mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-08-17 00:00:11 +02:00
Zahari Dichev
12546d1d9c
Reset the delay of the queue in case an item that expires sooner than the last inserted is put into the queue.
854 lines
25 KiB
Rust
854 lines
25 KiB
Rust
//! A queue of delayed elements.
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//!
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//! See [`DelayQueue`] for more details.
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//!
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//! [`DelayQueue`]: struct.DelayQueue.html
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use {Error, Delay};
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use clock::now;
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use wheel::{self, Wheel};
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use timer::Handle;
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use futures::{Future, Stream, Poll};
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use slab::Slab;
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use std::cmp;
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use std::marker::PhantomData;
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use std::time::{Duration, Instant};
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/// A queue of delayed elements.
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///
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/// Once an element is inserted into the `DelayQueue`, it is yielded once the
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/// specified deadline has been reached.
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///
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/// # Usage
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///
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/// Elements are inserted into `DelayQueue` using the [`insert`] or
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/// [`insert_at`] methods. A deadline is provided with the item and a [`Key`] is
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/// returned. The key is used to remove the entry or to change the deadline at
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/// which it should be yielded back.
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///
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/// Once delays have been configured, the `DelayQueue` is used via its
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/// [`Stream`] implementation. [`poll`] is called. If an entry has reached its
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/// deadline, it is returned. If not, `Async::NotReady` indicating that the
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/// current task will be notified once the deadline has been reached.
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///
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/// # `Stream` implementation
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///
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/// Items are retrieved from the queue via [`Stream::poll`]. If no delays have
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/// expired, no items are returned. In this case, `NotReady` is returned and the
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/// current task is registered to be notified once the next item's delay has
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/// expired.
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///
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/// If no items are in the queue, i.e. `is_empty()` returns `true`, then `poll`
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/// returns `Ready(None)`. This indicates that the stream has reached an end.
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/// However, if a new item is inserted *after*, `poll` will once again start
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/// returning items or `NotReady.
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///
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/// Items are returned ordered by their expirations. Items that are configured
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/// to expire first will be returned first. There are no ordering guarantees
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/// for items configured to expire the same instant. Also note that delays are
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/// rounded to the closest millisecond.
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///
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/// # Implementation
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///
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/// The `DelayQueue` is backed by the same hashed timing wheel implementation as
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/// [`Timer`] as such, it offers the same performance benefits. See [`Timer`]
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/// for further implementation notes.
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///
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/// State associated with each entry is stored in a [`slab`]. This allows
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/// amortizing the cost of allocation. Space created for expired entries is
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/// reused when inserting new entries.
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///
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/// Capacity can be checked using [`capacity`] and allocated preemptively by using
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/// the [`reserve`] method.
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///
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/// # Usage
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///
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/// Using `DelayQueue` to manage cache entries.
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///
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/// ```rust
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/// #[macro_use]
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/// extern crate futures;
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/// extern crate tokio;
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/// # type CacheKey = String;
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/// # type Value = String;
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/// use tokio::timer::{delay_queue, DelayQueue, Error};
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/// use futures::{Async, Poll, Stream};
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/// use std::collections::HashMap;
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/// use std::time::Duration;
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///
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/// struct Cache {
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/// entries: HashMap<CacheKey, (Value, delay_queue::Key)>,
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/// expirations: DelayQueue<CacheKey>,
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/// }
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///
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/// const TTL_SECS: u64 = 30;
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///
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/// impl Cache {
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/// fn insert(&mut self, key: CacheKey, value: Value) {
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/// let delay = self.expirations
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/// .insert(key.clone(), Duration::from_secs(TTL_SECS));
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///
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/// self.entries.insert(key, (value, delay));
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/// }
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///
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/// fn get(&self, key: &CacheKey) -> Option<&Value> {
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/// self.entries.get(key)
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/// .map(|&(ref v, _)| v)
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/// }
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///
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/// fn remove(&mut self, key: &CacheKey) {
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/// if let Some((_, cache_key)) = self.entries.remove(key) {
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/// self.expirations.remove(&cache_key);
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/// }
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/// }
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///
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/// fn poll_purge(&mut self) -> Poll<(), Error> {
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/// while let Some(entry) = try_ready!(self.expirations.poll()) {
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/// self.entries.remove(entry.get_ref());
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/// }
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///
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/// Ok(Async::Ready(()))
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/// }
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/// }
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/// # fn main() {}
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/// ```
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///
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/// [`insert`]: #method.insert
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/// [`insert_at`]: #method.insert_at
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/// [`Key`]: struct.Key.html
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/// [`Stream`]: https://docs.rs/futures/0.1/futures/stream/trait.Stream.html
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/// [`poll`]: #method.poll
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/// [`Stream::poll`]: #method.poll
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/// [`Timer`]: ../struct.Timer.html
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/// [`slab`]: https://docs.rs/slab
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/// [`capacity`]: #method.capacity
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/// [`reserve`]: #method.reserve
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#[derive(Debug)]
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pub struct DelayQueue<T> {
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/// Handle to the timer driving the `DelayQueue`
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handle: Handle,
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/// Stores data associated with entries
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slab: Slab<Data<T>>,
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/// Lookup structure tracking all delays in the queue
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wheel: Wheel<Stack<T>>,
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/// Delays that were inserted when already expired. These cannot be stored
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/// in the wheel
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expired: Stack<T>,
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/// Delay expiring when the *first* item in the queue expires
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delay: Option<Delay>,
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/// Wheel polling state
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poll: wheel::Poll,
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/// Instant at which the timer starts
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start: Instant,
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}
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/// An entry in `DelayQueue` that has expired and removed.
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///
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/// Values are returned by [`DelayQueue::poll`].
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///
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/// [`DelayQueue::poll`]: struct.DelayQueue.html#method.poll
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#[derive(Debug)]
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pub struct Expired<T> {
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/// The data stored in the queue
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data: T,
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/// The expiration time
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deadline: Instant,
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/// The key associated with the entry
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key: Key,
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}
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/// Token to a value stored in a `DelayQueue`.
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///
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/// Instances of `Key` are returned by [`DelayQueue::insert`]. See [`DelayQueue`]
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/// documentation for more details.
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///
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/// [`DelayQueue`]: struct.DelayQueue.html
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/// [`DelayQueue::insert`]: struct.DelayQueue.html#method.insert
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#[derive(Debug, Clone)]
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pub struct Key {
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index: usize,
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}
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#[derive(Debug)]
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struct Stack<T> {
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/// Head of the stack
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head: Option<usize>,
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_p: PhantomData<T>,
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}
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#[derive(Debug)]
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struct Data<T> {
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/// The data being stored in the queue and will be returned at the requested
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/// instant.
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inner: T,
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/// The instant at which the item is returned.
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when: u64,
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/// Set to true when stored in the `expired` queue
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expired: bool,
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/// Next entry in the stack
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next: Option<usize>,
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/// Previous entry in the stack
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prev: Option<usize>,
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}
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/// Maximum number of entries the queue can handle
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const MAX_ENTRIES: usize = (1 << 30) - 1;
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impl<T> DelayQueue<T> {
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/// Create a new, empty, `DelayQueue`
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///
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/// The queue will not allocate storage until items are inserted into it.
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///
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/// # Examples
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///
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/// ```rust
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/// # use tokio_timer::DelayQueue;
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/// let delay_queue: DelayQueue<u32> = DelayQueue::new();
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/// ```
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pub fn new() -> DelayQueue<T> {
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DelayQueue::with_capacity(0)
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}
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/// Create a new, empty, `DelayQueue` backed by the specified timer.
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///
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/// The queue will not allocate storage until items are inserted into it.
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// # use tokio_timer::DelayQueue;
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/// use tokio_timer::timer::Handle;
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///
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/// let handle = Handle::default();
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/// let delay_queue: DelayQueue<u32> = DelayQueue::with_capacity_and_handle(0, &handle);
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/// ```
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pub fn with_capacity_and_handle(capacity: usize, handle: &Handle) -> DelayQueue<T> {
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DelayQueue {
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handle: handle.clone(),
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wheel: Wheel::new(),
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slab: Slab::with_capacity(capacity),
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expired: Stack::default(),
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delay: None,
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poll: wheel::Poll::new(0),
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start: now(),
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}
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}
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/// Create a new, empty, `DelayQueue` with the specified capacity.
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///
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/// The queue will be able to hold at least `capacity` elements without
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/// reallocating. If `capacity` is 0, the queue will not allocate for
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/// storage.
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///
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/// # Examples
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///
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/// ```rust
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/// # use tokio_timer::DelayQueue;
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/// # use std::time::Duration;
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/// let mut delay_queue = DelayQueue::with_capacity(10);
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///
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/// // These insertions are done without further allocation
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/// for i in 0..10 {
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/// delay_queue.insert(i, Duration::from_secs(i));
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/// }
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///
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/// // This will make the queue allocate additional storage
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/// delay_queue.insert(11, Duration::from_secs(11));
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/// ```
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pub fn with_capacity(capacity: usize) -> DelayQueue<T> {
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DelayQueue::with_capacity_and_handle(capacity, &Handle::default())
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}
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/// Insert `value` into the queue set to expire at a specific instant in
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/// time.
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///
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/// This function is identical to `insert`, but takes an `Instant` instead
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/// of a `Duration`.
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///
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/// `value` is stored in the queue until `when` is reached. At which point,
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/// `value` will be returned from [`poll`]. If `when` has already been
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/// reached, then `value` is immediately made available to poll.
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///
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/// The return value represents the insertion and is used at an argument to
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/// [`remove`] and [`reset`]. Note that [`Key`] is token and is reused once
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/// `value` is removed from the queue either by calling [`poll`] after
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/// `when` is reached or by calling [`remove`]. At this point, the caller
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/// must take care to not use the returned [`Key`] again as it may reference
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/// a different item in the queue.
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///
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/// See [type] level documentation for more details.
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///
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/// # Panics
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///
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/// This function panics if `when` is too far in the future.
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///
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/// # Examples
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///
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/// Basic usage
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///
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/// ```rust
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/// # extern crate tokio;
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/// use tokio::timer::DelayQueue;
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/// use std::time::{Instant, Duration};
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///
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/// # fn main() {
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/// let mut delay_queue = DelayQueue::new();
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/// let key = delay_queue.insert_at(
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/// "foo", Instant::now() + Duration::from_secs(5));
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///
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/// // Remove the entry
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/// let item = delay_queue.remove(&key);
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/// assert_eq!(*item.get_ref(), "foo");
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/// # }
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/// ```
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///
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/// [`poll`]: #method.poll
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/// [`remove`]: #method.remove
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/// [`reset`]: #method.reset
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/// [`Key`]: struct.Key.html
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/// [type]: #
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pub fn insert_at(&mut self, value: T, when: Instant) -> Key {
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assert!(self.slab.len() < MAX_ENTRIES, "max entries exceeded");
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// Normalize the deadline. Values cannot be set to expire in the past.
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let when = self.normalize_deadline(when);
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// Insert the value in the store
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let key = self.slab.insert(Data {
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inner: value,
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when,
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expired: false,
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next: None,
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prev: None,
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});
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self.insert_idx(when, key);
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// Set a new delay if the current's deadline is later than the one of the new item
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let should_set_delay = if let Some(ref delay) = self.delay {
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let current_exp = self.normalize_deadline(delay.deadline());
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current_exp > when
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} else { false };
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if should_set_delay {
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self.delay = Some(self.handle.delay(self.start + Duration::from_millis(when)));
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}
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Key::new(key)
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}
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/// Insert `value` into the queue set to expire after the requested duration
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/// elapses.
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///
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/// This function is identical to `insert_at`, but takes a `Duration`
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/// instead of an `Instant`.
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///
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/// `value` is stored in the queue until `when` is reached. At which point,
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/// `value` will be returned from [`poll`]. If `when` has already been
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/// reached, then `value` is immediately made available to poll.
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///
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/// The return value represents the insertion and is used at an argument to
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/// [`remove`] and [`reset`]. Note that [`Key`] is token and is reused once
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/// `value` is removed from the queue either by calling [`poll`] after
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/// `when` is reached or by calling [`remove`]. At this point, the caller
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/// must take care to not use the returned [`Key`] again as it may reference
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/// a different item in the queue.
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///
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/// See [type] level documentation for more details.
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///
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/// # Panics
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///
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/// This function panics if `timeout` is greater than the maximum supported
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/// duration.
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///
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/// # Examples
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///
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/// Basic usage
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///
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/// ```rust
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/// # extern crate tokio;
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/// use tokio::timer::DelayQueue;
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/// use std::time::Duration;
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///
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/// # fn main() {
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/// let mut delay_queue = DelayQueue::new();
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/// let key = delay_queue.insert("foo", Duration::from_secs(5));
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///
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/// // Remove the entry
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/// let item = delay_queue.remove(&key);
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/// assert_eq!(*item.get_ref(), "foo");
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/// # }
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/// ```
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///
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/// [`poll`]: #method.poll
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/// [`remove`]: #method.remove
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/// [`reset`]: #method.reset
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/// [`Key`]: struct.Key.html
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/// [type]: #
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pub fn insert(&mut self, value: T, timeout: Duration) -> Key {
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self.insert_at(value, now() + timeout)
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}
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fn insert_idx(&mut self, when: u64, key: usize) {
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use self::wheel::{InsertError, Stack};
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// Register the deadline with the timer wheel
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match self.wheel.insert(when, key, &mut self.slab) {
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Ok(_) => {}
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Err((_, InsertError::Elapsed)) => {
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self.slab[key].expired = true;
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// The delay is already expired, store it in the expired queue
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self.expired.push(key, &mut self.slab);
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}
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Err((_, err)) => {
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panic!("invalid deadline; err={:?}", err)
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}
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}
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}
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/// Remove the item associated with `key` from the queue.
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///
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/// There must be an item associated with `key`. The function returns the
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/// removed item as well as the `Instant` at which it will the delay will
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/// have expired.
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///
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/// # Panics
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///
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/// The function panics if `key` is not contained by the queue.
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///
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/// # Examples
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///
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/// Basic usage
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///
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/// ```rust
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/// # extern crate tokio;
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/// use tokio::timer::DelayQueue;
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/// use std::time::Duration;
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///
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/// # fn main() {
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/// let mut delay_queue = DelayQueue::new();
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/// let key = delay_queue.insert("foo", Duration::from_secs(5));
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///
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/// // Remove the entry
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/// let item = delay_queue.remove(&key);
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/// assert_eq!(*item.get_ref(), "foo");
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/// # }
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/// ```
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pub fn remove(&mut self, key: &Key) -> Expired<T> {
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use wheel::Stack;
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// Special case the `expired` queue
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if self.slab[key.index].expired {
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self.expired.remove(&key.index, &mut self.slab);
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} else {
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self.wheel.remove(&key.index, &mut self.slab);
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}
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let data = self.slab.remove(key.index);
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Expired {
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key: Key::new(key.index),
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data: data.inner,
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deadline: self.start + Duration::from_millis(data.when),
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}
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}
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/// Sets the delay of the item associated with `key` to expire at `when`.
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///
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/// This function is identical to `reset` but takes an `Instant` instead of
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/// a `Duration`.
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///
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/// The item remains in the queue but the delay is set to expire at `when`.
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/// If `when` is in the past, then the item is immediately made available to
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/// the caller.
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///
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/// # Panics
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///
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/// This function panics if `when` is too far in the future or if `key` is
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/// not contained by the queue.
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///
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/// # Examples
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///
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/// Basic usage
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///
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/// ```rust
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/// # extern crate tokio;
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/// use tokio::timer::DelayQueue;
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/// use std::time::{Duration, Instant};
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///
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/// # fn main() {
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/// let mut delay_queue = DelayQueue::new();
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/// let key = delay_queue.insert("foo", Duration::from_secs(5));
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///
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/// // "foo" is scheduled to be returned in 5 seconds
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///
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/// delay_queue.reset_at(&key, Instant::now() + Duration::from_secs(10));
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///
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/// // "foo"is now scheduled to be returned in 10 seconds
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/// # }
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/// ```
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pub fn reset_at(&mut self, key: &Key, when: Instant) {
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self.wheel.remove(&key.index, &mut self.slab);
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// Normalize the deadline. Values cannot be set to expire in the past.
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let when = self.normalize_deadline(when);
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// This is needed only for the debug assertion inside the if-let.
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let old = self.start + Duration::from_millis(self.slab[key.index].when);
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self.slab[key.index].when = when;
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if let Some(ref mut delay) = self.delay {
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debug_assert!(old >= delay.deadline());
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let start = self.start;
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let next_poll = self.wheel.poll_at()
|
|
.map(move |t| start + Duration::from_millis(t));
|
|
|
|
if next_poll != Some(delay.deadline()) {
|
|
delay.reset(self.start + Duration::from_millis(when));
|
|
}
|
|
}
|
|
|
|
self.insert_idx(when, key.index);
|
|
}
|
|
|
|
/// Sets the delay of the item associated with `key` to expire after
|
|
/// `timeout`.
|
|
///
|
|
/// This function is identical to `reset_at` but takes a `Duration` instead
|
|
/// of an `Instant`.
|
|
///
|
|
/// The item remains in the queue but the delay is set to expire after
|
|
/// `timeout`. If `timeout` is zero, then the item is immediately made
|
|
/// available to the caller.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// This function panics if `timeout` is greater than the maximum supported
|
|
/// duration or if `key` is not contained by the queue.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// Basic usage
|
|
///
|
|
/// ```rust
|
|
/// # extern crate tokio;
|
|
/// use tokio::timer::DelayQueue;
|
|
/// use std::time::Duration;
|
|
///
|
|
/// # fn main() {
|
|
/// let mut delay_queue = DelayQueue::new();
|
|
/// let key = delay_queue.insert("foo", Duration::from_secs(5));
|
|
///
|
|
/// // "foo" is scheduled to be returned in 5 seconds
|
|
///
|
|
/// delay_queue.reset(&key, Duration::from_secs(10));
|
|
///
|
|
/// // "foo"is now scheduled to be returned in 10 seconds
|
|
/// # }
|
|
/// ```
|
|
pub fn reset(&mut self, key: &Key, timeout: Duration) {
|
|
self.reset_at(key, now() + timeout);
|
|
}
|
|
|
|
/// Clears the queue, removing all items.
|
|
///
|
|
/// After calling `clear`, [`poll`] will return `Ok(Ready(None))`.
|
|
///
|
|
/// Note that this method has no effect on the allocated capacity.
|
|
///
|
|
/// [`poll`]: #method.poll
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```rust
|
|
/// # extern crate tokio;
|
|
/// use tokio::timer::DelayQueue;
|
|
/// use std::time::Duration;
|
|
///
|
|
/// # fn main() {
|
|
/// let mut delay_queue = DelayQueue::new();
|
|
///
|
|
/// delay_queue.insert("foo", Duration::from_secs(5));
|
|
///
|
|
/// assert!(!delay_queue.is_empty());
|
|
///
|
|
/// delay_queue.clear();
|
|
///
|
|
/// assert!(delay_queue.is_empty());
|
|
/// # }
|
|
/// ```
|
|
pub fn clear(&mut self) {
|
|
self.slab.clear();
|
|
self.expired = Stack::default();
|
|
self.wheel = Wheel::new();
|
|
self.delay = None;
|
|
}
|
|
|
|
/// Returns the number of elements the queue can hold without reallocating.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```rust
|
|
/// # use tokio_timer::DelayQueue;
|
|
/// let delay_queue: DelayQueue<i32> = DelayQueue::with_capacity(10);
|
|
/// assert_eq!(delay_queue.capacity(), 10);
|
|
/// ```
|
|
pub fn capacity(&self) -> usize {
|
|
self.slab.capacity()
|
|
}
|
|
|
|
/// Reserve capacity for at least `additional` more items to be queued
|
|
/// without allocating.
|
|
///
|
|
/// `reserve` does nothing if the queue already has sufficient capacity for
|
|
/// `additional` more values. If more capacity is required, a new segment of
|
|
/// memory will be allocated and all existing values will be copied into it.
|
|
/// As such, if the queue is already very large, a call to `reserve` can end
|
|
/// up being expensive.
|
|
///
|
|
/// The queue may reserve more than `additional` extra space in order to
|
|
/// avoid frequent reallocations.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the new capacity exceeds the maximum number of entries the
|
|
/// queue can contain.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # use tokio_timer::DelayQueue;
|
|
/// # use std::time::Duration;
|
|
/// let mut delay_queue = DelayQueue::new();
|
|
/// delay_queue.insert("hello", Duration::from_secs(10));
|
|
/// delay_queue.reserve(10);
|
|
/// assert!(delay_queue.capacity() >= 11);
|
|
/// ```
|
|
pub fn reserve(&mut self, additional: usize) {
|
|
self.slab.reserve(additional);
|
|
}
|
|
|
|
/// Returns `true` if there are no items in the queue.
|
|
///
|
|
/// Note that this function returns `false` even if all items have not yet
|
|
/// expired and a call to `poll` will return `NotReady`.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # use tokio_timer::DelayQueue;
|
|
/// use std::time::Duration;
|
|
/// let mut delay_queue = DelayQueue::new();
|
|
/// assert!(delay_queue.is_empty());
|
|
///
|
|
/// delay_queue.insert("hello", Duration::from_secs(5));
|
|
/// assert!(!delay_queue.is_empty());
|
|
/// ```
|
|
pub fn is_empty(&self) -> bool {
|
|
self.slab.is_empty()
|
|
}
|
|
|
|
/// Polls the queue, returning the index of the next slot in the slab that
|
|
/// should be returned.
|
|
///
|
|
/// A slot should be returned when the associated deadline has been reached.
|
|
fn poll_idx(&mut self) -> Poll<Option<usize>, Error> {
|
|
use self::wheel::Stack;
|
|
|
|
let expired = self.expired.pop(&mut self.slab);
|
|
|
|
if expired.is_some() {
|
|
return Ok(expired.into());
|
|
}
|
|
|
|
loop {
|
|
if let Some(ref mut delay) = self.delay {
|
|
if !delay.is_elapsed() {
|
|
try_ready!(delay.poll());
|
|
}
|
|
|
|
let now = ::ms(delay.deadline() - self.start, ::Round::Down);
|
|
|
|
self.poll = wheel::Poll::new(now);
|
|
}
|
|
|
|
self.delay = None;
|
|
|
|
if let Some(idx) = self.wheel.poll(&mut self.poll, &mut self.slab) {
|
|
return Ok(Some(idx).into());
|
|
}
|
|
|
|
let deadline = match self.wheel.poll_at() {
|
|
Some(poll_at) => {
|
|
self.start + Duration::from_millis(poll_at)
|
|
}
|
|
None => return Ok(None.into()),
|
|
};
|
|
|
|
self.delay = Some(self.handle.delay(deadline));
|
|
}
|
|
}
|
|
|
|
fn normalize_deadline(&self, when: Instant) -> u64 {
|
|
let when = if when < self.start {
|
|
0
|
|
} else {
|
|
::ms(when - self.start, ::Round::Up)
|
|
};
|
|
|
|
cmp::max(when, self.wheel.elapsed())
|
|
}
|
|
}
|
|
|
|
impl<T> Stream for DelayQueue<T> {
|
|
type Item = Expired<T>;
|
|
type Error = Error;
|
|
|
|
fn poll(&mut self) -> Poll<Option<Self::Item>, Error> {
|
|
let item = try_ready!(self.poll_idx())
|
|
.map(|idx| {
|
|
let data = self.slab.remove(idx);
|
|
debug_assert!(data.next.is_none());
|
|
debug_assert!(data.prev.is_none());
|
|
|
|
Expired {
|
|
key: Key::new(idx),
|
|
data: data.inner,
|
|
deadline: self.start + Duration::from_millis(data.when),
|
|
}
|
|
});
|
|
|
|
Ok(item.into())
|
|
}
|
|
}
|
|
|
|
impl<T> wheel::Stack for Stack<T> {
|
|
type Owned = usize;
|
|
type Borrowed = usize;
|
|
type Store = Slab<Data<T>>;
|
|
|
|
fn is_empty(&self) -> bool {
|
|
self.head.is_none()
|
|
}
|
|
|
|
fn push(&mut self, item: Self::Owned, store: &mut Self::Store) {
|
|
// Ensure the entry is not already in a stack.
|
|
debug_assert!(store[item].next.is_none());
|
|
debug_assert!(store[item].prev.is_none());
|
|
|
|
// Remove the old head entry
|
|
let old = self.head.take();
|
|
|
|
if let Some(idx) = old {
|
|
store[idx].prev = Some(item);
|
|
}
|
|
|
|
store[item].next = old;
|
|
self.head = Some(item)
|
|
}
|
|
|
|
fn pop(&mut self, store: &mut Self::Store) -> Option<Self::Owned> {
|
|
if let Some(idx) = self.head {
|
|
self.head = store[idx].next;
|
|
|
|
if let Some(idx) = self.head {
|
|
store[idx].prev = None;
|
|
}
|
|
|
|
store[idx].next = None;
|
|
debug_assert!(store[idx].prev.is_none());
|
|
|
|
Some(idx)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
fn remove(&mut self, item: &Self::Borrowed, store: &mut Self::Store) {
|
|
assert!(store.contains(*item));
|
|
|
|
// Ensure that the entry is in fact contained by the stack
|
|
debug_assert!({
|
|
// This walks the full linked list even if an entry is found.
|
|
let mut next = self.head;
|
|
let mut contains = false;
|
|
|
|
while let Some(idx) = next {
|
|
if idx == *item {
|
|
debug_assert!(!contains);
|
|
contains = true;
|
|
}
|
|
|
|
next = store[idx].next;
|
|
}
|
|
|
|
contains
|
|
});
|
|
|
|
if let Some(next) = store[*item].next {
|
|
store[next].prev = store[*item].prev;
|
|
}
|
|
|
|
if let Some(prev) = store[*item].prev {
|
|
store[prev].next = store[*item].next;
|
|
} else {
|
|
self.head = store[*item].next;
|
|
}
|
|
|
|
store[*item].next = None;
|
|
store[*item].prev = None;
|
|
}
|
|
|
|
fn when(item: &Self::Borrowed, store: &Self::Store) -> u64 {
|
|
store[*item].when
|
|
}
|
|
}
|
|
|
|
impl<T> Default for Stack<T> {
|
|
fn default() -> Stack<T> {
|
|
Stack {
|
|
head: None,
|
|
_p: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Key {
|
|
pub(crate) fn new(index: usize) -> Key {
|
|
Key { index }
|
|
}
|
|
}
|
|
|
|
impl<T> Expired<T> {
|
|
/// Returns a reference to the inner value.
|
|
pub fn get_ref(&self) -> &T {
|
|
&self.data
|
|
}
|
|
|
|
/// Returns a mutable reference to the inner value.
|
|
pub fn get_mut(&mut self) -> &mut T {
|
|
&mut self.data
|
|
}
|
|
|
|
/// Consumes `self` and returns the inner value.
|
|
pub fn into_inner(self) -> T {
|
|
self.data
|
|
}
|
|
}
|