From c9598b5adc7b8eefad83665427f3763d4dea7b10 Mon Sep 17 00:00:00 2001
From: Michael Zhang <mail@mzhang.io>
Date: Mon, 22 Mar 2021 18:15:23 -0500
Subject: [PATCH] switch to async event loop to not use busy waiting

---
 Cargo.lock    |  1 +
 Cargo.toml    |  2 +-
 src/ui/mod.rs | 17 +++++++++--------
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 66e6c76..7ced088 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -527,6 +527,7 @@ checksum = "7c36c10130df424b2f3552fcc2ddcd9b28a27b1e54b358b45874f88d1ca6888c"
 dependencies = [
  "bitflags 1.2.1",
  "crossterm_winapi 0.7.0",
+ "futures-core",
  "lazy_static",
  "libc",
  "mio",
diff --git a/Cargo.toml b/Cargo.toml
index e8a55a9..3083462 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,7 +20,7 @@ async-trait = "0.1.48"
 cfg-if = "1.0.0"
 chrono = "0.4.19"
 chrono-humanize = "0.1.2"
-crossterm = "0.19.0"
+crossterm = { version = "0.19.0", features = ["event-stream"] }
 fern = { version = "0.6.0", features = ["colored"] }
 format-bytes = "0.2.2"
 futures = "0.3.13"
diff --git a/src/ui/mod.rs b/src/ui/mod.rs
index 4a062ab..c51e17a 100644
--- a/src/ui/mod.rs
+++ b/src/ui/mod.rs
@@ -22,7 +22,7 @@ use anyhow::Result;
 use chrono::{Local, TimeZone};
 use crossterm::{
     cursor,
-    event::{self, Event, KeyCode, KeyEvent},
+    event::{self, Event, KeyCode, KeyEvent, EventStream},
     style, terminal,
 };
 use downcast_rs::Downcast;
@@ -63,6 +63,7 @@ pub async fn run_ui2(
 
     let backend = CrosstermBackend::new(&mut stdout);
     let mut term = Terminal::new(backend)?;
+    let mut ui_events = EventStream::new();
 
     let should_exit = Arc::new(AtomicBool::new(false));
 
@@ -85,20 +86,20 @@ pub async fn run_ui2(
             ui.draw(f);
         })?;
 
-        // handle events coming from the UI
-        if event::poll(FRAME_DURATION)? {
-            let event = event::read()?;
-            ui.process_event(event)?;
-        }
-
         select! {
             // got an event from the mail thread
             evt = mail2ui_rx.recv().fuse() => if let Some(evt) = evt {
                 ui.process_mail_event(evt);
             },
 
+            // got an event from the ui thread
+            evt = ui_events.next().fuse() => if let Some(evt) = evt {
+                let evt = evt?;
+                ui.process_event(evt)?;
+            }
+
             // wait for approx 60fps
-            _ = time::sleep(FRAME_DURATION).fuse() => {},
+            // _ = time::sleep(FRAME_DURATION).fuse() => {},
         }
     }