oneshot

[0.1.13] - 2026-01-26

Fixed

• Fix documentation building on docs.rs by not using removed doc_auto_cfg feature.

Fixed:

• Fix race condition that could lead to use-after-free if the Receiver was polled asynchronously,
  but then dropped before completion. #74. RUSTSEC-2026-0005
• Fix race conditions/UB around atomic memory orderings. These were found by running tests under
  miri. #72

Fixed:

• Handle the UNPARKING state correctly in Receiver::drop(). Fixes a panic that could
  occur if a Receiver had been first polled as a future and then was being dropped
  in parallel with the Sender sending a message.

Added:

• Add is_closed and has_message to the Receiver. Allows polling for the channel
  state without modifying the channel or pulling the message from it.
• Make the cargo features show up on docs.rs for better discoverability.

Added:

• Implement Sync for Sender. There is not a whole lot someone can do with a &Sender,
  but this allows storing the sender in places that are overly conservative and require
  a Sync bound on the content.

• Change how loom concurrency testing is triggered. To get rid of loom in the dependency tree
  oneshot pulls in, it has in addition to being gated behind cfg(oneshot_loom) also been made
  an optional dependency. This makes this library way smaller for downstream consumers.
  This has the downside that the crate now exposes a loom feature.
  DOWNSTREAM USERS ARE NOT SUPPOSED TO EVER ENABLE THIS. No stability or semver
  guarantees exist around the loom feature.
  This change ultimately makes no difference for any user of oneshot in regular usage.

• Add is_closed method to the Sender.

Added

• Add into_raw and from_raw methods on both Sender and Receiver. Allows passing oneshot channels over FFI without an extra layer of heap allocation.

Fixed

• Handle the UNPARKING state correctly in all recv methods. try_recv will now not panic if used on a Receiver that is being unparked from an async wait. The other recv methods will still panic (as they should), but with a better error message.

Changed

• Upgrade to Rust edition 2021. Also increases the MSRV to Rust 1.60.
• Add null-pointer optimization to Sender, Receiver and SendError. This reduces the call stack size of Sender::send and it makes Option<Sender> and Option<Receiver> pointer sized (#18).
• Relax the memory ordering of all atomic operations from SeqCst to the most appropriate lower ordering (#17 + #20).

Fixed

• Fix undefined behavior due to multiple mutable references to the same channel instance (#18).
• Fix race condition that could happen during unparking of a receiving Receiver (#17 + #20).

Fixed

• Keep the last Waker in Future::poll, not the first one. Stops breaking the contract on how futures should work.

Fixed

• Fix unreachable code panic that happened if the Receiver of an empty but open channel was polled and then dropped.

Initial implementation. Supports basically all the (for now) intended functionality. Sender is as lock-free as I think it can get and the receiver can both do thread blocking and be awaited asynchronously. The receiver also has a wait-free try_recv method.

The crate has two features. They are activated by default, but the user can opt out of async support as well as usage of libstd (making the crate no_std but still requiring liballoc)

Name reserved on crate.io by someone other than the author of this crate.