Merge pull request #4 from epic-64/performance-adaptive-polling

performance: adaptive polling

README.md

@@ -37,12 +37,13 @@ There is one file for linux and one for windows (.exe).
 - press Enter to confirm choices
 - press Esc to exit a game mode or the game. CTRL+C also works to exit the game.
 
-## Retro aesthetics
-For the best experience, I recommend using Cool Retro Terminal on Linux, or Windows Terminal in Retro mode.  
-But the game should run fine in any terminal.
+## Recommended terminals
+The game should run fine in any terminal. If you want retro CRT effects, here are some recommendations:
+- Windows: Windows Terminal (enable experimental "retro mode")
+- Linux: Rio (with CRT shader), Cool Retro Term
 
 ## Build/Run from source
-You be inclined to not run binaries from the internet, and want to build from source instead.
+You may be inclined to not run binaries from the internet, and want to build from source instead.
 
 - download the source code
 - make sure you have Rust and Cargo installed, see [rustup.rs](https://rustup.rs/)

src/app.rs

@@ -7,10 +7,28 @@ use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
 use ratatui::prelude::{Color, Modifier, Span, Style, Widget};
 use ratatui::widgets::{List, ListItem, ListState};
+use std::cmp;
 use std::collections::HashMap;
 use std::thread;
 use std::time::Instant;
 use indoc::indoc;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+static LAST_SELECTED_INDEX: AtomicUsize = AtomicUsize::new(4);
+
+fn get_last_selected_index() -> usize {
+    LAST_SELECTED_INDEX.load(Ordering::Relaxed)
+}
+
+fn set_last_selected_index(index: usize) {
+    LAST_SELECTED_INDEX.store(index, Ordering::Relaxed);
+}
+
+#[derive(Copy, Clone, PartialEq, Debug)]
+enum FpsMode {
+    RealTime,    // 30 FPS with polling
+    Performance, // Block until input for minimal CPU
+}
 
 enum AppState {
     Start(StartMenuState),
@@ -24,6 +42,8 @@ fn handle_start_input(state: &mut StartMenuState, key: KeyEvent) -> Option<AppSt
         KeyCode::Down => state.select_next(),
         KeyCode::Enter => {
             let bits = state.selected_bits();
+            // Store the current selection before entering the game
+            set_last_selected_index(state.selected_index());
             return Some(AppState::Playing(BinaryNumbersGame::new(bits)));
         }
         KeyCode::Esc => return Some(AppState::Exit),
@@ -106,34 +126,7 @@ fn render_start_screen(state: &mut StartMenuState, area: Rect, buf: &mut Buffer)
     ratatui::widgets::StatefulWidget::render(list, list_area, buf, &mut state.list_state);
 }
 
-pub fn run_app(terminal: &mut ratatui::DefaultTerminal) -> color_eyre::Result<()> {
-    let mut app_state = AppState::Start(StartMenuState::new());
-    let mut last_frame_time = Instant::now();
-    let target_frame_duration = std::time::Duration::from_millis(33); // ~30 FPS
-
-    while !matches!(app_state, AppState::Exit) {
-        let now = Instant::now();
-        let dt = now - last_frame_time;
-        last_frame_time = now;
-
-        terminal.draw(|f| match &mut app_state {
-            AppState::Start(menu) => render_start_screen(menu, f.area(), f.buffer_mut()),
-            AppState::Playing(game) => f.render_widget(&mut *game, f.area()),
-            AppState::Exit => {}
-        })?;
-
-        // Advance game if playing
-        if let AppState::Playing(game) = &mut app_state {
-            game.run(dt.as_secs_f64());
-            if game.is_exit_intended() {
-                app_state = AppState::Start(StartMenuState::new());
-                continue;
-            }
-        }
-
-        // handle input
-        let poll_timeout = std::cmp::min(dt, target_frame_duration);
-        if event::poll(poll_timeout)? {
+fn handle_crossterm_events(app_state: &mut AppState) -> color_eyre::Result<()> {
     if let Event::Key(key) = event::read()? {
         if key.kind == KeyEventKind::Press {
             match key.code {
@@ -141,14 +134,16 @@ pub fn run_app(terminal: &mut ratatui::DefaultTerminal) -> color_eyre::Result<()
                 KeyCode::Char('c') | KeyCode::Char('C')
                     if key.modifiers == KeyModifiers::CONTROL =>
                 {
-                            app_state = AppState::Exit;
+                    *app_state = AppState::Exit;
                 }
 
                 // state-specific input handling
                 _ => {
-                            app_state = match app_state {
-                                AppState::Start(mut menu) => handle_start_input(&mut menu, key)
-                                    .unwrap_or(AppState::Start(menu)),
+                    *app_state = match std::mem::replace(app_state, AppState::Exit) {
+                        AppState::Start(mut menu) => {
+                            handle_start_input(&mut menu, key)
+                                .unwrap_or(AppState::Start(menu))
+                        }
                         AppState::Playing(mut game) => {
                             game.handle_input(key);
                             AppState::Playing(game)
@@ -159,6 +154,66 @@ pub fn run_app(terminal: &mut ratatui::DefaultTerminal) -> color_eyre::Result<()
             }
         }
     }
+    Ok(())
+}
+
+/// Determine the appropriate FPS mode based on the current game state
+fn get_fps_mode(game: &BinaryNumbersGame) -> FpsMode {
+    if game.is_active() {
+        FpsMode::RealTime  // Timer running, needs continuous updates
+    } else if game.needs_render() {
+        FpsMode::RealTime  // One frame after state transition
+    } else {
+        FpsMode::Performance  // All other cases, block for minimal CPU
+    }
+}
+
+pub fn run_app(terminal: &mut ratatui::DefaultTerminal) -> color_eyre::Result<()> {
+    let mut app_state = AppState::Start(StartMenuState::new());
+    let mut last_frame_time = Instant::now();
+    let target_frame_duration = std::time::Duration::from_millis(33); // ~30 FPS
+
+    while !matches!(app_state, AppState::Exit) {
+        let now = Instant::now();
+        let dt = now - last_frame_time;
+        last_frame_time = now;
+
+        // Advance game BEFORE drawing so stats are updated
+        if let AppState::Playing(game) = &mut app_state {
+            game.run(dt.as_secs_f64());
+            if game.is_exit_intended() {
+                app_state = AppState::Start(StartMenuState::new());
+                continue;
+            }
+        }
+
+        terminal.draw(|f| match &mut app_state {
+            AppState::Start(menu) => render_start_screen(menu, f.area(), f.buffer_mut()),
+            AppState::Playing(game) => f.render_widget(&mut *game, f.area()),
+            AppState::Exit => {}
+        })?;
+
+        // Clear needs_render flag after frame is rendered
+        // State transitions will set this flag again as needed, in performance mode
+        if let AppState::Playing(game) = &mut app_state {
+            game.clear_needs_render();
+        }
+
+        // handle input
+        if let AppState::Playing(game) = &app_state {
+            if get_fps_mode(game) == FpsMode::RealTime {
+                let poll_timeout = cmp::min(dt, target_frame_duration);
+                if event::poll(poll_timeout)? {
+                    handle_crossterm_events(&mut app_state)?;
+                }
+            } else {
+                // performance mode: block thread until an input event occurs
+                handle_crossterm_events(&mut app_state)?;
+            }
+        } else {
+            // For non-playing states (e.g., start menu), use performance mode
+            // to block until input and minimize CPU usage
+            handle_crossterm_events(&mut app_state)?;
         }
 
         // cap frame rate
@@ -225,6 +280,10 @@ struct StartMenuState {
 
 impl StartMenuState {
     fn new() -> Self {
+        Self::with_selected(get_last_selected_index())
+    }
+
+    fn with_selected(selected_index: usize) -> Self {
         let items = vec![
             ("easy       (4 bits)".to_string(), Bits::Four),
             ("easy+16    (4 bits*16)".to_string(), Bits::FourShift4),
@@ -234,11 +293,13 @@ impl StartMenuState {
             ("master     (12 bits)".to_string(), Bits::Twelve),
             ("insane     (16 bits)".to_string(), Bits::Sixteen),
         ];
+
         Self {
             items,
-            list_state: ListState::default().with_selected(Some(4)),
-        } // default to normal (8 bits)
+            list_state: ListState::default().with_selected(Some(selected_index)),
         }
+    }
+
     fn selected_index(&self) -> usize {
         self.list_state.selected().unwrap_or(0)
     }

src/binary_numbers.rs

@@ -129,7 +129,12 @@ impl WidgetRef for BinaryNumbersPuzzle {
             .render(inner, buf);
 
         let binary_string = self.current_to_binary_string();
-        let scale_suffix = match self.bits { Bits::FourShift4 => Some(" x16"), Bits::FourShift8 => Some(" x256"), Bits::FourShift12 => Some(" x4096"), _ => None };
+        let scale_suffix = match self.bits {
+            Bits::FourShift4 => Some(" x16"),
+            Bits::FourShift8 => Some(" x256"),
+            Bits::FourShift12 => Some(" x4096"),
+            _ => None
+        };
         let mut spans = vec![Span::raw(binary_string.clone())];
         if let Some(sfx) = scale_suffix { spans.push(Span::styled(sfx, Style::default().fg(Color::DarkGray))); }
         let total_width = spans.iter().map(|s| s.width()).sum::<usize>() as u16;
@@ -272,8 +277,10 @@ pub struct BinaryNumbersGame {
     high_scores: HighScores,
     prev_high_score_for_display: u32,
     new_high_score_reached: bool,
+    needs_render: bool,  // Flag to render one frame after state transition
 }
 
+
 #[derive(Copy, Clone, PartialEq, Debug)]
 enum GameState { Active, Result, PendingGameOver, GameOver }
 
@@ -295,7 +302,7 @@ impl BinaryNumbersGame {
     pub fn new_with_max_lives(bits: Bits, max_lives: u32) -> Self {
         let hs = HighScores::load();
         let starting_prev = hs.get(bits.high_score_key());
-        Self {
+        let mut game = Self {
             bits: bits.clone(),
             puzzle: Self::init_puzzle(bits.clone(), 0),
             exit_intended: false,
@@ -310,12 +317,31 @@ impl BinaryNumbersGame {
             high_scores: hs,
             prev_high_score_for_display: starting_prev,
             new_high_score_reached: false,
-        }
+            needs_render: true,  // Need to render initial state
+        };
+        // Initialize stats snapshot immediately so stats display on first render
+        game.refresh_stats_snapshot();
+        game
     }
 
     pub fn init_puzzle(bits: Bits, streak: u32) -> BinaryNumbersPuzzle {
         BinaryNumbersPuzzle::new(bits, streak)
     }
+
+    /// Check if the game is in Active state (timer running)
+    pub fn is_active(&self) -> bool {
+        self.game_state == GameState::Active
+    }
+
+    /// Check if we need to render one frame (e.g., after state transition)
+    pub fn needs_render(&self) -> bool {
+        self.needs_render
+    }
+
+    /// Clear the needs_render flag after rendering
+    pub fn clear_needs_render(&mut self) {
+        self.needs_render = false;
+    }
 }
 
 impl BinaryNumbersGame {
@@ -358,8 +384,10 @@ impl BinaryNumbersGame {
             // set state after round resolution
             if self.lives == 0 {
                 self.game_state = GameState::PendingGameOver; // defer summary until Enter
+                self.needs_render = true;  // Need to render result before blocking
             } else {
                 self.game_state = GameState::Result;
+                self.needs_render = true;  // Need to render result before blocking
             }
             self.puzzle_resolved = true;
         }
@@ -367,6 +395,7 @@ impl BinaryNumbersGame {
 
     pub fn handle_game_input(&mut self, input: KeyEvent) {
         if input.code == KeyCode::Esc { self.exit_intended = true; return; }
+
         if self.game_state == GameState::GameOver { self.handle_game_over_input(input); return; }
         match self.puzzle.guess_result {
             None => self.handle_no_result_yet(input),
@@ -513,6 +542,7 @@ pub struct BinaryNumbersPuzzle {
     guess_result: Option<GuessResult>,
     last_points_awarded: u32,
     stats_snapshot: Option<StatsSnapshot>,
+    skip_first_dt: bool, // Skip first dt to prevent timer jump when starting new puzzle
 }
 
 impl BinaryNumbersPuzzle {
@@ -556,6 +586,7 @@ impl BinaryNumbersPuzzle {
             guess_result,
             last_points_awarded,
             stats_snapshot: None,
+            skip_first_dt: true, // Skip first dt to prevent timer jump
         }
     }
 
@@ -579,6 +610,12 @@ impl BinaryNumbersPuzzle {
             return;
         }
 
+        // Skip first dt to prevent timer jump when starting new puzzle
+        if self.skip_first_dt {
+            self.skip_first_dt = false;
+            return;
+        }
+
         self.time_left = (self.time_left - dt).max(0.0);
 
         if self.time_left <= 0.0 {
@@ -724,6 +761,11 @@ mod tests {
     fn puzzle_timeout_sets_guess_result() {
         let mut p = BinaryNumbersPuzzle::new(Bits::Four, 0);
         p.time_left = 0.5;
+        // First run() skips dt due to skip_first_dt flag
+        // The reason for this is to prevent timer jump when starting a new puzzle
+        p.run(1.0);
+        assert_eq!(p.guess_result, None, "First run should skip dt");
+        // Second run() actually applies the dt and triggers timeout
         p.run(1.0); // exceed remaining time
         assert_eq!(p.guess_result, Some(GuessResult::Timeout));
     }