webgl: Add feature to store backtraces for each WebGL API call for easier debugging.

3 files changed, 31 insertions, 10 deletions

diff --git a/components/canvas/Cargo.toml b/components/canvas/Cargo.toml
index d65c1b4b110..4006947acf6 100644
--- a/components/canvas/Cargo.toml
+++ b/components/canvas/Cargo.toml
@@ -9,6 +9,9 @@ publish = false
 name = "canvas"
 path = "lib.rs"
 
+[features]
+webgl_backtrace = ["canvas_traits/webgl_backtrace"]
+
 [dependencies]
 azure = {git = "https://github.com/servo/rust-azure"}
 canvas_traits = {path = "../canvas_traits"}
diff --git a/components/canvas/gl_context.rs b/components/canvas/gl_context.rs
index 00e3f3ba4a9..c90ecec9cca 100644
--- a/components/canvas/gl_context.rs
+++ b/components/canvas/gl_context.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use canvas_traits::webgl::{WebGLCommand, WebGLVersion};
+use canvas_traits::webgl::{WebGLCommand, WebGLVersion, WebGLCommandBacktrace};
 use compositing::compositor_thread::{CompositorProxy, self};
 use euclid::Size2D;
 use gleam::gl;
@@ -144,13 +144,18 @@ impl GLContextWrapper {
         }
     }
 
-    pub fn apply_command(&self, cmd: WebGLCommand, state: &mut GLState) {
+    pub fn apply_command(
+        &self,
+        cmd: WebGLCommand,
+        backtrace: WebGLCommandBacktrace,
+        state: &mut GLState
+    ) {
         match *self {
             GLContextWrapper::Native(ref ctx) => {
-                WebGLImpl::apply(ctx, state, cmd);
+                WebGLImpl::apply(ctx, state, cmd, backtrace);
             }
             GLContextWrapper::OSMesa(ref ctx) => {
-                WebGLImpl::apply(ctx, state, cmd);
+                WebGLImpl::apply(ctx, state, cmd, backtrace);
             }
         }
     }
diff --git a/components/canvas/webgl_thread.rs b/components/canvas/webgl_thread.rs
index 9256692599a..4a2466d64e3 100644
--- a/components/canvas/webgl_thread.rs
+++ b/components/canvas/webgl_thread.rs
@@ -137,8 +137,8 @@ impl<VR: WebVRRenderHandler + 'static> WebGLThread<VR> {
             WebGLMsg::RemoveContext(ctx_id) => {
                 self.remove_webgl_context(ctx_id);
             },
-            WebGLMsg::WebGLCommand(ctx_id, command) => {
-                self.handle_webgl_command(ctx_id, command);
+            WebGLMsg::WebGLCommand(ctx_id, command, backtrace) => {
+                self.handle_webgl_command(ctx_id, command, backtrace);
             },
             WebGLMsg::WebVRCommand(ctx_id, command) => {
                 self.handle_webvr_command(ctx_id, command);
@@ -164,10 +164,15 @@ impl<VR: WebVRRenderHandler + 'static> WebGLThread<VR> {
     }
 
     /// Handles a WebGLCommand for a specific WebGLContext
-    fn handle_webgl_command(&mut self, context_id: WebGLContextId, command: WebGLCommand) {
+    fn handle_webgl_command(
+        &mut self,
+        context_id: WebGLContextId,
+        command: WebGLCommand,
+        backtrace: WebGLCommandBacktrace,
+    ) {
         let data = Self::make_current_if_needed_mut(context_id, &mut self.contexts, &mut self.bound_context_id);
         if let Some(data) = data {
-            data.ctx.apply_command(command, &mut data.state);
+            data.ctx.apply_command(command, backtrace, &mut data.state);
         }
     }
 
@@ -670,7 +675,8 @@ impl WebGLImpl {
     pub fn apply<Native: NativeGLContextMethods>(
         ctx: &GLContext<Native>,
         state: &mut GLState,
-        command: WebGLCommand
+        command: WebGLCommand,
+        _backtrace: WebGLCommandBacktrace,
     ) {
         match command {
             WebGLCommand::GetContextAttributes(ref sender) =>
@@ -1191,7 +1197,14 @@ impl WebGLImpl {
         // TODO: update test expectations in order to enable debug assertions
         let error = ctx.gl().get_error();
         if error != gl::NO_ERROR {
-            error!("Last GL operation failed: {:?}", command)
+            error!("Last GL operation failed: {:?}", command);
+            #[cfg(feature = "webgl_backtrace")]
+            {
+                error!("Backtrace from failed WebGL API:\n{}", _backtrace.backtrace);
+                if let Some(backtrace) = _backtrace.js_backtrace {
+                    error!("JS backtrace from failed WebGL API:\n{}", backtrace);
+                }
+            }
         }
         assert_eq!(error, gl::NO_ERROR, "Unexpected WebGL error: 0x{:x} ({})", error, error);
     }