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perf: reduce memory allocation by using a thread_local path for path …
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…methods
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@Boshen
Boshen committed Nov 22, 2024
1 parent 8ab444b commit 779a80a
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Showing 2 changed files with 55 additions and 17 deletions.
46 changes: 45 additions & 1 deletion src/cache.rs
View file
Original file line number Diff line number Diff line change
@@ -1,10 +1,11 @@
use std::{
borrow::{Borrow, Cow},
cell::UnsafeCell,
convert::AsRef,
hash::{BuildHasherDefault, Hash, Hasher},
io,
ops::Deref,
path::{Path, PathBuf},
path::{Component, Path, PathBuf},
sync::Arc,
};

Expand All @@ -17,6 +18,12 @@ use crate::{
FileSystem, ResolveError, ResolveOptions, TsConfig,
};

thread_local! {
/// Per-thread pre-allocated path that is used to perform operations on paths more quickly.
/// Learned from parcel <https://github.com/parcel-bundler/parcel/blob/a53f8f3ba1025c7ea8653e9719e0a61ef9717079/crates/parcel-resolver/src/cache.rs#L394>
pub static SCRATCH_PATH: UnsafeCell<PathBuf> = UnsafeCell::new(PathBuf::with_capacity(256));
}

#[derive(Default)]
pub struct Cache<Fs> {
pub(crate) fs: Fs,
Expand Down Expand Up @@ -303,6 +310,43 @@ impl CachedPathImpl {
}
result
}

/// Returns a new path by resolving the given subpath (including "." and ".." components) with this path.
pub fn normalize_with<P, Fs>(&self, subpath: P, cache: &Cache<Fs>) -> CachedPath
where
P: AsRef<Path>,
Fs: FileSystem,
{
SCRATCH_PATH.with(|path| {
let subpath = subpath.as_ref();
let mut components = subpath.components();
let Some(head) = components.next() else { return cache.value(subpath) };
if matches!(head, Component::Prefix(..) | Component::RootDir) {
return cache.value(subpath);
}

// SAFETY: ???
let path = unsafe { &mut *path.get() };
path.clear();
path.push(&self.path);
for component in std::iter::once(head).chain(components) {
match component {
Component::CurDir => {}
Component::ParentDir => {
path.pop();
}
Component::Normal(c) => {
path.push(c);
}
Component::Prefix(..) | Component::RootDir => {
unreachable!("Path {:?} Subpath {:?}", self.path, subpath)

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}
}
}

cache.value(path)
})
}
}

/// Memoized cache key, code adapted from <https://stackoverflow.com/a/50478038>.
Expand Down
26 changes: 10 additions & 16 deletions src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -395,8 +395,7 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
c,
Component::CurDir | Component::ParentDir | Component::Normal(_)
)));
let path = cached_path.path().normalize_with(specifier);
let cached_path = self.cache.value(&path);
let cached_path = cached_path.normalize_with(specifier, &self.cache);
// a. LOAD_AS_FILE(Y + X)
// b. LOAD_AS_DIRECTORY(Y + X)
if let Some(path) = self.load_as_file_or_directory(&cached_path, specifier, ctx)? {
Expand Down Expand Up @@ -546,9 +545,8 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
// b. If "main" is a falsy value, GOTO 2.
for main_field in package_json.main_fields(&self.options.main_fields) {
// c. let M = X + (json main field)
let main_field_path = cached_path.path().normalize_with(main_field);
let cached_path = cached_path.normalize_with(main_field, &self.cache);
// d. LOAD_AS_FILE(M)
let cached_path = self.cache.value(&main_field_path);
if let Some(path) = self.load_as_file(&cached_path, ctx)? {
return Ok(Some(path));
}
Expand Down Expand Up @@ -648,8 +646,7 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {

fn load_index(&self, cached_path: &CachedPath, ctx: &mut Ctx) -> ResolveResult {
for main_file in &self.options.main_files {
let main_path = cached_path.path().normalize_with(main_file);
let cached_path = self.cache.value(&main_path);
let cached_path = cached_path.normalize_with(main_file, &self.cache);
if self.options.enforce_extension.is_disabled() {
if let Some(path) = self.load_alias_or_file(&cached_path, ctx)? {
return Ok(Some(path));
Expand Down Expand Up @@ -722,8 +719,7 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
// 1. Try to interpret X as a combination of NAME and SUBPATH where the name
// may have a @scope/ prefix and the subpath begins with a slash (`/`).
if !package_name.is_empty() {
let package_path = cached_path.path().normalize_with(package_name);
let cached_path = self.cache.value(&package_path);
let cached_path = cached_path.normalize_with(package_name, &self.cache);
// Try foo/node_modules/package_name
if cached_path.is_dir(&self.cache.fs, ctx) {
// a. LOAD_PACKAGE_EXPORTS(X, DIR)
Expand Down Expand Up @@ -752,8 +748,7 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
// Try as file or directory for all other cases
// b. LOAD_AS_FILE(DIR/X)
// c. LOAD_AS_DIRECTORY(DIR/X)
let node_module_file = cached_path.path().normalize_with(specifier);
let cached_path = self.cache.value(&node_module_file);
let cached_path = cached_path.normalize_with(specifier, &self.cache);
if let Some(path) = self.load_as_file_or_directory(&cached_path, specifier, ctx)? {
return Ok(Some(path));
}
Expand Down Expand Up @@ -984,8 +979,8 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
}
}
AliasValue::Ignore => {
let path = cached_path.path().normalize_with(alias_key);
return Err(ResolveError::Ignored(path));
let cached_path = cached_path.normalize_with(alias_key, &self.cache);
return Err(ResolveError::Ignored(cached_path.to_path_buf()));
}
}
}
Expand Down Expand Up @@ -1271,8 +1266,7 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
continue;
};
// 2. Set parentURL to the parent folder URL of parentURL.
let package_path = cached_path.path().normalize_with(package_name);
let cached_path = self.cache.value(&package_path);
let cached_path = cached_path.normalize_with(package_name, &self.cache);
// 3. If the folder at packageURL does not exist, then
// 1. Continue the next loop iteration.
if cached_path.is_dir(&self.cache.fs, ctx) {
Expand All @@ -1297,8 +1291,8 @@ impl<Fs: FileSystem> ResolverGeneric<Fs> {
// 1. If pjson.main is a string, then
for main_field in package_json.main_fields(&self.options.main_fields) {
// 1. Return the URL resolution of main in packageURL.
let path = cached_path.path().normalize_with(main_field);
let cached_path = self.cache.value(&path);
let cached_path =
cached_path.normalize_with(main_field, &self.cache);

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if cached_path.is_file(&self.cache.fs, ctx) {
return Ok(Some(cached_path));
}
Expand Down

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