Add support for watching of the settings file

crates/gitbutler-settings/Cargo.toml

@@ -11,6 +11,8 @@ serde = { workspace = true, features = ["std"] }
 serde_json = { version = "1.0", features = ["std", "arbitrary_precision"] }
 serde_json_lenient = "0.2.3"
 gitbutler-fs.workspace = true
+notify = { version = "6.0.1" }
+tracing.workspace = true
 
 [[test]]
 name = "settings"

crates/gitbutler-settings/src/lib.rs

@@ -4,5 +4,7 @@ pub use legacy::LegacySettings;
 
 mod app_settings;
 mod json;
-pub mod persistence;
+mod persistence;
+mod watch;
 pub use app_settings::AppSettings;
+pub use watch::SettingsHandle;

crates/gitbutler-settings/src/persistence.rs

@@ -6,13 +6,10 @@ use anyhow::Result;
 use serde_json::json;
 
 static DEFAULTS: &str = include_str!("../assets/defaults.jsonc");
-const SETTINGS_FILE: &str = "settings.json";
 
 impl AppSettings {
     /// Load the settings from the configuration directory. If a config file name is not provided, the default `gitbutler_settings.json` one is used.
-    pub fn load(config_dir: impl Into<PathBuf>) -> Result<Self> {
-        let config_path = config_dir.into().join(SETTINGS_FILE);
-
+    pub fn load(config_path: PathBuf) -> Result<Self> {
         // Load the defaults
         let mut settings: serde_json::Value = serde_json_lenient::from_str(DEFAULTS)?;
 
@@ -25,12 +22,9 @@ impl AppSettings {
     }
 
     /// Save the updated fields of the AppSettings in the custom configuration file.
-    pub fn save(&self, config_dir: impl Into<PathBuf>) -> Result<()> {
-        let config_dir = config_dir.into();
-        let config_path = config_dir.clone().join(SETTINGS_FILE);
-
+    pub fn save(&self, config_path: PathBuf) -> Result<()> {
         // Load the current settings
-        let current = serde_json::to_value(AppSettings::load(config_dir)?)?;
+        let current = serde_json::to_value(AppSettings::load(config_path.clone())?)?;
 
         // Derive changed values only compared to the current settings
         let update = serde_json::to_value(self)?;

crates/gitbutler-settings/src/watch.rs

@@ -0,0 +1,66 @@
+use std::{
+    path::PathBuf,
+    sync::{mpsc::channel, OnceLock, RwLock},
+    time::Duration,
+};
+
+use crate::{app_settings, AppSettings};
+use anyhow::Result;
+use notify::{Event, RecommendedWatcher, RecursiveMode, Watcher};
+
+pub struct SettingsHandle<'a> {
+    config_path: PathBuf,
+    app_settings: &'a RwLock<AppSettings>,
+}
+
+const SETTINGS_FILE: &str = "settings.json";
+
+impl<'a> SettingsHandle<'a> {
+    pub fn create(config_dir: impl Into<PathBuf>) -> Result<Self> {
+        let config_path = config_dir.into().join(SETTINGS_FILE);
+        let app_settings = app_settings::AppSettings::load(config_path.clone())?;
+
+        static CONFIG: OnceLock<RwLock<AppSettings>> = OnceLock::new();
+        let app_settings = CONFIG.get_or_init(|| RwLock::new(app_settings));
+
+        Ok(Self {
+            config_path,
+            app_settings,
+        })
+    }
+
+    pub fn settings(&self) -> &'a RwLock<AppSettings> {
+        self.app_settings
+    }
+
+    pub fn watch(&self) -> Result<()> {
+        let (tx, rx) = channel();
+        let mut watcher: RecommendedWatcher = Watcher::new(
+            tx,
+            notify::Config::default().with_poll_interval(Duration::from_secs(2)),
+        )?;
+        watcher.watch(self.config_path.as_path(), RecursiveMode::NonRecursive)?;
+
+        loop {
+            match rx.recv() {
+                Ok(Ok(Event {
+                    kind: notify::event::EventKind::Modify(_),
+                    ..
+                })) => {
+                    println!("settings.json written; refreshing configuration...");
+                    // TODO: How can we avoid this unwrap?
+                    let mut write = self.app_settings.write().unwrap();
+                    *write = app_settings::AppSettings::load(self.config_path.clone())?;
+                }
+
+                Err(e) => {
+                    tracing::error!("Error watching config file {:?}: {:?}", self.config_path, e)
+                }
+
+                _ => {
+                    // Noop
+                }
+            }
+        }
+    }
+}

crates/gitbutler-settings/tests/mod.rs

@@ -3,7 +3,8 @@ use gitbutler_settings::AppSettings;
 #[test]
 #[allow(clippy::bool_assert_comparison)]
 fn test_load_settings() {
-    let settings = AppSettings::load("tests/fixtures/modify_default_true_to_false").unwrap();
+    let settings =
+        AppSettings::load("tests/fixtures/modify_default_true_to_false.json".into()).unwrap();
     assert_eq!(settings.telemetry.app_metrics_enabled, false); // modified
     assert_eq!(settings.telemetry.app_error_reporting_enabled, true); // default
     assert_eq!(settings.telemetry.app_non_anon_metrics_enabled, false); // default