20 lines
563 B
Rust
20 lines
563 B
Rust
use {
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crate::oserror::{OsError, OsErrorExt},
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smallvec::{SmallVec, smallvec_inline},
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uapi::c,
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};
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pub fn num_cpus() -> Result<u32, OsError> {
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let mut buf: SmallVec<[usize; 32]> = smallvec_inline![0; 32];
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loop {
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match uapi::sched_getaffinity(0, &mut buf).to_os_error() {
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Ok(_) => return Ok(count(&buf)),
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Err(OsError(c::EINVAL)) => buf.extend_from_slice(&[0; 32][..]),
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Err(e) => return Err(e),
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}
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}
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}
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fn count(buf: &[usize]) -> u32 {
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buf.iter().copied().map(|n| n.count_ones()).sum()
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}
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