Config synchronizes across app

src/app.rs

@@ -23,7 +23,7 @@ use winit::{
 };
 
 use crate::{
-    config::{AppConfig, CliArgs},
+    config::{AppConfig, CliArgs, Config},
     controller::ControllerManager,
     emulator::{EmulatorClient, EmulatorCommand, SimId},
     filesystem::Persistence,
@@ -94,7 +94,7 @@ impl Application {
         handle: OwnedDisplayHandle,
         persistence: Persistence,
         args: CliArgs,
-        config: AppConfig,
+        config: Config<AppConfig>,
     ) -> Self {
         let wgpu = WgpuState::new(handle, config);
         let icon = load_icon().ok().map(Arc::new);
@@ -504,11 +504,11 @@ impl ApplicationHandler<UserEvent> for Application {
 struct WgpuState {
     instance: wgpu::Instance,
     device_descriptor: Arc<dyn Fn(&wgpu::Adapter) -> wgpu::DeviceDescriptor<'static> + Send + Sync>,
-    config: AppConfig,
+    config: Config<AppConfig>,
 }
 
 impl WgpuState {
-    fn new(handle: OwnedDisplayHandle, config: AppConfig) -> Self {
+    fn new(handle: OwnedDisplayHandle, config: Config<AppConfig>) -> Self {
         #[allow(unused_variables)]
         let egui_wgpu::WgpuSetupCreateNew {
             instance_descriptor: wgpu::InstanceDescriptor { backends, .. },
@@ -531,6 +531,7 @@ impl WgpuState {
     }
 
     fn init(&mut self, window: &Window) -> egui_wgpu::WgpuSetupExisting {
+        self.config.refresh();
         let power_preference =
             wgpu::PowerPreference::from_env().unwrap_or(self.config.power_preference);
         debug!("power preference: {power_preference:?}");

src/config.rs

@@ -1,9 +1,9 @@
-use anyhow::Result;
 use bytemuck::NoUninit;
 use clap::{Parser, ValueEnum};
 use egui::{Color32, Pos2, Vec2};
 use serde::{Deserialize, Serialize};
 
+pub use crate::filesystem::Config;
 use crate::{emulator::SimId, filesystem::Persistence, window::DisplayMode};
 use std::path::PathBuf;
 
@@ -116,38 +116,31 @@ pub struct AppConfig {
     #[serde(default = "default_save_data_location")]
     pub save_data_location: SaveDataLocation,
 }
-
-impl AppConfig {
-    pub fn load(persistence: &Persistence) -> Self {
-        if let Ok(config) = persistence.load_config(APP_CONFIG_FILENAME) {
-            return config;
-        }
+impl Default for AppConfig {
+    fn default() -> Self {
         Self {
             power_preference: default_power_preference(),
             force_fallback: false,
             save_data_location: default_save_data_location(),
         }
     }
+}
 
-    pub fn save(&self, persistence: &Persistence) -> Result<()> {
-        persistence.save_config(APP_CONFIG_FILENAME, &self)
+impl AppConfig {
+    pub fn load(persistence: &Persistence) -> Config<Self> {
+        persistence.config(APP_CONFIG_FILENAME)
     }
 
-    pub fn update(&mut self, args: &CliArgs) -> bool {
-        let mut updated = false;
+    pub fn apply_updates(&mut self, args: &CliArgs) {
         if let Some(pref) = args.wgpu_power_preference {
             self.power_preference = pref.into();
-            updated = true;
         }
         if let Some(force_fallback) = args.wgpu_force_fallback {
             self.force_fallback = force_fallback;
-            updated = true;
         }
         if let Some(save_data_location) = args.save_data_location {
             self.save_data_location = save_data_location;
-            updated = true;
         }
-        updated
     }
 }
 
@@ -171,12 +164,8 @@ pub struct SimConfig {
     #[serde(default)]
     pub position: Option<Pos2>,
 }
-
-impl SimConfig {
-    pub fn load(persistence: &Persistence, sim_id: SimId) -> Self {
-        if let Ok(config) = persistence.load_config(sim_config_filename(sim_id)) {
-            return config;
-        }
+impl Default for SimConfig {
+    fn default() -> Self {
         Self {
             display_mode: DisplayMode::Anaglyph,
             colors: COLOR_PRESETS[0],
@@ -187,9 +176,11 @@ impl SimConfig {
             position: None,
         }
     }
+}
 
-    pub fn save(&self, persistence: &Persistence, sim_id: SimId) -> Result<()> {
-        persistence.save_config(sim_config_filename(sim_id), self)
+impl SimConfig {
+    pub fn load(persistence: &Persistence, sim_id: SimId) -> Config<Self> {
+        persistence.config(sim_config_filename(sim_id))
     }
 }
 

src/filesystem.rs

@@ -1,4 +1,13 @@
-use std::{fs, path::PathBuf};
+use std::{
+    collections::HashMap,
+    fs,
+    ops::Deref,
+    path::PathBuf,
+    sync::{
+        Arc, Mutex,
+        atomic::{AtomicU64, Ordering},
+    },
+};
 
 use anyhow::{Result, bail};
 use directories::ProjectDirs;
@@ -7,12 +16,42 @@ use serde::{Deserialize, Serialize};
 #[derive(Clone)]
 pub struct Persistence {
     config_dir: Option<PathBuf>,
+    versions: Arc<Mutex<HashMap<String, Arc<AtomicU64>>>>,
 }
 
 impl Persistence {
     pub fn new() -> Self {
         Self {
             config_dir: init_config_dir(),
+            versions: Arc::new(Mutex::new(HashMap::new())),
+        }
+    }
+
+    pub fn config<T: ConfigCompatible>(&self, file: &str) -> Config<T> {
+        let latest_version = self
+            .versions
+            .lock()
+            .unwrap()
+            .entry(file.to_string())
+            .or_default()
+            .clone();
+        let path = self
+            .config_dir
+            .as_ref()
+            .map(|p| p.join(file).with_extension("json"));
+        let value = if let Some(p) = path.as_ref()
+            && let Ok(bytes) = fs::read(p)
+            && let Ok(v) = serde_json::from_slice(&bytes)
+        {
+            v
+        } else {
+            T::default()
+        };
+        Config {
+            value,
+            version: latest_version.load(Ordering::Relaxed),
+            latest_version,
+            path,
         }
     }
 
@@ -50,3 +89,55 @@ pub fn init_data_dir() -> Option<PathBuf> {
 fn project_dirs() -> Option<ProjectDirs> {
     ProjectDirs::from("com", "virtual-boy", "Lemur")
 }
+
+pub trait ConfigCompatible: Clone + Default + Eq + Serialize + for<'a> Deserialize<'a> {}
+impl<T: Clone + Default + Eq + Serialize + for<'a> Deserialize<'a>> ConfigCompatible for T {}
+
+// A wrapper for a T (probably) stored on the filesystem.
+// Cheap to dereference, easy to sync changes to all copies.
+pub struct Config<T> {
+    value: T,
+    version: u64,
+    latest_version: Arc<AtomicU64>,
+    path: Option<PathBuf>,
+}
+
+impl<T> Deref for Config<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.value
+    }
+}
+
+impl<T: ConfigCompatible> Config<T> {
+    pub fn refresh(&mut self) {
+        let version = self.latest_version.load(Ordering::Relaxed);
+        if self.version == version {
+            return;
+        }
+        if let Some(path) = &self.path
+            && let Ok(bytes) = fs::read(path)
+            && let Ok(latest) = serde_json::from_slice(&bytes)
+        {
+            self.value = latest;
+        }
+        self.version = version;
+    }
+
+    pub fn update(&mut self, update: impl FnOnce(&mut T)) {
+        let mut new_value = self.value.clone();
+        update(&mut new_value);
+        if self.value == new_value {
+            return;
+        }
+        if let Some(path) = &self.path
+            && let Ok(bytes) = serde_json::to_vec(&new_value)
+        {
+            let _ = fs::write(path, bytes);
+        }
+        let version = self.latest_version.fetch_add(1, Ordering::Relaxed) + 1;
+        self.value = new_value.clone();
+        self.version = version;
+    }
+}

src/main.rs

@@ -94,9 +94,8 @@ fn main() -> Result<()> {
     let persistence = Persistence::new();
 
     let mut config = AppConfig::load(&persistence);
-    if config.update(&args) {
-        let _ = config.save(&persistence);
-    }
+    config.update(|c| c.apply_updates(&args));
+
     let p1 = SimConfig::load(&persistence, SimId::Player1);
     let p2 = SimConfig::load(&persistence, SimId::Player2);
 

src/window/game.rs

@@ -7,7 +7,7 @@ use std::{
 
 use crate::{
     app::UserEvent,
-    config::{AppConfig, COLOR_PRESETS, SaveDataLocation, SimConfig},
+    config::{AppConfig, COLOR_PRESETS, Config, SaveDataLocation, SimConfig},
     emulator::{EmulatorClient, EmulatorCommand, EmulatorState, SimId, SimState},
     filepicker::FilePicker,
     filesystem::Persistence,
@@ -42,7 +42,7 @@ pub struct GameWindow {
     persistence: Persistence,
     shortcuts: ShortcutProvider,
     sim_id: SimId,
-    config: SimConfig,
+    config: Config<SimConfig>,
     toasts: Toasts,
     screen: Option<GameScreen>,
     messages: mpsc::Receiver<Toast>,
@@ -334,7 +334,7 @@ impl GameWindow {
             }
             let watch_rom = self.client.is_rom_watched(self.sim_id);
             if ui.selectable_button(watch_rom, "Watch ROM").clicked() {
-                self.update_config(|c| c.watch_rom = !watch_rom);
+                self.config.update(|c| c.watch_rom = !watch_rom);
                 self.client
                     .send_command(EmulatorCommand::WatchRom(self.sim_id, !watch_rom));
             }
@@ -395,7 +395,7 @@ impl GameWindow {
             ui.separator();
             let low_battery = self.config.low_battery;
             if ui.selectable_button(low_battery, "Low Battery").clicked() {
-                self.update_config(|c| c.low_battery = !low_battery);
+                self.config.update(|c| c.low_battery = !low_battery);
                 let _ = self
                     .proxy
                     .send_event(UserEvent::LowBattery(self.sim_id, !low_battery));
@@ -551,7 +551,7 @@ impl GameWindow {
                     ui.send_viewport_cmd(ViewportCommand::InnerSize(current_dims * scale));
                 }
 
-                self.update_config(|c| {
+                self.config.update(|c| {
                     c.display_mode = display_mode;
                     c.dimensions = current_dims * scale;
                 });
@@ -559,7 +559,7 @@ impl GameWindow {
             ui.menu_button("Colors", |ui| {
                 for preset in COLOR_PRESETS {
                     if ui.color_pair_button(preset[0], preset[1]).clicked() {
-                        self.update_config(|c| c.colors = preset);
+                        self.config.update(|c| c.colors = preset);
                     }
                 }
                 ui.with_layout(ui.layout().with_cross_align(egui::Align::Center), |ui| {
@@ -589,7 +589,7 @@ impl GameWindow {
                 .selectable_button(self.config.audio_enabled, "Enabled")
                 .clicked()
             {
-                self.update_config(|c| c.audio_enabled = !c.audio_enabled);
+                self.config.update(|c| c.audio_enabled = !c.audio_enabled);
                 self.client.send_command(EmulatorCommand::SetAudioEnabled(
                     self.sim_id,
                     self.config.audio_enabled,
@@ -611,8 +611,7 @@ impl GameWindow {
                     return;
                 };
                 let mut app_config = AppConfig::load(&self.persistence);
-                app_config.save_data_location = new_location;
-                let _ = app_config.save(&self.persistence);
+                app_config.update(|c| c.save_data_location = new_location);
                 self.client
                     .send_command(EmulatorCommand::SetSaveDataLocation(new_location));
             };
@@ -662,19 +661,10 @@ impl GameWindow {
             self.color_picker = None;
         }
         if updated {
-            self.update_config(|c| c.colors = colors);
+            self.config.update(|c| c.colors = colors);
         }
     }
 
-    fn update_config(&mut self, update: impl FnOnce(&mut SimConfig)) {
-        let mut new_config = self.config.clone();
-        update(&mut new_config);
-        if self.config != new_config {
-            let _ = new_config.save(&self.persistence, self.sim_id);
-        }
-        self.config = new_config;
-    }
-
     fn button_for(&self, ctx: &Context, text: &str, command: Command) -> Button<'_> {
         let button = Button::new(text);
         match self.shortcuts.shortcut_for(command) {
@@ -701,6 +691,7 @@ impl AppWindow for GameWindow {
     }
 
     fn show(&mut self, ui: &mut Ui) {
+        self.config.refresh();
         let has_player_2 = self.client.has_player_2();
         if !self.show_player_name && has_player_2 {
             ui.send_viewport_cmd(ViewportCommand::Title(format!("Lemur ({})", self.sim_id)));
@@ -731,7 +722,7 @@ impl AppWindow for GameWindow {
             bounds.max - bounds.min
         };
         let position = ui.input(|i| i.viewport().outer_rect.map(|r| r.min));
-        self.update_config(|c| {
+        self.config.update(|c| {
             c.dimensions = dimensions;
             c.position = position;
         });