Add std:🧵:available_concurrency
This commit is contained in:
Yoshua Wuyts
parent
a8d6da3f57
commit
3717646366
4 changed files with 166 additions and 101 deletions
157
library/std/src/thread/available_concurrency.rs
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157
library/std/src/thread/available_concurrency.rs
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@ -0,0 +1,157 @@
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use crate::io;
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use crate::num::NonZeroUsize;
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/// Returns the number of hardware threads available to the program.
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///
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/// This value should be considered only a hint.
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///
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/// # Platform-specific behavior
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///
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/// If interpreted as the number of actual hardware threads, it may undercount on
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/// Windows systems with more than 64 hardware threads. If interpreted as the
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/// available concurrency for that process, it may overcount on Windows systems
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/// when limited by a process wide affinity mask or job object limitations, and
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/// it may overcount on Linux systems when limited by a process wide affinity
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/// mask or affected by cgroups limits.
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///
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/// # Errors
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///
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/// This function will return an error in the following situations, but is not
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/// limited to just these cases:
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///
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/// - If the number of hardware threads is not known for the target platform.
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/// - The process lacks permissions to view the number of hardware threads
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/// available.
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///
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/// # Examples
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///
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/// ```
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/// # #![allow(dead_code)]
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/// #![feature(available_concurrency)]
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/// use std::thread;
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///
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/// let count = thread::available_concurrency().map(|n| n.get()).unwrap_or(1);
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/// ```
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#[unstable(feature = "available_concurrency", issue = "74479")]
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pub fn available_concurrency() -> io::Result<NonZeroUsize> {
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available_concurrency_internal()
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}
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cfg_if::cfg_if! {
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if #[cfg(windows)] {
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#[allow(nonstandard_style)]
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fn available_concurrency_internal() -> io::Result<NonZeroUsize> {
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#[repr(C)]
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struct SYSTEM_INFO {
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wProcessorArchitecture: u16,
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wReserved: u16,
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dwPageSize: u32,
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lpMinimumApplicationAddress: *mut u8,
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lpMaximumApplicationAddress: *mut u8,
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dwActiveProcessorMask: *mut u8,
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dwNumberOfProcessors: u32,
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dwProcessorType: u32,
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dwAllocationGranularity: u32,
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wProcessorLevel: u16,
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wProcessorRevision: u16,
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}
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extern "system" {
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fn GetSystemInfo(info: *mut SYSTEM_INFO) -> i32;
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}
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let res = unsafe {
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let mut sysinfo = crate::mem::zeroed();
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GetSystemInfo(&mut sysinfo);
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sysinfo.dwNumberOfProcessors as usize
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};
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match res {
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0 => Err(io::Error::new(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform")),
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cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus) }),
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}
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}
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} else if #[cfg(any(
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target_os = "android",
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target_os = "cloudabi",
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target_os = "emscripten",
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target_os = "fuchsia",
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target_os = "ios",
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target_os = "linux",
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target_os = "macos",
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target_os = "solaris",
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target_os = "illumos",
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))] {
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fn available_concurrency_internal() -> io::Result<NonZeroUsize> {
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match unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) } {
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-1 => Err(io::Error::last_os_error()),
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0 => Err(io::Error::new(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform")),
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cpus => Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) }),
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}
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}
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} else if #[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "netbsd"))] {
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fn available_concurrency_internal() -> io::Result<NonZeroUsize> {
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use crate::ptr;
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let mut cpus: libc::c_uint = 0;
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let mut cpus_size = crate::mem::size_of_val(&cpus);
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unsafe {
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cpus = libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as libc::c_uint;
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}
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// Fallback approach in case of errors or no hardware threads.
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if cpus < 1 {
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let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
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let res = unsafe {
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libc::sysctl(
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mib.as_mut_ptr(),
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2,
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&mut cpus as *mut _ as *mut _,
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&mut cpus_size as *mut _ as *mut _,
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ptr::null_mut(),
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0,
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)
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};
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// Handle errors if any.
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if res == -1 {
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return Err(io::Error::last_os_error());
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} else if cpus == 0 {
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return Err(io::Error::new(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"));
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}
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}
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Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) })
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}
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} else if #[cfg(target_os = "openbsd")] {
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fn available_concurrency_internal() -> io::Result<NonZeroUsize> {
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use crate::ptr;
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let mut cpus: libc::c_uint = 0;
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let mut cpus_size = crate::mem::size_of_val(&cpus);
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let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
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let res = unsafe {
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libc::sysctl(
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mib.as_mut_ptr(),
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2,
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&mut cpus as *mut _ as *mut _,
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&mut cpus_size as *mut _ as *mut _,
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ptr::null_mut(),
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0,
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)
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};
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// Handle errors if any.
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if res == -1 {
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return Err(io::Error::last_os_error());
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} else if cpus == 0 {
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return Err(io::Error::new(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"));
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}
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Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) })
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}
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} else {
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// FIXME: implement on vxWorks, Redox, HermitCore, Haiku, l4re
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fn available_concurrency_internal() -> io::Result<NonZeroUsize> {
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Err(io::Error::new(io::ErrorKind::NotFound, "The number of hardware threads is not known for the target platform"))
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}
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}
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}
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@ -175,9 +175,15 @@ use crate::time::Duration;
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#[macro_use]
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mod local;
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#[unstable(feature = "available_concurrency", issue = "74479")]
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mod available_concurrency;
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use self::local::{AccessError, LocalKey};
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#[unstable(feature = "available_concurrency", issue = "74479")]
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pub use available_concurrency::available_concurrency;
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// The types used by the thread_local! macro to access TLS keys. Note that there
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// are two types, the "OS" type and the "fast" type. The OS thread local key
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// type is accessed via platform-specific API calls and is slow, while the fast
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@ -1,6 +1,7 @@
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//! Helper module which helps to determine amount of threads to be used
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//! during tests execution.
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use std::env;
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use std::thread;
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#[allow(deprecated)]
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pub fn get_concurrency() -> usize {
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@ -12,106 +13,6 @@ pub fn get_concurrency() -> usize {
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_ => panic!("RUST_TEST_THREADS is `{}`, should be a positive integer.", s),
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}
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}
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Err(..) => num_cpus(),
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}
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}
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cfg_if::cfg_if! {
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if #[cfg(windows)] {
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#[allow(nonstandard_style)]
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fn num_cpus() -> usize {
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#[repr(C)]
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struct SYSTEM_INFO {
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wProcessorArchitecture: u16,
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wReserved: u16,
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dwPageSize: u32,
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lpMinimumApplicationAddress: *mut u8,
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lpMaximumApplicationAddress: *mut u8,
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dwActiveProcessorMask: *mut u8,
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dwNumberOfProcessors: u32,
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dwProcessorType: u32,
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dwAllocationGranularity: u32,
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wProcessorLevel: u16,
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wProcessorRevision: u16,
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}
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extern "system" {
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fn GetSystemInfo(info: *mut SYSTEM_INFO) -> i32;
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}
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unsafe {
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let mut sysinfo = std::mem::zeroed();
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GetSystemInfo(&mut sysinfo);
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sysinfo.dwNumberOfProcessors as usize
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}
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}
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} else if #[cfg(any(
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target_os = "android",
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target_os = "cloudabi",
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target_os = "emscripten",
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target_os = "fuchsia",
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target_os = "ios",
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target_os = "linux",
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target_os = "macos",
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target_os = "solaris",
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target_os = "illumos",
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))] {
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fn num_cpus() -> usize {
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unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as usize }
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}
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} else if #[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "netbsd"))] {
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fn num_cpus() -> usize {
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use std::ptr;
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let mut cpus: libc::c_uint = 0;
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let mut cpus_size = std::mem::size_of_val(&cpus);
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unsafe {
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cpus = libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as libc::c_uint;
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}
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if cpus < 1 {
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let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
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unsafe {
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libc::sysctl(
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mib.as_mut_ptr(),
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2,
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&mut cpus as *mut _ as *mut _,
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&mut cpus_size as *mut _ as *mut _,
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ptr::null_mut(),
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0,
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);
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}
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if cpus < 1 {
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cpus = 1;
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}
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}
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cpus as usize
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}
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} else if #[cfg(target_os = "openbsd")] {
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fn num_cpus() -> usize {
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use std::ptr;
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let mut cpus: libc::c_uint = 0;
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let mut cpus_size = std::mem::size_of_val(&cpus);
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let mut mib = [libc::CTL_HW, libc::HW_NCPU, 0, 0];
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unsafe {
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libc::sysctl(
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mib.as_mut_ptr(),
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2,
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&mut cpus as *mut _ as *mut _,
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&mut cpus_size as *mut _ as *mut _,
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ptr::null_mut(),
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0,
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);
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}
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if cpus < 1 {
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cpus = 1;
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}
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cpus as usize
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}
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} else {
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// FIXME: implement on vxWorks, Redox, HermitCore, Haiku, l4re
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fn num_cpus() -> usize {
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1
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}
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Err(..) => thread::available_concurrency().map(|n| n.get()).unwrap_or(1),
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}
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}
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@ -24,6 +24,7 @@
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#![feature(rustc_private)]
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#![feature(nll)]
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#![feature(bool_to_option)]
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#![feature(available_concurrency)]
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#![feature(set_stdio)]
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#![feature(panic_unwind)]
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#![feature(staged_api)]
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