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// Copyright 2020 Pierre Krieger // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the "Software"), // to deal in the Software without restriction, including without limitation // the rights to use, copy, modify, merge, publish, distribute, sublicense, // and/or sell copies of the Software, and to permit persons to whom the // Software is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // DEALINGS IN THE SOFTWARE. use std::time::{Duration, Instant}; /// Returns the number of nanoseconds that have elapsed between `time` and the first time this /// function has been called in the program ever. /// /// Note that, consequently, keep in mind that the value of `diff` in the following code will /// be 0: /// /// ```ignore /// let before = Instant::now(); /// thread::sleep(Duration::from_secs(5)); /// let after = Instant::now(); /// /// let bef_ns = elapsed_since_abs_time(before); /// let after_ns = elapsed_since_abs_time(after); /// let diff = after_ns - bef_ns; /// assert_eq!(diff, 0); /// ``` /// /// To remedy this, please call `elapsed_since_abs_time` as soon as possible. pub(crate) fn elapsed_since_abs_time(time: Instant) -> u64 { lazy_static::lazy_static! { static ref REF_INSTANT: Instant = Instant::now(); } let ref_instant = *REF_INSTANT; let dur = if time > ref_instant { time - ref_instant } else { Duration::new(0, 0) }; dur.as_secs() .saturating_mul(1_000_000_000) .saturating_add(u64::from(dur.subsec_nanos())) } /// Shortcut for `elapsed_since_abs_time(Instant::now())`. pub(crate) fn now_since_abs_time() -> u64 { elapsed_since_abs_time(Instant::now()) }