From c6456d04b9f16ed8f5ad0f256a38218b514de5dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Wed, 24 Feb 2021 13:13:49 +0900
Subject: [PATCH] syntax: Drop the rayon dependency for threadpool.

We just need a small concurrent threadpool for compilation.
---
 Cargo.lock              | 92 +++++------------------------------------
 helix-syntax/Cargo.toml |  2 +-
 helix-syntax/build.rs   | 26 +++++++++---
 3 files changed, 32 insertions(+), 88 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 125e77845..bf7920fa4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -226,47 +226,6 @@ dependencies = [
  "cache-padded",
 ]
 
-[[package]]
-name = "const_fn"
-version = "0.4.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "28b9d6de7f49e22cf97ad17fc4036ece69300032f45f78f30b4a4482cdc3f4a6"
-
-[[package]]
-name = "crossbeam-channel"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dca26ee1f8d361640700bde38b2c37d8c22b3ce2d360e1fc1c74ea4b0aa7d775"
-dependencies = [
- "cfg-if 1.0.0",
- "crossbeam-utils",
-]
-
-[[package]]
-name = "crossbeam-deque"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94af6efb46fef72616855b036a624cf27ba656ffc9be1b9a3c931cfc7749a9a9"
-dependencies = [
- "cfg-if 1.0.0",
- "crossbeam-epoch",
- "crossbeam-utils",
-]
-
-[[package]]
-name = "crossbeam-epoch"
-version = "0.9.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1aaa739f95311c2c7887a76863f500026092fb1dce0161dab577e559ef3569d"
-dependencies = [
- "cfg-if 1.0.0",
- "const_fn",
- "crossbeam-utils",
- "lazy_static",
- "memoffset",
- "scopeguard",
-]
-
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.1"
@@ -325,12 +284,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "either"
-version = "1.6.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
-
 [[package]]
 name = "event-listener"
 version = "2.5.1"
@@ -579,7 +532,7 @@ name = "helix-syntax"
 version = "0.1.0"
 dependencies = [
  "cc",
- "rayon",
+ "threadpool",
  "tree-sitter",
 ]
 
@@ -769,15 +722,6 @@ version = "2.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ee1c47aaa256ecabcaea351eae4a9b01ef39ed810004e298d2511ed284b1525"
 
-[[package]]
-name = "memoffset"
-version = "0.6.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "157b4208e3059a8f9e78d559edc658e13df41410cb3ae03979c83130067fdd87"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "mio"
 version = "0.7.8"
@@ -971,31 +915,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "rayon"
-version = "1.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8b0d8e0819fadc20c74ea8373106ead0600e3a67ef1fe8da56e39b9ae7275674"
-dependencies = [
- "autocfg",
- "crossbeam-deque",
- "either",
- "rayon-core",
-]
-
-[[package]]
-name = "rayon-core"
-version = "1.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ab346ac5921dc62ffa9f89b7a773907511cdfa5490c572ae9be1be33e8afa4a"
-dependencies = [
- "crossbeam-channel",
- "crossbeam-deque",
- "crossbeam-utils",
- "lazy_static",
- "num_cpus",
-]
-
 [[package]]
 name = "redox_syscall"
 version = "0.2.5"
@@ -1264,6 +1183,15 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "threadpool"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d050e60b33d41c19108b32cea32164033a9013fe3b46cbd4457559bfbf77afaa"
+dependencies = [
+ "num_cpus",
+]
+
 [[package]]
 name = "tinyvec"
 version = "1.1.1"
diff --git a/helix-syntax/Cargo.toml b/helix-syntax/Cargo.toml
index 86aaf360a..c50e30911 100644
--- a/helix-syntax/Cargo.toml
+++ b/helix-syntax/Cargo.toml
@@ -11,4 +11,4 @@ tree-sitter = "0.17"
 
 [build-dependencies]
 cc = { version = "1",  features = ["parallel"] }
-rayon = { version = "1.5" }
+threadpool = { version = "1.0" }
diff --git a/helix-syntax/build.rs b/helix-syntax/build.rs
index 627a0290d..89641225c 100644
--- a/helix-syntax/build.rs
+++ b/helix-syntax/build.rs
@@ -1,7 +1,8 @@
-use rayon::prelude::*;
 use std::path::PathBuf;
 use std::{env, fs};
 
+use std::sync::mpsc::channel;
+
 fn get_opt_level() -> u32 {
     env::var("OPT_LEVEL").unwrap().parse::<u32>().unwrap()
 }
@@ -115,10 +116,25 @@ fn main() {
         "tree-sitter-cpp".to_string(),
     ];
     let dirs = collect_tree_sitter_dirs(ignore);
-    dirs.par_iter().for_each(|dir| {
-        let language = &dir[12..]; // skip tree-sitter- prefix
-        build_dir(&dir, &language);
-    });
+
+    let mut n_jobs = 0;
+    let pool = threadpool::Builder::new().build(); // by going through the builder, it'll use num_cpus
+    let (tx, rx) = channel();
+
+    for dir in dirs {
+        let tx = tx.clone();
+        n_jobs += 1;
+
+        pool.execute(move || {
+            let language = &dir[12..]; // skip tree-sitter- prefix
+            build_dir(&dir, &language);
+
+            // report progress
+            tx.send(1).unwrap();
+        });
+    }
+    assert_eq!(rx.iter().take(n_jobs).fold(0, |a, b| a + b), n_jobs);
+
     build_dir("tree-sitter-typescript/tsx", "tsx");
     build_dir("tree-sitter-typescript/typescript", "typescript");
 }