load syntaxes in parallel

crates/treehouse/src/config.rs

@@ -1,6 +1,7 @@
 use std::{collections::HashMap, ops::ControlFlow};
 
 use anyhow::{anyhow, Context};
+use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
 use serde::{Deserialize, Serialize};
 use tracing::{error, info_span, instrument};
 
@@ -10,7 +11,7 @@ use crate::{
         Syntax,
     },
     import_map::ImportRoot,
-    vfs::{self, Dir, ImageSize, VPath, VPathBuf},
+    vfs::{self, Dir, DynDir, ImageSize, VPath, VPathBuf},
 };
 
 #[derive(Debug, Clone, Deserialize, Serialize)]
@@ -159,9 +160,18 @@ impl Config {
 
     /// Loads all syntax definition files.
     #[instrument(name = "Config::load_syntaxes", skip(self))]
-    pub fn load_syntaxes(&mut self, dir: &dyn Dir) -> anyhow::Result<()> {
+    pub fn load_syntaxes(&mut self, dir: DynDir) -> anyhow::Result<()> {
-        vfs::walk_dir_rec(dir, VPath::ROOT, &mut |path| {
+        let mut paths = vec![];
+        vfs::walk_dir_rec(&dir, VPath::ROOT, &mut |path| {
             if path.extension() == Some("json") {
+                paths.push(path.to_owned());
+            }
+            ControlFlow::Continue(())
+        });
+
+        let syntaxes: Vec<_> = paths
+            .par_iter()
+            .flat_map(|path| {
                 let name = path
                     .file_stem()
                     .expect("syntax file name should have a stem due to the .json extension");
@@ -180,14 +190,19 @@ impl Config {
                     Ok(syntax) => {
                         let _span = info_span!("Config::load_syntaxes::compile", ?name).entered();
                         let compiled = compile_syntax(&syntax);
-                        self.syntaxes.insert(name.to_owned(), compiled);
+                        Some((name.to_owned(), compiled))
+                    }
+                    Err(err) => {
+                        error!("error while loading syntax file `{path}`: {err}");
+                        None
                     }
-                    Err(err) => error!("error while loading syntax file `{path}`: {err}"),
                 }
-            }
+            })
+            .collect();
 
-            ControlFlow::Continue(())
+        for (name, compiled) in syntaxes {
-        });
+            self.syntaxes.insert(name, compiled);
+        }
 
         Ok(())
     }

crates/treehouse/src/generate.rs

@@ -320,7 +320,7 @@ impl Sources {
             config.site = std::env::var("TREEHOUSE_SITE").unwrap_or(config.site);
             config.autopopulate_emoji(&*dirs.emoji)?;
             config.autopopulate_pics(&*dirs.pic)?;
-            config.load_syntaxes(&*dirs.syntax)?;
+            config.load_syntaxes(dirs.syntax.clone())?;
             config
         };