hierarchical_hash_wheel_timer 1.4.0

A low-level timer implementation using a hierarchical four-level hash wheel with overflow.
Documentation 
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//! This module contains the level 1 and 2 APIs for building event timers.

use super::*;
use std::{
    cmp::Eq,
    convert::Infallible,
    fmt::Debug,
    hash::Hash,
    mem,
    rc::{Rc, Weak},
    time::Duration,
};

pub mod byte_wheel;
pub mod cancellable;
pub mod quad_wheel;

/// Result of a [can_skip](quad_wheel::QuadWheelWithOverflow::can_skip) invocation
#[derive(PartialEq, Debug)]
pub enum Skip {
    /// The wheel is completely empty, so there's no point in skipping
    ///
    /// In fact, this may be a good opportunity to reset the wheel, if the
    /// time semantics allow for that.
    Empty,
    /// It's possible to skip up to the provided number of ticks (in ms)
    Millis(u32),
    /// Nothing can be skipped, as the next tick has expiring timers
    None,
}

impl Skip {
    /// Provide a skip instance from ms
    ///
    /// A `ms` value of `0` will result in a `Skip::None`.
    pub fn from_millis(ms: u32) -> Skip {
        if ms == 0 {
            Skip::None
        } else {
            Skip::Millis(ms)
        }
    }

    /// A skip instance for empty wheels
    pub fn empty() -> Skip {
        Skip::Empty
    }
}

/// A trait for timer entries that store their delay along the with the state
pub trait TimerEntryWithDelay: Debug {
    /// Returns the time until the timeout is supposed to be triggered
    fn delay(&self) -> Duration;
}