forked from mirrors/gecko-dev
52 lines
1.4 KiB
Rust
52 lines
1.4 KiB
Rust
use std::io::{self, Write};
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use std::time::{Duration, Instant};
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/// RAII timer to measure how long phases take.
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#[derive(Debug)]
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pub struct Timer<'a> {
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output: bool,
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name: &'a str,
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start: Instant,
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}
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impl<'a> Timer<'a> {
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/// Creates a Timer with the given name, and starts it. By default,
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/// will print to stderr when it is `drop`'d
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pub fn new(name: &'a str) -> Self {
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Timer {
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output: true,
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name,
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start: Instant::now(),
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}
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}
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/// Sets whether or not the Timer will print a message
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/// when it is dropped.
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pub fn with_output(mut self, output: bool) -> Self {
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self.output = output;
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self
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}
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/// Returns the time elapsed since the timer's creation
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pub fn elapsed(&self) -> Duration {
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Instant::now() - self.start
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}
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fn print_elapsed(&mut self) {
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if self.output {
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let elapsed = self.elapsed();
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let time = (elapsed.as_secs() as f64) * 1e3 +
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(elapsed.subsec_nanos() as f64) / 1e6;
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let stderr = io::stderr();
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// Arbitrary output format, subject to change.
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writeln!(stderr.lock(), " time: {:>9.3} ms.\t{}", time, self.name)
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.expect("timer write should not fail");
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}
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}
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}
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impl<'a> Drop for Timer<'a> {
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fn drop(&mut self) {
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self.print_elapsed();
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}
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}
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