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denoland-deno/ext/web/timers.rs
David Sherret 386d5c8310
refactor: remove PermissionsContainer in deno_runtime (#24119)
Also removes permissions being passed in for node resolution. It was
completely useless because we only checked it for reading package.json
files, but Deno reading package.json files for resolution is perfectly
fine.

My guess is this is also a perf improvement because Deno is doing less
work.
2024-06-06 23:37:53 -04:00

55 lines
1.6 KiB
Rust

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
//! This module helps deno implement timers and performance APIs.
use deno_core::op2;
use deno_core::OpState;
use std::time::Instant;
pub trait TimersPermission {
fn allow_hrtime(&mut self) -> bool;
}
impl TimersPermission for deno_permissions::PermissionsContainer {
#[inline(always)]
fn allow_hrtime(&mut self) -> bool {
deno_permissions::PermissionsContainer::allow_hrtime(self)
}
}
pub type StartTime = Instant;
// Returns a milliseconds and nanoseconds subsec
// since the start time of the deno runtime.
// If the High precision flag is not set, the
// nanoseconds are rounded on 2ms.
#[op2(fast)]
pub fn op_now<TP>(state: &mut OpState, #[buffer] buf: &mut [u8])
where
TP: TimersPermission + 'static,
{
let start_time = state.borrow::<StartTime>();
let elapsed = start_time.elapsed();
let seconds = elapsed.as_secs();
let mut subsec_nanos = elapsed.subsec_nanos();
// If the permission is not enabled
// Round the nano result on 2 milliseconds
// see: https://developer.mozilla.org/en-US/docs/Web/API/DOMHighResTimeStamp#Reduced_time_precision
if !state.borrow_mut::<TP>().allow_hrtime() {
let reduced_time_precision = 2_000_000; // 2ms in nanoseconds
subsec_nanos -= subsec_nanos % reduced_time_precision;
}
if buf.len() < 8 {
return;
}
let buf: &mut [u32] =
// SAFETY: buffer is at least 8 bytes long.
unsafe { std::slice::from_raw_parts_mut(buf.as_mut_ptr() as _, 2) };
buf[0] = seconds as u32;
buf[1] = subsec_nanos;
}
#[allow(clippy::unused_async)]
#[op2(async(lazy), fast)]
pub async fn op_defer() {}