Implement basic Time To First Paint and First Contentful Paint PWMs

components/metrics/lib.rs

@@ -0,0 +1,113 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+extern crate gfx;
+extern crate profile_traits;
+extern crate servo_config;
+extern crate time;
+
+use gfx::display_list::{DisplayItem, DisplayList};
+use profile_traits::time::{ProfilerChan, ProfilerCategory, send_profile_data};
+use profile_traits::time::TimerMetadata;
+use servo_config::opts;
+use std::cell::Cell;
+
+pub trait ProfilerMetadataFactory {
+    fn new_metadata(&self) -> Option<TimerMetadata>;
+}
+
+macro_rules! make_time_setter(
+    ( $attr:ident, $func:ident, $category:ident, $label:expr ) => (
+        fn $func<T>(&self, profiler_metadata_factory: &T)
+            where T: ProfilerMetadataFactory {
+            let navigation_start = match self.navigation_start {
+                Some(time) => time,
+                None => {
+                    println!("Trying to set metric before navigation start");
+                    return;
+                }
+            };
+
+            let now = time::precise_time_ns() as f64;
+            let time = now - navigation_start;
+            self.$attr.set(Some(time));
+
+            // Send the metric to the time profiler.
+            send_profile_data(ProfilerCategory::$category,
+                              profiler_metadata_factory.new_metadata(),
+                              &self.time_profiler_chan,
+                              time as u64, time as u64, 0, 0);
+
+            // Print the metric to console if the print-pwm option was given.
+            if opts::get().print_pwm {
+                println!("{:?} {:?}", $label, time);
+            }
+        }
+    );
+);
+
+pub struct PaintTimeMetrics {
+    navigation_start: Option<f64>,
+    first_paint: Cell<Option<f64>>,
+    first_contentful_paint: Cell<Option<f64>>,
+    time_profiler_chan: ProfilerChan,
+}
+
+impl PaintTimeMetrics {
+    pub fn new(time_profiler_chan: ProfilerChan)
+        -> PaintTimeMetrics {
+        PaintTimeMetrics {
+            navigation_start: None,
+            first_paint: Cell::new(None),
+            first_contentful_paint: Cell::new(None),
+            time_profiler_chan: time_profiler_chan,
+        }
+    }
+
+    pub fn set_navigation_start(&mut self, time: f64) {
+        self.navigation_start = Some(time);
+    }
+
+    make_time_setter!(first_paint, set_first_paint,
+                      TimeToFirstPaint,
+                      "first-paint");
+    make_time_setter!(first_contentful_paint, set_first_contentful_paint,
+                      TimeToFirstContentfulPaint,
+                      "first-contentful-paint");
+
+    pub fn maybe_set_first_paint<T>(&self, profiler_metadata_factory: &T)
+        where T: ProfilerMetadataFactory {
+        {
+            if self.first_paint.get().is_some() {
+                return;
+            }
+        }
+
+        self.set_first_paint(profiler_metadata_factory);
+    }
+
+    pub fn maybe_set_first_contentful_paint<T>(&self, profiler_metadata_factory: &T,
+                                               display_list: &DisplayList)
+        where T: ProfilerMetadataFactory {
+        {
+            if self.first_contentful_paint.get().is_some() {
+                return;
+            }
+        }
+
+        // Analyze display list to figure out if this is the first contentful
+        // paint (i.e. the display list contains items of type text, image,
+        // non-white canvas or SVG)
+        for item in &display_list.list {
+            match item {
+                &DisplayItem::Text(_) |
+                &DisplayItem::Image(_) => {
+                    self.set_first_contentful_paint(profiler_metadata_factory);
+                    return;
+                },
+                _ => (),
+            }
+        }
+    }
+}