Implement simple caching for -fstype

src/find/matchers/fs.rs

@@ -3,6 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
+use std::cell::RefCell;
 use std::path::Path;
 use std::{
  error::Error,
@@ -11,10 +12,16 @@ use std::{
 
 use super::Matcher;
 
+/// The latest mapping from dev_id to fs_type, used for saving mount info reads
+pub struct Cache {
+ dev_id: String,
+ fs_type: String,
+}
+
 /// Get the filesystem type of a file.
 /// 1. get the metadata of the file
 /// 2. get the device ID of the metadata
-/// 3. search the filesystem list
+/// 3. search the cache, then the filesystem list
 ///
 /// Returns an empty string when no file system list matches.
 ///
@@ -24,14 +31,24 @@ use super::Matcher;
 ///
 /// This is only supported on Unix.
 #[cfg(unix)]
-pub fn get_file_system_type(path: &Path) -> Result<String, Box<dyn Error>> {
+pub fn get_file_system_type(
+ path: &Path,
+ cache: &RefCell<Option<Cache>>,
+) -> Result<String, Box<dyn Error>> {
  use std::os::unix::fs::MetadataExt;
 
  let metadata = match path.metadata() {
  Ok(metadata) => metadata,
  Err(err) => Err(err)?,
  };
  let dev_id = metadata.dev().to_string();
+
+ if let Some(cache) = cache.borrow().as_ref() {
+ if cache.dev_id == dev_id {
+ return Ok(cache.fs_type.clone());
+ }
+ }
+
  let fs_list = match uucore::fsext::read_fs_list() {
  Ok(fs_list) => fs_list,
  Err(err) => Err(err)?,
@@ -41,6 +58,12 @@ pub fn get_file_system_type(path: &Path) -> Result<String, Box<dyn Error>> {
  .find(|fs| fs.dev_id == dev_id)
  .map_or_else(String::new, |fs| fs.fs_type);
 
+ // cache the latest query if not a match before
+ cache.replace(Some(Cache {
+ dev_id,
+ fs_type: result.clone(),
+ }));
+
  Ok(result)
 }
 
@@ -50,11 +73,15 @@ pub fn get_file_system_type(path: &Path) -> Result<String, Box<dyn Error>> {
 /// This is only supported on Unix.
 pub struct FileSystemMatcher {
  fs_text: String,
+ cache: RefCell<Option<Cache>>,
 }
 
 impl FileSystemMatcher {
  pub fn new(fs_text: String) -> Self {
- Self { fs_text }
+ Self {
+ fs_text,
+ cache: RefCell::new(None),
+ }
  }
 }
 
@@ -66,7 +93,7 @@ impl Matcher for FileSystemMatcher {
  }
  #[cfg(unix)]
  {
- match get_file_system_type(file_info.path()) {
+ match get_file_system_type(file_info.path(), &self.cache) {
  Ok(result) => result == self.fs_text,
  Err(_) => {
  writeln!(
@@ -89,9 +116,14 @@ mod tests {
  #[cfg(unix)]
  fn test_fs_matcher() {
  use crate::find::{
- matchers::{fs::get_file_system_type, tests::get_dir_entry_for, Matcher},
+ matchers::{
+ fs::{get_file_system_type, Cache},
+ tests::get_dir_entry_for,
+ Matcher,
+ },
  tests::FakeDependencies,
  };
+ use std::cell::RefCell;
  use std::fs::File;
  use tempfile::Builder;
 
@@ -105,7 +137,26 @@ mod tests {
  let _ = File::create(foo_path).expect("create temp file");
  let file_info = get_dir_entry_for(&temp_dir.path().to_string_lossy(), "foo");
 
- let target_fs_type = get_file_system_type(file_info.path()).unwrap();
+ // create an empty cache for initial fs type lookup
+ let empty_cache = RefCell::new(None);
+ let target_fs_type = get_file_system_type(file_info.path(), &empty_cache).unwrap();
+
+ // should work with unmatched cache, and the cache should be set to the last query result
+ let unmatched_cache = RefCell::new(Some(Cache {
+ dev_id: "foo".to_string(),
+ fs_type: "bar".to_string(),
+ }));
+ let target_fs_type_unmatched_cache =
+ get_file_system_type(file_info.path(), &unmatched_cache).unwrap();
+ assert_eq!(
+ target_fs_type, target_fs_type_unmatched_cache,
+ "get_file_system_type should return correct result with unmatched cache"
+ );
+ assert_eq!(
+ unmatched_cache.borrow().as_ref().unwrap().fs_type,
+ target_fs_type,
+ "get_file_system_type should set the cache to the last query result"
+ );
 
  // should match fs type
  let matcher = super::FileSystemMatcher::new(target_fs_type.clone());

src/find/mod.rs

@@ -1206,10 +1206,12 @@ mod tests {
  fn test_fs_matcher() {
  use crate::find::tests::FakeDependencies;
  use matchers::fs::get_file_system_type;
+ use std::cell::RefCell;
  use std::path::Path;
 
  let path = Path::new("./test_data/simple/subdir");
- let target_fs_type = get_file_system_type(path).unwrap();
+ let empty_cache = RefCell::new(None);
+ let target_fs_type = get_file_system_type(path, &empty_cache).unwrap();
 
  // should match fs type
  let deps = FakeDependencies::new();

tests/find_cmd_tests.rs

@@ -785,10 +785,12 @@ fn find_age_range() {
 #[serial(working_dir)]
 fn find_fs() {
  use findutils::find::matchers::fs::get_file_system_type;
+ use std::cell::RefCell;
  use std::path::Path;
 
  let path = Path::new("./test_data/simple/subdir");
- let target_fs_type = get_file_system_type(path).unwrap();
+ let empty_cache = RefCell::new(None);
+ let target_fs_type = get_file_system_type(path, &empty_cache).unwrap();
 
  // match fs type
  Command::cargo_bin("find")