Crate subms_hdr_histogram 

Log-linear bucket histogram with significant-digit precision.

Each value is mapped to a bucket index built from two pieces:

• Major bucket: floor(log2(value)) - log2(sub_count) + 1, clamped at 0. Each major covers a doubling range (1, 2, 4, 8, …).
• Sub-bucket: linear position within the major range.

Together they give constant relative error within the significant-digit precision: a value’s bucket is never wider than 1 / sub_count of the value itself. sub_count is 2 * 10^d rounded up to a power of two, so d = 3 gives 2^11 = 2048 sub-buckets and a worst-case quantisation error of 1/2048 (0.049%), inside the half-unit-in-the-third-digit that three significant digits demands.

The counter array starts at sub_count entries and grows lazily to cover the largest value recorded: at d = 3 a range topping out at 10^6 lands at index 20290 (~20k counters, 163 KB), and one topping out at 10^9 at index 40678 (~41k counters, 326 KB).

use subms_hdr_histogram::HdrHistogram;
let mut h = HdrHistogram::new(3);
for v in [10u64, 20, 30, 40, 50] { h.record(v); }
assert_eq!(h.count(), 5);
let p50 = h.value_at_percentile(0.5);
assert!((20..=30).contains(&p50), "p50={p50}");
assert_eq!(h.max(), 50);

Full writeup, design notes and measured benchmarks: https://www.submillisecond.com/cookbook/recipes/subms-hdr-histogram

Re-exports

pub use features::concurrent_writes::ConcurrentHdrHistogram;

pub use features::decay::Clock;

pub use features::decay::DecayingHdrHistogram;

pub use features::decay::ManualClock;

pub use features::dual_recorder::DualRecorder;

pub use features::iterators::HdrLinearIter;

pub use features::iterators::HdrLogarithmicIter;

pub use features::iterators::HdrPercentileIter;

pub use features::iterators::IterEntry;

pub use features::merge::merge;

pub use features::value_tagging::TaggedHdrHistogram;

Modules

features

Opt-in feature modules. Each entry is gated by its own Cargo feature; the base HdrHistogram in lib.rs stays zero-dep + std-only.

growth

SubMsGrowthRecipe impl.

recipe

SubMsRecipe impl.

Structs

HdrHistogram

Histogram with significant_digits of precision in [1, 5].