68 lines
2.4 KiB
Markdown
68 lines
2.4 KiB
Markdown
# parking
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[](
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https://github.com/smol-rs/parking/actions)
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[](
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https://github.com/smol-rs/parking)
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[](
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https://crates.io/crates/parking)
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[](
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https://docs.rs/parking)
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Thread parking and unparking.
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A `Parker` is in either the notified or unnotified state. The `park()` method blocks
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the current thread until the `Parker` becomes notified and then puts it back into the unnotified
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state. The `unpark()` method puts it into the notified state.
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This API is similar to [`thread::park()`] and [`Thread::unpark()`] from the standard library.
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The difference is that the state "token" managed by those functions is shared across an entire
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thread, and anyone can call [`thread::current()`] to access it. If you use `park` and `unpark`,
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but you also call a function that uses `park` and `unpark` internally, that function could
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cause a deadlock by consuming a wakeup that was intended for you. The `Parker` object in this
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crate avoids that problem by managing its own state, which isn't shared with unrelated callers.
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[`thread::park()`]: https://doc.rust-lang.org/std/thread/fn.park.html
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[`Thread::unpark()`]: https://doc.rust-lang.org/std/thread/struct.Thread.html#method.unpark
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[`thread::current()`]: https://doc.rust-lang.org/std/thread/fn.current.html
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## Examples
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```rust
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use std::thread;
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use std::time::Duration;
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use parking::Parker;
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let p = Parker::new();
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let u = p.unparker();
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// Notify the parker.
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u.unpark();
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// Wakes up immediately because the parker is notified.
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p.park();
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thread::spawn(move || {
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thread::sleep(Duration::from_millis(500));
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u.unpark();
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});
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// Wakes up when `u.unpark()` notifies and then goes back into unnotified state.
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p.park();
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```
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## License
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Licensed under either of
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* Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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* MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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at your option.
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#### Contribution
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Unless you explicitly state otherwise, any contribution intentionally submitted
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for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
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dual licensed as above, without any additional terms or conditions.
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