Struct SamplingDispatcher 

pub struct SamplingDispatcher {
    pub default: CodecKind,
    pub entropy_threshold: f64,
}

入力 sample を見て codec を選ぶ dispatcher。

判定順 (上位優先):

1. 短すぎる入力 (<128 byte) → default
2. magic bytes が既圧縮フォーマット (gzip / zstd / png / jpeg / mp4 / zip / pdf / 7z / xz / bzip2) → Passthrough (再圧縮しても意味がない)
3. Shannon entropy が entropy_threshold (default 7.5 bits/byte) 以上 → Passthrough (高エントロピー = ほぼランダム = 圧縮余地なし)
4. それ以外 → default (text / log / parquet 数値列等、圧縮余地あり)

Phase 1 では default = CpuZstd 想定。Phase 1 後半で integer-column 検出を加え、 default 分岐を「数値列なら NvcompBitcomp、そうでなければ CpuZstd」に拡張する。

Fields

default: CodecKind

entropy_threshold: f64

Implementations

impl SamplingDispatcher

pub const DEFAULT_ENTROPY_THRESHOLD: f64 = 7.5

pub const MIN_SAMPLE_BYTES: usize = 128

pub fn new(default: CodecKind) -> Self

pub fn with_entropy_threshold(self, t: f64) -> Self

Trait Implementations

impl Clone for SamplingDispatcher

fn clone(&self) -> SamplingDispatcher

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CodecDispatcher for SamplingDispatcher

fn pick<'life0, 'life1, 'async_trait>( &'life0 self, sample: &'life1 [u8], ) -> Pin<Box<dyn Future<Output = CodecKind> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

impl Debug for SamplingDispatcher

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.