ethers-rs/ethers-middleware/src/gas_escalator/geometric.rs

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use super::GasEscalator;
use ethers_core::types::U256;
/// Geometrically increasing gas price.
///
/// Start with `initial_price`, then increase it every 'every_secs' seconds by a fixed coefficient.
/// Coefficient defaults to 1.125 (12.5%), the minimum increase for Parity to replace a transaction.
/// Coefficient can be adjusted, and there is an optional upper limit.
///
/// https://github.com/makerdao/pymaker/blob/master/pymaker/gas.py#L168
#[derive(Clone, Debug)]
pub struct GeometricGasPrice {
every_secs: u64,
coefficient: f64,
max_price: Option<U256>,
}
impl GeometricGasPrice {
/// Constructor
///
/// Note: Providing `None` to `max_price` requires giving it a type-hint, so you'll need
/// to call this like `GeometricGasPrice::new(1.125, 60u64, None::<u64>)`.
pub fn new<T: Into<U256>, K: Into<u64>>(
coefficient: f64,
every_secs: K,
max_price: Option<T>,
) -> Self {
GeometricGasPrice {
every_secs: every_secs.into(),
coefficient,
max_price: max_price.map(Into::into),
}
}
}
impl GasEscalator for GeometricGasPrice {
fn get_gas_price(&self, initial_price: U256, time_elapsed: u64) -> U256 {
let mut result = initial_price.as_u64() as f64;
if time_elapsed >= self.every_secs {
let iters = time_elapsed / self.every_secs;
for _ in 0..iters {
result *= self.coefficient;
}
}
let mut result = U256::from(result.ceil() as u64);
if let Some(max_price) = self.max_price {
result = std::cmp::min(result, max_price);
}
result
}
}
#[cfg(test)]
// https://github.com/makerdao/pymaker/blob/master/tests/test_gas.py#L165
mod tests {
use super::*;
#[test]
fn gas_price_increases_with_time() {
let oracle = GeometricGasPrice::new(1.125, 10u64, None::<u64>);
let initial_price = U256::from(100);
assert_eq!(oracle.get_gas_price(initial_price, 0), 100.into());
assert_eq!(oracle.get_gas_price(initial_price, 1), 100.into());
assert_eq!(oracle.get_gas_price(initial_price, 10), 113.into());
assert_eq!(oracle.get_gas_price(initial_price, 15), 113.into());
assert_eq!(oracle.get_gas_price(initial_price, 20), 127.into());
assert_eq!(oracle.get_gas_price(initial_price, 30), 143.into());
assert_eq!(oracle.get_gas_price(initial_price, 50), 181.into());
assert_eq!(oracle.get_gas_price(initial_price, 100), 325.into());
}
#[test]
fn gas_price_should_obey_max_value() {
let oracle = GeometricGasPrice::new(1.125, 60u64, Some(2500));
let initial_price = U256::from(1000);
assert_eq!(oracle.get_gas_price(initial_price, 0), 1000.into());
assert_eq!(oracle.get_gas_price(initial_price, 1), 1000.into());
assert_eq!(oracle.get_gas_price(initial_price, 59), 1000.into());
assert_eq!(oracle.get_gas_price(initial_price, 60), 1125.into());
assert_eq!(oracle.get_gas_price(initial_price, 119), 1125.into());
assert_eq!(oracle.get_gas_price(initial_price, 120), 1266.into());
assert_eq!(oracle.get_gas_price(initial_price, 1200), 2500.into());
assert_eq!(oracle.get_gas_price(initial_price, 3000), 2500.into());
assert_eq!(oracle.get_gas_price(initial_price, 1000000), 2500.into());
}
#[test]
2021-07-05 11:03:38 +00:00
#[allow(clippy::float_cmp)]
fn behaves_with_realistic_values() {
let oracle = GeometricGasPrice::new(1.25, 10u64, None::<u64>);
const GWEI: f64 = 1000000000.0;
let initial_price = U256::from(100 * GWEI as u64);
for seconds in &[0u64, 1, 10, 12, 30, 60] {
println!(
"gas price after {} seconds is {}",
seconds,
oracle.get_gas_price(initial_price, *seconds).as_u64() as f64 / GWEI
);
}
let normalized = |time| oracle.get_gas_price(initial_price, time).as_u64() as f64 / GWEI;
assert_eq!(normalized(0), 100.0);
assert_eq!(normalized(1), 100.0);
assert_eq!(normalized(10), 125.0);
assert_eq!(normalized(12), 125.0);
assert_eq!(normalized(30), 195.3125);
assert_eq!(normalized(60), 381.469726563);
}
}