Vendor things

third-party/vendor/crossbeam-channel/README.md

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+# Crossbeam Channel
+
+[![Build Status](https://github.com/crossbeam-rs/crossbeam/workflows/CI/badge.svg)](
+https://github.com/crossbeam-rs/crossbeam/actions)
+[![License](https://img.shields.io/badge/license-MIT_OR_Apache--2.0-blue.svg)](
+https://github.com/crossbeam-rs/crossbeam/tree/master/crossbeam-channel#license)
+[![Cargo](https://img.shields.io/crates/v/crossbeam-channel.svg)](
+https://crates.io/crates/crossbeam-channel)
+[![Documentation](https://docs.rs/crossbeam-channel/badge.svg)](
+https://docs.rs/crossbeam-channel)
+[![Rust 1.60+](https://img.shields.io/badge/rust-1.60+-lightgray.svg)](
+https://www.rust-lang.org)
+[![chat](https://img.shields.io/discord/569610676205781012.svg?logo=discord)](https://discord.com/invite/JXYwgWZ)
+
+This crate provides multi-producer multi-consumer channels for message passing.
+It is an alternative to [`std::sync::mpsc`] with more features and better performance.
+
+Some highlights:
+
+* [`Sender`]s and [`Receiver`]s can be cloned and shared among threads.
+* Two main kinds of channels are [`bounded`] and [`unbounded`].
+* Convenient extra channels like [`after`], [`never`], and [`tick`].
+* The [`select!`] macro can block on multiple channel operations.
+* [`Select`] can select over a dynamically built list of channel operations.
+* Channels use locks very sparingly for maximum [performance](benchmarks).
+
+[`std::sync::mpsc`]: https://doc.rust-lang.org/std/sync/mpsc/index.html
+[`Sender`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/struct.Sender.html
+[`Receiver`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/struct.Receiver.html
+[`bounded`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/fn.bounded.html
+[`unbounded`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/fn.unbounded.html
+[`after`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/fn.after.html
+[`never`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/fn.never.html
+[`tick`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/fn.tick.html
+[`select!`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/macro.select.html
+[`Select`]: https://docs.rs/crossbeam-channel/*/crossbeam_channel/struct.Select.html
+
+## Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+crossbeam-channel = "0.5"
+```
+
+## Compatibility
+
+Crossbeam Channel supports stable Rust releases going back at least six months,
+and every time the minimum supported Rust version is increased, a new minor
+version is released. Currently, the minimum supported Rust version is 1.60.
+
+## License
+
+Licensed under either of
+
+ * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+#### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.
+
+#### Third party software
+
+This product includes copies and modifications of software developed by third parties:
+
+* [examples/matching.rs](examples/matching.rs) includes
+  [matching.go](http://www.nada.kth.se/~snilsson/concurrency/src/matching.go) by Stefan Nilsson,
+  licensed under Creative Commons Attribution 3.0 Unported License.
+
+* [tests/mpsc.rs](tests/mpsc.rs) includes modifications of code from The Rust Programming Language,
+  licensed under the MIT License and the Apache License, Version 2.0.
+
+* [tests/golang.rs](tests/golang.rs) is based on code from The Go Programming Language, licensed
+  under the 3-Clause BSD License.
+
+See the source code files for more details.
+
+Copies of third party licenses can be found in [LICENSE-THIRD-PARTY](LICENSE-THIRD-PARTY).