From eefd31ad05cac1d7bd72cf5a87725ca06a86aa99 Mon Sep 17 00:00:00 2001
From: Stephan Dilly <dilly.stephan@gmail.com>
Date: Thu, 19 Mar 2020 12:55:38 +0100
Subject: [PATCH] almost a magnitude of perf win by moving input polling into
 thread

---
 README.md   |  2 +-
 src/main.rs | 18 +++++++--------
 src/poll.rs | 65 ++++++++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 66 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index c5c9a253..0c18ef8f 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ Over the last 2 years my go to GUI tool for this was [fork](https://git-fork.com
 * [x] (un)stage files
 * [x] inspect diffs
 * [x] commit
-* [ ] input polling in thread
+* [x] input polling in thread
 * [ ] file watcher instead of polling git
 * [ ] log view
 
diff --git a/src/main.rs b/src/main.rs
index 9e0390c9..6449c368 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,7 +6,7 @@ mod git_utils;
 mod poll;
 mod tui_utils;
 
-use app::App;
+use crate::{app::App, poll::QueueEvent};
 use crossterm::{
     event::{DisableMouseCapture, EnableMouseCapture},
     terminal::{
@@ -15,8 +15,7 @@ use crossterm::{
     },
     ExecutableCommand, Result,
 };
-use poll::PollResult;
-use std::{io, time::Duration};
+use std::io;
 use tui::{backend::CrosstermBackend, Terminal};
 
 fn main() -> Result<()> {
@@ -33,18 +32,17 @@ fn main() -> Result<()> {
 
     let mut app = App::new();
 
+    let receiver = poll::start_polling_thread();
+
     loop {
         app.update();
 
         terminal.draw(|mut f| app.draw(&mut f))?;
 
-        loop {
-            if let PollResult::Event(e) =
-                poll::poll(Duration::from_millis(10))
-            {
-                app.event(e);
-            } else {
-                break;
+        let events = receiver.recv().unwrap();
+        for e in events {
+            if let QueueEvent::Event(ev) = e {
+                app.event(ev);
             }
         }
 
diff --git a/src/poll.rs b/src/poll.rs
index cf82fa96..cc2c78a4 100644
--- a/src/poll.rs
+++ b/src/poll.rs
@@ -1,20 +1,69 @@
 use crossterm::event::{self, Event};
-use std::time::Duration;
+use std::{
+    sync::mpsc::{self, Receiver},
+    thread::{self, sleep},
+    time::{Duration, Instant},
+};
 
-/// as
-pub enum PollResult {
-    Timeout,
+///
+#[derive(Clone)]
+pub enum QueueEvent {
+    Tick,
     Event(Event),
 }
 
+static MAX_POLL_DURATION: Duration = Duration::from_secs(2);
+static MIN_POLL_DURATION: Duration = Duration::from_millis(5);
+static MAX_BATCHING_DURATION: Duration = Duration::from_millis(25);
+static TICK_DURATION: Duration = Duration::from_secs(2);
+
+/// we run 2 threads feeding us with update events.
 ///
-pub fn poll(dur: Duration) -> PollResult {
+/// Thread 1:
+///     We will
+pub fn start_polling_thread() -> Receiver<Vec<QueueEvent>> {
+    let (tx, rx) = mpsc::channel();
+
+    let tx1 = tx.clone();
+    thread::spawn(move || {
+        let mut last_send = Instant::now();
+        let mut batch = Vec::new();
+
+        loop {
+            let timeout = if batch.len() > 0 {
+                MIN_POLL_DURATION
+            } else {
+                MAX_POLL_DURATION
+            };
+            if let Some(e) = poll(timeout) {
+                batch.push(QueueEvent::Event(e));
+            }
+
+            if batch.len() > 0
+                && last_send.elapsed() > MAX_BATCHING_DURATION
+            {
+                tx1.send(batch).unwrap();
+                batch = Vec::new();
+                last_send = Instant::now();
+            }
+        }
+    });
+
+    thread::spawn(move || loop {
+        tx.send(vec![QueueEvent::Tick]).unwrap();
+        sleep(TICK_DURATION);
+    });
+
+    rx
+}
+
+///
+fn poll(dur: Duration) -> Option<Event> {
     if event::poll(dur).unwrap() {
         // It's guaranteed that read() wont block if `poll` returns `Ok(true)`
         let event = event::read().unwrap();
-
-        PollResult::Event(event)
+        Some(event)
     } else {
-        PollResult::Timeout
+        None
     }
 }