Add a visualization of thread activity

fontc/src/args.rs

@@ -31,6 +31,12 @@ pub struct Args {
     #[arg(long, default_value = "false")]
     pub flatten_components: bool,
 
+    /// Whether to out timing data, notably a visualization of threadpool execution of tasks.
+    ///
+    /// See <https://github.com/googlefonts/fontc/pull/443>
+    #[arg(long, default_value = "false")]
+    pub emit_timing: bool,
+
     /// Working directory for the build process. If emit-ir is on, written here.
     #[arg(short, long, default_value = "build")]
     pub build_dir: PathBuf,
@@ -53,6 +59,7 @@ impl Args {
         flags.set(Flags::EMIT_DEBUG, self.emit_debug);
         flags.set(Flags::PREFER_SIMPLE_GLYPHS, self.prefer_simple_glyphs);
         flags.set(Flags::FLATTEN_COMPONENTS, self.flatten_components);
+        flags.set(Flags::EMIT_TIMING, self.emit_timing);
 
         flags
     }
@@ -69,6 +76,7 @@ impl Args {
             source,
             emit_ir: true,
             emit_debug: false, // they get destroyed by test cleanup
+            emit_timing: false,
             build_dir: build_dir.to_path_buf(),
             prefer_simple_glyphs: Flags::default().contains(Flags::PREFER_SIMPLE_GLYPHS),
             flatten_components: Flags::default().contains(Flags::FLATTEN_COMPONENTS),

fontc/src/change_detector.rs

@@ -1,6 +1,6 @@
 //! tracking changes during compilation
 
-use std::{ffi::OsStr, fmt::Debug, fs, path::Path};
+use std::{ffi::OsStr, fmt::Debug, fs, path::Path, time::Instant};
 
 use bitflags::bitflags;
 use fontbe::{
@@ -165,8 +165,8 @@ impl ChangeDetector {
         workload.add(work, run);
     }
 
-    pub fn create_workload(&mut self) -> Result<Workload, Error> {
-        let mut workload = Workload::new(self);
+    pub fn create_workload(&mut self, t0: Instant) -> Result<Workload, Error> {
+        let mut workload = Workload::new(self, t0);
 
         // Create work roughly in the order it would typically occur
         // Work is eligible to run as soon as all dependencies are complete

fontc/src/lib.rs

@@ -4,6 +4,7 @@ mod args;
 mod change_detector;
 mod config;
 mod error;
+mod timing;
 pub mod work;
 mod workload;
 
@@ -17,6 +18,7 @@ use workload::Workload;
 use std::{
     fs, io,
     path::{Path, PathBuf},
+    time::Instant,
 };
 
 use fontbe::{
@@ -260,8 +262,11 @@ fn add_glyph_be_job(workload: &mut Workload, glyph_name: GlyphName) {
 }
 
 //FIXME: I should be a method on ChangeDetector
-pub fn create_workload(change_detector: &mut ChangeDetector) -> Result<Workload, Error> {
-    let mut workload = change_detector.create_workload()?;
+pub fn create_workload(
+    change_detector: &mut ChangeDetector,
+    t0: Instant,
+) -> Result<Workload, Error> {
+    let mut workload = change_detector.create_workload(t0)?;
 
     // FE: f(source) => IR
     add_feature_ir_job(&mut workload)?;
@@ -462,6 +467,7 @@ mod tests {
     }
 
     fn compile(args: Args) -> TestCompile {
+        let t0 = Instant::now();
         let _ = env_logger::builder().is_test(true).try_init();
 
         info!("Compile {args:?}");
@@ -474,7 +480,7 @@ mod tests {
         let mut change_detector =
             ChangeDetector::new(config.clone(), ir_paths.clone(), prev_inputs).unwrap();
 
-        let mut workload = create_workload(&mut change_detector).unwrap();
+        let mut workload = create_workload(&mut change_detector, t0).unwrap();
 
         // Try to do the work
         // As we currently don't stress dependencies just run one by one

fontc/src/main.rs

@@ -1,10 +1,14 @@
-use std::io::Write;
+use std::{
+    fs::OpenOptions,
+    io::{BufWriter, Write},
+    time::Instant,
+};
 
 use clap::Parser;
 
 use fontbe::orchestration::Context as BeContext;
 use fontc::{init_paths, write_font_file, Args, ChangeDetector, Config, Error};
-use fontir::orchestration::Context as FeContext;
+use fontir::orchestration::{Context as FeContext, Flags};
 
 fn main() {
     // catch and print errors manually, to avoid just seeing the Debug impls
@@ -16,6 +20,7 @@ fn main() {
 }
 
 fn run() -> Result<(), Error> {
+    let t0 = Instant::now();
     env_logger::builder()
         .format(|buf, record| {
             let ts = buf.timestamp_micros();
@@ -38,15 +43,26 @@ fn run() -> Result<(), Error> {
     let prev_inputs = config.init()?;
 
     let mut change_detector = ChangeDetector::new(config.clone(), ir_paths.clone(), prev_inputs)?;
-    let workload = fontc::create_workload(&mut change_detector)?;
+    let workload = fontc::create_workload(&mut change_detector, t0)?;
 
     let fe_root = FeContext::new_root(
         config.args.flags(),
         ir_paths,
         workload.current_inputs().clone(),
     );
     let be_root = BeContext::new_root(config.args.flags(), be_paths, &fe_root);
-    workload.exec(&fe_root, &be_root)?;
+    let mut timing = workload.exec(&fe_root, &be_root)?;
+
+    if config.args.flags().contains(Flags::EMIT_TIMING) {
+        let out_file = OpenOptions::new()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(config.args.build_dir.join("threads.svg"))
+            .map_err(Error::IoError)?;
+        let mut buf = BufWriter::new(out_file);
+        timing.write_svg(&mut buf)?
+    }
 
     change_detector.finish_successfully()?;