Batch key handling (#448)

* Batch input events and only query once they are finished

This simplifies the code a lot (no more bounded channel) and yields
the same performance improvement with scroll wheel spam while fixing copy/paste

* Clippy

* fmt

* Use blocking wait before emptying events channel

This was causing a busy loop

* Update query on filter mode change

2 files changed, 27 insertions, 26 deletions

diff --git a/src/command/client/event.rs b/src/command/client/event.rs
index f818d728..8044e278 100644
--- a/src/command/client/event.rs
+++ b/src/command/client/event.rs
@@ -1,6 +1,6 @@
 use std::{thread, time::Duration};
 
-use crossbeam_channel::{bounded, TrySendError};
+use crossbeam_channel::unbounded;
 use termion::{event::Event as TermEvent, event::Key, input::TermRead};
 
 pub enum Event<I> {
@@ -35,22 +35,16 @@ impl Events {
     }
 
     pub fn with_config(config: Config) -> Events {
-        // Keep channel small so scroll events don't stack for ages.
-        let (tx, rx) = bounded(1);
+        let (tx, rx) = unbounded();
 
         {
             let tx = tx.clone();
             thread::spawn(move || {
                 let tty = termion::get_tty().expect("Could not find tty");
                 for event in tty.events().flatten() {
-                    if let Err(err) = tx.try_send(Event::Input(event)) {
-                        if let TrySendError::Full(_) = err {
-                            // Silently ignore send fails when buffer is full.
-                            // This will most likely be scroll wheel spam and we can drop some events.
-                        } else {
-                            eprintln!("{}", err);
-                            return;
-                        }
+                    if let Err(err) = tx.send(Event::Input(event)) {
+                        eprintln!("{}", err);
+                        return;
                     }
                 }
             })
@@ -69,4 +63,8 @@ impl Events {
     pub fn next(&self) -> Result<Event<TermEvent>, crossbeam_channel::RecvError> {
         self.rx.recv()
     }
+
+    pub fn try_next(&self) -> Result<Event<TermEvent>, crossbeam_channel::TryRecvError> {
+        self.rx.try_recv()
+    }
 }
diff --git a/src/command/client/search.rs b/src/command/client/search.rs
index 4e0de683..c50c492c 100644
--- a/src/command/client/search.rs
+++ b/src/command/client/search.rs
@@ -307,12 +307,7 @@ fn remove_char_from_input(app: &mut State, i: usize) -> char {
 }
 
 #[allow(clippy::too_many_lines)]
-async fn key_handler(
-    input: TermEvent,
-    search_mode: SearchMode,
-    db: &mut impl Database,
-    app: &mut State,
-) -> Option<String> {
+fn key_handler(input: &TermEvent, app: &mut State) -> Option<String> {
     match input {
         TermEvent::Key(Key::Esc | Key::Ctrl('c' | 'd' | 'g')) => return Some(String::from("")),
         TermEvent::Key(Key::Char('\n')) => {
@@ -324,7 +319,7 @@ async fn key_handler(
                     .map_or(app.input.clone(), |h| h.command.clone()),
             );
         }
-        TermEvent::Key(Key::Alt(c)) if ('1'..='9').contains(&c) => {
+        TermEvent::Key(Key::Alt(c)) if ('1'..='9').contains(c) => {
             let c = c.to_digit(10)? as usize;
             let i = app.results_state.selected()? + c;
 
@@ -351,9 +346,8 @@ async fn key_handler(
             app.cursor_index = app.input.chars().count();
         }
         TermEvent::Key(Key::Char(c)) => {
-            insert_char_into_input(app, app.cursor_index, c);
+            insert_char_into_input(app, app.cursor_index, *c);
             app.cursor_index += 1;
-            query_results(app, search_mode, db).await.unwrap();
         }
         TermEvent::Key(Key::Backspace) => {
             if app.cursor_index == 0 {
@@ -361,7 +355,6 @@ async fn key_handler(
             }
             remove_char_from_input(app, app.cursor_index);
             app.cursor_index -= 1;
-            query_results(app, search_mode, db).await.unwrap();
         }
         TermEvent::Key(Key::Ctrl('w')) => {
             let mut stop_on_next_whitespace = false;
@@ -379,12 +372,10 @@ async fn key_handler(
                 }
                 app.cursor_index -= 1;
             }
-            query_results(app, search_mode, db).await.unwrap();
         }
         TermEvent::Key(Key::Ctrl('u')) => {
             app.input = String::from("");
             app.cursor_index = 0;
-            query_results(app, search_mode, db).await.unwrap();
         }
         TermEvent::Key(Key::Ctrl('r')) => {
             app.filter_mode = match app.filter_mode {
@@ -393,8 +384,6 @@ async fn key_handler(
                 FilterMode::Session => FilterMode::Directory,
                 FilterMode::Directory => FilterMode::Global,
             };
-
-            query_results(app, search_mode, db).await.unwrap();
         }
         TermEvent::Key(Key::Down | Key::Ctrl('n' | 'j'))
         | TermEvent::Mouse(MouseEvent::Press(MouseButton::WheelDown, _, _)) => {
@@ -632,13 +621,27 @@ async fn select_history(
 
     loop {
         let history_count = db.history_count().await?;
+        let initial_input = app.input.clone();
+        let initial_filter_mode = app.filter_mode;
+
         // Handle input
         if let Event::Input(input) = events.next()? {
-            if let Some(output) = key_handler(input, search_mode, db, &mut app).await {
+            if let Some(output) = key_handler(&input, &mut app) {
                 return Ok(output);
             }
         }
 
+        // After we receive input process the whole event channel before query/render.
+        while let Ok(Event::Input(input)) = events.try_next() {
+            if let Some(output) = key_handler(&input, &mut app) {
+                return Ok(output);
+            }
+        }
+
+        if initial_input != app.input || initial_filter_mode != app.filter_mode {
+            query_results(&mut app, search_mode, db).await?;
+        }
+
         let compact = match style {
             atuin_client::settings::Style::Auto => {
                 terminal.size().map(|size| size.height < 14).unwrap_or(true)