From 4ce51c813841af211fb9b36284f4df4db6078a53 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 9 Mar 2023 07:26:22 +0100
Subject: [PATCH] Limit dirty buffer save optimization to multi-buffers

---
 crates/editor/src/items.rs    | 31 ++++++++++++++++++++++++++++---
 crates/project/src/project.rs | 14 +-------------
 2 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/crates/editor/src/items.rs b/crates/editor/src/items.rs
index 0d594a66ef354ab49152a2e0e3d318592f6c3233..cda702de00f6411e10bda7ad890d8136688ebf42 100644
--- a/crates/editor/src/items.rs
+++ b/crates/editor/src/items.rs
@@ -612,9 +612,34 @@ impl Item for Editor {
         let buffers = self.buffer().clone().read(cx).all_buffers();
         cx.as_mut().spawn(|mut cx| async move {
             format.await?;
-            project
-                .update(&mut cx, |project, cx| project.save_buffers(buffers, cx))
-                .await?;
+
+            if buffers.len() == 1 {
+                project
+                    .update(&mut cx, |project, cx| project.save_buffers(buffers, cx))
+                    .await?;
+            } else {
+                // For multi-buffers, only save those ones that contain changes. For clean buffers
+                // we simulate saving by calling `Buffer::did_save`, so that language servers or
+                // other downstream listeners of save events get notified.
+                let (dirty_buffers, clean_buffers) = buffers.into_iter().partition(|buffer| {
+                    buffer.read_with(&cx, |buffer, _| buffer.is_dirty() || buffer.has_conflict())
+                });
+
+                project
+                    .update(&mut cx, |project, cx| {
+                        project.save_buffers(dirty_buffers, cx)
+                    })
+                    .await?;
+                for buffer in clean_buffers {
+                    buffer.update(&mut cx, |buffer, cx| {
+                        let version = buffer.saved_version().clone();
+                        let fingerprint = buffer.saved_version_fingerprint();
+                        let mtime = buffer.saved_mtime();
+                        buffer.did_save(version, fingerprint, mtime, cx);
+                    });
+                }
+            }
+
             Ok(())
         })
     }
diff --git a/crates/project/src/project.rs b/crates/project/src/project.rs
index f93de8e1d847d263dad2526dbcaaa77b0571b118..2ebea8d07dad811a378a065a7f666caaf594c6d3 100644
--- a/crates/project/src/project.rs
+++ b/crates/project/src/project.rs
@@ -1434,19 +1434,7 @@ impl Project {
         let worktree = file.worktree.clone();
         let path = file.path.clone();
         worktree.update(cx, |worktree, cx| match worktree {
-            Worktree::Local(worktree) => {
-                if buffer.read(cx).is_dirty() || buffer.read(cx).has_conflict() {
-                    worktree.save_buffer(buffer, path, false, cx)
-                } else {
-                    buffer.update(cx, |buffer, cx| {
-                        let version = buffer.saved_version().clone();
-                        let fingerprint = buffer.saved_version_fingerprint();
-                        let mtime = buffer.saved_mtime();
-                        buffer.did_save(version.clone(), fingerprint, mtime, cx);
-                        Task::ready(Ok((version, fingerprint, mtime)))
-                    })
-                }
-            }
+            Worktree::Local(worktree) => worktree.save_buffer(buffer, path, false, cx),
             Worktree::Remote(worktree) => worktree.save_buffer(buffer, cx),
         })
     }