alsa: update to alsa-rs 0.11 and fix device access issues

.github/workflows/platforms.yml

@@ -25,7 +25,7 @@ on:
 env:
   # MSRV varies by backend due to platform-specific dependencies
   MSRV_AAUDIO: "1.82"
-  MSRV_ALSA: "1.77"
+  MSRV_ALSA: "1.82"
   MSRV_COREAUDIO: "1.80"
   MSRV_JACK: "1.82"
   MSRV_WASIP1: "1.78"

CHANGELOG.md

@@ -5,23 +5,43 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- `DeviceBusy` error variant for retriable device access errors (EBUSY, EAGAIN).
+- **ALSA**: `Debug` implementations for `Host`, `Device`, `Stream`, and internal types.
+- **ALSA**: Example demonstrating ALSA error suppression during enumeration.
+
+### Changed
+
+- Overall MSRV increased to 1.78.
+- **ALSA**: Update `alsa` dependency from 0.10 to 0.11.
+- **ALSA**: MSRV increased from 1.77 to 1.82 (required by alsa-sys 0.4.0).
+
+### Fixed
+
+- **ALSA**: Enumerating input and output devices no longer interferes with each other.
+- **ALSA**: Device handles are no longer exclusively held between operations.
+- **ALSA**: Valgrind memory leak reports from ALSA global configuration cache.
+
 ## [0.17.1] - 2026-01-04
 
 ### Added
 
 - **ALSA**: `Default` implementation for `Device` (returns the ALSA "default" device).
 - **CI**: Checks default/no-default/all feature sets with platform-dependent MSRV for JACK.
 
+### Changed
+
+- **ALSA**: Devices now report direction from hint metadata and physical hardware probing.
+
 ### Fixed
 
 - **ALSA**: Device enumeration now includes both hints and physical cards.
 - **JACK**: No longer builds on iOS.
 - **WASM**: WasmBindgen no longer crashes (regression from 0.17.0).
 
-### Changed
-
-- **ALSA**: Devices now report direction from hint metadata and physical hardware probing.
-
 ## [0.17.0] - 2025-12-20
 
 ### Added
@@ -1034,6 +1054,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Initial commit.
 
+[Unreleased]: https://github.com/RustAudio/cpal/compare/v0.17.1...HEAD
 [0.17.1]: https://github.com/RustAudio/cpal/compare/v0.17.0...v0.17.1
 [0.17.0]: https://github.com/RustAudio/cpal/compare/v0.16.0...v0.17.0
 [0.16.0]: https://github.com/RustAudio/cpal/compare/v0.15.3...v0.16.0

Cargo.toml

@@ -7,7 +7,7 @@ documentation = "https://docs.rs/cpal"
 license = "Apache-2.0"
 keywords = ["audio", "sound"]
 edition = "2021"
-rust-version = "1.77"
+rust-version = "1.78"
 
 [features]
 # ASIO backend for Windows
@@ -85,7 +85,7 @@ num-traits = { version = "0.2", optional = true }
 jack = { version = "0.13", optional = true }
 
 [target.'cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "netbsd"))'.dependencies]
-alsa = "0.10"
+alsa = "0.11"
 libc = "0.2"
 audio_thread_priority = { version = "0.34", optional = true }
 jack = { version = "0.13", optional = true }

README.md

@@ -10,7 +10,7 @@ Low-level library for audio input and output in pure Rust.
 The minimum Rust version required depends on which audio backend and features you're using, as each platform has different dependencies:
 
 - **AAudio (Android):** Rust **1.82** (due to `ndk` crate requirements)
-- **ALSA (Linux/BSD):** Rust **1.77** (due to `alsa-sys` crate requirements)
+- **ALSA (Linux/BSD):** Rust **1.82** (due to `alsa-sys` crate requirements)
 - **CoreAudio (macOS/iOS):** Rust **1.80** (due to `coreaudio-rs` crate requirements)
 - **JACK (Linux/BSD/macOS/Windows):** Rust **1.82** (due to `jack` crate requirements)
 - **WASAPI/ASIO (Windows):** Rust **1.82** (due to `windows` crate requirements)

examples/enumerate.rs

@@ -15,6 +15,10 @@ extern crate cpal;
 use cpal::traits::{DeviceTrait, HostTrait};
 
 fn main() -> Result<(), anyhow::Error> {
+    // To print raw ALSA errors to stderr during enumeration, comment out the line below:
+    #[cfg(target_os = "linux")]
+    let _silence_alsa_errors = alsa::Output::local_error_handler()?;
+
     println!("Supported hosts:\n  {:?}", cpal::ALL_HOSTS);
     let available_hosts = cpal::available_hosts();
     println!("Available hosts:\n  {available_hosts:?}");

src/error.rs

@@ -122,6 +122,9 @@ pub enum SupportedStreamConfigsError {
     /// The device no longer exists. This can happen if the device is disconnected while the
     /// program is running.
     DeviceNotAvailable,
+    /// The device is temporarily busy. This can happen when another application or stream
+    /// is using the device. Retrying after a short delay may succeed.
+    DeviceBusy,
     /// We called something the C-Layer did not understand
     InvalidArgument,
     /// See the [`BackendSpecificError`] docs for more information about this error variant.
@@ -133,6 +136,7 @@ impl Display for SupportedStreamConfigsError {
         match self {
             Self::BackendSpecific { err } => err.fmt(f),
             Self::DeviceNotAvailable => f.write_str("The requested device is no longer available. For example, it has been unplugged."),
+            Self::DeviceBusy => f.write_str("The requested device is temporarily busy. Another application or stream may be using it."),
             Self::InvalidArgument => f.write_str("Invalid argument passed to the backend. For example, this happens when trying to read capture capabilities when the device does not support it.")
         }
     }
@@ -152,6 +156,9 @@ pub enum DefaultStreamConfigError {
     /// The device no longer exists. This can happen if the device is disconnected while the
     /// program is running.
     DeviceNotAvailable,
+    /// The device is temporarily busy. This can happen when another application or stream
+    /// is using the device. Retrying after a short delay may succeed.
+    DeviceBusy,
     /// Returned if e.g. the default input format was requested on an output-only audio device.
     StreamTypeNotSupported,
     /// See the [`BackendSpecificError`] docs for more information about this error variant.
@@ -165,6 +172,9 @@ impl Display for DefaultStreamConfigError {
             Self::DeviceNotAvailable => f.write_str(
                 "The requested device is no longer available. For example, it has been unplugged.",
             ),
+            Self::DeviceBusy => f.write_str(
+                "The requested device is temporarily busy. Another application or stream may be using it.",
+            ),
             Self::StreamTypeNotSupported => {
                 f.write_str("The requested stream type is not supported by the device.")
             }
@@ -185,6 +195,9 @@ pub enum BuildStreamError {
     /// The device no longer exists. This can happen if the device is disconnected while the
     /// program is running.
     DeviceNotAvailable,
+    /// The device is temporarily busy. This can happen when another application or stream
+    /// is using the device. Retrying after a short delay may succeed.
+    DeviceBusy,
     /// The specified stream configuration is not supported.
     StreamConfigNotSupported,
     /// We called something the C-Layer did not understand
@@ -205,6 +218,9 @@ impl Display for BuildStreamError {
             Self::DeviceNotAvailable => f.write_str(
                 "The requested device is no longer available. For example, it has been unplugged.",
             ),
+            Self::DeviceBusy => f.write_str(
+                "The requested device is temporarily busy. Another application or stream may be using it.",
+            ),
             Self::StreamConfigNotSupported => {
                 f.write_str("The requested stream configuration is not supported by the device.")
             }

src/host/alsa/enumerate.rs

@@ -1,9 +1,6 @@
-use std::{
-    collections::HashSet,
-    sync::{Arc, Mutex},
-};
+use std::collections::HashSet;
 
-use super::{alsa, Device};
+use super::{alsa, Device, Host};
 use crate::{BackendSpecificError, DeviceDirection, DevicesError};
 
 const HW_PREFIX: &str = "hw";
@@ -21,47 +18,60 @@ struct PhysicalDevice {
 /// Iterator over available ALSA PCM devices (physical hardware and virtual/plugin devices).
 pub type Devices = std::vec::IntoIter<Device>;
 
-/// Enumerates all available ALSA PCM devices (physical hardware and virtual/plugin devices).
-///
-/// We enumerate both ALSA hints and physical devices because:
-/// - Hints provide virtual devices, user configurations, and card-specific devices with metadata
-/// - Physical probing provides traditional numeric naming (hw:CARD=0,DEV=0) for compatibility
-pub fn devices() -> Result<Devices, DevicesError> {
-    let mut devices = Vec::new();
-    let mut seen_pcm_ids = HashSet::new();
-
-    let physical_devices = physical_devices();
-
-    // Add all hint devices, including virtual devices
-    if let Ok(hints) = alsa::device_name::HintIter::new_str(None, "pcm") {
-        for hint in hints {
-            if let Ok(device) = Device::try_from(hint) {
-                seen_pcm_ids.insert(device.pcm_id.clone());
-                devices.push(device);
+impl Host {
+    /// Enumerates all available ALSA PCM devices (physical hardware and virtual/plugin devices).
+    ///
+    /// We enumerate both ALSA hints and physical devices because:
+    /// - Hints provide virtual devices, user configs, and card-specific devices with metadata
+    /// - Physical probing provides traditional numeric naming (hw:CARD=0,DEV=0) for compatibility
+    pub(super) fn enumerate_devices(&self) -> Result<Devices, DevicesError> {
+        let mut devices = Vec::new();
+        let mut seen_pcm_ids = HashSet::new();
+
+        let physical_devices = physical_devices();
+
+        // Add all hint devices, including virtual devices
+        if let Ok(hints) = alsa::device_name::HintIter::new_str(None, "pcm") {
+            for hint in hints {
+                if let Some(pcm_id) = hint.name {
+                    // Per ALSA docs (https://alsa-project.org/alsa-doc/alsa-lib/group___hint.html),
+                    // NULL IOID means both Input/Output. Whether a stream can actually open in a
+                    // given direction can only be determined by attempting to open it.
+                    let direction = hint.direction.map_or(DeviceDirection::Duplex, Into::into);
+                    let device = Device {
+                        pcm_id,
+                        desc: hint.desc,
+                        direction,
+                        _context: self.inner.clone(),
+                    };
+
+                    seen_pcm_ids.insert(device.pcm_id.clone());
+                    devices.push(device);
+                }
             }
         }
-    }
 
-    // Add hw:/plughw: for all physical devices with numeric index (traditional naming)
-    for phys_dev in physical_devices {
-        for prefix in [HW_PREFIX, PLUGHW_PREFIX] {
-            let pcm_id = format!(
-                "{}:CARD={},DEV={}",
-                prefix, phys_dev.card_index, phys_dev.device_index
-            );
-
-            if seen_pcm_ids.insert(pcm_id.clone()) {
-                devices.push(Device {
-                    pcm_id,
-                    desc: Some(format_device_description(&phys_dev, prefix)),
-                    direction: phys_dev.direction,
-                    handles: Arc::new(Mutex::new(Default::default())),
-                });
+        // Add hw:/plughw: for all physical devices with numeric index (traditional naming)
+        for phys_dev in physical_devices {
+            for prefix in [HW_PREFIX, PLUGHW_PREFIX] {
+                let pcm_id = format!(
+                    "{}:CARD={},DEV={}",
+                    prefix, phys_dev.card_index, phys_dev.device_index
+                );
+
+                if seen_pcm_ids.insert(pcm_id.clone()) {
+                    devices.push(Device {
+                        pcm_id,
+                        desc: Some(format_device_description(&phys_dev, prefix)),
+                        direction: phys_dev.direction,
+                        _context: self.inner.clone(),
+                    });
+                }
             }
         }
-    }
 
-    Ok(devices.into_iter())
+        Ok(devices.into_iter())
+    }
 }
 
 /// Formats device description in ALSA style: "Card Name, Device Name\nPurpose"
@@ -144,28 +154,6 @@ impl From<alsa::Error> for DevicesError {
     }
 }
 
-impl TryFrom<alsa::device_name::Hint> for Device {
-    type Error = BackendSpecificError;
-
-    fn try_from(hint: alsa::device_name::Hint) -> Result<Self, Self::Error> {
-        let pcm_id = hint.name.ok_or_else(|| Self::Error {
-            description: "ALSA hint missing PCM ID".to_string(),
-        })?;
-
-        // Per ALSA docs (https://alsa-project.org/alsa-doc/alsa-lib/group___hint.html),
-        // NULL IOID means both Input/Output. Whether a stream can actually open in a given
-        // direction can only be determined by attempting to open it.
-        let direction = hint.direction.map_or(DeviceDirection::Duplex, Into::into);
-
-        Ok(Self {
-            pcm_id: pcm_id.to_owned(),
-            desc: hint.desc,
-            direction,
-            handles: Arc::new(Mutex::new(Default::default())),
-        })
-    }
-}
-
 impl From<alsa::Direction> for DeviceDirection {
     fn from(direction: alsa::Direction) -> Self {
         match direction {