Only reset directories if we modify the contents

crates/applesauce/src/threads/mod.rs

@@ -76,7 +76,7 @@ pub struct Context {
     // Fields are dropped in top-down order, so ensure we update the parent's times before
     // dropping the operation (which will notify that the operation is done if this is the last
     // file).
-    _parent_reset: Option<Arc<times::Resetter>>,
+    parent_resetter: Option<Arc<times::Resetter>>,
     operation: Arc<OperationContext>,
     path: PathBuf,
     progress: Box<dyn progress::Task + Send + Sync>,
@@ -205,7 +205,7 @@ impl BackgroundThreads {
                         path,
                         progress: inner_progress,
                         orig_metadata: metadata,
-                        _parent_reset: dir_reset,
+                        parent_resetter: dir_reset,
                         orig_times: saved_times,
                     }),
                 })

crates/applesauce/src/threads/writer.rs

@@ -157,6 +157,9 @@ impl Handler {
             let _entered = tracing::debug_span!("rename tmp file").entered();
             tmp_file.persist(&item.context.path)?
         };
+        if let Some(resetter) = &item.context.parent_resetter {
+            resetter.activate();
+        }
         if let Err(e) = times::reset_times(&new_file, &item.context.orig_times) {
             tracing::error!("Unable to reset times: {e}");
         }
@@ -184,6 +187,9 @@ impl Handler {
         )?;
 
         let new_file = tmp_file.persist(&item.context.path)?;
+        if let Some(resetter) = &item.context.parent_resetter {
+            resetter.activate();
+        }
         if let Err(e) = times::reset_times(&new_file, &item.context.orig_times) {
             tracing::error!("Unable to reset times: {e}");
         }

crates/applesauce/src/times.rs

@@ -5,6 +5,7 @@ use std::mem::MaybeUninit;
 use std::os::fd::AsRawFd;
 use std::os::unix::ffi::OsStrExt;
 use std::path::Path;
+use std::sync::atomic::AtomicBool;
 use std::{io, mem, ptr};
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@@ -200,10 +201,14 @@ pub fn reset_times<F: GetSet + std::fmt::Debug + ?Sized>(f: &F, saved: &Saved) -
     f.reset_times(saved)
 }
 
+/// Reset the times of a file/dir
+///
+/// By default, will do nothing on drop, unless `activate` is called at least once
 #[derive(Debug)]
 pub struct Resetter {
     dir_path: CString,
     saved_times: Saved,
+    activated: AtomicBool,
 }
 
 impl Resetter {
@@ -212,12 +217,20 @@ impl Resetter {
         Ok(Self {
             dir_path,
             saved_times,
+            activated: AtomicBool::new(false),
         })
     }
+
+    pub fn activate(&self) {
+        self.activated
+            .store(true, std::sync::atomic::Ordering::Relaxed);
+    }
 }
 
 impl Drop for Resetter {
     fn drop(&mut self) {
-        let _ = times::reset_times(self.dir_path.as_c_str(), &self.saved_times);
+        if self.activated.load(std::sync::atomic::Ordering::Relaxed) {
+            let _ = times::reset_times(self.dir_path.as_c_str(), &self.saved_times);
+        }
     }
 }