parallelize file generation (syntax highlighting)

Cargo.lock

@@ -216,6 +216,49 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2dd04ddaf88237dc3b8d8f9a3c1004b506b54b3313403944054d23c0870c521"
+dependencies = [
+ "cfg-if",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "715e8152b692bba2d374b53d4875445368fdf21a94751410af607a5ac677d1fc"
+dependencies = [
+ "cfg-if",
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "01a9af1f4c2ef74bb8aa1f7e19706bc72d03598c8a570bb5de72243c7a9d9d5a"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+ "crossbeam-utils",
+ "memoffset",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4fb766fa798726286dbbb842f174001dab8abc7b627a1dd86e0b7222a95d929f"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -286,6 +329,12 @@ dependencies = [
  "crypto-common",
 ]
 
+[[package]]
+name = "either"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90e5c1c8368803113bf0c9584fc495a58b86dc8a29edbf8fe877d21d9507e797"
+
 [[package]]
 name = "errno"
 version = "0.2.8"
@@ -535,6 +584,7 @@ dependencies = [
  "clap",
  "git2",
  "pulldown-cmark",
+ "rayon",
  "serde",
  "syntect",
  "tera",
@@ -656,6 +706,15 @@ version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
+[[package]]
+name = "memoffset"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5de893c32cde5f383baa4c04c5d6dbdd735cfd4a794b0debdb2bb1b421da5ff4"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "miniz_oxide"
 version = "0.6.2"
@@ -684,6 +743,16 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "num_cpus"
+version = "1.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fac9e2da13b5eb447a6ce3d392f23a29d8694bff781bf03a16cd9ac8697593b"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.17.0"
@@ -945,6 +1014,28 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db3a213adf02b3bcfd2d3846bb41cb22857d131789e01df434fb7e7bc0759b7"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cac410af5d00ab6884528b4ab69d1e8e146e8d471201800fa1b4524126de6ad3"
+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "num_cpus",
+]
+
 [[package]]
 name = "regex"
 version = "1.7.0"
@@ -997,6 +1088,12 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "scratch"
 version = "1.0.3"

Cargo.toml

@@ -22,6 +22,7 @@ chrono = { version = "0.4.23", features=["clock"] }
 clap = { version="4.0.32", features=["derive"] }
 git2 = "0.15.0"
 pulldown-cmark = { version = "0.9.2", optional = true }
+rayon = "1.6.1"
 serde = { version = "1.0.152", features = ["derive"] }
 syntect = { version = "5.0.0", default-features = false, optional = true }
 tera = "1.17.1"

src/main.rs

@@ -5,6 +5,7 @@ use chrono::{
 };
 use clap::Parser;
 use git2::{DiffOptions, Repository, Error};
+use rayon::prelude::*;
 use serde::{Serialize, Deserialize};
 use std::cell::RefCell;
 use std::collections::{BTreeMap, HashMap, HashSet};
@@ -1029,12 +1030,14 @@ fn main() {
     tera.register_function("ts_to_git_timestamp", TsTimestampFn{});
 
     macro_rules! size_check {
-        ($settings:ident, $cur:ident, $total:expr) => {
+        ($settings:ident, $cur:expr, $total:expr, $action:expr) => {
-            if $cur > $settings.limit_repo_size.unwrap_or(usize::MAX) {
+            let cur: usize = $cur;
-                break;
+            if cur > $settings.limit_repo_size.unwrap_or(usize::MAX) {
+                $action;
             }
-            if $total + $cur > $settings.limit_total_size.unwrap_or(usize::MAX) {
+            let total: usize = $total;
-                break;
+            if total.saturating_add($cur) > $settings.limit_total_size.unwrap_or(usize::MAX) {
+                $action;
             }
         }
     }
@@ -1184,7 +1187,7 @@ fn main() {
         }
 
         for branch in &summary.branches {
-            size_check!(repo_desc, repo_bytes, total_bytes);
+            size_check!(repo_desc, repo_bytes, total_bytes, break);
             local_ctx.insert("branch", branch);
             if let Some(templ_file) = settings.templates.branch.as_deref() {
                 match tera.render(templ_file, &local_ctx) {
@@ -1200,7 +1203,7 @@ fn main() {
         }
 
         for tag in &summary.tags {
-            size_check!(repo_desc, repo_bytes, total_bytes);
+            size_check!(repo_desc, repo_bytes, total_bytes, break);
             local_ctx.insert("tag", tag);
             if let Some(tagged_id) = tag.tagged_id.as_ref() {
                 if let Some(commit) = summary.commits.get(tagged_id) {
@@ -1222,7 +1225,7 @@ fn main() {
         }
 
         for (_id, commit) in &summary.commits {
-            size_check!(repo_desc, repo_bytes, total_bytes);
+            size_check!(repo_desc, repo_bytes, total_bytes, break);
             local_ctx.try_insert("commit", &commit).expect("Failed to add commit to template engine.");
             if let Some(templ_file) = settings.templates.commit.as_deref() {
                 match tera.render(templ_file, &local_ctx) {
@@ -1237,11 +1240,6 @@ fn main() {
             local_ctx.remove("commit");
         }
 
-        // TODO: most of these generation blocks can be done in
-        // parallel.  This one is particularly costly, especially with
-        // markdown+highlighting, and would probably benefit from it.
-        // A potential drawback is that each parallel run needs a
-        // clone of the Tera context.
         #[cfg(any(feature = "highlight", feature = "highlight_fast"))]
         if settings.templates.file.is_some() {
             let ts = ThemeSet::load_defaults();
@@ -1252,17 +1250,29 @@ fn main() {
             repo_bytes += write_rendered(&settings.outputs.syntax_css(Some(&summary), None), css.as_str());
         }
 
-        for file in summary.all_files.iter().filter(|x| x.kind == "file") {
+
-            size_check!(repo_desc, repo_bytes, total_bytes);
+        // TODO: parallelize the rest of the processing steps.  This one is
+        // done first because syntax highlighting is very slow.
+        let files: Vec<&GitFile> = summary.all_files.iter().filter(|x| x.kind == "file").collect();
+        let atomic_bytes: AtomicUsize = AtomicUsize::new(repo_bytes);
+        let _ = files.par_iter().fold(|| Some(0), |acc, file| {
+            // These two have to be recreated.  Cloning the Tera context is expensive.
+            let repo = Repository::open(&repo_path).expect("Unable to find git repository.");
+            let mut local_ctx = local_ctx.clone();
+
+            let mut local_bytes = 0;
+            let cur_repo_bytes = atomic_bytes.load(Ordering::Relaxed);
+            size_check!(repo_desc, cur_repo_bytes, total_bytes, return None);
             let file = match file.size < repo_desc.limit_file_size.unwrap_or(usize::MAX) {
                 true => fill_file_contents(&repo, &file, &repo_desc).expect("Failed to parse file."),
-                false => file.clone(),
+                false => (*file).clone(),
             };
             local_ctx.try_insert("file", &file).expect("Failed to add file to template engine.");
             if let Some(templ_file) = settings.templates.file.as_deref() {
                 match tera.render(templ_file, &local_ctx) {
                     Ok(rendered) => {
-                        repo_bytes += write_rendered(&settings.outputs.file(Some(&summary), Some(&file)), &rendered);
+                        local_bytes = write_rendered(&settings.outputs.file(Some(&summary), Some(&file)), &rendered);
+                        atomic_bytes.fetch_add(local_bytes, Ordering::Relaxed);
                     },
                     Err(x) => match x.kind {
                         _ => error!("ERROR: {:?}", x),
@@ -1270,10 +1280,13 @@ fn main() {
                 }
             }
             local_ctx.remove("file");
-        }
+            Some(acc.unwrap() + local_bytes)})
+            .while_some() // allow short-circuiting if size limit is reached
+            .sum::<usize>();
+        repo_bytes = atomic_bytes.load(Ordering::Relaxed);
 
         for dir in summary.all_files.iter().filter(|x| x.kind == "dir") {
-            size_check!(repo_desc, repo_bytes, total_bytes);
+            size_check!(repo_desc, repo_bytes, total_bytes, break);
             if dir.tree_depth >= repo_desc.limit_tree_depth.unwrap_or(usize::MAX) - 1 {
                 continue;
             }
@@ -1317,7 +1330,7 @@ fn main() {
                 },
                 start_repo.elapsed().as_secs_f32(), repo_bytes);
         total_bytes += repo_bytes;
-        size_check!(repo_desc, repo_bytes, total_bytes);
+        size_check!(repo_desc, 0, total_bytes, break); // break if total is exceeded
     }
 
     let start_global = Instant::now();