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// 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 {
true
}
}
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() {}
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