Function build_bloom_with_params

nodedb-columnar/src/predicate.rs:444–459

Build a `BloomFilter` with explicit `k` (hash function count) and `m` (bit-array size). `m` must be a power of two and at least 8. This is useful when tuning the filter for a specific target false-positive rate. Use `build_bloom` for the standard default parameters.

(values: &[&str], k: u8, m: u32)

/// This is useful when tuning the filter for a specific target false-positive
/// rate. Use `build_bloom` for the standard default parameters.
pub fn build_bloom_with_params(values: &[&str], k: u8, m: u32) -> BloomFilter {
    debug_assert!(
        m >= 8 && m.is_power_of_two(),
        "m must be a power of two ≥ 8"
    );
    let byte_count = (m as usize).div_ceil(8);
    let mut bloom = BloomFilter {
        k,
        m,
        bytes: vec![0u8; byte_count],
    };
    for v in values {
        bloom_insert(&mut bloom, v);
    }
    bloom
}

#[cfg(test)]
mod tests {