Update alsa backend for addition of `StreamEvent` type
This commit significantly refactors the alsa backend's `EventLoop::run` implementation in order to allow for better error handling throughout the loop. This removes many cases that would previously `panic!` in favour of calling the user callback with the necessary error and removing the corrupt stream. Seeing as the method cannot return, a catch-all `panic!` still exists at the end of the method, however this refactor should make it much easier to remove this restriction in the future.
This commit is contained in:
mitchmindtree
parent
59c789fbcd
commit
e41baa248b
426
src/alsa/mod.rs
426
src/alsa/mod.rs
|
|
@ -14,7 +14,10 @@ use PlayStreamError;
|
|||
use SupportedFormatsError;
|
||||
use SampleFormat;
|
||||
use SampleRate;
|
||||
use StreamCloseCause;
|
||||
use StreamData;
|
||||
use StreamError;
|
||||
use StreamEvent;
|
||||
use SupportedFormat;
|
||||
use UnknownTypeInputBuffer;
|
||||
use UnknownTypeOutputBuffer;
|
||||
|
|
@ -353,7 +356,7 @@ pub struct EventLoop {
|
|||
|
||||
// A trigger that uses a `pipe()` as backend. Signalled whenever a new command is ready, so
|
||||
// that `poll()` can wake up and pick the changes.
|
||||
pending_trigger: Trigger,
|
||||
pending_command_trigger: Trigger,
|
||||
|
||||
// This field is locked by the `run()` method.
|
||||
// The mutex also ensures that only one thread at a time has `run()` running.
|
||||
|
|
@ -377,7 +380,7 @@ enum Command {
|
|||
}
|
||||
|
||||
struct RunContext {
|
||||
// Descriptors to wait for. Always contains `pending_trigger.read_fd()` as first element.
|
||||
// Descriptors to wait for. Always contains `pending_command_trigger.read_fd()` as first element.
|
||||
descriptors: Vec<libc::pollfd>,
|
||||
// List of streams that are written in `descriptors`.
|
||||
streams: Vec<StreamInner>,
|
||||
|
|
@ -421,24 +424,25 @@ struct StreamInner {
|
|||
// Lazily allocated buffer that is reused inside the loop.
|
||||
// Zero-allocate a new buffer (the fastest way to have zeroed memory) at the first time this is
|
||||
// used.
|
||||
buffer: Option<Vec<u8>>,
|
||||
buffer: Vec<u8>,
|
||||
}
|
||||
|
||||
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
|
||||
#[derive(Copy, Debug, Clone, PartialEq, Eq, Hash)]
|
||||
pub struct StreamId(usize);
|
||||
|
||||
enum StreamType { Input, Output }
|
||||
|
||||
|
||||
impl EventLoop {
|
||||
#[inline]
|
||||
pub fn new() -> EventLoop {
|
||||
let pending_trigger = Trigger::new();
|
||||
let pending_command_trigger = Trigger::new();
|
||||
|
||||
let initial_descriptors = vec![
|
||||
libc::pollfd {
|
||||
fd: pending_trigger.read_fd(),
|
||||
events: libc::POLLIN,
|
||||
revents: 0,
|
||||
},
|
||||
];
|
||||
let mut initial_descriptors = vec![];
|
||||
reset_descriptors_with_pending_command_trigger(
|
||||
&mut initial_descriptors,
|
||||
&pending_command_trigger,
|
||||
);
|
||||
|
||||
let (tx, rx) = channel();
|
||||
|
||||
|
|
@ -450,7 +454,7 @@ impl EventLoop {
|
|||
|
||||
EventLoop {
|
||||
next_stream_id: AtomicUsize::new(0),
|
||||
pending_trigger: pending_trigger,
|
||||
pending_command_trigger: pending_command_trigger,
|
||||
run_context,
|
||||
commands: tx,
|
||||
}
|
||||
|
|
@ -458,220 +462,191 @@ impl EventLoop {
|
|||
|
||||
#[inline]
|
||||
pub fn run<F>(&self, mut callback: F) -> !
|
||||
where F: FnMut(StreamId, StreamData)
|
||||
where F: FnMut(StreamId, StreamEvent)
|
||||
{
|
||||
self.run_inner(&mut callback)
|
||||
}
|
||||
|
||||
fn run_inner(&self, callback: &mut FnMut(StreamId, StreamData)) -> ! {
|
||||
fn run_inner(&self, callback: &mut dyn FnMut(StreamId, StreamEvent)) -> ! {
|
||||
unsafe {
|
||||
let mut run_context = self.run_context.lock().unwrap();
|
||||
let run_context = &mut *run_context;
|
||||
|
||||
loop {
|
||||
{
|
||||
for command in run_context.commands.try_iter() {
|
||||
match command {
|
||||
Command::DestroyStream(stream_id) => {
|
||||
run_context.streams.retain(|s| s.id != stream_id);
|
||||
},
|
||||
Command::PlayStream(stream_id) => {
|
||||
if let Some(stream) = run_context.streams.iter_mut()
|
||||
.find(|stream| stream.can_pause && stream.id == stream_id)
|
||||
{
|
||||
alsa::snd_pcm_pause(stream.channel, 0);
|
||||
stream.is_paused = false;
|
||||
}
|
||||
},
|
||||
Command::PauseStream(stream_id) => {
|
||||
if let Some(stream) = run_context.streams.iter_mut()
|
||||
.find(|stream| stream.can_pause && stream.id == stream_id)
|
||||
{
|
||||
alsa::snd_pcm_pause(stream.channel, 1);
|
||||
stream.is_paused = true;
|
||||
}
|
||||
},
|
||||
Command::NewStream(stream_inner) => {
|
||||
run_context.streams.push(stream_inner);
|
||||
},
|
||||
'stream_loop: loop {
|
||||
process_commands(run_context, callback);
|
||||
|
||||
reset_descriptors_with_pending_command_trigger(
|
||||
&mut run_context.descriptors,
|
||||
&self.pending_command_trigger,
|
||||
);
|
||||
append_stream_poll_descriptors(run_context);
|
||||
|
||||
// At this point, this should include the command `pending_commands_trigger` along
|
||||
// with the poll descriptors for each stream.
|
||||
match poll_all_descriptors(&mut run_context.descriptors) {
|
||||
Ok(true) => (),
|
||||
Ok(false) => continue,
|
||||
Err(err) => {
|
||||
for stream in run_context.streams.iter() {
|
||||
let event = StreamEvent::Close(err.clone().into());
|
||||
callback(stream.id, event);
|
||||
}
|
||||
}
|
||||
|
||||
run_context.descriptors = vec![
|
||||
libc::pollfd {
|
||||
fd: self.pending_trigger.read_fd(),
|
||||
events: libc::POLLIN,
|
||||
revents: 0,
|
||||
},
|
||||
];
|
||||
for stream in run_context.streams.iter() {
|
||||
run_context.descriptors.reserve(stream.num_descriptors);
|
||||
let len = run_context.descriptors.len();
|
||||
let filled = alsa::snd_pcm_poll_descriptors(stream.channel,
|
||||
run_context
|
||||
.descriptors
|
||||
.as_mut_ptr()
|
||||
.offset(len as isize),
|
||||
stream.num_descriptors as
|
||||
libc::c_uint);
|
||||
debug_assert_eq!(filled, stream.num_descriptors as libc::c_int);
|
||||
run_context.descriptors.set_len(len + stream.num_descriptors);
|
||||
run_context.streams.clear();
|
||||
break 'stream_loop;
|
||||
}
|
||||
}
|
||||
|
||||
let ret = libc::poll(run_context.descriptors.as_mut_ptr(),
|
||||
run_context.descriptors.len() as libc::nfds_t,
|
||||
-1 /* infinite */);
|
||||
assert!(ret >= 0, "poll() failed");
|
||||
|
||||
if ret == 0 {
|
||||
continue;
|
||||
}
|
||||
|
||||
// If the `pending_trigger` was signaled, we need to process the comands.
|
||||
// If the `pending_command_trigger` was signaled, we need to process the comands.
|
||||
if run_context.descriptors[0].revents != 0 {
|
||||
run_context.descriptors[0].revents = 0;
|
||||
self.pending_trigger.clear_pipe();
|
||||
self.pending_command_trigger.clear_pipe();
|
||||
}
|
||||
|
||||
// The set of streams that error within the following loop and should be removed.
|
||||
let mut streams_to_remove: Vec<(StreamId, StreamError)> = vec![];
|
||||
|
||||
// Iterate over each individual stream/descriptor.
|
||||
let mut i_stream = 0;
|
||||
let mut i_descriptor = 1;
|
||||
while (i_descriptor as usize) < run_context.descriptors.len() {
|
||||
enum StreamType { Input, Output }
|
||||
let stream_type;
|
||||
let stream_inner = run_context.streams.get_mut(i_stream).unwrap();
|
||||
let stream = &mut run_context.streams[i_stream];
|
||||
let stream_descriptor_ptr = run_context.descriptors.as_mut_ptr().offset(i_descriptor);
|
||||
|
||||
// Check whether the event is `POLLOUT` or `POLLIN`. If neither, `continue`.
|
||||
{
|
||||
let mut revent = mem::uninitialized();
|
||||
|
||||
{
|
||||
let num_descriptors = stream_inner.num_descriptors as libc::c_uint;
|
||||
let desc_ptr =
|
||||
run_context.descriptors.as_mut_ptr().offset(i_descriptor);
|
||||
let res = alsa::snd_pcm_poll_descriptors_revents(stream_inner.channel,
|
||||
desc_ptr,
|
||||
num_descriptors,
|
||||
&mut revent);
|
||||
check_errors(res).unwrap();
|
||||
}
|
||||
|
||||
if revent as i16 == libc::POLLOUT {
|
||||
stream_type = StreamType::Output;
|
||||
} else if revent as i16 == libc::POLLIN {
|
||||
stream_type = StreamType::Input;
|
||||
} else {
|
||||
i_descriptor += stream_inner.num_descriptors as isize;
|
||||
// Only go on if this event was a pollout or pollin event.
|
||||
let stream_type = match check_for_pollout_or_pollin(stream, stream_descriptor_ptr) {
|
||||
Ok(Some(ty)) => ty,
|
||||
Ok(None) => {
|
||||
i_descriptor += stream.num_descriptors as isize;
|
||||
i_stream += 1;
|
||||
continue;
|
||||
},
|
||||
Err(err) => {
|
||||
streams_to_remove.push((stream.id, err.into()));
|
||||
i_descriptor += stream.num_descriptors as isize;
|
||||
i_stream += 1;
|
||||
continue;
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
// Determine the number of samples that are available to read/write.
|
||||
let available_samples = {
|
||||
let available = alsa::snd_pcm_avail(stream_inner.channel); // TODO: what about snd_pcm_avail_update?
|
||||
|
||||
if available == -32 {
|
||||
// buffer underrun
|
||||
stream_inner.buffer_len
|
||||
} else if available < 0 {
|
||||
check_errors(available as libc::c_int)
|
||||
.expect("buffer is not available");
|
||||
unreachable!()
|
||||
} else {
|
||||
(available * stream_inner.num_channels as alsa::snd_pcm_sframes_t) as
|
||||
usize
|
||||
// Get the number of available samples for reading/writing.
|
||||
let available_samples = match get_available_samples(stream) {
|
||||
Ok(n) => n,
|
||||
Err(err) => {
|
||||
streams_to_remove.push((stream.id, err.into()));
|
||||
i_descriptor += stream.num_descriptors as isize;
|
||||
i_stream += 1;
|
||||
continue;
|
||||
}
|
||||
};
|
||||
|
||||
if available_samples < stream_inner.period_len {
|
||||
i_descriptor += stream_inner.num_descriptors as isize;
|
||||
// Only go on if there is at least `stream.period_len` samples.
|
||||
if available_samples < stream.period_len {
|
||||
i_descriptor += stream.num_descriptors as isize;
|
||||
i_stream += 1;
|
||||
continue;
|
||||
}
|
||||
|
||||
let stream_id = stream_inner.id.clone();
|
||||
|
||||
let available_frames = available_samples / stream_inner.num_channels as usize;
|
||||
|
||||
let buffer_size = stream_inner.sample_format.sample_size() * available_samples;
|
||||
// Could be written with a match with improved borrow checking
|
||||
if stream_inner.buffer.is_none() {
|
||||
stream_inner.buffer = Some(vec![0u8; buffer_size]);
|
||||
} else {
|
||||
stream_inner.buffer.as_mut().unwrap().resize(buffer_size, 0u8);
|
||||
}
|
||||
let buffer = stream_inner.buffer.as_mut().unwrap();
|
||||
// Prepare the data buffer.
|
||||
let buffer_size = stream.sample_format.sample_size() * available_samples;
|
||||
stream.buffer.resize(buffer_size, 0u8);
|
||||
let available_frames = available_samples / stream.num_channels as usize;
|
||||
|
||||
match stream_type {
|
||||
StreamType::Input => {
|
||||
let err = alsa::snd_pcm_readi(
|
||||
stream_inner.channel,
|
||||
buffer.as_mut_ptr() as *mut _,
|
||||
let result = alsa::snd_pcm_readi(
|
||||
stream.channel,
|
||||
stream.buffer.as_mut_ptr() as *mut _,
|
||||
available_frames as alsa::snd_pcm_uframes_t,
|
||||
);
|
||||
check_errors(err as _).expect("snd_pcm_readi error");
|
||||
if let Err(err) = check_errors(result as _) {
|
||||
let description = format!("`snd_pcm_readi` failed: {}", err);
|
||||
let err = BackendSpecificError { description };
|
||||
streams_to_remove.push((stream.id, err.into()));
|
||||
continue;
|
||||
}
|
||||
|
||||
let input_buffer = match stream_inner.sample_format {
|
||||
let input_buffer = match stream.sample_format {
|
||||
SampleFormat::I16 => UnknownTypeInputBuffer::I16(::InputBuffer {
|
||||
buffer: cast_input_buffer(buffer),
|
||||
buffer: cast_input_buffer(&mut stream.buffer),
|
||||
}),
|
||||
SampleFormat::U16 => UnknownTypeInputBuffer::U16(::InputBuffer {
|
||||
buffer: cast_input_buffer(buffer),
|
||||
buffer: cast_input_buffer(&mut stream.buffer),
|
||||
}),
|
||||
SampleFormat::F32 => UnknownTypeInputBuffer::F32(::InputBuffer {
|
||||
buffer: cast_input_buffer(buffer),
|
||||
buffer: cast_input_buffer(&mut stream.buffer),
|
||||
}),
|
||||
};
|
||||
let stream_data = StreamData::Input {
|
||||
buffer: input_buffer,
|
||||
};
|
||||
callback(stream_id, stream_data);
|
||||
let event = StreamEvent::Data(stream_data);
|
||||
callback(stream.id, event);
|
||||
},
|
||||
StreamType::Output => {
|
||||
{
|
||||
// We're now sure that we're ready to write data.
|
||||
let output_buffer = match stream_inner.sample_format {
|
||||
let output_buffer = match stream.sample_format {
|
||||
SampleFormat::I16 => UnknownTypeOutputBuffer::I16(::OutputBuffer {
|
||||
buffer: cast_output_buffer(buffer),
|
||||
buffer: cast_output_buffer(&mut stream.buffer),
|
||||
}),
|
||||
SampleFormat::U16 => UnknownTypeOutputBuffer::U16(::OutputBuffer {
|
||||
buffer: cast_output_buffer(buffer),
|
||||
buffer: cast_output_buffer(&mut stream.buffer),
|
||||
}),
|
||||
SampleFormat::F32 => UnknownTypeOutputBuffer::F32(::OutputBuffer {
|
||||
buffer: cast_output_buffer(buffer),
|
||||
buffer: cast_output_buffer(&mut stream.buffer),
|
||||
}),
|
||||
};
|
||||
|
||||
let stream_data = StreamData::Output {
|
||||
buffer: output_buffer,
|
||||
};
|
||||
callback(stream_id, stream_data);
|
||||
let event = StreamEvent::Data(stream_data);
|
||||
callback(stream.id, event);
|
||||
}
|
||||
loop {
|
||||
let result = alsa::snd_pcm_writei(
|
||||
stream_inner.channel,
|
||||
buffer.as_ptr() as *const _,
|
||||
stream.channel,
|
||||
stream.buffer.as_ptr() as *const _,
|
||||
available_frames as alsa::snd_pcm_uframes_t,
|
||||
);
|
||||
|
||||
if result == -32 {
|
||||
// buffer underrun
|
||||
alsa::snd_pcm_prepare(stream_inner.channel);
|
||||
} else if result < 0 {
|
||||
check_errors(result as libc::c_int)
|
||||
.expect("could not write pcm");
|
||||
// TODO: Notify the user of this.
|
||||
alsa::snd_pcm_prepare(stream.channel);
|
||||
} else if let Err(err) = check_errors(result as _) {
|
||||
let description = format!("`snd_pcm_writei` failed: {}", err);
|
||||
let err = BackendSpecificError { description };
|
||||
streams_to_remove.push((stream.id, err.into()));
|
||||
continue;
|
||||
} else if result as usize != available_frames {
|
||||
let description = format!(
|
||||
"unexpected number of frames written: expected {}, \
|
||||
result {} (this should never happen)",
|
||||
available_frames,
|
||||
result,
|
||||
);
|
||||
let err = BackendSpecificError { description };
|
||||
streams_to_remove.push((stream.id, err.into()));
|
||||
continue;
|
||||
} else {
|
||||
assert_eq!(result as usize, available_frames);
|
||||
break;
|
||||
}
|
||||
}
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
// Remove any streams that have errored and notify the user.
|
||||
for (stream_id, err) in streams_to_remove {
|
||||
run_context.streams.retain(|s| s.id != stream_id);
|
||||
let event = StreamEvent::Close(err.into());
|
||||
callback(stream_id, event);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
panic!("`cpal::EventLoop::run` API currently disallows returning");
|
||||
}
|
||||
|
||||
pub fn build_input_stream(
|
||||
|
|
@ -739,7 +714,7 @@ impl EventLoop {
|
|||
can_pause: can_pause,
|
||||
is_paused: false,
|
||||
resume_trigger: Trigger::new(),
|
||||
buffer: None,
|
||||
buffer: vec![],
|
||||
};
|
||||
|
||||
if let Err(desc) = check_errors(alsa::snd_pcm_start(capture_handle)) {
|
||||
|
|
@ -818,7 +793,7 @@ impl EventLoop {
|
|||
can_pause: can_pause,
|
||||
is_paused: false,
|
||||
resume_trigger: Trigger::new(),
|
||||
buffer: None,
|
||||
buffer: vec![],
|
||||
};
|
||||
|
||||
self.push_command(Command::NewStream(stream_inner));
|
||||
|
|
@ -830,7 +805,7 @@ impl EventLoop {
|
|||
fn push_command(&self, command: Command) {
|
||||
// Safe to unwrap: sender outlives receiver.
|
||||
self.commands.send(command).unwrap();
|
||||
self.pending_trigger.wakeup();
|
||||
self.pending_command_trigger.wakeup();
|
||||
}
|
||||
|
||||
#[inline]
|
||||
|
|
@ -851,6 +826,157 @@ impl EventLoop {
|
|||
}
|
||||
}
|
||||
|
||||
// Process any pending `Command`s within the `RunContext`'s queue.
|
||||
fn process_commands(
|
||||
run_context: &mut RunContext,
|
||||
callback: &mut dyn FnMut(StreamId, StreamEvent),
|
||||
) {
|
||||
for command in run_context.commands.try_iter() {
|
||||
match command {
|
||||
Command::DestroyStream(stream_id) => {
|
||||
run_context.streams.retain(|s| s.id != stream_id);
|
||||
let event = StreamCloseCause::UserDestroyed.into();
|
||||
callback(stream_id, event);
|
||||
},
|
||||
Command::PlayStream(stream_id) => {
|
||||
if let Some(stream) = run_context.streams.iter_mut()
|
||||
.find(|stream| stream.can_pause && stream.id == stream_id)
|
||||
{
|
||||
callback(stream_id, StreamEvent::Play);
|
||||
unsafe {
|
||||
alsa::snd_pcm_pause(stream.channel, 0);
|
||||
}
|
||||
stream.is_paused = false;
|
||||
}
|
||||
},
|
||||
Command::PauseStream(stream_id) => {
|
||||
if let Some(stream) = run_context.streams.iter_mut()
|
||||
.find(|stream| stream.can_pause && stream.id == stream_id)
|
||||
{
|
||||
callback(stream_id, StreamEvent::Pause);
|
||||
unsafe {
|
||||
alsa::snd_pcm_pause(stream.channel, 1);
|
||||
}
|
||||
stream.is_paused = true;
|
||||
}
|
||||
},
|
||||
Command::NewStream(stream_inner) => {
|
||||
run_context.streams.push(stream_inner);
|
||||
},
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Resets the descriptors so that only `pending_command_trigger.read_fd()` is contained.
|
||||
fn reset_descriptors_with_pending_command_trigger(
|
||||
descriptors: &mut Vec<libc::pollfd>,
|
||||
pending_command_trigger: &Trigger,
|
||||
) {
|
||||
descriptors.clear();
|
||||
descriptors.push(libc::pollfd {
|
||||
fd: pending_command_trigger.read_fd(),
|
||||
events: libc::POLLIN,
|
||||
revents: 0,
|
||||
});
|
||||
}
|
||||
|
||||
// Appends the `poll` descriptors for each stream onto the `RunContext`'s descriptor slice, ready
|
||||
// for a call to `libc::poll`.
|
||||
fn append_stream_poll_descriptors(run_context: &mut RunContext) {
|
||||
for stream in run_context.streams.iter() {
|
||||
run_context.descriptors.reserve(stream.num_descriptors);
|
||||
let len = run_context.descriptors.len();
|
||||
let filled = unsafe {
|
||||
alsa::snd_pcm_poll_descriptors(
|
||||
stream.channel,
|
||||
run_context.descriptors.as_mut_ptr().offset(len as isize),
|
||||
stream.num_descriptors as libc::c_uint,
|
||||
)
|
||||
};
|
||||
debug_assert_eq!(filled, stream.num_descriptors as libc::c_int);
|
||||
unsafe {
|
||||
run_context.descriptors.set_len(len + stream.num_descriptors);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Poll all descriptors within the given set.
|
||||
//
|
||||
// Returns `Ok(true)` if some event has occurred or `Ok(false)` if no events have
|
||||
// occurred.
|
||||
//
|
||||
// Returns an `Err` if `libc::poll` returns a negative value for some reason.
|
||||
fn poll_all_descriptors(descriptors: &mut [libc::pollfd]) -> Result<bool, BackendSpecificError> {
|
||||
let res = unsafe {
|
||||
// Don't timeout, wait forever.
|
||||
libc::poll(descriptors.as_mut_ptr(), descriptors.len() as libc::nfds_t, -1)
|
||||
};
|
||||
if res < 0 {
|
||||
let description = format!("`libc::poll()` failed: {}", res);
|
||||
Err(BackendSpecificError { description })
|
||||
} else if res == 0 {
|
||||
Ok(false)
|
||||
} else {
|
||||
Ok(true)
|
||||
}
|
||||
}
|
||||
|
||||
// Check whether the event is `POLLOUT` or `POLLIN`.
|
||||
//
|
||||
// If so, return the stream type associated with the event.
|
||||
//
|
||||
// Otherwise, returns `Ok(None)`.
|
||||
//
|
||||
// Returns an `Err` if the `snd_pcm_poll_descriptors_revents` call fails.
|
||||
fn check_for_pollout_or_pollin(
|
||||
stream: &StreamInner,
|
||||
stream_descriptor_ptr: *mut libc::pollfd,
|
||||
) -> Result<Option<StreamType>, BackendSpecificError> {
|
||||
let (revent, res) = unsafe {
|
||||
let mut revent = mem::uninitialized();
|
||||
let res = alsa::snd_pcm_poll_descriptors_revents(
|
||||
stream.channel,
|
||||
stream_descriptor_ptr,
|
||||
stream.num_descriptors as libc::c_uint,
|
||||
&mut revent,
|
||||
);
|
||||
(revent, res)
|
||||
};
|
||||
if let Err(desc) = check_errors(res) {
|
||||
let description =
|
||||
format!("`snd_pcm_poll_descriptors_revents` failed: {}",desc);
|
||||
let err = BackendSpecificError { description };
|
||||
return Err(err);
|
||||
}
|
||||
|
||||
if revent as i16 == libc::POLLOUT {
|
||||
Ok(Some(StreamType::Output))
|
||||
} else if revent as i16 == libc::POLLIN {
|
||||
Ok(Some(StreamType::Input))
|
||||
} else {
|
||||
Ok(None)
|
||||
}
|
||||
}
|
||||
|
||||
// Determine the number of samples that are available to read/write.
|
||||
fn get_available_samples(stream: &StreamInner) -> Result<usize, BackendSpecificError> {
|
||||
// TODO: what about snd_pcm_avail_update?
|
||||
let available = unsafe {
|
||||
alsa::snd_pcm_avail(stream.channel)
|
||||
};
|
||||
if available == -32 {
|
||||
// buffer underrun
|
||||
// TODO: Notify the user some how.
|
||||
Ok(stream.buffer_len)
|
||||
} else if let Err(desc) = check_errors(available as libc::c_int) {
|
||||
let description = format!("failed to get available samples: {}", desc);
|
||||
let err = BackendSpecificError { description };
|
||||
Err(err)
|
||||
} else {
|
||||
Ok((available * stream.num_channels as alsa::snd_pcm_sframes_t) as usize)
|
||||
}
|
||||
}
|
||||
|
||||
unsafe fn set_hw_params_from_format(
|
||||
pcm_handle: *mut alsa::snd_pcm_t,
|
||||
hw_params: &HwParams,
|
||||
|
|
|
|||
Loading…
Reference in New Issue