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#![allow(clippy::mutex_atomic)]
use std::error;
use std::fmt;
use std::fmt::Formatter;
use std::sync::{Arc, Condvar, Mutex, PoisonError};
use std::time::Duration;
pub type WaitHandleResult<T> = std::result::Result<T, WaitHandleError>;
pub fn new() -> (WaitHandleSignaler, WaitHandleListener) {
let wait_handle = Arc::new(WaitHandle::new());
let signaler = WaitHandleSignaler::new(wait_handle.clone());
let listener = WaitHandleListener::new(wait_handle);
(signaler, listener)
}
#[derive(Debug, Default)]
struct WaitHandle {
pair: Arc<(Mutex<bool>, Condvar)>,
}
impl WaitHandle {
pub fn new() -> Self {
let pair = Arc::new((Mutex::new(false), Condvar::new()));
return WaitHandle { pair };
}
pub fn check(&self) -> WaitHandleResult<bool> {
self.wait(Duration::from_micros(0))
}
pub fn wait(&self, timeout: Duration) -> WaitHandleResult<bool> {
let (lock, cvar) = &*self.pair;
let mut guard = lock.lock()?;
let result = cvar.wait_timeout_while(guard, timeout, |&mut pending| !pending)?;
guard = result.0;
if *guard {
return Ok(true);
}
Ok(false)
}
pub fn reset(&self) -> WaitHandleResult<()> {
self.set(false)
}
pub fn signal(&self) -> WaitHandleResult<()> {
self.set(true)
}
fn set(&self, value: bool) -> WaitHandleResult<()> {
let (lock, cvar) = &*self.pair;
let mut guard = lock.lock()?;
if *guard != value {
*guard = value;
cvar.notify_one();
}
Ok(())
}
}
#[derive(Clone)]
pub struct WaitHandleSignaler {
handle: Arc<WaitHandle>,
}
impl WaitHandleSignaler {
fn new(handle: Arc<WaitHandle>) -> Self {
Self { handle }
}
pub fn reset(&self) -> WaitHandleResult<()> {
self.handle.reset()
}
pub fn signal(&self) -> WaitHandleResult<()> {
self.handle.signal()
}
}
#[derive(Clone)]
pub struct WaitHandleListener {
handle: Arc<WaitHandle>,
}
impl WaitHandleListener {
fn new(handle: Arc<WaitHandle>) -> Self {
Self { handle }
}
pub fn check(&self) -> WaitHandleResult<bool> {
self.handle.check()
}
pub fn wait(&self, timeout: Duration) -> WaitHandleResult<bool> {
self.handle.wait(timeout)
}
}
#[derive(Debug, Clone)]
pub enum WaitHandleError {
LockPoisoned,
}
impl fmt::Display for WaitHandleError {
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
match self {
WaitHandleError::LockPoisoned => write!(f, "wait handle lock poisoned"),
}
}
}
impl error::Error for WaitHandleError {
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
None
}
}
impl<T> From<PoisonError<T>> for WaitHandleError {
fn from(_: PoisonError<T>) -> Self {
WaitHandleError::LockPoisoned
}
}