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</pre><pre class="rust ">
<span class="comment">// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="doccomment">//! Temporal quantification.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Example:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! use std::time::Duration;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let five_seconds = Duration::new(5, 0);</span>
<span class="doccomment">//! // both declarations are equivalent</span>
<span class="doccomment">//! assert_eq!(Duration::new(5, 0), Duration::from_secs(5));</span>
<span class="doccomment">//! ```</span>
<span class="attribute">#![<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.3.0"</span>)]</span>
<span class="kw">use</span> <span class="ident">error</span>::<span class="ident">Error</span>;
<span class="kw">use</span> <span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">ops</span>::{<span class="ident">Add</span>, <span class="ident">Sub</span>, <span class="ident">AddAssign</span>, <span class="ident">SubAssign</span>};
<span class="kw">use</span> <span class="ident">sys</span>::<span class="ident">time</span>;
<span class="kw">use</span> <span class="ident">sys_common</span>::<span class="ident">FromInner</span>;
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.3.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">core</span>::<span class="ident">time</span>::<span class="ident">Duration</span>;
<span class="doccomment">/// A measurement of a monotonically nondecreasing clock.</span>
<span class="doccomment">/// Opaque and useful only with `Duration`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Instants are always guaranteed to be no less than any previously measured</span>
<span class="doccomment">/// instant when created, and are often useful for tasks such as measuring</span>
<span class="doccomment">/// benchmarks or timing how long an operation takes.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Note, however, that instants are not guaranteed to be **steady**. In other</span>
<span class="doccomment">/// words, each tick of the underlying clock may not be the same length (e.g.</span>
<span class="doccomment">/// some seconds may be longer than others). An instant may jump forwards or</span>
<span class="doccomment">/// experience time dilation (slow down or speed up), but it will never go</span>
<span class="doccomment">/// backwards.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Instants are opaque types that can only be compared to one another. There is</span>
<span class="doccomment">/// no method to get "the number of seconds" from an instant. Instead, it only</span>
<span class="doccomment">/// allows measuring the duration between two instants (or comparing two</span>
<span class="doccomment">/// instants).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The size of an `Instant` struct may vary depending on the target operating</span>
<span class="doccomment">/// system.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Example:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::time::{Duration, Instant};</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn main() {</span>
<span class="doccomment">/// let now = Instant::now();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // we sleep for 2 seconds</span>
<span class="doccomment">/// sleep(Duration::new(2, 0));</span>
<span class="doccomment">/// // it prints '2'</span>
<span class="doccomment">/// println!("{}", now.elapsed().as_secs());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">PartialOrd</span>, <span class="ident">Ord</span>, <span class="ident">Hash</span>)]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Instant</span>(<span class="ident">time</span>::<span class="ident">Instant</span>);
<span class="doccomment">/// A measurement of the system clock, useful for talking to</span>
<span class="doccomment">/// external entities like the file system or other processes.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Distinct from the [`Instant`] type, this time measurement **is not</span>
<span class="doccomment">/// monotonic**. This means that you can save a file to the file system, then</span>
<span class="doccomment">/// save another file to the file system, **and the second file has a</span>
<span class="doccomment">/// `SystemTime` measurement earlier than the first**. In other words, an</span>
<span class="doccomment">/// operation that happens after another operation in real time may have an</span>
<span class="doccomment">/// earlier `SystemTime`!</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Consequently, comparing two `SystemTime` instances to learn about the</span>
<span class="doccomment">/// duration between them returns a [`Result`] instead of an infallible [`Duration`]</span>
<span class="doccomment">/// to indicate that this sort of time drift may happen and needs to be handled.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Although a `SystemTime` cannot be directly inspected, the [`UNIX_EPOCH`]</span>
<span class="doccomment">/// constant is provided in this module as an anchor in time to learn</span>
<span class="doccomment">/// information about a `SystemTime`. By calculating the duration from this</span>
<span class="doccomment">/// fixed point in time, a `SystemTime` can be converted to a human-readable time,</span>
<span class="doccomment">/// or perhaps some other string representation.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The size of a `SystemTime` struct may vary depending on the target operating</span>
<span class="doccomment">/// system.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Instant`]: ../../std/time/struct.Instant.html</span>
<span class="doccomment">/// [`Result`]: ../../std/result/enum.Result.html</span>
<span class="doccomment">/// [`Duration`]: ../../std/time/struct.Duration.html</span>
<span class="doccomment">/// [`UNIX_EPOCH`]: ../../std/time/constant.UNIX_EPOCH.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Example:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::time::{Duration, SystemTime};</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn main() {</span>
<span class="doccomment">/// let now = SystemTime::now();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // we sleep for 2 seconds</span>
<span class="doccomment">/// sleep(Duration::new(2, 0));</span>
<span class="doccomment">/// match now.elapsed() {</span>
<span class="doccomment">/// Ok(elapsed) => {</span>
<span class="doccomment">/// // it prints '2'</span>
<span class="doccomment">/// println!("{}", elapsed.as_secs());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// Err(e) => {</span>
<span class="doccomment">/// // an error occurred!</span>
<span class="doccomment">/// println!("Error: {:?}", e);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Copy</span>, <span class="ident">Clone</span>, <span class="ident">PartialEq</span>, <span class="ident">Eq</span>, <span class="ident">PartialOrd</span>, <span class="ident">Ord</span>, <span class="ident">Hash</span>)]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SystemTime</span>(<span class="ident">time</span>::<span class="ident">SystemTime</span>);
<span class="doccomment">/// An error returned from the `duration_since` and `elapsed` methods on</span>
<span class="doccomment">/// `SystemTime`, used to learn how far in the opposite direction a system time</span>
<span class="doccomment">/// lies.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">/// use std::time::{Duration, SystemTime};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let sys_time = SystemTime::now();</span>
<span class="doccomment">/// sleep(Duration::from_secs(1));</span>
<span class="doccomment">/// let new_sys_time = SystemTime::now();</span>
<span class="doccomment">/// match sys_time.duration_since(new_sys_time) {</span>
<span class="doccomment">/// Ok(_) => {}</span>
<span class="doccomment">/// Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SystemTimeError</span>(<span class="ident">Duration</span>);
<span class="kw">impl</span> <span class="ident">Instant</span> {
<span class="doccomment">/// Returns an instant corresponding to "now".</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::time::Instant;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let now = Instant::now();</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">now</span>() <span class="op">-></span> <span class="ident">Instant</span> {
<span class="ident">Instant</span>(<span class="ident">time</span>::<span class="ident">Instant</span>::<span class="ident">now</span>())
}
<span class="doccomment">/// Returns the amount of time elapsed from another instant to this one.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function will panic if `earlier` is later than `self`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::time::{Duration, Instant};</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let now = Instant::now();</span>
<span class="doccomment">/// sleep(Duration::new(1, 0));</span>
<span class="doccomment">/// let new_now = Instant::now();</span>
<span class="doccomment">/// println!("{:?}", new_now.duration_since(now));</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">duration_since</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">earlier</span>: <span class="ident">Instant</span>) <span class="op">-></span> <span class="ident">Duration</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">sub_instant</span>(<span class="kw-2">&</span><span class="ident">earlier</span>.<span class="number">0</span>)
}
<span class="doccomment">/// Returns the amount of time elapsed since this instant was created.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function may panic if the current time is earlier than this</span>
<span class="doccomment">/// instant, which is something that can happen if an `Instant` is</span>
<span class="doccomment">/// produced synthetically.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">/// use std::time::{Duration, Instant};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let instant = Instant::now();</span>
<span class="doccomment">/// let three_secs = Duration::from_secs(3);</span>
<span class="doccomment">/// sleep(three_secs);</span>
<span class="doccomment">/// assert!(instant.elapsed() >= three_secs);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">elapsed</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Duration</span> {
<span class="ident">Instant</span>::<span class="ident">now</span>() <span class="op">-</span> <span class="kw-2">*</span><span class="self">self</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Add</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">Instant</span>;
<span class="kw">fn</span> <span class="ident">add</span>(<span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) <span class="op">-></span> <span class="ident">Instant</span> {
<span class="ident">Instant</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">add_duration</span>(<span class="kw-2">&</span><span class="ident">other</span>))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time_augmented_assignment"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">AddAssign</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">fn</span> <span class="ident">add_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> <span class="op">+</span> <span class="ident">other</span>;
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Sub</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">Instant</span>;
<span class="kw">fn</span> <span class="ident">sub</span>(<span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) <span class="op">-></span> <span class="ident">Instant</span> {
<span class="ident">Instant</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">sub_duration</span>(<span class="kw-2">&</span><span class="ident">other</span>))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time_augmented_assignment"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">SubAssign</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">fn</span> <span class="ident">sub_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> <span class="op">-</span> <span class="ident">other</span>;
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Sub</span><span class="op"><</span><span class="ident">Instant</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">Duration</span>;
<span class="kw">fn</span> <span class="ident">sub</span>(<span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Instant</span>) <span class="op">-></span> <span class="ident">Duration</span> {
<span class="self">self</span>.<span class="ident">duration_since</span>(<span class="ident">other</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Instant</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">fmt</span>(<span class="ident">f</span>)
}
}
<span class="kw">impl</span> <span class="ident">SystemTime</span> {
<span class="doccomment">/// An anchor in time which can be used to create new `SystemTime` instances or</span>
<span class="doccomment">/// learn about where in time a `SystemTime` lies.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with</span>
<span class="doccomment">/// respect to the system clock. Using `duration_since` on an existing</span>
<span class="doccomment">/// `SystemTime` instance can tell how far away from this point in time a</span>
<span class="doccomment">/// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a</span>
<span class="doccomment">/// `SystemTime` instance to represent another fixed point in time.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::time::SystemTime;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {</span>
<span class="doccomment">/// Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),</span>
<span class="doccomment">/// Err(_) => panic!("SystemTime before UNIX EPOCH!"),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"assoc_unix_epoch"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.28.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">UNIX_EPOCH</span>: <span class="ident">SystemTime</span> <span class="op">=</span> <span class="ident">UNIX_EPOCH</span>;
<span class="doccomment">/// Returns the system time corresponding to "now".</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::time::SystemTime;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let sys_time = SystemTime::now();</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">now</span>() <span class="op">-></span> <span class="ident">SystemTime</span> {
<span class="ident">SystemTime</span>(<span class="ident">time</span>::<span class="ident">SystemTime</span>::<span class="ident">now</span>())
}
<span class="doccomment">/// Returns the amount of time elapsed from an earlier point in time.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function may fail because measurements taken earlier are not</span>
<span class="doccomment">/// guaranteed to always be before later measurements (due to anomalies such</span>
<span class="doccomment">/// as the system clock being adjusted either forwards or backwards).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If successful, [`Ok`]`(`[`Duration`]`)` is returned where the duration represents</span>
<span class="doccomment">/// the amount of time elapsed from the specified measurement to this one.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns an [`Err`] if `earlier` is later than `self`, and the error</span>
<span class="doccomment">/// contains how far from `self` the time is.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok</span>
<span class="doccomment">/// [`Duration`]: ../../std/time/struct.Duration.html</span>
<span class="doccomment">/// [`Err`]: ../../std/result/enum.Result.html#variant.Err</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::time::SystemTime;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let sys_time = SystemTime::now();</span>
<span class="doccomment">/// let difference = sys_time.duration_since(sys_time)</span>
<span class="doccomment">/// .expect("SystemTime::duration_since failed");</span>
<span class="doccomment">/// println!("{:?}", difference);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">duration_since</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">earlier</span>: <span class="ident">SystemTime</span>)
<span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Duration</span>, <span class="ident">SystemTimeError</span><span class="op">></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">sub_time</span>(<span class="kw-2">&</span><span class="ident">earlier</span>.<span class="number">0</span>).<span class="ident">map_err</span>(<span class="ident">SystemTimeError</span>)
}
<span class="doccomment">/// Returns the amount of time elapsed since this system time was created.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function may fail as the underlying system clock is susceptible to</span>
<span class="doccomment">/// drift and updates (e.g. the system clock could go backwards), so this</span>
<span class="doccomment">/// function may not always succeed. If successful, [`Ok`]`(`[`Duration`]`)` is</span>
<span class="doccomment">/// returned where the duration represents the amount of time elapsed from</span>
<span class="doccomment">/// this time measurement to the current time.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns an [`Err`] if `self` is later than the current system time, and</span>
<span class="doccomment">/// the error contains how far from the current system time `self` is.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok</span>
<span class="doccomment">/// [`Duration`]: ../../std/time/struct.Duration.html</span>
<span class="doccomment">/// [`Err`]: ../../std/result/enum.Result.html#variant.Err</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">/// use std::time::{Duration, SystemTime};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let sys_time = SystemTime::now();</span>
<span class="doccomment">/// let one_sec = Duration::from_secs(1);</span>
<span class="doccomment">/// sleep(one_sec);</span>
<span class="doccomment">/// assert!(sys_time.elapsed().unwrap() >= one_sec);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">elapsed</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Duration</span>, <span class="ident">SystemTimeError</span><span class="op">></span> {
<span class="ident">SystemTime</span>::<span class="ident">now</span>().<span class="ident">duration_since</span>(<span class="kw-2">*</span><span class="self">self</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Add</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">SystemTime</span>;
<span class="kw">fn</span> <span class="ident">add</span>(<span class="self">self</span>, <span class="ident">dur</span>: <span class="ident">Duration</span>) <span class="op">-></span> <span class="ident">SystemTime</span> {
<span class="ident">SystemTime</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">add_duration</span>(<span class="kw-2">&</span><span class="ident">dur</span>))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time_augmented_assignment"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">AddAssign</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">fn</span> <span class="ident">add_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> <span class="op">+</span> <span class="ident">other</span>;
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Sub</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">SystemTime</span>;
<span class="kw">fn</span> <span class="ident">sub</span>(<span class="self">self</span>, <span class="ident">dur</span>: <span class="ident">Duration</span>) <span class="op">-></span> <span class="ident">SystemTime</span> {
<span class="ident">SystemTime</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">sub_duration</span>(<span class="kw-2">&</span><span class="ident">dur</span>))
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time_augmented_assignment"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.9.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">SubAssign</span><span class="op"><</span><span class="ident">Duration</span><span class="op">></span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">fn</span> <span class="ident">sub_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">other</span>: <span class="ident">Duration</span>) {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> <span class="op">-</span> <span class="ident">other</span>;
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">fmt</span>(<span class="ident">f</span>)
}
}
<span class="doccomment">/// An anchor in time which can be used to create new `SystemTime` instances or</span>
<span class="doccomment">/// learn about where in time a `SystemTime` lies.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This constant is defined to be "1970-01-01 00:00:00 UTC" on all systems with</span>
<span class="doccomment">/// respect to the system clock. Using `duration_since` on an existing</span>
<span class="doccomment">/// [`SystemTime`] instance can tell how far away from this point in time a</span>
<span class="doccomment">/// measurement lies, and using `UNIX_EPOCH + duration` can be used to create a</span>
<span class="doccomment">/// [`SystemTime`] instance to represent another fixed point in time.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`SystemTime`]: ../../std/time/struct.SystemTime.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::time::{SystemTime, UNIX_EPOCH};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// match SystemTime::now().duration_since(UNIX_EPOCH) {</span>
<span class="doccomment">/// Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),</span>
<span class="doccomment">/// Err(_) => panic!("SystemTime before UNIX EPOCH!"),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">UNIX_EPOCH</span>: <span class="ident">SystemTime</span> <span class="op">=</span> <span class="ident">SystemTime</span>(<span class="ident">time</span>::<span class="ident">UNIX_EPOCH</span>);
<span class="kw">impl</span> <span class="ident">SystemTimeError</span> {
<span class="doccomment">/// Returns the positive duration which represents how far forward the</span>
<span class="doccomment">/// second system time was from the first.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// A `SystemTimeError` is returned from the [`duration_since`] and [`elapsed`]</span>
<span class="doccomment">/// methods of [`SystemTime`] whenever the second system time represents a point later</span>
<span class="doccomment">/// in time than the `self` of the method call.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`duration_since`]: ../../std/time/struct.SystemTime.html#method.duration_since</span>
<span class="doccomment">/// [`elapsed`]: ../../std/time/struct.SystemTime.html#method.elapsed</span>
<span class="doccomment">/// [`SystemTime`]: ../../std/time/struct.SystemTime.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```no_run</span>
<span class="doccomment">/// use std::thread::sleep;</span>
<span class="doccomment">/// use std::time::{Duration, SystemTime};</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let sys_time = SystemTime::now();</span>
<span class="doccomment">/// sleep(Duration::from_secs(1));</span>
<span class="doccomment">/// let new_sys_time = SystemTime::now();</span>
<span class="doccomment">/// match sys_time.duration_since(new_sys_time) {</span>
<span class="doccomment">/// Ok(_) => {}</span>
<span class="doccomment">/// Err(e) => println!("SystemTimeError difference: {:?}", e.duration()),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">duration</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Duration</span> {
<span class="self">self</span>.<span class="number">0</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">SystemTimeError</span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> { <span class="string">"other time was not earlier than self"</span> }
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"time2"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.8.0"</span>)]</span>
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">SystemTimeError</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"second time provided was later than self"</span>)
}
}
<span class="kw">impl</span> <span class="ident">FromInner</span><span class="op"><</span><span class="ident">time</span>::<span class="ident">SystemTime</span><span class="op">></span> <span class="kw">for</span> <span class="ident">SystemTime</span> {
<span class="kw">fn</span> <span class="ident">from_inner</span>(<span class="ident">time</span>: <span class="ident">time</span>::<span class="ident">SystemTime</span>) <span class="op">-></span> <span class="ident">SystemTime</span> {
<span class="ident">SystemTime</span>(<span class="ident">time</span>)
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">test</span>)]</span>
<span class="kw">mod</span> <span class="ident">tests</span> {
<span class="kw">use</span> <span class="kw">super</span>::{<span class="ident">Instant</span>, <span class="ident">SystemTime</span>, <span class="ident">Duration</span>, <span class="ident">UNIX_EPOCH</span>};
<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">assert_almost_eq</span> {
(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>:<span class="ident">expr</span>) <span class="op">=></span> ({
<span class="kw">let</span> (<span class="ident">a</span>, <span class="ident">b</span>) <span class="op">=</span> (<span class="macro-nonterminal">$</span><span class="macro-nonterminal">a</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">b</span>);
<span class="kw">if</span> <span class="ident">a</span> <span class="op">!=</span> <span class="ident">b</span> {
<span class="kw">let</span> (<span class="ident">a</span>, <span class="ident">b</span>) <span class="op">=</span> <span class="kw">if</span> <span class="ident">a</span> <span class="op">></span> <span class="ident">b</span> {(<span class="ident">a</span>, <span class="ident">b</span>)} <span class="kw">else</span> {(<span class="ident">b</span>, <span class="ident">a</span>)};
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">0</span>, <span class="number">100</span>) <span class="op"><=</span> <span class="ident">b</span>);
}
})
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">instant_monotonic</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">>=</span> <span class="ident">a</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">instant_elapsed</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
<span class="ident">a</span>.<span class="ident">elapsed</span>();
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">instant_math</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
<span class="kw">let</span> <span class="ident">dur</span> <span class="op">=</span> <span class="ident">b</span>.<span class="ident">duration_since</span>(<span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">-</span> <span class="ident">dur</span>, <span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">+</span> <span class="ident">dur</span>, <span class="ident">b</span>);
<span class="kw">let</span> <span class="ident">second</span> <span class="op">=</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">second</span> <span class="op">+</span> <span class="ident">second</span>, <span class="ident">a</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="attribute">#[<span class="ident">should_panic</span>]</span>
<span class="kw">fn</span> <span class="ident">instant_duration_panic</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">Instant</span>::<span class="ident">now</span>();
(<span class="ident">a</span> <span class="op">-</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>)).<span class="ident">duration_since</span>(<span class="ident">a</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">system_time_math</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">SystemTime</span>::<span class="ident">now</span>();
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">SystemTime</span>::<span class="ident">now</span>();
<span class="kw">match</span> <span class="ident">b</span>.<span class="ident">duration_since</span>(<span class="ident">a</span>) {
<span class="prelude-val">Ok</span>(<span class="ident">dur</span>) <span class="kw">if</span> <span class="ident">dur</span> <span class="op">==</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">0</span>, <span class="number">0</span>) <span class="op">=></span> {
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span>, <span class="ident">b</span>);
}
<span class="prelude-val">Ok</span>(<span class="ident">dur</span>) <span class="op">=></span> {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">></span> <span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">-</span> <span class="ident">dur</span>, <span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">+</span> <span class="ident">dur</span>, <span class="ident">b</span>);
}
<span class="prelude-val">Err</span>(<span class="ident">dur</span>) <span class="op">=></span> {
<span class="kw">let</span> <span class="ident">dur</span> <span class="op">=</span> <span class="ident">dur</span>.<span class="ident">duration</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">></span> <span class="ident">b</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">+</span> <span class="ident">dur</span>, <span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">dur</span>, <span class="ident">b</span>);
}
}
<span class="kw">let</span> <span class="ident">second</span> <span class="op">=</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">duration_since</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">second</span>).<span class="ident">unwrap</span>(), <span class="ident">second</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span>.<span class="ident">duration_since</span>(<span class="ident">a</span> <span class="op">+</span> <span class="ident">second</span>).<span class="ident">unwrap_err</span>()
.<span class="ident">duration</span>(), <span class="ident">second</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">second</span> <span class="op">+</span> <span class="ident">second</span>, <span class="ident">a</span>);
<span class="comment">// A difference of 80 and 800 years cannot fit inside a 32-bit time_t</span>
<span class="kw">if</span> <span class="op">!</span>(<span class="macro">cfg</span><span class="macro">!</span>(<span class="ident">unix</span>) <span class="op">&&</span> ::<span class="ident">mem</span>::<span class="ident">size_of</span>::<span class="op"><</span>::<span class="ident">libc</span>::<span class="ident">time_t</span><span class="op">></span>() <span class="op"><=</span> <span class="number">4</span>) {
<span class="kw">let</span> <span class="ident">eighty_years</span> <span class="op">=</span> <span class="ident">second</span> <span class="op">*</span> <span class="number">60</span> <span class="op">*</span> <span class="number">60</span> <span class="op">*</span> <span class="number">24</span> <span class="op">*</span> <span class="number">365</span> <span class="op">*</span> <span class="number">80</span>;
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> <span class="ident">eighty_years</span> <span class="op">+</span> <span class="ident">eighty_years</span>, <span class="ident">a</span>);
<span class="macro">assert_almost_eq</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">-</span> (<span class="ident">eighty_years</span> <span class="op">*</span> <span class="number">10</span>) <span class="op">+</span> (<span class="ident">eighty_years</span> <span class="op">*</span> <span class="number">10</span>), <span class="ident">a</span>);
}
<span class="kw">let</span> <span class="ident">one_second_from_epoch</span> <span class="op">=</span> <span class="ident">UNIX_EPOCH</span> <span class="op">+</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>);
<span class="kw">let</span> <span class="ident">one_second_from_epoch2</span> <span class="op">=</span> <span class="ident">UNIX_EPOCH</span> <span class="op">+</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">0</span>, <span class="number">500_000_000</span>)
<span class="op">+</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">0</span>, <span class="number">500_000_000</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">one_second_from_epoch</span>, <span class="ident">one_second_from_epoch2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">system_time_elapsed</span>() {
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">SystemTime</span>::<span class="ident">now</span>();
<span class="ident">drop</span>(<span class="ident">a</span>.<span class="ident">elapsed</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">since_epoch</span>() {
<span class="kw">let</span> <span class="ident">ts</span> <span class="op">=</span> <span class="ident">SystemTime</span>::<span class="ident">now</span>();
<span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">ts</span>.<span class="ident">duration_since</span>(<span class="ident">UNIX_EPOCH</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">ts</span>.<span class="ident">duration_since</span>(<span class="ident">UNIX_EPOCH</span> <span class="op">-</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>)).<span class="ident">unwrap</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">></span> <span class="ident">a</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">b</span> <span class="op">-</span> <span class="ident">a</span>, <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>));
<span class="kw">let</span> <span class="ident">thirty_years</span> <span class="op">=</span> <span class="ident">Duration</span>::<span class="ident">new</span>(<span class="number">1</span>, <span class="number">0</span>) <span class="op">*</span> <span class="number">60</span> <span class="op">*</span> <span class="number">60</span> <span class="op">*</span> <span class="number">24</span> <span class="op">*</span> <span class="number">365</span> <span class="op">*</span> <span class="number">30</span>;
<span class="comment">// Right now for CI this test is run in an emulator, and apparently the</span>
<span class="comment">// aarch64 emulator's sense of time is that we're still living in the</span>
<span class="comment">// 70s.</span>
<span class="comment">//</span>
<span class="comment">// Otherwise let's assume that we're all running computers later than</span>
<span class="comment">// 2000.</span>
<span class="kw">if</span> <span class="op">!</span><span class="macro">cfg</span><span class="macro">!</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"aarch64"</span>) {
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op">></span> <span class="ident">thirty_years</span>);
}
<span class="comment">// let's assume that we're all running computers earlier than 2090.</span>
<span class="comment">// Should give us ~70 years to fix this!</span>
<span class="kw">let</span> <span class="ident">hundred_twenty_years</span> <span class="op">=</span> <span class="ident">thirty_years</span> <span class="op">*</span> <span class="number">4</span>;
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">a</span> <span class="op"><</span> <span class="ident">hundred_twenty_years</span>);
}
}
</pre>
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