Load a file's head text on file load just to get started

Cargo.lock

@@ -2224,6 +2224,21 @@ dependencies = [
  "stable_deref_trait",
 ]
 
+[[package]]
+name = "git2"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2994bee4a3a6a51eb90c218523be382fd7ea09b16380b9312e9dbe955ff7c7d1"
+dependencies = [
+ "bitflags",
+ "libc",
+ "libgit2-sys",
+ "log",
+ "openssl-probe",
+ "openssl-sys",
+ "url",
+]
+
 [[package]]
 name = "glob"
 version = "0.3.0"
@@ -2894,6 +2909,20 @@ version = "0.2.126"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "349d5a591cd28b49e1d1037471617a32ddcda5731b99419008085f72d5a53836"
 
+[[package]]
+name = "libgit2-sys"
+version = "0.14.0+1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47a00859c70c8a4f7218e6d1cc32875c4b55f6799445b842b0d8ed5e4c3d959b"
+dependencies = [
+ "cc",
+ "libc",
+ "libssh2-sys",
+ "libz-sys",
+ "openssl-sys",
+ "pkg-config",
+]
+
 [[package]]
 name = "libloading"
 version = "0.7.3"
@@ -2934,6 +2963,20 @@ dependencies = [
  "zstd-sys",
 ]
 
+[[package]]
+name = "libssh2-sys"
+version = "0.2.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b094a36eb4b8b8c8a7b4b8ae43b2944502be3e59cd87687595cf6b0a71b3f4ca"
+dependencies = [
+ "cc",
+ "libc",
+ "libz-sys",
+ "openssl-sys",
+ "pkg-config",
+ "vcpkg",
+]
+
 [[package]]
 name = "libz-sys"
 version = "1.1.8"
@@ -3970,6 +4013,7 @@ dependencies = [
  "fsevent",
  "futures",
  "fuzzy",
+ "git2",
  "gpui",
  "ignore",
  "language",

crates/language/src/buffer.rs

@@ -47,6 +47,7 @@ pub use lsp::DiagnosticSeverity;
 
 pub struct Buffer {
     text: TextBuffer,
+    head_text: Option<String>,
     file: Option<Arc<dyn File>>,
     saved_version: clock::Global,
     saved_version_fingerprint: String,
@@ -328,17 +329,20 @@ impl Buffer {
         Self::build(
             TextBuffer::new(replica_id, cx.model_id() as u64, base_text.into()),
             None,
+            None,
         )
     }
 
     pub fn from_file<T: Into<String>>(
         replica_id: ReplicaId,
         base_text: T,
+        head_text: Option<T>,
         file: Arc<dyn File>,
         cx: &mut ModelContext<Self>,
     ) -> Self {
         Self::build(
             TextBuffer::new(replica_id, cx.model_id() as u64, base_text.into()),
+            head_text.map(|h| h.into()),
             Some(file),
         )
     }
@@ -349,7 +353,7 @@ impl Buffer {
         file: Option<Arc<dyn File>>,
     ) -> Result<Self> {
         let buffer = TextBuffer::new(replica_id, message.id, message.base_text);
-        let mut this = Self::build(buffer, file);
+        let mut this = Self::build(buffer, message.head_text, file);
         this.text.set_line_ending(proto::deserialize_line_ending(
             proto::LineEnding::from_i32(message.line_ending)
                 .ok_or_else(|| anyhow!("missing line_ending"))?,
@@ -362,6 +366,7 @@ impl Buffer {
             id: self.remote_id(),
             file: self.file.as_ref().map(|f| f.to_proto()),
             base_text: self.base_text().to_string(),
+            head_text: self.head_text.clone(),
             line_ending: proto::serialize_line_ending(self.line_ending()) as i32,
         }
     }
@@ -404,7 +409,7 @@ impl Buffer {
         self
     }
 
-    fn build(buffer: TextBuffer, file: Option<Arc<dyn File>>) -> Self {
+    fn build(buffer: TextBuffer, head_text: Option<String>, file: Option<Arc<dyn File>>) -> Self {
         let saved_mtime = if let Some(file) = file.as_ref() {
             file.mtime()
         } else {
@@ -418,6 +423,7 @@ impl Buffer {
             transaction_depth: 0,
             was_dirty_before_starting_transaction: None,
             text: buffer,
+            head_text,
             file,
             syntax_map: Mutex::new(SyntaxMap::new()),
             parsing_in_background: false,

crates/project/Cargo.toml

@@ -52,6 +52,7 @@ smol = "1.2.5"
 thiserror = "1.0.29"
 toml = "0.5"
 rocksdb = "0.18"
+git2 = "0.15"
 
 [dev-dependencies]
 client = { path = "../client", features = ["test-support"] }

crates/project/src/fs.rs

@@ -1,9 +1,11 @@
 use anyhow::{anyhow, Result};
 use fsevent::EventStream;
 use futures::{future::BoxFuture, Stream, StreamExt};
+use git2::{Repository, RepositoryOpenFlags};
 use language::LineEnding;
 use smol::io::{AsyncReadExt, AsyncWriteExt};
 use std::{
+    ffi::OsStr,
     io,
     os::unix::fs::MetadataExt,
     path::{Component, Path, PathBuf},
@@ -29,6 +31,7 @@ pub trait Fs: Send + Sync {
     async fn remove_file(&self, path: &Path, options: RemoveOptions) -> Result<()>;
     async fn open_sync(&self, path: &Path) -> Result<Box<dyn io::Read>>;
     async fn load(&self, path: &Path) -> Result<String>;
+    async fn load_head_text(&self, path: &Path) -> Option<String>;
     async fn save(&self, path: &Path, text: &Rope, line_ending: LineEnding) -> Result<()>;
     async fn canonicalize(&self, path: &Path) -> Result<PathBuf>;
     async fn is_file(&self, path: &Path) -> bool;
@@ -161,6 +164,38 @@ impl Fs for RealFs {
         Ok(text)
     }
 
+    async fn load_head_text(&self, path: &Path) -> Option<String> {
+        fn logic(path: &Path) -> Result<Option<String>> {
+            let repo = Repository::open_ext(path, RepositoryOpenFlags::empty(), &[OsStr::new("")])?;
+            assert!(repo.path().ends_with(".git"));
+            let repo_root_path = match repo.path().parent() {
+                Some(root) => root,
+                None => return Ok(None),
+            };
+
+            let relative_path = path.strip_prefix(repo_root_path)?;
+            let object = repo
+                .head()?
+                .peel_to_tree()?
+                .get_path(relative_path)?
+                .to_object(&repo)?;
+
+            let content = match object.as_blob() {
+                Some(blob) => blob.content().to_owned(),
+                None => return Ok(None),
+            };
+
+            let head_text = String::from_utf8(content.to_owned())?;
+            Ok(Some(head_text))
+        }
+
+        match logic(path) {
+            Ok(value) => return value,
+            Err(err) => log::error!("Error loading head text: {:?}", err),
+        }
+        None
+    }
+
     async fn save(&self, path: &Path, text: &Rope, line_ending: LineEnding) -> Result<()> {
         let buffer_size = text.summary().len.min(10 * 1024);
         let file = smol::fs::File::create(path).await?;
@@ -748,6 +783,10 @@ impl Fs for FakeFs {
         entry.file_content(&path).cloned()
     }
 
+    async fn load_head_text(&self, _: &Path) -> Option<String> {
+        None
+    }
+
     async fn save(&self, path: &Path, text: &Rope, line_ending: LineEnding) -> Result<()> {
         self.simulate_random_delay().await;
         let path = normalize_path(path);

crates/project/src/worktree.rs

@@ -446,10 +446,10 @@ impl LocalWorktree {
     ) -> Task<Result<ModelHandle<Buffer>>> {
         let path = Arc::from(path);
         cx.spawn(move |this, mut cx| async move {
-            let (file, contents) = this
+            let (file, contents, head_text) = this
                 .update(&mut cx, |t, cx| t.as_local().unwrap().load(&path, cx))
                 .await?;
-            Ok(cx.add_model(|cx| Buffer::from_file(0, contents, Arc::new(file), cx)))
+            Ok(cx.add_model(|cx| Buffer::from_file(0, contents, head_text, Arc::new(file), cx)))
         })
     }
 
@@ -558,13 +558,19 @@ impl LocalWorktree {
         }
     }
 
-    fn load(&self, path: &Path, cx: &mut ModelContext<Worktree>) -> Task<Result<(File, String)>> {
+    fn load(
+        &self,
+        path: &Path,
+        cx: &mut ModelContext<Worktree>,
+    ) -> Task<Result<(File, String, Option<String>)>> {
         let handle = cx.handle();
         let path = Arc::from(path);
         let abs_path = self.absolutize(&path);
         let fs = self.fs.clone();
         cx.spawn(|this, mut cx| async move {
             let text = fs.load(&abs_path).await?;
+            let head_text = fs.load_head_text(&abs_path).await;
+
             // Eagerly populate the snapshot with an updated entry for the loaded file
             let entry = this
                 .update(&mut cx, |this, cx| {
@@ -573,6 +579,7 @@ impl LocalWorktree {
                         .refresh_entry(path, abs_path, None, cx)
                 })
                 .await?;
+
             Ok((
                 File {
                     entry_id: Some(entry.id),
@@ -582,6 +589,7 @@ impl LocalWorktree {
                     is_local: true,
                 },
                 text,
+                head_text,
             ))
         })
     }

crates/rpc/proto/zed.proto

@@ -821,7 +821,8 @@ message BufferState {
     uint64 id = 1;
     optional File file = 2;
     string base_text = 3;
-    LineEnding line_ending = 4;
+    optional string head_text = 4;
+    LineEnding line_ending = 5;
 }
 
 message BufferChunk {