layout: Add an option to visualize parallel layout

2 files changed, 16 insertions, 1 deletions

diff --git a/components/util/opts.rs b/components/util/opts.rs
index d868d47dd92..baad6654b8b 100644
--- a/components/util/opts.rs
+++ b/components/util/opts.rs
@@ -72,12 +72,16 @@ pub struct Opts {
     /// debugging purposes (`--show-debug-borders`).
     pub show_debug_borders: bool,
 
-    /// True if we should show borders on all fragments for debugging purposes (`--show-debug-fragment-borders`).
+    /// True if we should show borders on all fragments for debugging purposes
+    /// (`--show-debug-fragment-borders`).
     pub show_debug_fragment_borders: bool,
 
     /// True if we should paint tiles with overlays based on which thread painted them.
     pub show_debug_parallel_paint: bool,
 
+    /// True if we should paint borders around flows based on which thread painted them.
+    pub show_debug_parallel_layout: bool,
+
     /// If set with --disable-text-aa, disable antialiasing on fonts. This is primarily useful for reftests
     /// where pixel perfect results are required when using fonts such as the Ahem
     /// font for layout tests.
@@ -132,6 +136,7 @@ pub fn print_debug_usage(app: &str)  {
     print_option("show-compositor-borders", "Paint borders along layer and tile boundaries.");
     print_option("show-fragment-borders", "Paint borders along fragment boundaries.");
     print_option("show-parallel-paint", "Overlay tiles with colors showing which thread painted them.");
+    print_option("show-parallel-layout", "Mark which thread laid each flow out with colors.");
     print_option("trace-layout", "Write layout trace to an external file for debugging.");
     print_option("validate-display-list-geometry",
                  "Display an error when display list geometry escapes overflow region.");
@@ -171,6 +176,7 @@ pub fn default_opts() -> Opts {
         show_debug_borders: false,
         show_debug_fragment_borders: false,
         show_debug_parallel_paint: false,
+        show_debug_parallel_layout: false,
         enable_text_antialiasing: false,
         trace_layout: false,
         devtools_port: None,
@@ -321,6 +327,7 @@ pub fn from_cmdline_args(args: &[String]) -> bool {
         show_debug_borders: debug_options.contains(&"show-compositor-borders"),
         show_debug_fragment_borders: debug_options.contains(&"show-fragment-borders"),
         show_debug_parallel_paint: debug_options.contains(&"show-parallel-paint"),
+        show_debug_parallel_layout: debug_options.contains(&"show-parallel-layout"),
         enable_text_antialiasing: !debug_options.contains(&"disable-text-aa"),
         dump_flow_tree: debug_options.contains(&"dump-flow-tree"),
         validate_display_list_geometry: debug_options.contains(&"validate-display-list-geometry"),
diff --git a/components/util/workqueue.rs b/components/util/workqueue.rs
index 69fbce97b7e..ad39b1e349f 100644
--- a/components/util/workqueue.rs
+++ b/components/util/workqueue.rs
@@ -157,6 +157,7 @@ impl<QueueData: Send, WorkData: Send> WorkerThread<QueueData, WorkData> {
                     worker: &mut deque,
                     ref_count: ref_count,
                     queue_data: queue_data,
+                    worker_index: self.index as u8,
                 };
                 (work_unit.fun)(work_unit.data, &mut proxy);
 
@@ -180,6 +181,7 @@ pub struct WorkerProxy<'a, QueueData: 'a, WorkData: 'a> {
     worker: &'a mut Worker<WorkUnit<QueueData, WorkData>>,
     ref_count: *mut AtomicUint,
     queue_data: *const QueueData,
+    worker_index: u8,
 }
 
 impl<'a, QueueData: 'static, WorkData: Send> WorkerProxy<'a, QueueData, WorkData> {
@@ -199,6 +201,12 @@ impl<'a, QueueData: 'static, WorkData: Send> WorkerProxy<'a, QueueData, WorkData
             mem::transmute(self.queue_data)
         }
     }
+
+    /// Retrieves the index of the worker.
+    #[inline]
+    pub fn worker_index(&self) -> u8 {
+        self.worker_index
+    }
 }
 
 /// A work queue on which units of work can be submitted.