fix performance regression in revlog

Author: Stephan Dilly

asyncgit/src/lib.rs

@@ -12,7 +12,7 @@ pub mod sync;
 
 pub use crate::{
     diff::{AsyncDiff, DiffParams},
-    revlog::AsyncLog,
+    revlog::{AsyncLog, FetchStatus},
     status::{AsyncStatus, StatusParams},
     sync::{
         diff::{DiffLine, DiffLineType, FileDiff},

asyncgit/src/revlog.rs

@@ -13,16 +13,32 @@ use std::{
         atomic::{AtomicBool, Ordering},
         Arc, Mutex,
     },
+    thread,
+    time::Duration,
 };
 
+///
+#[derive(PartialEq)]
+pub enum FetchStatus {
+    /// previous fetch still running
+    Pending,
+    /// no change expected
+    NoChange,
+    /// new walk was started
+    Started,
+}
+
 ///
 pub struct AsyncLog {
     current: Arc<Mutex<Vec<Oid>>>,
     sender: Sender<AsyncNotification>,
     pending: Arc<AtomicBool>,
+    background: Arc<AtomicBool>,
 }
 
-static LIMIT_COUNT: usize = 1000;
+static LIMIT_COUNT: usize = 3000;
+static SLEEP_FOREGROUND: Duration = Duration::from_millis(2);
+static SLEEP_BACKGROUND: Duration = Duration::from_millis(1000);
 
 impl AsyncLog {
     ///
@@ -31,6 +47,7 @@ impl AsyncLog {
             current: Arc::new(Mutex::new(Vec::new())),
             sender,
             pending: Arc::new(AtomicBool::new(false)),
+            background: Arc::new(AtomicBool::new(false)),
         }
     }
 
@@ -58,6 +75,11 @@ impl AsyncLog {
         self.pending.load(Ordering::Relaxed)
     }
 
+    ///
+    pub fn set_background(&mut self) {
+        self.background.store(true, Ordering::Relaxed)
+    }
+
     ///
     fn current_head(&self) -> Result<Oid> {
         Ok(self.current.lock()?.first().map_or(Oid::zero(), |f| *f))
@@ -79,29 +101,44 @@ impl AsyncLog {
     }
 
     ///
-    pub fn fetch(&mut self) -> Result<()> {
-        if !self.is_pending() && self.head_changed()? {
-            self.clear()?;
+    pub fn fetch(&mut self) -> Result<FetchStatus> {
+        self.background.store(false, Ordering::Relaxed);
 
-            let arc_current = Arc::clone(&self.current);
-            let sender = self.sender.clone();
-            let arc_pending = Arc::clone(&self.pending);
-
-            rayon_core::spawn(move || {
-                scope_time!("async::revlog");
+        if self.is_pending() {
+            return Ok(FetchStatus::Pending);
+        }
 
-                arc_pending.store(true, Ordering::Relaxed);
-                AsyncLog::fetch_helper(arc_current, &sender)
-                    .expect("failed to fetch");
-                arc_pending.store(false, Ordering::Relaxed);
-                Self::notify(&sender);
-            });
+        if !self.head_changed()? {
+            return Ok(FetchStatus::NoChange);
         }
-        Ok(())
+
+        self.clear()?;
+
+        let arc_current = Arc::clone(&self.current);
+        let sender = self.sender.clone();
+        let arc_pending = Arc::clone(&self.pending);
+        let arc_background = Arc::clone(&self.background);
+
+        rayon_core::spawn(move || {
+            scope_time!("async::revlog");
+
+            arc_pending.store(true, Ordering::Relaxed);
+            AsyncLog::fetch_helper(
+                arc_current,
+                arc_background,
+                &sender,
+            )
+            .expect("failed to fetch");
+            arc_pending.store(false, Ordering::Relaxed);
+            Self::notify(&sender);
+        });
+
+        Ok(FetchStatus::Started)
     }
 
     fn fetch_helper(
         arc_current: Arc<Mutex<Vec<Oid>>>,
+        arc_background: Arc<AtomicBool>,
         sender: &Sender<AsyncNotification>,
     ) -> Result<()> {
         let mut entries = Vec::with_capacity(LIMIT_COUNT);
@@ -121,6 +158,14 @@ impl AsyncLog {
                 break;
             } else {
                 Self::notify(&sender);
+
+                let sleep_duration =
+                    if arc_background.load(Ordering::Relaxed) {
+                        SLEEP_BACKGROUND
+                    } else {
+                        SLEEP_FOREGROUND
+                    };
+                thread::sleep(sleep_duration);
             }
         }
 

src/tabs/revlog/mod.rs

@@ -10,7 +10,7 @@ use crate::{
     ui::calc_scroll_top,
     ui::style::Theme,
 };
-use asyncgit::{sync, AsyncLog, AsyncNotification, CWD};
+use asyncgit::{sync, AsyncLog, AsyncNotification, CWD, FetchStatus};
 use crossbeam_channel::Sender;
 use crossterm::event::Event;
 use std::{borrow::Cow, cmp, convert::TryFrom, time::Instant};
@@ -32,7 +32,6 @@ pub struct Revlog {
     items: ItemBatch,
     git_log: AsyncLog,
     visible: bool,
-    first_open_done: bool,
     scroll_state: (Instant, f32),
     tags: Tags,
     current_size: (u16, u16),
@@ -52,7 +51,6 @@ impl Revlog {
             selection: 0,
             count_total: 0,
             visible: false,
-            first_open_done: false,
             scroll_state: (Instant::now(), 0_f32),
             tags: Tags::new(),
             current_size: (0, 0),
@@ -73,20 +71,22 @@ impl Revlog {
     ///
     pub fn update(&mut self) {
         if self.visible {
-            self.git_log.fetch().unwrap();
-        }
+            let log_changed =
+                self.git_log.fetch().unwrap() == FetchStatus::Started;
 
-        let old_total = self.count_total;
-        self.count_total = self.git_log.count().unwrap();
+            self.count_total = self.git_log.count().unwrap();
 
-        if self.items.needs_data(self.selection, self.selection_max())
-            || old_total != self.count_total
-        {
-            self.fetch_commits();
-        }
+            if self
+                .items
+                .needs_data(self.selection, self.selection_max())
+                || log_changed
+            {
+                self.fetch_commits();
+            }
 
-        if self.tags.is_empty() {
-            self.tags = sync::get_tags(CWD).unwrap();
+            if self.tags.is_empty() {
+                self.tags = sync::get_tags(CWD).unwrap();
+            }
         }
     }
 
@@ -340,14 +340,11 @@ impl Component for Revlog {
 
     fn hide(&mut self) {
         self.visible = false;
+        self.git_log.set_background();
     }
 
     fn show(&mut self) {
         self.visible = true;
-
-        if !self.first_open_done {
-            self.first_open_done = true;
-            self.git_log.fetch().unwrap();
-        }
+        self.git_log.fetch().unwrap();
     }
 }