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//! Objects for asynchronous notification of audio thread events.
use parking_lot::{Mutex, Condvar};
use std::sync::Arc;
use std::time::{Duration, Instant};
use bounded_spsc_queue::{Producer, Consumer};
use super::CONTROL_BUFFER_SIZE;
use bounded_spsc_queue;
use uuid::Uuid;
pub use thread::Player;
/// A message from the audio thread.
pub enum AudioThreadMessage {
/// The player with a given `Uuid` was successfully added.
PlayerAdded(Uuid),
/// This player was rejected due to you exceeding `MAX_PLAYERS`.
PlayerRejected(Player),
/// This player was removed on account of not being `alive`.
PlayerRemoved(Player),
/// The player with a given `Uuid` has an invalid output patch. Playback has been stopped.
///
/// To resume playback, you MUST change the output patch to a valid channel
/// number, and call `set_active(true)`.
PlayerInvalidOutpatch(Uuid),
/// The player with a given `Uuid`'s buffer is half full.
///
/// This is just to let you know, so that you can start refilling the buffer before it
/// runs out.
PlayerBufHalf(Uuid),
/// The player with a given `Uuid`'s buffer is empty.
///
/// This could simply mean that playback has ended, or it could mean that you didn't
/// refill the buffer and your audio has now stopped. In the latter case, you OUGHT TO refill the
/// buffer.
PlayerBufEmpty(Uuid),
/// The audio thread has experienced an under- or over- run.
///
/// This REALLY SHOULD NOT happen under normal circumstances. If your sample rate and buffer size
/// are set to reasonable values, [file a bug!](https://github.com/eeeeeta/sqa-engine).
/// You MAY WISH TO inform the user that their audio just glitched, and that they should adjust
/// the sample rate and buffer size to remedy the problem.
Xrun
}
/// A commmunication channel to receive messages from the audio thread.
pub struct AudioThreadHandle {
inner: Arc<(Mutex<()>, Condvar)>,
rx: Consumer<AudioThreadMessage>
}
impl AudioThreadHandle {
pub(crate) unsafe fn make() -> (AudioThreadHandle, AudioThreadSender) {
let (p, c) = bounded_spsc_queue::make(CONTROL_BUFFER_SIZE);
let arc = Arc::new((Mutex::new(()), Condvar::new()));
(AudioThreadHandle {
inner: arc.clone(),
rx: c
}, AudioThreadSender {
inner: arc,
tx: p,
written_t: 0,
cur_t: 1
})
}
/// Attempt to receive a message from the audio thread, returning `None` if none is available.
pub fn try_recv(&mut self) -> Option<AudioThreadMessage> {
self.rx.try_pop()
}
/// Wait (forever, if necessary) until a message is available, and return it.
///
/// This blocks the thread on a condition variable, consuming no CPU time whilst blocked.
pub fn recv(&mut self) -> AudioThreadMessage {
if let Some(x) = self.rx.try_pop() { return x; }
let mut lock = self.inner.0.lock();
loop {
self.inner.1.wait(&mut lock);
if let Some(x) = self.rx.try_pop() { return x; }
}
}
/// Wait until a message is available, timing out after the specified time instant. Return a
/// message if obtained in the time period, otherwise `None`.
///
/// The semantics of this function are equivalent to `recv()` except that the thread will be
/// blocked roughly until the timeout is reached. This method should not be used for precise timing
/// due to anomalies such as preemption or platform differences that may not cause the maximum
/// amount of time waited to be precisely the value given.
///
/// Note that the best effort is made to ensure that the time waited is measured with a monotonic
/// clock, and not affected by the changes made to the system time.
pub fn wait_until(&mut self, timeout: Instant) -> Option<AudioThreadMessage> {
if let Some(x) = self.rx.try_pop() { return Some(x); }
let mut lock = self.inner.0.lock();
self.inner.1.wait_until(&mut lock, timeout);
self.rx.try_pop()
}
/// Wait until a message is available, timing out after a specified duration. Return a
/// message if obtained in the time period, otherwise `None`.
///
/// The semantics of this function are equivalent to `recv()` except that the thread will be
/// blocked for roughly no longer than `timeout`. This method should not be used for precise
/// timing due to anomalies such as preemption or platform differences that may not cause the
/// maximum amount of time waited to be precisely `timeout`.
///
/// Note that the best effort is made to ensure that the time waited is measured with a monotonic
/// clock, and not affected by the changes made to the system time.
pub fn wait_for(&mut self, timeout: Duration) -> Option<AudioThreadMessage> {
if let Some(x) = self.rx.try_pop() { return Some(x); }
let mut lock = self.inner.0.lock();
self.inner.1.wait_for(&mut lock, timeout);
self.rx.try_pop()
}
}
pub(crate) struct AudioThreadSender {
inner: Arc<(Mutex<()>, Condvar)>,
tx: Producer<AudioThreadMessage>,
written_t: u64,
cur_t: u64
}
impl AudioThreadSender {
#[inline(always)]
pub(crate) fn init(&mut self, t: u64) {
self.cur_t = t;
}
#[inline(always)]
pub(crate) fn send(&mut self, data: AudioThreadMessage) {
self.written_t = self.cur_t;
if let Some(remnant) = self.tx.try_push(data) {
// If we can't send the data to the main thread for deallocation,
// we don't want to deallocate it in the audio thread!
::std::mem::forget(remnant);
}
}
#[inline(always)]
pub(crate) fn notify(&mut self) {
if self.written_t == self.cur_t {
self.inner.1.notify_one();
}
}
}