cache branchname lookup (closes #159)

Author: Stephan Dilly

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - hooks ignored when running `gitui` in subfolder of workdir ([#151](https://github.com/extrawurst/gitui/issues/151))
 - better scrolling in file-trees [[@tisorlawan](https://github.com/tisorlawan)] ([#144](https://github.com/extrawurst/gitui/issues/144))
 - show untracked files in stash commit details [[@MCord](https://github.com/MCord)] ([#130](https://github.com/extrawurst/gitui/issues/130))
+- in some repos looking up the branch name was a bottleneck ([#159](https://github.com/extrawurst/gitui/issues/159))
 - some optimizations in reflog
 
 ## [0.7.0] - 2020-06-15

asyncgit/src/cached/branchname.rs

@@ -0,0 +1,41 @@
+use crate::{
+    error::Result,
+    sync::{self, CommitId},
+};
+
+///
+pub struct BranchName {
+    last_result: Option<(CommitId, String)>,
+    repo_path: String,
+}
+
+impl BranchName {
+    ///
+    pub fn new(path: &str) -> Self {
+        Self {
+            repo_path: path.to_string(),
+            last_result: None,
+        }
+    }
+
+    ///
+    pub fn lookup(&mut self) -> Result<String> {
+        let current_head = sync::get_head(self.repo_path.as_str())?;
+
+        if let Some((last_head, branch_name)) =
+            self.last_result.as_ref()
+        {
+            if *last_head == current_head {
+                return Ok(branch_name.clone());
+            }
+        }
+
+        self.fetch(current_head)
+    }
+
+    fn fetch(&mut self, head: CommitId) -> Result<String> {
+        let name = sync::get_branch_name(self.repo_path.as_str())?;
+        self.last_result = Some((head, name.clone()));
+        Ok(name)
+    }
+}

asyncgit/src/cached/mod.rs

@@ -0,0 +1,7 @@
+//! cached lookups:
+//! parts of the sync api that might take longer
+//! to compute but change seldom so doing them async might be overkill
+
+mod branchname;
+
+pub use branchname::BranchName;

asyncgit/src/lib.rs

@@ -6,6 +6,7 @@
 #![deny(clippy::result_unwrap_used)]
 #![deny(clippy::panic)]
 
+pub mod cached;
 mod commit_files;
 mod diff;
 mod error;

asyncgit/src/sync/branch.rs

@@ -7,7 +7,8 @@ use crate::{
 use scopetime::scope_time;
 
 /// returns the branch-name head is currently pointing to
-pub fn get_branch_name(repo_path: &str) -> Result<String> {
+/// this might be expensive, see `cached::BranchName`
+pub(crate) fn get_branch_name(repo_path: &str) -> Result<String> {
     scope_time!("get_branch_name");
 
     let repo = utils::repo(repo_path)?;

asyncgit/src/sync/mod.rs

@@ -16,7 +16,7 @@ pub mod status;
 mod tags;
 pub mod utils;
 
-pub use branch::get_branch_name;
+pub(crate) use branch::get_branch_name;
 pub use commit::{amend, commit};
 pub use commit_details::{get_commit_details, CommitDetails};
 pub use commit_files::get_commit_files;

src/components/changes.rs

@@ -11,7 +11,7 @@ use crate::{
     ui::style::SharedTheme,
 };
 use anyhow::Result;
-use asyncgit::{sync, StatusItem, StatusItemType, CWD};
+use asyncgit::{cached, sync, StatusItem, StatusItemType, CWD};
 use crossterm::event::Event;
 use std::path::Path;
 use strings::commands;
@@ -39,6 +39,7 @@ pub struct ChangesComponent {
     files: FileTreeComponent,
     is_working_dir: bool,
     queue: Queue,
+    branch_name: cached::BranchName,
 }
 
 impl ChangesComponent {
@@ -60,13 +61,14 @@ impl ChangesComponent {
             ),
             is_working_dir,
             queue,
+            branch_name: cached::BranchName::new(CWD),
         }
     }
 
     ///
     pub fn update(&mut self, list: &[StatusItem]) -> Result<()> {
         if self.is_working_dir {
-            if let Ok(branch_name) = sync::get_branch_name(CWD) {
+            if let Ok(branch_name) = self.branch_name.lookup() {
                 self.files.set_title(format!(
                     "{} - {{{}}}",
                     &self.title, branch_name,

src/tabs/revlog.rs

@@ -11,6 +11,7 @@ use crate::{
 };
 use anyhow::Result;
 use asyncgit::{
+    cached,
     sync::{self, CommitId},
     AsyncLog, AsyncNotification, FetchStatus, CWD,
 };
@@ -31,6 +32,7 @@ pub struct Revlog {
     git_log: AsyncLog,
     queue: Queue,
     visible: bool,
+    branch_name: cached::BranchName,
 }
 
 impl Revlog {
@@ -50,6 +52,7 @@ impl Revlog {
             list: CommitList::new(strings::LOG_TITLE, theme),
             git_log: AsyncLog::new(sender),
             visible: false,
+            branch_name: cached::BranchName::new(CWD),
         }
     }
 
@@ -80,7 +83,7 @@ impl Revlog {
             }
 
             self.list.set_branch(
-                sync::get_branch_name(CWD).map(Some).unwrap_or(None),
+                self.branch_name.lookup().map(Some).unwrap_or(None),
             );
 
             if self.commit_details.is_visible() {