return;
+    }
 
     // Destination helper struct, maps the gbm_bo object into CPU-memory space and copies from the accompanying Source in fill().
     struct Destination {
@@ -3614,6 +3620,7 @@ void MediaPlayerPrivateGStreamer::pushDMABufToCompositor()
     // The updated buffer is pushed into the composition stage. The DMABufObject handle uses the swapchain address as the handle base.
     // When the buffer is pushed for the first time, the lambda will be invoked to retrieve a more complete DMABufObject for the
     // given GBMBufferSwapchain::Buffer object.
+    GST_TRACE_OBJECT(pipeline(), "Pushing DMABuf object to TextureMapper");
     downcast<TextureMapperPlatformLayerProxyDMABuf>(proxy).pushDMABuf(
         DMABufObject(reinterpret_cast<uintptr_t>(m_swapchain.get()) + swapchainBuffer->handle()),
         [&](auto&& initialObject) {

Source/WebCore/platform/graphics/gstreamer/PlatformDisplayGStreamer.cpp

@@ -32,41 +32,58 @@
 #undef GST_USE_UNSTABLE_API
 #include <wtf/glib/GUniquePtr.h>
 
-GST_DEBUG_CATEGORY_EXTERN(webkit_media_player_debug);
-#define GST_CAT_DEFAULT webkit_media_player_debug
+GST_DEBUG_CATEGORY(webkit_display_debug);
+#define GST_CAT_DEFAULT webkit_display_debug
 
 namespace WebCore {
 
+static void ensureDebugCategoryInitialized()
+{
+    static std::once_flag debugRegisteredFlag;
+    std::call_once(debugRegisteredFlag, [] {
+        GST_DEBUG_CATEGORY_INIT(webkit_display_debug, "webkitdisplay", 0, "WebKit Display");
+    });
+}
+
 GstGLDisplay* PlatformDisplay::gstGLDisplay() const
 {
+    ensureDebugCategoryInitialized();
     if (!m_gstGLDisplay)
         m_gstGLDisplay = adoptGRef(GST_GL_DISPLAY(gst_gl_display_egl_new_with_egl_display(eglDisplay())));
+    GST_TRACE("Using GL display %" GST_PTR_FORMAT, m_gstGLDisplay.get());
     return m_gstGLDisplay.get();
 }
 
 GstGLContext* PlatformDisplay::gstGLContext() const
 {
+    ensureDebugCategoryInitialized();
+
     if (m_gstGLContext)
         return m_gstGLContext.get();
 
     auto* gstDisplay = gstGLDisplay();
-    if (!gstDisplay)
+    if (!gstDisplay) {
+        GST_ERROR("No GL display");
         return nullptr;
+    }
 
     auto* context = const_cast<PlatformDisplay*>(this)->sharingGLContext();
-    if (!context)
+    if (!context) {
+        GST_ERROR("No sharing GL context");
         return nullptr;
+    }
 
     m_gstGLContext = adoptGRef(gst_gl_context_new_wrapped(gstDisplay, reinterpret_cast<guintptr>(context->platformContext()), GST_GL_PLATFORM_EGL, GST_GL_API_GLES2));
     {
         GLContext::ScopedGLContextCurrent scopedCurrent(*context);
         if (gst_gl_context_activate(m_gstGLContext.get(), TRUE)) {
             GUniqueOutPtr<GError> error;
             if (!gst_gl_context_fill_info(m_gstGLContext.get(), &error.outPtr()))
-                GST_WARNING("Failed to fill in GStreamer context: %s", error->message);
+                GST_ERROR("Failed to fill in GStreamer context: %s", error->message);
             gst_gl_context_activate(m_gstGLContext.get(), FALSE);
         }
     }
+    GST_DEBUG("Created GL context %" GST_PTR_FORMAT, m_gstGLContext.get());
     return m_gstGLContext.get();
 }
 
@@ -78,4 +95,6 @@ void PlatformDisplay::clearGStreamerGLState()
 
 } // namespace WebCore
 
+#undef GST_CAT_DEFAULT
+
 #endif // USE(GSTREAMER_GL)