From ad9da96336d4b39825d465b586e0f601897b3640 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Sat, 29 Dec 2018 17:08:49 -0800
Subject: [PATCH] Build objects in parallel!

---
 Cargo.lock                 |  1 +
 utils/tile-svg/Cargo.toml  |  1 +
 utils/tile-svg/src/main.rs | 23 ++++++++++++++++++++---
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index a02d6ea3..fdec8c66 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1492,6 +1492,7 @@ dependencies = [
  "quick-xml 0.12.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "quickcheck 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rayon 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "svgtypes 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
diff --git a/utils/tile-svg/Cargo.toml b/utils/tile-svg/Cargo.toml
index e8a899ed..111a8242 100644
--- a/utils/tile-svg/Cargo.toml
+++ b/utils/tile-svg/Cargo.toml
@@ -14,6 +14,7 @@ jemallocator = "0.1"
 lyon_geom = "0.12"
 lyon_path = "0.12"
 quick-xml = "0.12"
+rayon = "1.0"
 svgtypes = "0.2"
 
 [dependencies.pathfinder_path_utils]
diff --git a/utils/tile-svg/src/main.rs b/utils/tile-svg/src/main.rs
index 55598acc..afb5d0e3 100644
--- a/utils/tile-svg/src/main.rs
+++ b/utils/tile-svg/src/main.rs
@@ -28,6 +28,7 @@ use lyon_path::iterator::PathIter;
 use pathfinder_path_utils::stroke::{StrokeStyle, StrokeToFillIter};
 use quick_xml::Reader;
 use quick_xml::events::{BytesStart, Event};
+use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
 use std::cmp::Ordering;
 use std::fmt::{self, Debug, Formatter};
 use std::fs::File;
@@ -57,6 +58,9 @@ fn main() {
                                                        .value_name("COUNT")
                                                        .takes_value(true)
                                                        .help("Run a benchmark with COUNT runs"))
+                            .arg(Arg::with_name("sequential").short("s")
+                                                             .long("sequential")
+                                                             .help("Use only one thread"))
                             .arg(Arg::with_name("INPUT").help("Path to the SVG file to render")
                                                         .required(true)
                                                         .index(1))
@@ -68,6 +72,7 @@ fn main() {
         Some(runs) => runs.parse().unwrap(),
         None => 1,
     };
+    let sequential = matches.is_present("sequential");
     let input_path = PathBuf::from(matches.value_of("INPUT").unwrap());
     let output_path = matches.value_of("OUTPUT").map(PathBuf::from);
 
@@ -77,7 +82,12 @@ fn main() {
     let start_time = Instant::now();
     let mut built_scene = BuiltScene::new(&scene.view_box, scene.objects.len() as u32);
     for _ in 0..runs {
-        built_scene = BuiltScene::from_objects(&scene.view_box, &scene.build_objects());
+        let built_objects = if sequential {
+            scene.build_objects_sequentially()
+        } else {
+            scene.build_objects_in_parallel()
+        };
+        built_scene = BuiltScene::from_objects(&scene.view_box, &built_objects);
     }
     let elapsed_time = Instant::now() - start_time;
 
@@ -311,8 +321,7 @@ impl Scene {
         &self.styles[style.0 as usize]
     }
 
-    fn build_objects(&self) -> Vec<BuiltObject> {
-        // TODO(pcwalton): Parallelize!
+    fn build_objects_sequentially(&self) -> Vec<BuiltObject> {
         self.objects.iter().enumerate().map(|(object_index, object)| {
             let mut tiler = Tiler::new(&object.outline, object_index as u32, &self.view_box);
             tiler.generate_tiles();
@@ -320,6 +329,14 @@ impl Scene {
         }).collect()
     }
 
+    fn build_objects_in_parallel(&self) -> Vec<BuiltObject> {
+        self.objects.par_iter().enumerate().map(|(object_index, object)| {
+            let mut tiler = Tiler::new(&object.outline, object_index as u32, &self.view_box);
+            tiler.generate_tiles();
+            tiler.built_object
+        }).collect()
+    }
+
     fn push_svg_path(&mut self, value: &str, style: StyleId, name: String) {
         if self.get_style(style).stroke_color.is_some() {
             let computed_style = self.get_style(style);