Allow webcam sleep duration to be set in config

src/als/webcam.rs

@@ -14,15 +14,21 @@ use v4l::{Device, FourCC};
 
 const DEFAULT_LUX: u64 = 100;
 const WAITING_SLEEP_MS: u64 = 2000;
+const MIN_WAITING_SLEEP_MS: u64 = 1000;
 
 pub struct Webcam {
     webcam_tx: Sender<u64>,
     video: usize,
+    sleep_ms: u64,
 }
 
 impl Webcam {
-    pub fn new(webcam_tx: Sender<u64>, video: usize) -> Self {
-        Self { webcam_tx, video }
+    pub fn new(webcam_tx: Sender<u64>, video: usize, sleep_ms: Option<u64>) -> Self {
+        Self {
+            webcam_tx,
+            video,
+            sleep_ms: sleep_ms.filter(|&s| s >= MIN_WAITING_SLEEP_MS).unwrap_or(WAITING_SLEEP_MS),
+        }
     }
 
     pub fn run(&mut self) {
@@ -40,7 +46,7 @@ impl Webcam {
                 .expect("Unable to send new webcam lux value, channel is dead");
         };
 
-        thread::sleep(Duration::from_millis(WAITING_SLEEP_MS));
+        thread::sleep(Duration::from_millis(self.sleep_ms));
     }
 
     fn frame(&mut self) -> Result<(Vec<u8>, usize), Box<dyn Error>> {
@@ -123,6 +129,30 @@ mod tests {
         (als, webcam_tx)
     }
 
+    #[test]
+    fn test_sleep_ms_is_custom_value_when_present_in_config() -> Result<(), Box<dyn Error>> {
+        let (webcam_tx, _) = mpsc::channel();
+        let webcam = Webcam::new(webcam_tx, 0, Some(10000));
+        assert_eq!(10000, webcam.sleep_ms);
+        Ok(())
+    }
+
+    #[test]
+    fn test_sleep_ms_is_default_value_when_not_present_in_config() -> Result<(), Box<dyn Error>> {
+        let (webcam_tx, _) = mpsc::channel();
+        let webcam = Webcam::new(webcam_tx, 0, None);
+        assert_eq!(WAITING_SLEEP_MS, webcam.sleep_ms);
+        Ok(())
+    }
+
+    #[test]
+    fn test_sleep_ms_is_default_value_when_invalid_in_config() -> Result<(), Box<dyn Error>> {
+        let (webcam_tx, _) = mpsc::channel();
+        let webcam = Webcam::new(webcam_tx, 0, Some(MIN_WAITING_SLEEP_MS - 1));
+        assert_eq!(WAITING_SLEEP_MS, webcam.sleep_ms);
+        Ok(())
+    }
+
     #[test]
     fn test_get_raw_returns_default_value_when_no_data_from_webcam() -> Result<(), Box<dyn Error>> {
         let (als, _) = setup();

src/config/app.rs

@@ -17,6 +17,7 @@ pub enum Als {
     },
     Webcam {
         video: usize,
+        sleep_ms: Option<u64>,
         thresholds: HashMap<u64, String>,
     },
     None,

src/config/file.rs

@@ -20,6 +20,7 @@ pub enum Als {
     },
     Webcam {
         video: usize,
+        sleep_ms: Option<u64>,
         thresholds: HashMap<String, String>,
     },
     None,

src/config/mod.rs

@@ -64,8 +64,13 @@ fn parse() -> Result<app::Config, toml::de::Error> {
                 path,
                 thresholds: parse_als_thresholds(thresholds),
             },
-            file::Als::Webcam { video, thresholds } => app::Als::Webcam {
+            file::Als::Webcam {
                 video,
+                sleep_ms,
+                thresholds,
+            } => app::Als::Webcam {
+                video,
+                sleep_ms,
                 thresholds: parse_als_thresholds(thresholds),
             },
             file::Als::Time { thresholds } => app::Als::Time {

src/main.rs

@@ -112,12 +112,12 @@ fn main() {
                         .expect("Unable to initialize ALS IIO sensor"),
                 ),
                 config::Als::Time { thresholds } => Box::new(als::time::Als::new(thresholds)),
-                config::Als::Webcam { video, thresholds } => Box::new({
+                config::Als::Webcam { video, thresholds, sleep_ms } => Box::new({
                     let (webcam_tx, webcam_rx) = mpsc::channel();
                     std::thread::Builder::new()
                         .name("als-webcam".to_string())
                         .spawn(move || {
-                            als::webcam::Webcam::new(webcam_tx, video).run();
+                            als::webcam::Webcam::new(webcam_tx, video, sleep_ms).run();
                         })
                         .expect("Unable to start thread: als-webcam");
                     als::webcam::Als::new(webcam_rx, thresholds)