Add File.disk_state enum to clarify filesystem states (#20776)

Motivation for this is to make things more understandable while figuring
out #20775.

This is intended to be a refactoring that does not affect behavior, but
there are a few tricky spots:

* Previously `File.mtime()` (now `File.disk_state().mtime()`) would
return last known modification time for deleted files. Looking at uses,
I believe this will not affect anything. If there are behavior changes
here I believe they would be improvements.

* `BufferEvent::DirtyChanged` is now only emitted if dirtiness actually
changed, rather than if it may have changed. This should only be an
efficiency improvement.

Release Notes:

- N/A

Co-authored-by: Mikayla Maki <mikayla@zed.dev>

crates/project/src/buffer_store.rs

@@ -20,7 +20,7 @@ use language::{
         deserialize_line_ending, deserialize_version, serialize_line_ending, serialize_version,
         split_operations,
     },
-    Buffer, BufferEvent, Capability, File as _, Language, Operation,
+    Buffer, BufferEvent, Capability, DiskState, File as _, Language, Operation,
 };
 use rpc::{proto, AnyProtoClient, ErrorExt as _, TypedEnvelope};
 use smol::channel::Receiver;
@@ -434,7 +434,10 @@ impl LocalBufferStore {
         let line_ending = buffer.line_ending();
         let version = buffer.version();
         let buffer_id = buffer.remote_id();
-        if buffer.file().is_some_and(|file| !file.is_created()) {
+        if buffer
+            .file()
+            .is_some_and(|file| file.disk_state() == DiskState::New)
+        {
             has_changed_file = true;
         }
 
@@ -444,7 +447,7 @@ impl LocalBufferStore {
 
         cx.spawn(move |this, mut cx| async move {
             let new_file = save.await?;
-            let mtime = new_file.mtime;
+            let mtime = new_file.disk_state().mtime();
             this.update(&mut cx, |this, cx| {
                 if let Some((downstream_client, project_id)) = this.downstream_client(cx) {
                     if has_changed_file {
@@ -658,37 +661,30 @@ impl LocalBufferStore {
                 return None;
             }
 
-            let new_file = if let Some(entry) = old_file
+            let snapshot_entry = old_file
                 .entry_id
                 .and_then(|entry_id| snapshot.entry_for_id(entry_id))
-            {
+                .or_else(|| snapshot.entry_for_path(old_file.path.as_ref()));
+
+            let new_file = if let Some(entry) = snapshot_entry {
                 File {
+                    disk_state: match entry.mtime {
+                        Some(mtime) => DiskState::Present { mtime },
+                        None => old_file.disk_state,
+                    },
                     is_local: true,
                     entry_id: Some(entry.id),
-                    mtime: entry.mtime,
                     path: entry.path.clone(),
                     worktree: worktree.clone(),
-                    is_deleted: false,
-                    is_private: entry.is_private,
-                }
-            } else if let Some(entry) = snapshot.entry_for_path(old_file.path.as_ref()) {
-                File {
-                    is_local: true,
-                    entry_id: Some(entry.id),
-                    mtime: entry.mtime,
-                    path: entry.path.clone(),
-                    worktree: worktree.clone(),
-                    is_deleted: false,
                     is_private: entry.is_private,
                 }
             } else {
                 File {
+                    disk_state: DiskState::Deleted,
                     is_local: true,
                     entry_id: old_file.entry_id,
                     path: old_file.path.clone(),
-                    mtime: old_file.mtime,
                     worktree: worktree.clone(),
-                    is_deleted: true,
                     is_private: old_file.is_private,
                 }
             };
@@ -867,10 +863,9 @@ impl BufferStoreImpl for Model<LocalBufferStore> {
                             Some(Arc::new(File {
                                 worktree,
                                 path,
-                                mtime: None,
+                                disk_state: DiskState::New,
                                 entry_id: None,
                                 is_local: true,
-                                is_deleted: false,
                                 is_private: false,
                             })),
                             Capability::ReadWrite,

crates/project/src/image_store.rs

@@ -9,7 +9,7 @@ use gpui::{
     hash, prelude::*, AppContext, EventEmitter, Img, Model, ModelContext, Subscription, Task,
     WeakModel,
 };
-use language::File;
+use language::{DiskState, File};
 use rpc::{AnyProtoClient, ErrorExt as _};
 use std::ffi::OsStr;
 use std::num::NonZeroU64;
@@ -74,11 +74,12 @@ impl ImageItem {
             file_changed = true;
         }
 
-        if !new_file.is_deleted() {
-            let new_mtime = new_file.mtime();
-            if new_mtime != old_file.mtime() {
-                file_changed = true;
-                cx.emit(ImageItemEvent::ReloadNeeded);
+        let old_state = old_file.disk_state();
+        let new_state = new_file.disk_state();
+        if old_state != new_state {
+            file_changed = true;
+            if matches!(new_state, DiskState::Present { .. }) {
+                cx.emit(ImageItemEvent::ReloadNeeded)
             }
         }
 
@@ -503,37 +504,30 @@ impl LocalImageStore {
                 return;
             }
 
-            let new_file = if let Some(entry) = old_file
+            let snapshot_entry = old_file
                 .entry_id
                 .and_then(|entry_id| snapshot.entry_for_id(entry_id))
-            {
+                .or_else(|| snapshot.entry_for_path(old_file.path.as_ref()));
+
+            let new_file = if let Some(entry) = snapshot_entry {
                 worktree::File {
+                    disk_state: match entry.mtime {
+                        Some(mtime) => DiskState::Present { mtime },
+                        None => old_file.disk_state,
+                    },
                     is_local: true,
                     entry_id: Some(entry.id),
-                    mtime: entry.mtime,
                     path: entry.path.clone(),
                     worktree: worktree.clone(),
-                    is_deleted: false,
-                    is_private: entry.is_private,
-                }
-            } else if let Some(entry) = snapshot.entry_for_path(old_file.path.as_ref()) {
-                worktree::File {
-                    is_local: true,
-                    entry_id: Some(entry.id),
-                    mtime: entry.mtime,
-                    path: entry.path.clone(),
-                    worktree: worktree.clone(),
-                    is_deleted: false,
                     is_private: entry.is_private,
                 }
             } else {
                 worktree::File {
+                    disk_state: DiskState::Deleted,
                     is_local: true,
                     entry_id: old_file.entry_id,
                     path: old_file.path.clone(),
-                    mtime: old_file.mtime,
                     worktree: worktree.clone(),
-                    is_deleted: true,
                     is_private: old_file.is_private,
                 }
             };

crates/project/src/project_tests.rs

@@ -5,12 +5,12 @@ use gpui::{AppContext, SemanticVersion, UpdateGlobal};
 use http_client::Url;
 use language::{
     language_settings::{language_settings, AllLanguageSettings, LanguageSettingsContent},
-    tree_sitter_rust, tree_sitter_typescript, Diagnostic, DiagnosticSet, FakeLspAdapter,
+    tree_sitter_rust, tree_sitter_typescript, Diagnostic, DiagnosticSet, DiskState, FakeLspAdapter,
     LanguageConfig, LanguageMatcher, LanguageName, LineEnding, OffsetRangeExt, Point, ToPoint,
 };
 use lsp::{DiagnosticSeverity, NumberOrString};
 use parking_lot::Mutex;
-use pretty_assertions::assert_eq;
+use pretty_assertions::{assert_eq, assert_matches};
 use serde_json::json;
 #[cfg(not(windows))]
 use std::os;
@@ -3239,10 +3239,22 @@ async fn test_rescan_and_remote_updates(cx: &mut gpui::TestAppContext) {
             Path::new("b/c/file5")
         );
 
-        assert!(!buffer2.read(cx).file().unwrap().is_deleted());
-        assert!(!buffer3.read(cx).file().unwrap().is_deleted());
-        assert!(!buffer4.read(cx).file().unwrap().is_deleted());
-        assert!(buffer5.read(cx).file().unwrap().is_deleted());
+        assert_matches!(
+            buffer2.read(cx).file().unwrap().disk_state(),
+            DiskState::Present { .. }
+        );
+        assert_matches!(
+            buffer3.read(cx).file().unwrap().disk_state(),
+            DiskState::Present { .. }
+        );
+        assert_matches!(
+            buffer4.read(cx).file().unwrap().disk_state(),
+            DiskState::Present { .. }
+        );
+        assert_eq!(
+            buffer5.read(cx).file().unwrap().disk_state(),
+            DiskState::Deleted
+        );
     });
 
     // Update the remote worktree. Check that it becomes consistent with the
@@ -3416,7 +3428,11 @@ async fn test_buffer_is_dirty(cx: &mut gpui::TestAppContext) {
             ]
         );
         events.lock().clear();
-        buffer.did_save(buffer.version(), buffer.file().unwrap().mtime(), cx);
+        buffer.did_save(
+            buffer.version(),
+            buffer.file().unwrap().disk_state().mtime(),
+            cx,
+        );
     });
 
     // after saving, the buffer is not dirty, and emits a saved event.