atlas-rayon-threadlimit 3.0.0

use {log::warn, std::env};
//TODO remove this hack when rayon fixes itself

// reduce the number of threads each pool is allowed to half the cpu core count, to avoid rayon
// hogging cpu
static MAX_RAYON_THREADS: std::sync::LazyLock<usize> = std::sync::LazyLock::new(|| {
    env::var("ATLAS_RAYON_THREADS")
        .ok()
        .and_then(|num_threads| {
            warn!(
                "Use of ATLAS_RAYON_THREADS has been deprecated and will be removed soon. Use \
                 the individual agave-validator CLI flags to configure threadpool sizes"
            );
            num_threads.parse().ok()
        })
        .unwrap_or_else(|| num_cpus::get() / 2)
        .max(1)
});

pub fn get_thread_count() -> usize {
    *MAX_RAYON_THREADS
}

#[deprecated(
    since = "3.0.0",
    note = "The atlas-rayon-threadlimit crate will be removed, use num_cpus::get() or something \
            similar instead"
)]
pub fn get_max_thread_count() -> usize {
    get_thread_count().saturating_mul(2)
}