Make RodioSink Send and improve error handling

Cargo.lock

@@ -1375,6 +1375,7 @@ dependencies = [
  "rodio",
  "sdl2",
  "shell-words",
+ "thiserror",
  "zerocopy",
 ]
 

playback/Cargo.toml

@@ -29,19 +29,22 @@ libpulse-binding        = { version = "2.13", optional = true, default-features
 libpulse-simple-binding = { version = "2.13", optional = true, default-features = false }
 jack            = { version = "0.6", optional = true }
 libc            = { version = "0.2", optional = true }
-rodio           = { version = "0.13", optional = true, default-features = false }
-cpal            = { version = "0.13", optional = true }
 sdl2            = { version = "0.34", optional = true }
 gstreamer       = { version = "0.16", optional = true }
 gstreamer-app   = { version = "0.16", optional = true }
 glib            = { version = "0.10", optional = true }
 zerocopy        = { version = "0.3", optional = true }
 
+# Rodio dependencies
+rodio           = { version = "0.13", optional = true, default-features = false }
+cpal            = { version = "0.13", optional = true }
+thiserror       = { version = "1", optional = true }
+
 [features]
 alsa-backend = ["alsa"]
 portaudio-backend = ["portaudio-rs"]
 pulseaudio-backend = ["libpulse-binding", "libpulse-simple-binding"]
 jackaudio-backend = ["jack"]
-rodio-backend = ["rodio", "cpal"]
+rodio-backend = ["rodio", "cpal", "thiserror"]
 sdl-backend = ["sdl2"]
 gstreamer-backend = ["gstreamer", "gstreamer-app", "glib", "zerocopy"]

playback/src/audio_backend/rodio.rs

@@ -1,20 +1,36 @@
-use super::{Open, Sink};
-extern crate cpal;
-extern crate rodio;
-use cpal::traits::{DeviceTrait, HostTrait};
 use std::process::exit;
+use std::{convert::Infallible, sync::mpsc};
 use std::{io, thread, time};
 
+use cpal::traits::{DeviceTrait, HostTrait};
+use thiserror::Error;
+
+use super::{Open, Sink};
+
+#[derive(Debug, Error)]
+pub enum RodioError {
+    #[error("Rodio: no device available")]
+    NoDeviceAvailable,
+    #[error("Rodio: device \"{0}\" is not available")]
+    DeviceNotAvailable(String),
+    #[error("Rodio play error: {0}")]
+    PlayError(#[from] rodio::PlayError),
+    #[error("Rodio stream error: {0}")]
+    StreamError(#[from] rodio::StreamError),
+    #[error("Cannot get audio devices: {0}")]
+    DevicesError(#[from] cpal::DevicesError),
+}
+
 pub struct RodioSink {
     rodio_sink: rodio::Sink,
-    // We have to keep hold of this object, or the Sink can't play...
-    #[allow(dead_code)]
-    stream: rodio::OutputStream,
+
+    // will produce a TryRecvError on the receiver side when it is dropped.
+    _close_tx: mpsc::SyncSender<Infallible>,
 }
 
-fn list_formats(ref device: &rodio::Device) {
+fn list_formats(device: &rodio::Device) {
     let default_fmt = match device.default_output_config() {
-        Ok(fmt) => cpal::SupportedStreamConfig::from(fmt),
+        Ok(fmt) => fmt,
         Err(e) => {
             warn!("Error getting default rodio::Sink config: {}", e);
             return;
@@ -39,8 +55,8 @@ fn list_formats(ref device: &rodio::Device) {
     }
 }
 
-fn list_outputs() {
-    let default_device = get_default_device();
+fn list_outputs_and_exit() -> ! {
+    let default_device = get_default_device().unwrap();
     let default_device_name = default_device.name().expect("cannot get output name");
     println!("Default Audio Device:\n  {}", default_device_name);
     list_formats(&default_device);
@@ -56,54 +72,69 @@ fn list_outputs() {
             list_formats(&device);
         }
     }
+
+    exit(0)
 }
 
-fn get_default_device() -> rodio::Device {
+fn get_default_device() -> Result<rodio::Device, RodioError> {
     cpal::default_host()
         .default_output_device()
-        .expect("no default output device available")
+        .ok_or(RodioError::NoDeviceAvailable)
 }
 
-fn match_device(device: Option<String>) -> rodio::Device {
-    match device {
+fn create_sink(device: Option<String>) -> Result<(rodio::Sink, rodio::OutputStream), RodioError> {
+    let rodio_device = match device {
+        Some(ask) if &ask == "?" => list_outputs_and_exit(),
         Some(device_name) => {
-            if device_name == "?".to_string() {
-                list_outputs();
-                exit(0)
-            }
-            for d in cpal::default_host()
-                .output_devices()
-                .expect("cannot get list of output devices")
-            {
-                if d.name().expect("cannot get output name") == device_name {
-                    return d;
-                }
-            }
-            println!("No output sink matching '{}' found.", device_name);
-            exit(0)
-        }
-        None => return get_default_device(),
+            cpal::default_host()
+                .output_devices()?
+                .find(|d| d.name().ok().map_or(false, |name| name == device_name)) // Ignore devices for which getting name fails
+                .ok_or(RodioError::DeviceNotAvailable(device_name))?
         }
+        None => get_default_device()?,
+    };
+
+    let name = rodio_device.name().ok();
+    info!(
+        "Using audio device: {}",
+        name.as_deref().unwrap_or("(unknown name)")
+    );
+
+    let (stream, handle) = rodio::OutputStream::try_from_device(&rodio_device)?;
+    let sink = rodio::Sink::try_new(&handle)?;
+    Ok((sink, stream))
 }
 
 impl Open for RodioSink {
     fn open(device: Option<String>) -> RodioSink {
         debug!(
             "Using rodio sink with cpal host: {:?}",
-            cpal::default_host().id()
+            cpal::default_host().id().name()
         );
 
-        let rodio_device = match_device(device);
-        debug!("Using cpal device");
-        let stream = rodio::OutputStream::try_from_device(&rodio_device)
-            .expect("Couldn't open output stream.");
-        debug!("Using rodio stream");
-        let sink = rodio::Sink::try_new(&stream.1).expect("Couldn't create output sink.");
-        debug!("Using rodio sink");
+        let (sink_tx, sink_rx) = mpsc::sync_channel(1);
+        let (close_tx, close_rx) = mpsc::sync_channel(1);
 
+        std::thread::spawn(move || match create_sink(device) {
+            Ok((sink, stream)) => {
+                sink_tx.send(Ok(sink)).unwrap();
+
+                close_rx.recv().unwrap_err(); // This will fail as soon as the sender is dropped
+                debug!("drop rodio::OutputStream");
+                drop(stream);
+            }
+            Err(e) => {
+                sink_tx.send(Err(e)).unwrap();
+            }
+        });
+
+        // Instead of the second `unwrap`, better error handling could be introduced
+        let sink = sink_rx.recv().unwrap().unwrap();
+
+        debug!("Rodio sink was created");
         RodioSink {
             rodio_sink: sink,
-            stream: stream.0,
+            _close_tx: close_tx,
         }
     }
 }