Struct PrivacyBudget 

pub struct PrivacyBudget { /* private fields */ }

👎Deprecated since 0.4.0:

not differentially private (predictable xorshift64 state, time-derived seed, floating-point inverse transform); use alice_crypto::dp instead. Removed in 0.5.0

Track cumulative privacy budget (composition theorem)

Under sequential composition, ε values add up. Under parallel composition over disjoint data, use max.

Implementations

impl PrivacyBudget

pub const fn new(max_epsilon: f64) -> Self

Create a new privacy budget tracker

pub fn try_spend(&mut self, epsilon: f64) -> bool

Try to spend epsilon from budget

Returns true and charges the ledger if the request is well formed and fits in the remaining budget; returns false and leaves every field untouched otherwise.

A request is well formed when epsilon is finite and not negative. 0.0 (and -0.0) is well formed: it charges nothing and counts a query.

Rejecting a negative epsilon is the whole point of the type. Until 2026-10-07 the guard was only the budget comparison total + epsilon <= max, which a negative value passes trivially, so try_spend(-10.0) returned true and raised the remaining budget from 1 to 11; -inf raised it to infinity. A caller that spends a negative epsilon between two honest queries escapes the limit the budget exists to enforce. NaN and +inf were already refused, though only as a side effect of the comparison being false — they are now refused by the same explicit check.

pub fn remaining(&self) -> f64

Get remaining budget

pub const fn spent(&self) -> f64

Get total spent

pub const fn query_count(&self) -> u64

Get query count

pub fn is_exhausted(&self) -> bool

Check if budget is exhausted

pub const fn reset(&mut self)

Reset the budget

Trait Implementations

impl Clone for PrivacyBudget

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PrivacyBudget

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

Formats the value using the given formatter.