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less repetitive match arms; https://github.com/neondatabase/neon/pull/9851#discussion_r1860535860

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This commit is contained in:
Christian Schwarz
2024-11-29 16:10:27 +01:00
parent 0d28084985
commit 53e18b24fc
1 changed files with 74 additions and 61 deletions
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135
libs/utils/src/sync/spsc_fold.rs
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@@ -95,24 +95,16 @@ impl<T: Send> Sender<T> {
}
}
}
State::TryFoldFailed => {
unreachable!();
}
State::SenderWaitsForReceiverToConsume(_data) => {
// Really, we shouldn't be polled until receiver has consumed and wakes us.
Poll::Pending
}
State::ReceiverGone => Poll::Ready(Err(SendError::ReceiverGone)),
State::SenderGone(_) => {
unreachable!();
}
State::AllGone => {
unreachable!();
}
State::SenderDropping => {
unreachable!();
}
State::ReceiverDropping => {
State::SenderGone(_)
| State::AllGone
| State::SenderDropping
| State::ReceiverDropping
| State::TryFoldFailed => {
unreachable!();
}
}
@@ -131,12 +123,14 @@ impl<T> Drop for Sender<T> {
State::HasData(data) | State::SenderWaitsForReceiverToConsume(data) => {
State::SenderGone(Some(data))
}
State::TryFoldFailed => unreachable!(),
State::SenderGone(_) => unreachable!(),
State::ReceiverGone => State::AllGone,
State::AllGone => unreachable!(),
State::SenderDropping => unreachable!(),
State::ReceiverDropping => unreachable!(),
State::TryFoldFailed
| State::SenderGone(_)
| State::AllGone
| State::SenderDropping
| State::ReceiverDropping => {
unreachable!("unreachable state {:?}", guard.discriminant_str())
}
}
}
}
@@ -160,48 +154,22 @@ impl<T: Send> Receiver<T> {
}
Poll::Pending
}
guard @ State::HasData(_) => {
let State::HasData(data) = std::mem::replace(guard, State::NoData) else {
unreachable!("this match arm guarantees that the guard is HasData");
};
guard @ State::HasData(_)
| guard @ State::SenderWaitsForReceiverToConsume(_)
| guard @ State::SenderGone(Some(_)) => {
let data = guard
.take_data()
.expect("in these states, data is guaranteed to be present");
self.state.wake_sender.notify();
Poll::Ready(Ok(data))
}
State::TryFoldFailed => {
unreachable!();
}
guard @ State::SenderWaitsForReceiverToConsume(_) => {
let State::SenderWaitsForReceiverToConsume(data) =
std::mem::replace(guard, State::NoData) else {
unreachable!(
"this match arm guarantees that the guard is SenderWaitsForReceiverToConsume"
);
};
self.state.wake_sender.notify();
Poll::Ready(Ok(data))
}
guard @ State::SenderGone(Some(_)) => {
let State::SenderGone(Some(data)) =
std::mem::replace(guard, State::SenderGone(None))
else {
unreachable!(
"this match arm guarantees that the guard is SenderGone(Some(_))"
);
};
Poll::Ready(Ok(data))
}
State::SenderGone(None) => Poll::Ready(Err(RecvError::SenderGone)),
State::ReceiverGone => {
unreachable!();
}
State::AllGone => {
unreachable!();
}
State::SenderDropping => {
unreachable!();
}
State::ReceiverDropping => {
unreachable!();
State::ReceiverGone
| State::AllGone
| State::SenderDropping
| State::ReceiverDropping
| State::TryFoldFailed => {
unreachable!("unreachable state {:?}", guard.discriminant_str());
}
}
})
@@ -217,12 +185,57 @@ impl<T> Drop for Receiver<T> {
*guard = match std::mem::replace(&mut *guard, State::ReceiverDropping) {
State::NoData => State::ReceiverGone,
State::HasData(_) | State::SenderWaitsForReceiverToConsume(_) => State::ReceiverGone,
State::TryFoldFailed => unreachable!(),
State::SenderGone(_) => State::AllGone,
State::ReceiverGone => unreachable!(),
State::AllGone => unreachable!(),
State::SenderDropping => unreachable!(),
State::ReceiverDropping => unreachable!(),
State::TryFoldFailed
| State::ReceiverGone
| State::AllGone
| State::SenderDropping
| State::ReceiverDropping => {
unreachable!("unreachable state {:?}", guard.discriminant_str())
}
}
}
}
impl<T> State<T> {
fn take_data(&mut self) -> Option<T> {
match self {
State::HasData(_) => {
let State::HasData(data) = std::mem::replace(self, State::NoData) else {
unreachable!("this match arm guarantees that the state is HasData");
};
Some(data)
}
State::SenderWaitsForReceiverToConsume(_) => {
let State::SenderWaitsForReceiverToConsume(data) =
std::mem::replace(self, State::NoData)
else {
unreachable!(
"this match arm guarantees that the state is SenderWaitsForReceiverToConsume"
);
};
Some(data)
}
State::SenderGone(data) => Some(data.take().unwrap()),
State::NoData
| State::TryFoldFailed
| State::ReceiverGone
| State::AllGone
| State::SenderDropping
| State::ReceiverDropping => None,
}
}
fn discriminant_str(&self) -> &'static str {
match self {
State::NoData => "NoData",
State::HasData(_) => "HasData",
State::TryFoldFailed => "TryFoldFailed",
State::SenderWaitsForReceiverToConsume(_) => "SenderWaitsForReceiverToConsume",
State::SenderGone(_) => "SenderGone",
State::ReceiverGone => "ReceiverGone",
State::AllGone => "AllGone",
State::SenderDropping => "SenderDropping",
State::ReceiverDropping => "ReceiverDropping",
}
}
}