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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
//! This module helps deno implement timers and performance APIs.
use deno_core::error::AnyError;use deno_core::op;
use deno_core::CancelFuture;use deno_core::CancelHandle;use deno_core::OpState;use deno_core::Resource;use deno_core::ResourceId;use std::borrow::Cow;use std::cell::RefCell;use std::rc::Rc;use std::time::Duration;use std::time::Instant;
pub trait TimersPermission {  fn allow_hrtime(&mut self) -> bool;  fn check_unstable(&self, state: &OpState, api_name: &'static str);}
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.#[op(fast)]pub fn op_now<TP>(state: &mut OpState, 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 as u32;}
pub struct TimerHandle(Rc<CancelHandle>);
impl Resource for TimerHandle {  fn name(&self) -> Cow<str> {    "timer".into()  }
  fn close(self: Rc<Self>) {    self.0.cancel();  }}
/// Creates a [`TimerHandle`] resource that can be used to cancel invocations of/// [`op_sleep`].#[op]pub fn op_timer_handle(state: &mut OpState) -> ResourceId {  state    .resource_table    .add(TimerHandle(CancelHandle::new_rc()))}
/// Waits asynchronously until either `millis` milliseconds have passed or the/// [`TimerHandle`] resource given by `rid` has been canceled.////// If the timer is canceled, this returns `false`. Otherwise, it returns `true`.#[op(deferred)]pub async fn op_sleep(  state: Rc<RefCell<OpState>>,  millis: u64,  rid: ResourceId,) -> Result<bool, AnyError> {  let handle = state.borrow().resource_table.get::<TimerHandle>(rid)?;  let res = tokio::time::sleep(Duration::from_millis(millis))    .or_cancel(handle.0.clone())    .await;  Ok(res.is_ok())}