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* cargo.toml: add `allow_attributes` lint * fix lints * fixes * fmt * fix docs * fix docs * fix expect msg
101 lines
3.2 KiB
Rust
101 lines
3.2 KiB
Rust
//! System thread related
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//!
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//! Requires `std`.
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//---------------------------------------------------------------------------------------------------- Use
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use std::{cmp::max, num::NonZeroUsize};
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//---------------------------------------------------------------------------------------------------- Thread Count & Percent
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/// Get the total amount of system threads.
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///
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/// ```rust
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/// # use cuprate_helper::thread::*;
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/// assert!(threads().get() >= 1);
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/// ```
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pub fn threads() -> NonZeroUsize {
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std::thread::available_parallelism().unwrap_or(NonZeroUsize::MIN)
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}
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// Implement a function for the various
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// `x` thread-percent functions below.
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macro_rules! impl_thread_percent {
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($(
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$(#[$doc:meta])*
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$fn_name:ident => // Name of the function
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$percent:literal // The target percent of threads
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),* $(,)?) => {
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$(
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$(#[$doc])*
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pub fn $fn_name() -> NonZeroUsize {
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// unwrap here is okay because:
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// - THREADS().get() is always non-zero
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// - max() guards against 0
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#[expect(
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clippy::cast_possible_truncation,
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clippy::cast_sign_loss,
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clippy::cast_precision_loss,
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reason = "we need to round integers"
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)]
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NonZeroUsize::new(max(1, (threads().get() as f64 * $percent).floor() as usize)).unwrap()
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}
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)*
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}
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}
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impl_thread_percent! {
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/// Get 90% (rounded down) of available amount of system threads.
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threads_90 => 0.90,
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/// Get 75% (rounded down) of available amount of system threads.
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threads_75 => 0.75,
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/// Get 50% (rounded down) of available amount of system threads.
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threads_50 => 0.50,
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/// Get 25% (rounded down) of available amount of system threads.
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threads_25 => 0.25,
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/// Get 10% (rounded down) of available amount of system threads.
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threads_10 => 0.10,
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}
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//---------------------------------------------------------------------------------------------------- Thread Priority
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/// Low Priority Thread
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///
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/// Sets the calling thread’s priority to the lowest platform-specific value possible.
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///
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/// Originally from <https://docs.rs/lpt>.
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///
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/// # Windows
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/// Uses `SetThreadPriority()` with `THREAD_PRIORITY_IDLE` (-15).
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///
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/// # Unix
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/// Uses `libc::nice()` with the max nice level.
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///
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/// On macOS and *BSD: +20
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/// On Linux: +19
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pub fn low_priority_thread() {
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#[cfg(target_os = "windows")]
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{
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use target_os_lib as windows;
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use windows::Win32::System::Threading::*;
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// SAFETY: calling C.
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// We are _lowering_ our priority, not increasing, so this function should never fail.
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unsafe {
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drop(SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_IDLE));
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}
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}
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#[cfg(target_family = "unix")]
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{
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use target_os_lib as libc;
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const NICE_MAX: libc::c_int = if cfg!(target_os = "linux") { 19 } else { 20 };
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// SAFETY: calling C.
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// We are _lowering_ our priority, not increasing, so this function should never fail.
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unsafe {
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libc::nice(NICE_MAX);
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}
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}
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}
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//---------------------------------------------------------------------------------------------------- TESTS
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#[cfg(test)]
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mod tests {}
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