Cargo.toml
README.md
www/index.md
www/changelog.md
src/err.rs
src/lib.rs
src/tx.rs
src/rx.rs
tests/basic.rs
tests/closed.rs
tests/ctrl.rs

[package]
name = "limqch"
version = "0.2.0"
edition = "2024"
license = "0BSD"
# https://crates.io/category_slugs
categories = [ "concurrency" ]
keywords = [ "channel", "bounded" ]
repository = "https://repos.qrnch.tech/pub/limqch"
description = "A channel built on top of limq."
rust-version = "1.85"
exclude = [
  ".fossil-settings",
  ".efiles",
  ".fslckout",
  "www",
  "bacon.toml",
  "rustfmt.toml"
]

# https://doc.rust-lang.org/cargo/reference/manifest.html#the-badges-section
[badges]
maintenance = { status = "actively-developed" }

[dependencies]
limq = { version = "0.3.0" }
parking_lot = { version = "0.12.3" }
wakerizer = { version = "0.1.0" }

[dev-dependencies]
tokio = { version = "1.44.1", features = ["macros", "rt", "rt-multi-thread"] }

[package.metadata.docs.rs]

blank_lines_upper_bound = 2
comment_width = 79
edition = "2024"
format_strings = true
max_width = 79
match_block_trailing_comma = false
# merge_imports = true
newline_style = "Unix"
tab_spaces = 2
trailing_comma = "Never"
unstable_features = true
wrap_comments = true
#reorder_imports = false
#reorder_modules = false

use std::fmt;

/// Errors that [`Sender`](super::Sender) and [`Receiver`](super::Receiver)
/// methods can return.
#[derive(PartialEq, Eq)]
pub enum Error<T> {
  /// No remote channel end-points remain.
  Closed,

  /// The node will currently not fit in the queue.
  WontFit(T),

  /// The node can't fit in the queue (unless reconfigured to allow larger
  /// nodes).
  CantFit(T)
}

impl<T> std::error::Error for Error<T> {}

impl<T> fmt::Debug for Error<T> {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    match self {
      Self::Closed => write!(f, "Error::Closed"),
      Self::WontFit(_) => write!(f, "Error::WontFit"),
      Self::CantFit(_) => write!(f, "Error::CantFit")
    }
  }
}

impl<T> fmt::Display for Error<T> {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    match self {
      Self::Closed => write!(f, "Remote end-points closed"),
      Self::WontFit(_) => write!(f, "Won't fit"),
      Self::CantFit(_) => write!(f, "Can't fit")
    }
  }
}

impl<T> From<limq::Error<T>> for Error<T> {
  fn from(err: limq::Error<T>) -> Self {
    match err {
      limq::Error::WontFit(n) => Self::WontFit(n),
      limq::Error::CantFit(n) => Self::CantFit(n)
    }
  }
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

//! Channel based on [`LimQ`].

mod err;
mod rx;
mod tx;

use std::sync::Arc;

use parking_lot::{Condvar, Mutex};

use limq::LimQ;

use wakerizer::Wakers;

pub use err::Error;
pub use limq::{Controller, Overflow};
pub use rx::{Receiver, RecvFuture};
pub use tx::Sender;

struct Inner<C, T>
where
  C: Controller<Item = T>
{

  q: LimQ<C, T>,
  tx_count: usize,
  rx_count: usize
}

impl<C, T> Inner<C, T>
where
  C: Controller<Item = T>
{
  fn new(lc: C) -> Self {
    Self {
      q: LimQ::new(lc),
      tx_count: 0,
      rx_count: 0
    }
  }
}

struct Shared<C, T>
where
  C: Controller<Item = T>
{
  inner: Mutex<Inner<C, T>>,

  /// Used from receivers in order to wait for senders to add new elements to
  /// the queue.
  tx_wakers: Wakers,

  tx_signal: Condvar,

  /// Used from senders in order to wait for receivers to make room available
  /// in the queue.
  rx_wakers: Wakers,

  rx_signal: Condvar
}

impl<C, T> Shared<C, T>
where
  C: Controller<Item = T>
{
  fn new(lc: C) -> Self {
    let inner = Inner::new(lc);
    let inner = Mutex::new(inner);
    Self {
      inner,
      tx_wakers: Wakers::new(),
      rx_wakers: Wakers::new(),
      tx_signal: Condvar::new(),
      rx_signal: Condvar::new()
    }
  }

  /// Called by the receiver end-point when a node has been takwn off the
  /// queue, in case any sendera are waiting for space to become available.
  fn wake_senders(&self) {
    self.tx_wakers.wake_all();
    self.tx_signal.notify_one();
  }

  /// Called by the sender end-point when a node has been added to the queue in
  /// case any receivers are waiting for nodes to become available.
  fn wake_receivers(&self) {
    self.rx_wakers.wake_all();
    self.rx_signal.notify_one();
  }
}


/// Create a channel pair, with an optional internal queue limit.
///
/// ```
/// use limqch::{channel, Error};
/// use limq::{LimQ, LengthLimit};
///
/// // Construct a channel which uses an internal queue that is limited to
/// // 2 elements.
/// let lenlim = LengthLimit::new(2);
/// let (tx, rx) = channel(lenlim);
///
/// tx.try_send(1).unwrap();
/// tx.try_send(2).unwrap();
/// let Err(Error::WontFit(n)) = tx.try_send(3) else {
///   panic!("Unexpectedly not Error::WontFit");
/// };
///
/// let n = rx.try_recv().unwrap().unwrap();
/// assert_eq!(n, 1);
/// ```
#[must_use]
pub fn channel<C, T>(lc: C) -> (Sender<C, T>, Receiver<C, T>)
where
  C: Controller<Item = T>,
  T: Send + Sync
{
  let sh = Shared::new(lc);
  let sh = Arc::new(sh);

  let tx = Sender::new(Arc::clone(&sh));
  let rx = Receiver::new(sh);

  (tx, rx)
}

/*
/// Object that can be used to spawn sender and receiver end-points.
pub struct Spawner<C, T>(Arc<Shared<C, T>>)
where
  C: Controller<Item = T>;

impl<C, T> Spawner<C, T>
where
  C: Controller<Item = T>,
  T: Send + Sync
{
  #[must_use]
  pub fn new(lc: C) -> Self {
    let sh = Shared::new(lc);
    let sh = Arc::new(sh);
    Self(sh)
  }

  #[must_use]
  pub fn sender(&self) -> Sender<C, T> {
    Sender::new(Arc::clone(&self.0))
  }

  #[must_use]
  pub fn receiver(&self) -> Receiver<C, T> {
    Receiver::new(Arc::clone(&self.0))
  }
}
*/


/// Proxy object to allow [`Sender`] and [`Receiver`] instances to
/// access the internal queue's [`Controller`].
#[derive(Clone)]
#[repr(transparent)]
pub struct Ctrl<C, T>(Arc<Shared<C, T>>)
where
  C: Controller<Item = T>;

impl<C, T> Ctrl<C, T>
where
  C: Controller<Item = T>
{
  /// Access the underlying [`Controller`] in a closure.
  ///
  /// This can be used to access the `Controller`.
  ///
  /// # Caveat Utilitor
  /// An internal lock is held while the closure is called.  The application
  /// must return quickly to avoid holding up the channel end-points (or,
  /// worse, holding up an an async runtime).
  pub fn with_ctrl<F, R>(&self, f: F) -> R
  where
    F: FnOnce(&C) -> R
  {
    let inner = self.0.inner.lock();
    f(inner.q.controller())
  }

  /// Access the underlying [`Controller`] mutably in a closure.
  ///
  /// This can be used to reconfigure the `Controller`, if it support
  /// reconfiguration.
  ///
  /// # Caveat Utilitor
  /// An internal lock is held while the closure is called.  The application
  /// must return quickly to avoid holding up the channel end-points (or,
  /// worse, holding up an an async runtime).
  pub fn with_ctrl_mut<F, R>(&self, f: F) -> R
  where
    F: FnOnce(&mut C) -> R
  {
    let mut inner = self.0.inner.lock();
    f(inner.q.controller_mut())
  }
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

use std::{
  future::Future,
  pin::Pin,
  sync::Arc,
  task::{Context, Poll}
};

use wakerizer::Waiter;

use super::{Controller, Ctrl, Error, Shared};

/// Channel receiver end-point.

pub struct Receiver<C, T>
where
  C: Controller<Item = T>
{
  sh: Arc<Shared<C, T>>
}

impl<C, T> Clone for Receiver<C, T>
where
  C: Controller<Item = T>
{
  fn clone(&self) -> Self {
    let mut inner = self.sh.inner.lock();
    inner.rx_count += 1;
    drop(inner);

    let sh = Arc::clone(&self.sh);
    Self { sh }
  }
}

impl<C, T> Receiver<C, T>
where
  C: Controller<Item = T>
{
  #[must_use]
  pub(super) fn new(sh: Arc<Shared<C, T>>) -> Self {
    let mut inner = sh.inner.lock();
    inner.rx_count += 1;
    drop(inner);
    Self { sh }
  }

  /// Return a [`Ctrl`], which can be used to access the internal
  /// [`Controller`].
  #[must_use]
  pub fn ctrl(&self) -> Ctrl<C, T> {
    Ctrl(Arc::clone(&self.sh))
  }

  /// Receive a node from queue.  If the queue is empty, block and wait for a
  /// new node to arrive.
  ///
  /// # Errors
  /// [`Error::Closed`] means that the queue is empty and all the
  /// [`Sender`](super::Sender)s have been dropped.
  pub fn recv_blocking(&self) -> Result<T, Error<T>> {
    let mut inner = self.sh.inner.lock();

    let n = loop {
      if inner.q.is_empty() && inner.tx_count == 0 {
        return Err(Error::Closed);
      }

      if let Some(n) = inner.q.pop() {
        break n;
      }
      self.sh.rx_signal.wait(&mut inner);
    };

    // Wake up any async senders that are waiting for space to become
    // available.

    self.sh.wake_senders();


    drop(inner);

    Ok(n)
  }

  /// Returns a `Future` that is the `async` equivalent of
  /// [`Receiver::recv_blocking()`].
  #[must_use]
  pub fn recv_async(&self) -> RecvFuture<C, T> {
    RecvFuture {
      sh: Arc::clone(&self.sh),
      waiter: self.sh.rx_wakers.waiter()
    }
  }

  /// Attempt to retreive a node from the queue.
  ///
  /// Returns `Ok(Some(T))` if there's a node available for immediate pickup.
  /// Returns `Ok(None)` is there are no nodes to pick up.
  ///
  /// # Errors
  /// [`Error::Closed`] means that the queue is empty and all the
  /// [`Sender`](super::Sender)s have been dropped.
  pub fn try_recv(&self) -> Result<Option<T>, Error<T>> {
    let mut inner = self.sh.inner.lock();
    if inner.q.is_empty() && inner.tx_count == 0 {
      return Err(Error::Closed);
    }
    Ok(inner.q.pop().map_or_else(
      || None,
      |n| {

        // Wake up any async senders that are waiting for space to become

        // available.
        self.sh.wake_senders();


        drop(inner);

        Some(n)
      }
    ))
  }
}

impl<C, T> Drop for Receiver<C, T>
where
  C: Controller<Item = T>
{
  fn drop(&mut self) {
    let mut inner = self.sh.inner.lock();
    inner.rx_count -= 1;
    drop(inner);

    self.sh.wake_senders();
  }
}


/// A `Future` that will will resolve when there's data that can be returned
/// from the channel, of it the internal queue is empty but all the
/// [`Sender`](super::Sender) end-points have been dropped.
pub struct RecvFuture<C, T>
where
  C: Controller<Item = T>
{
  sh: Arc<Shared<C, T>>,
  waiter: Waiter
}

impl<C, T> Future for RecvFuture<C, T>
where
  C: Controller<Item = T>
{
  type Output = Result<T, Error<T>>;
  fn poll(
    mut self: Pin<&mut Self>,
    ctx: &mut Context<'_>
  ) -> Poll<Self::Output> {
    let mut inner = self.sh.inner.lock();
    if let Some(n) = inner.q.pop() {
      Poll::Ready(Ok(n))
    } else if inner.tx_count == 0 {
      Poll::Ready(Err(Error::Closed))
    } else {
      drop(inner); // happy borrow-checker
      self.waiter.prime(ctx);
      Poll::Pending
    }
  }
}

use std::{
  future::Future,
  pin::Pin,
  sync::Arc,
  task::{Context, Poll}
};

use wakerizer::Waiter;

use super::{Controller, Ctrl, Error, Overflow, Shared};

/// Channel transmitter end-point.

pub struct Sender<C, T>
where
  C: Controller<Item = T>
{
  sh: Arc<Shared<C, T>>
}

impl<C, T> Clone for Sender<C, T>
where
  C: Controller<Item = T>
{
  fn clone(&self) -> Self {
    let mut inner = self.sh.inner.lock();
    inner.tx_count += 1;
    drop(inner);

    let sh = Arc::clone(&self.sh);
    Self { sh }
  }
}

impl<C, T> Sender<C, T>
where
  C: Controller<Item = T>,
  T: Send + Sync
{
  pub(super) fn new(sh: Arc<Shared<C, T>>) -> Self {
    let mut inner = sh.inner.lock();
    inner.tx_count += 1;
    drop(inner);
    Self { sh }
  }

  /// Return a [`Ctrl`], which can be used to access the internal
  /// [`Controller`].
  #[must_use]
  pub fn ctrl(&self) -> Ctrl<C, T> {
    Ctrl(Arc::clone(&self.sh))
  }

  /// Send an element over channel.
  ///
  /// If the channel has a limit, and the limit has been reached, then block
  /// and wait until a [`Receiver`](super::Receiver) has make more room
  /// available on the queue.
  ///
  /// # Errors
  /// [`Error::CantFit`] means the node was rejected by the
  /// [`Controller`]. [`Error::Closed`] means there are no more
  /// [`Receiver`](super::Receiver)s available.

  pub fn send_blocking(&self, mut n: T) -> Result<(), Error<T>> {
    let mut inner = self.sh.inner.lock();

    // Keep trying to `try_push()` until successful.
    loop {
      if inner.rx_count == 0 {
        return Err(Error::Closed);
      }

      n = match inner.q.try_push(n) {
        Ok(()) => break,
        Err(e) => match e {
          limq::Error::WontFit(n) => n,
          limq::Error::CantFit(n) => {
            return Err(Error::CantFit(n));
          }
        }
      };
      self.sh.tx_signal.wait(&mut inner);
    }

    drop(inner);

    // Have a new element in queue -- wake up a waiting receiver
    self.sh.wake_receivers();

    Ok(())
  }

  /// This exists only because the compiler thinks `send_async()` is not `Send`
  /// (because it thinks `inner` is held past the `await`, even though it
  /// isn't.
  ///

  /// # Errors
  /// [`Error::CantFit`] means the node was rejected by the
  /// [`Controller`]. [`Error::Closed`] means there are no more
  /// [`Receiver`](super::Receiver)s available.
  fn try_push(&self, n: T) -> Result<(), Error<T>> {
    let mut inner = self.sh.inner.lock();
    if inner.rx_count == 0 {
      return Err(Error::Closed);
    }

    inner.q.try_push(n)?;
    drop(inner);
    Ok(())


  }

  /// Send an element over channel.
  ///
  /// If the channel has a limit, and the limit has been reached, then block
  /// and wait until a [`Receiver`](super::Receiver) has make more room
  /// available on the queue.
  ///
  /// # Errors
  /// [`Error::CantFit`] means the [`Controller`] rejected the node.
  /// [`Error::Closed`] means not [`Receiver`](super::Receiver)s remain.

  pub async fn send_async(&self, mut n: T) -> Result<(), Error<T>> {
    // In an ideal world, there'd be a SendFuture that takes in the new node.
    // However, if the queue is full the node needs to be stored somewhere
    // until the task is woken up, and this presents a few annoying challenges.
    //
    // Instead, we'll use a Future that simply waits for there to be space
    // available and when that resolves immediate all the node to the queue.
    //
    // For multithreaded runtimes it is possible for a TOCTOU issue here so we
    // need to loop until the try_push() is successful.
    loop {
      // Attempt to push node onto queue.
      n = match self.try_push(n) {
        Ok(()) => break,
        Err(e) => match e {
          Error::Closed => return Err(Error::Closed),
          Error::WontFit(n) => n,
          Error::CantFit(n) => return Err(Error::CantFit(n))
        }
      };

      let fut = ReserveSpaceFuture {
        sh: Arc::clone(&self.sh),
        waiter: self.sh.tx_wakers.waiter(),
        n: &n
      };
      match fut.await {
        Ok(()) => {
          // fall through
        }

        Err(e) => match e {
          limq::CheckErr::WontFit => {
            // fall through
          }


          limq::CheckErr::CantFit => {
            return Err(Error::CantFit(n));

          }
        }
      }
    }

    // Have a new element in queue -- wake up waiting receivers
    self.sh.wake_receivers();

    Ok(())
  }

  /// Fallible sending.
  ///
  /// # Errors
  /// [`Error::CantFit`] means the [`Controller`] permanently rejected the
  /// node.  [`Error::WontFit`] means the [`Controller`] temporarily
  /// rejected the node.  [`Error::Closed`] means not
  /// [`Receiver`](super::Receiver)s remain.
  pub fn try_send(&self, n: T) -> Result<(), Error<T>> {
    let mut inner = self.sh.inner.lock();
    if inner.rx_count == 0 {
      return Err(Error::Closed);



    }
    inner.q.try_push(n)?;
    drop(inner);

    self.sh.wake_receivers();

    Ok(())
  }

  /// Forcibly add an element to the queue.
  ///
  /// If the queue has a limit and the queue is full, then the oldest node will
  /// be removed before the new element is added.
  ///
  /// # Errors
  /// [`Error::CantFit`] means the [`Controller`] rejected the node.
  /// [`Error::Closed`] means not [`Receiver`](super::Receiver)s remain.
  pub fn force_send(&self, n: T) -> Result<(), Error<T>> {
    let mut inner = self.sh.inner.lock();
    inner.q.force_push(n)?;

    drop(inner);

    // Have a new element in queue -- wake up a waiting receiver
    self.sh.wake_receivers();

    Ok(())
  }

  /// Forcibly add an element to rhe channel, allowing the caller to determine
  /// how overflow is handled.
  ///
  /// # Errors
  /// [`Error::CantFit`] means the [`Controller`] rejected the node.
  /// [`Error::Closed`] means not [`Receiver`](super::Receiver)s remain.
  pub fn force_send_oc(
    &self,
    n: T,
    overflow: Overflow
  ) -> Result<(), Error<T>> {
    let mut inner = self.sh.inner.lock();
    inner.q.force_push_oc(n, overflow)?;

    drop(inner);

    // Have a new element in queue -- wake up a waiting receiver
    self.sh.wake_receivers();

    Ok(())
  }
}

impl<C, T> Drop for Sender<C, T>
where
  C: Controller<Item = T>
{
  fn drop(&mut self) {
    let mut inner = self.sh.inner.lock();
    inner.tx_count -= 1;
    drop(inner);

    self.sh.wake_receivers();
  }
}


/// A [`Future`] that will resolve when the queue is not full.
struct ReserveSpaceFuture<'n, C, T>
where
  C: Controller<Item = T>,
  T: Send
{
  sh: Arc<Shared<C, T>>,
  waiter: Waiter,
  n: &'n T
}

impl<C, T> Future for ReserveSpaceFuture<'_, C, T>
where
  C: Controller<Item = T>,
  T: Send
{
  type Output = Result<(), limq::CheckErr>;
  fn poll(
    mut self: Pin<&mut Self>,
    ctx: &mut Context<'_>
  ) -> Poll<Self::Output> {
    let inner = self.sh.inner.lock();

    match inner.q.would_fit(self.n) {
      Ok(()) => Poll::Ready(Ok(())),
      Err(e) => match e {
        limq::CheckErr::WontFit => {
          drop(inner); // happy borrow-checker
          self.waiter.prime(ctx);
          Poll::Pending
        }

        limq::CheckErr::CantFit => Poll::Ready(Err(limq::CheckErr::CantFit))
      }
    }
  }
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

use std::thread;

use tokio::task;

use limq::OptLenLim;

use limqch::{Error, channel};


#[test]
fn try_send_full() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);
  tx.send_blocking(1).unwrap();
  tx.send_blocking(2).unwrap();
  assert_eq!(tx.try_send(3), Err(Error::WontFit(3)));

  assert_eq!(rx.recv_blocking().unwrap(), 1);
  assert_eq!(rx.try_recv().unwrap(), Some(2));
  assert_eq!(rx.try_recv().unwrap(), None);
}

#[tokio::test]
async fn try_on_full() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);
  tx.send_async(1).await.unwrap();
  tx.send_async(2).await.unwrap();
  assert_eq!(tx.try_send(3), Err(Error::WontFit(3)));

  assert_eq!(rx.recv_async().await.unwrap(), 1);
  assert_eq!(rx.try_recv().unwrap(), Some(2));
  assert_eq!(rx.try_recv().unwrap(), None);
}

#[tokio::test]
async fn send_from_spawned_task() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);

  task::spawn(async move {
    tx.send_async(1).await.unwrap();
  });

  assert_eq!(rx.recv_async().await.unwrap(), 1);
}

#[tokio::test]
async fn blocking_send_from_thread() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);

  thread::spawn(move || {
    tx.send_blocking(1).unwrap();
  });

  assert_eq!(rx.recv_blocking().unwrap(), 1);
}

#[tokio::test]
async fn task_to_task() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);

  task::spawn(async move {
    tx.send_async(1).await.unwrap();
  });

  task::spawn_blocking(move || {
    assert_eq!(rx.recv_blocking().unwrap(), 1);
  })
  .await
  .unwrap();
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

use limq::OptLenLim;

use limqch::{Error, channel};

// No receiver exists, so sending is pointless
#[test]
fn rx_closed_sync() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Drop the only receiver
  drop(rx);

  // Transmitter should now return Error::Closed
  let Err(Error::Closed) = tx.send_blocking(11) else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };

  let Err(Error::Closed) = tx.try_send(11) else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

// No receiver exists, so sending is pointless
#[tokio::test]
async fn rx_closed_async() {
  let lenlim = OptLenLim::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Drop the only receiver
  drop(rx);

  // Transmitter should now return Error::Closed
  let Err(Error::Closed) = tx.send_async(11).await else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

#[test]
fn tx_closed_empty_sync() {
  let lenlim = OptLenLim::<u32>::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Drop the only transmitter
  drop(tx);

  // Transmitter should now return Error::Closed, because the queue is empty
  // and there are no receivers.
  let Err(Error::Closed) = rx.recv_blocking() else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };

  let Err(Error::Closed) = rx.try_recv() else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

#[tokio::test]
async fn tx_closed_empty_async() {
  let lenlim = OptLenLim::<u32>::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Drop the only transmitter
  drop(tx);

  // Transmitter should now return Error::Closed, because the queue is empty
  // and there are no receivers.
  let Err(Error::Closed) = rx.recv_async().await else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

#[test]
fn tx_closed_nonempty_sync() {
  let lenlim = OptLenLim::<u32>::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Add two nodes
  tx.try_send(1).unwrap();
  tx.try_send(2).unwrap();

  // Drop the only transmitter
  drop(tx);

  // Should succeed
  let Ok(1) = rx.recv_blocking() else {
    panic!("Unexpectedly not Ok(Some(1))");
  };
  let Ok(Some(2)) = rx.try_recv() else {
    panic!("Unexpectedly not Ok(Some(2))");
  };

  // queue is now empty, so it should be returning Error::Closed
  let Err(Error::Closed) = rx.recv_blocking() else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };

  let Err(Error::Closed) = rx.try_recv() else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

#[tokio::test]
async fn tx_closed_nonempty_async() {
  let lenlim = OptLenLim::<u32>::new(Some(2));
  let (tx, rx) = channel(lenlim);

  // Add a node
  tx.try_send(1).unwrap();

  // Drop the only transmitter
  drop(tx);

  // Should succeed
  let Ok(1) = rx.recv_async().await else {
    panic!("Unexpectedly not Ok(Some(1))");
  };

  // queue is now empty, so it should be returning Error::Closed
  let Err(Error::Closed) = rx.recv_async().await else {
    panic!("Unexpectedly not Err(Error::Closed)");
  };
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

use limq::BufLim;

use limqch::channel;

#[test]
fn access_controller() {
  let lenlim = BufLim::new(None, None);
  let (tx, _rx) = channel(lenlim);

  let max_len = tx.ctrl().with_ctrl(BufLim::get_max_len);
  assert_eq!(max_len, None);

  let max_size = tx.ctrl().with_ctrl(BufLim::get_max_size);
  assert_eq!(max_size, None);

  tx.ctrl().with_ctrl_mut(|c| c.set_max_len(Some(2)));
  tx.ctrl().with_ctrl_mut(|c| c.set_max_size(Some(8)));

  let max_len = tx.ctrl().with_ctrl(BufLim::get_max_len);
  assert_eq!(max_len, Some(2));

  let max_size = tx.ctrl().with_ctrl(BufLim::get_max_size);
  assert_eq!(max_size, Some(8));
}

// vim: set ft=rust et sw=2 ts=2 sts=2 cinoptions=2 tw=79 :

# Change Log

⚠️  indicates a breaking change.

## [Unreleased]

[Details](/vdiff?from=limqch-0.2.0&to=trunk)

### Added

### Changed

### Removed

---

## [0.2.0] - 2025-04-11

[Details](/vdiff?from=limqch-0.1.0&to=limqch-0.2.0)

### Changed

-⚠️ Update for `limq` `0.3.0`.  Creating a limq channel now requires a
  `Controller` implementation.

### Removed

- `Spawner` was removed.

---

## [0.1.0] - 2025-04-01

Initial release.