From 0813147b97b8d7538704e167bf2463d4588ba7ee Mon Sep 17 00:00:00 2001
From: Nikolay Minaev <noktoborus@gmail.com>
Date: Sat, 27 Jul 2024 19:47:23 +0400
Subject: [PATCH] Use fs' mtime to avoid saving problem on out-of-synced
 network fs (#11142)

In the case of network file systems, if the server time is ahead
of the local system time, then helix could annoy with messages
that the file has already been modified by another application.
---
 helix-term/src/application.rs |  2 +-
 helix-view/src/document.rs    | 36 ++++++++++++++++++++++++++++++-----
 helix-view/src/editor.rs      |  2 +-
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/helix-term/src/application.rs b/helix-term/src/application.rs
index 60bc5b7cf..7da96b08a 100644
--- a/helix-term/src/application.rs
+++ b/helix-term/src/application.rs
@@ -575,7 +575,7 @@ pub fn handle_document_write(&mut self, doc_save_event: DocumentSavedEventResult
             doc_save_event.revision
         );
 
-        doc.set_last_saved_revision(doc_save_event.revision);
+        doc.set_last_saved_revision(doc_save_event.revision, doc_save_event.save_time);
 
         let lines = doc_save_event.text.len_lines();
         let bytes = doc_save_event.text.len_bytes();
diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 489555112..346f04ed8 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -106,6 +106,7 @@ fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
 #[derive(Debug, Clone)]
 pub struct DocumentSavedEvent {
     pub revision: usize,
+    pub save_time: SystemTime,
     pub doc_id: DocumentId,
     pub path: PathBuf,
     pub text: Rope,
@@ -965,6 +966,11 @@ impl Future<Output = Result<DocumentSavedEvent, anyhow::Error>> + 'static + Send
             }
             .await;
 
+            let save_time = match fs::metadata(&write_path).await {
+                Ok(metadata) => metadata.modified().map_or(SystemTime::now(), |mtime| mtime),
+                Err(_) => SystemTime::now(),
+            };
+
             if let Some(backup) = backup {
                 if write_result.is_err() {
                     // restore backup
@@ -987,6 +993,7 @@ impl Future<Output = Result<DocumentSavedEvent, anyhow::Error>> + 'static + Send
 
             let event = DocumentSavedEvent {
                 revision: current_rev,
+                save_time,
                 doc_id,
                 path,
                 text: text.clone(),
@@ -1045,6 +1052,26 @@ pub fn detect_indent_and_line_ending(&mut self) {
         }
     }
 
+    pub fn pickup_last_saved_time(&mut self) {
+        self.last_saved_time = match self.path.as_mut().unwrap().metadata() {
+            Ok(metadata) => match metadata.modified() {
+                Ok(mtime) => mtime,
+                Err(_) => {
+                    log::error!(
+                        "Use a system time instead of fs' mtime not supported on this platform"
+                    );
+                    SystemTime::now()
+                }
+            },
+            Err(e) => {
+                log::error!(
+                    "Use a system time instead of fs' mtime: failed to file's metadata: {e}"
+                );
+                SystemTime::now()
+            }
+        };
+    }
+
     // Detect if the file is readonly and change the readonly field if necessary (unix only)
     pub fn detect_readonly(&mut self) {
         // Allows setting the flag for files the user cannot modify, like root files
@@ -1082,9 +1109,7 @@ pub fn reload(
         self.apply(&transaction, view.id);
         self.append_changes_to_history(view);
         self.reset_modified();
-
-        self.last_saved_time = SystemTime::now();
-
+        self.pickup_last_saved_time();
         self.detect_indent_and_line_ending();
 
         match provider_registry.get_diff_base(&path) {
@@ -1123,6 +1148,7 @@ pub fn set_path(&mut self, path: Option<&Path>) {
         self.path = path;
 
         self.detect_readonly();
+        self.pickup_last_saved_time();
     }
 
     /// Set the programming language for the file and load associated data (e.g. highlighting)
@@ -1603,7 +1629,7 @@ pub fn reset_modified(&mut self) {
     }
 
     /// Set the document's latest saved revision to the given one.
-    pub fn set_last_saved_revision(&mut self, rev: usize) {
+    pub fn set_last_saved_revision(&mut self, rev: usize, save_time: SystemTime) {
         log::debug!(
             "doc {} revision updated {} -> {}",
             self.id,
@@ -1611,7 +1637,7 @@ pub fn set_last_saved_revision(&mut self, rev: usize) {
             rev
         );
         self.last_saved_revision = rev;
-        self.last_saved_time = SystemTime::now();
+        self.last_saved_time = save_time;
     }
 
     /// Get the document's latest saved revision.
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index ba7337f22..4249db1d5 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -2083,7 +2083,7 @@ pub async fn flush_writes(&mut self) -> anyhow::Result<()> {
                 };
 
                 let doc = doc_mut!(self, &save_event.doc_id);
-                doc.set_last_saved_revision(save_event.revision);
+                doc.set_last_saved_revision(save_event.revision, save_event.save_time);
             }
         }