27 lines
1.0 KiB
Rust
27 lines
1.0 KiB
Rust
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use std::sync::atomic::{AtomicUsize, Ordering};
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/// Stream concurrency factor; this is a live value.
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static WIDTH: AtomicUsize = AtomicUsize::new(32);
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/// Practicable limits on the stream width
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pub const WIDTH_LIMIT: (usize, usize) = (1, 1024);
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/// Sets the live concurrency factor. The first return value is the previous
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/// width which was replaced. The second return value is the value which was set
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/// after any applied limits.
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pub fn set_width(width: usize) -> (usize, usize) {
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let width = width.clamp(WIDTH_LIMIT.0, WIDTH_LIMIT.1);
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(WIDTH.swap(width, Ordering::Relaxed), width)
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}
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/// Used by stream operations where the concurrency factor hasn't been manually
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/// supplied by the caller (most uses). Instead we provide a default value which
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/// is adjusted at startup for the specific system and also dynamically.
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#[inline]
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pub fn automatic_width() -> usize {
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let width = WIDTH.load(Ordering::Relaxed);
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debug_assert!(width >= WIDTH_LIMIT.0, "WIDTH should not be zero");
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debug_assert!(width <= WIDTH_LIMIT.1, "WIDTH is probably too large");
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width
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}
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