Add Handle type

examples/basic.rs

@@ -2,8 +2,15 @@ extern crate rodio;
 
 fn main() {
     let file = std::fs::File::open("examples/beep.wav").unwrap();
+    let beep1 = rodio::play_once(file);
 
+    std::thread::sleep_ms(1000);
+
+    let file = std::fs::File::open("examples/beep2.wav").unwrap();
     rodio::play_once(file);
 
-    std::thread::sleep_ms(10000);
+    std::thread::sleep_ms(1000);
+    beep1.stop();
+
+    std::thread::sleep_ms(8000);
 }

src/engine.rs

@@ -1,31 +1,58 @@
 use std::thread;
 use std::sync::mpsc::{self, Sender, Receiver};
+use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Mutex;
 
 use cpal::Voice;
 use decoder::Decoder;
 
-pub enum Command {
-    Play(Box<Decoder + Send>)
-}
-
 pub struct Engine {
+    /// Communication with the background thread.
     commands: Mutex<Sender<Command>>,
+    /// Counter that is incremented whenever a sound starts playing.
+    sound_ids: AtomicUsize,
 }
 
 impl Engine {
     pub fn new() -> Engine {
         let (tx, rx) = mpsc::channel();
         thread::spawn(move || background(rx));
-        Engine { commands: Mutex::new(tx) }
+        Engine { commands: Mutex::new(tx), sound_ids: AtomicUsize::new(0) }
     }
 
-    pub fn play_once(&self, decoder: Box<Decoder + Send>) {
+    pub fn play(&self, decoder: Box<Decoder + Send>) -> Handle {
+        let sound_id = self.sound_ids.fetch_add(1, Ordering::Relaxed);
+
         let commands = self.commands.lock().unwrap();
-        commands.send(Command::Play(decoder)).unwrap();
+        commands.send(Command::Play(sound_id, decoder)).unwrap();
+
+        Handle {
+            engine: self,
+            id: sound_id,
+        }
     }
 }
 
+/// Handle to a playing sound.
+///
+/// Note that dropping the handle doesn't stop the sound. You must call `stop` explicitely.
+pub struct Handle<'a> {
+    engine: &'a Engine,
+    id: usize,
+}
+
+impl<'a> Handle<'a> {
+    pub fn stop(self) {
+        let commands = self.engine.commands.lock().unwrap();
+        commands.send(Command::Stop(self.id)).unwrap();
+    }
+}
+
+pub enum Command {
+    Play(usize, Box<Decoder + Send>),
+    Stop(usize),
+}
+
 fn background(rx: Receiver<Command>) {
     let mut sounds = Vec::new();
 
@@ -33,11 +60,12 @@ fn background(rx: Receiver<Command>) {
         // polling for new sounds
         if let Ok(command) = rx.try_recv() {
             match command {
-                Command::Play(decoder) => sounds.push((Voice::new(), decoder)),
+                Command::Play(id, decoder) => sounds.push((id, Voice::new(), decoder)),
+                Command::Stop(id) => sounds.retain(|&(id2, _, _)| id2 != id),
             }
         }
 
-        for &mut (ref mut voice, ref mut decoder) in sounds.iter_mut() {
+        for &mut (_, ref mut voice, ref mut decoder) in sounds.iter_mut() {
             decoder.write(voice);
             voice.play();
         }

src/lib.rs

@@ -12,8 +12,19 @@ lazy_static! {
     static ref ENGINE: engine::Engine = engine::Engine::new();
 }
 
-/// Plays a sound once. There's no way to stop the sound except by exiting the program.
-pub fn play_once<R>(input: R) where R: Read + Send + 'static {
-    let decoder = decoder::decode(input);
-    ENGINE.play_once(decoder);
+/// Handle to a playing sound.
+///
+/// Note that dropping the handle doesn't stop the sound. You must call `stop` explicitely.
+pub struct Handle(engine::Handle<'static>);
+
+impl Handle {
+    pub fn stop(self) {
+        self.0.stop()
+    }
+}
+
+/// Plays a sound once. There's no way to stop the sound except by exiting the program.
+pub fn play_once<R>(input: R) -> Handle where R: Read + Send + 'static {
+    let decoder = decoder::decode(input);
+    Handle(ENGINE.play(decoder))
 }