Struct ExprFuelCounter 

pub struct ExprFuelCounter { /* private fields */ }

Expression fuel counter for limiting expression evaluation complexity

Uses a fuel-based approach where each operation consumes fuel. This prevents both deep recursion (many nested calls) and wide recursion (many sibling calls).

Thread Safety

ExprFuelCounter uses atomic operations and is safe to share between threads.

Example

use sqry_core::query::security::ExprFuelCounter;

fn evaluate_expr(expr: &str, fuel: &ExprFuelCounter) -> Result<(), Box<dyn std::error::Error>> {
    fuel.consume(1)?;
    // Evaluate expression...
    Ok(())
}

let fuel = ExprFuelCounter::new(1000)?;
evaluate_expr("a AND b", &fuel)?;

Implementations

impl ExprFuelCounter

pub fn new(initial_fuel: usize) -> Result<Self>

Create a new fuel counter with the specified initial fuel

Errors

Returns an error if initial_fuel is 0.

pub fn consume(&self, amount: usize) -> Result<(), RecursionError>

Consume the specified amount of fuel

Errors

Returns RecursionError::FuelExhausted if there is not enough fuel remaining.

Implementation Note

Uses fetch_update for atomic check-then-subtract to prevent underflow (per FINAL_CORRECTIONS.md ExprFuelCounter bug fix).

pub fn remaining(&self) -> usize

Get the current fuel remaining

pub fn initial_fuel(&self) -> usize

Get the initial fuel amount

pub fn consumed(&self) -> usize

Get the amount of fuel consumed so far

pub fn has_fuel(&self, amount: usize) -> bool

Check if there is enough fuel remaining

pub fn reset(&self)

Reset the fuel counter to its initial value

Useful for reusing a fuel counter across multiple operations.

Trait Implementations

impl Debug for ExprFuelCounter

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

Formats the value using the given formatter.