From 9529138c36e3ffe63699527760af8e9f93f8d9f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bartek=20Iwa=C5=84czuk?= <biwanczuk@gmail.com>
Date: Mon, 6 Feb 2023 16:20:20 +0100
Subject: [PATCH] refactor(npm): use per-thread package.json cache (#17644)

This commit adds a per-thread cache for `package.json` files. It's
similar to what Node.js is doing.
---
 ext/node/package_json.rs | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/ext/node/package_json.rs b/ext/node/package_json.rs
index 5894b88313..e40448930b 100644
--- a/ext/node/package_json.rs
+++ b/ext/node/package_json.rs
@@ -11,9 +11,15 @@ use deno_core::serde_json;
 use deno_core::serde_json::Map;
 use deno_core::serde_json::Value;
 use serde::Serialize;
+use std::cell::RefCell;
+use std::collections::HashMap;
 use std::io::ErrorKind;
 use std::path::PathBuf;
 
+thread_local! {
+  static CACHE: RefCell<HashMap<PathBuf, PackageJson>> = RefCell::new(HashMap::new());
+}
+
 #[derive(Clone, Debug, Serialize)]
 pub struct PackageJson {
   pub exists: bool,
@@ -58,6 +64,12 @@ impl PackageJson {
   pub fn load_skip_read_permission(
     path: PathBuf,
   ) -> Result<PackageJson, AnyError> {
+    assert!(path.is_absolute());
+
+    if CACHE.with(|cache| cache.borrow().contains_key(&path)) {
+      return Ok(CACHE.with(|cache| cache.borrow()[&path].clone()));
+    }
+
     let source = match std::fs::read_to_string(&path) {
       Ok(source) => source,
       Err(err) if err.kind() == ErrorKind::NotFound => {
@@ -136,6 +148,12 @@ impl PackageJson {
       imports,
       bin,
     };
+
+    CACHE.with(|cache| {
+      cache
+        .borrow_mut()
+        .insert(package_json.path.clone(), package_json.clone());
+    });
     Ok(package_json)
   }