Adding some communication between UI and backend to ensure sync at connection start

CHANGELOG.md

@@ -14,6 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Removed
 
 ### Fixed
+- [\#164](https://github.com/Manta-Network/manta-signer/pull/164) Adding some communication between UI and backend to ensure sync at connection start
 
 ### Security
 

ui/src-tauri/src/main.rs

@@ -26,7 +26,10 @@
 
 extern crate alloc;
 
-use core::time::Duration;
+use core::{
+    sync::atomic::{AtomicBool, Ordering},
+    time::Duration,
+};
 use manta_signer::{
     config::{Config, Setup},
     secret::{
@@ -36,13 +39,64 @@ use manta_signer::{
     serde::Serialize,
     service::Server,
     storage::Store,
-    tokio::time::sleep,
 };
+use std::time::Instant;
 use tauri::{
     async_runtime::spawn, CustomMenuItem, Manager, RunEvent, Runtime, State, SystemTray,
     SystemTrayEvent, SystemTrayMenu, Window, WindowEvent,
 };
 
+/// App State
+///
+/// Keeps track of global state flags that we need for specific behaviors.
+#[derive(Debug)]
+pub struct AppState {
+    /// UI is Connected
+    pub ui_connected: AtomicBool,
+}
+
+impl AppState {
+    /// Builds a new [`AppState`].
+    #[inline]
+    pub const fn new() -> Self {
+        Self {
+            ui_connected: AtomicBool::new(false),
+        }
+    }
+
+    /// Returns the UI connection status.
+    #[inline]
+    pub fn get_ui_connected(&self) -> bool {
+        self.ui_connected.load(Ordering::Relaxed)
+    }
+
+    /// Sets the UI connection status.
+    #[inline]
+    pub fn set_ui_connected(&self, ui_connected: bool) {
+        self.ui_connected.store(ui_connected, Ordering::Relaxed)
+    }
+}
+
+/// Application State
+pub static APP_STATE: AppState = AppState::new();
+
+/// Repeatedly executes `f` until the `timeout` is reached calling `exit` to return from the
+/// function.
+#[inline]
+pub fn while_timeout<F, E, T>(timeout: Duration, mut f: F, exit: E) -> T
+where
+    F: FnMut(),
+    E: FnOnce(Instant, Duration) -> T,
+{
+    let time_start = Instant::now();
+    loop {
+        f();
+        if time_start.elapsed() >= timeout {
+            return exit(time_start, timeout);
+        }
+    }
+}
+
 /// User
 pub struct User {
     /// Main Window
@@ -107,11 +161,23 @@ impl Authorizer for User {
     fn setup<'s>(&'s mut self, setup: &'s Setup) -> UnitFuture<'s> {
         let window = self.window.clone();
         Box::pin(async move {
-            // NOTE: We have to wait here until the UI listener is registered.
-            sleep(Duration::from_millis(500)).await;
-            window
-                .emit("connect", setup)
-                .expect("The `connect` command failed to be emitted to the window.");
+            while_timeout(
+                Duration::from_millis(5000),
+                move || {
+                    if APP_STATE.get_ui_connected() {
+                        return;
+                    }
+                    window
+                        .emit("connect", setup)
+                        .expect("The `connect` command failed to be emitted to the window.");
+                },
+                move |time_start, timeout| {
+                    panic!(
+                        "Connection attempt timed-out! Started: {:?} with {:?} timeout.",
+                        time_start, timeout
+                    );
+                },
+            )
         })
     }
 
@@ -136,6 +202,16 @@ pub type PasswordStore = Store<PasswordSender>;
 /// Server Store
 pub type ServerStore = Store<Server<User>>;
 
+/// Called from the UI after it recieves a `connect` event.
+///
+/// To ensure proper connection you should emit `connect` continuously until the
+/// [`AppState::ui_connected`] flag is `true` then stop. This is the only way for now to ensure they
+/// are synchronized. Tauri is working on a better way.
+#[tauri::command]
+fn ui_connected() {
+    APP_STATE.set_ui_connected(true);
+}
+
 /// Sends the current `password` into storage from the UI.
 #[tauri::command]
 async fn send_password(
@@ -220,6 +296,7 @@ fn main() {
         .invoke_handler(tauri::generate_handler![
             send_password,
             stop_password_prompt,
+            ui_connected,
         ])
         .build(tauri::generate_context!())
         .expect("Error while building UI.");

ui/src/App.js

@@ -24,6 +24,7 @@ function App() {
     if (isConnected) return;
     const beginInitialConnectionPhase = async () => {
       await once('connect', (event) => {
+        invoke('ui_connected');
         console.log("[INFO]: Connect Event: ", event);
         let payload = event.payload;
         switch (payload.type) {