Struct StoreConfig 

pub struct StoreConfig {
    pub writer: WriterArm,
    pub index: IndexArm,
    pub gc: GcArm,
    pub redb_cache_bytes: usize,
}

One implementation of each trait, chosen.

A plain Copy value with no interior state: it is read once, at construction, and from then on the store holds the built objects rather than this. Handing it around after that is a description of what was built, not a switch anything consults.

Fields

writer: WriterArm

index: IndexArm

gc: GcArm

redb_cache_bytes: usize

The redb page-cache ceiling the store’s two databases are opened under. Not an arm — it selects nothing — but it is part of what was built, and a Display of the config that left it out would have hidden the one key that was “falsified” on 2026-08-11 by never reaching the container at all. StoreConfig::from_env fills it from redb_cache_bytes; DEFAULT is DEFAULT_REDB_CACHE_BYTES.

Implementations

impl StoreConfig

pub const DEFAULT: StoreConfig

What shipped before this module existed, and what still ships.

SafeWriter + ObjectReadStack<OneTableFourColumns> + NewGeneration. GitStore::open builds exactly this and consults no environment to do it.

pub fn from_env() -> Result<Self>

Read the three arms and the cache ceiling. Four getenvs, once, here.

It is called from a store’s constructor and from nowhere on a serving path; env_reads is what makes that assertable rather than asserted- by-comment. An unset or empty variable takes the default; a variable set to an unknown value is an error rather than a silent fallback, so a typo cannot make a measurement look like it came from an arm that never ran.

The ceiling rides along because it is read on the same construction path and printed by the same Display: a caller that logs from_env()’s result once at store open has then logged every per-store variable this crate consults, and ZNIPPY_GIT_REDB_CACHE_BYTES is no longer the one that can be set on a host, stop at a container boundary, and leave no trace of having done so.

pub fn with_writer(self, w: WriterArm) -> Self

Same three arms with a different writer. For a bench that sweeps one axis.

pub fn with_index(self, i: IndexArm) -> Self

pub fn with_gc(self, g: GcArm) -> Self

pub fn with_redb_cache_bytes(self, bytes: usize) -> Self

Same arms, a different redb page-cache ceiling. What GitStore::open uses to put the environment’s ceiling on the default arms without reading any arm.

Trait Implementations

impl Clone for StoreConfig

fn clone(&self) -> StoreConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for StoreConfig

impl Debug for StoreConfig

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

Formats the value using the given formatter.

impl Default for StoreConfig

fn default() -> Self

StoreConfig::DEFAULT, spelled out. A derived Default would put a zero-byte page cache on the shipping combination.

impl Display for StoreConfig

KEY=value for every per-store variable, in the spelling an operator would type — so one log line at store open is a complete, reproducible statement of what the environment selected, including the ceiling.

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

Formats the value using the given formatter.

impl Eq for StoreConfig

impl PartialEq for StoreConfig

fn eq(&self, other: &StoreConfig) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StoreConfig