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