//! Utilities for tracking time.
//!
//! This module provides a number of types for executing code after a set period
//! of time.
//!
//! * `Delay` is a future that does no work and completes at a specific `Instant`
//! in time.
//!
//! * `Interval` is a stream yielding a value at a fixed period. It is
//! initialized with a `Duration` and repeatedly yields each time the duration
//! elapses.
//!
//! * `Timeout`: Wraps a future or stream, setting an upper bound to the amount
//! of time it is allowed to execute. If the future or stream does not
//! complete in time, then it is canceled and an error is returned.
//!
//! * `DelayQueue`: A queue where items are returned once the requested delay
//! has expired.
//!
//! These types are sufficient for handling a large number of scenarios
//! involving time.
//!
//! These types must be used from within the context of the `Runtime`.
//!
//! # Examples
//!
//! Wait 100ms and print "Hello World!"
//!
//! ```
//! use tokio::time::delay_for;
//!
//! use std::time::Duration;
//!
//!
//! #[tokio::main]
//! async fn main() {
//! delay_for(Duration::from_millis(100)).await;
//! println!("100 ms have elapsed");
//! }
//! ```
//!
//! Require that an operation takes no more than 300ms. Note that this uses the
//! `timeout` function on the `FutureExt` trait. This trait is included in the
//! prelude.
//!
//! ```
//! use tokio::time::{timeout, Duration};
//!
//! async fn long_future() {
//! // do work here
//! }
//!
//! # async fn dox() {
//! let res = timeout(Duration::from_secs(1), long_future()).await;
//!
//! if res.is_err() {
//! println!("operation timed out");
//! }
//! # }
//! ```
pub use Clock;
pub use ;
pub use DelayQueue;
pub use ;
pub
pub use Error;
pub use Instant;
pub use ;
pub use ;
cfg_stream!
// Re-export for convenience
pub use Duration;
// ===== Internal utils =====
/// Convert a `Duration` to milliseconds, rounding up and saturating at
/// `u64::MAX`.
///
/// The saturating is fine because `u64::MAX` milliseconds are still many
/// million years.