ethers_middleware/gas_escalator/
geometric.rs

1use super::GasEscalator;
2use ethers_core::types::U256;
3
4/// Geometrically increasing gas price.
5///
6/// Start with `initial_price`, then increase it every 'every_secs' seconds by a fixed coefficient.
7/// Coefficient defaults to 1.125 (12.5%), the minimum increase for Parity to replace a transaction.
8/// Coefficient can be adjusted, and there is an optional upper limit.
9///
10/// <https://github.com/makerdao/pymaker/blob/master/pymaker/gas.py#L168>
11#[derive(Clone, Debug)]
12pub struct GeometricGasPrice {
13    every_secs: u64,
14    coefficient: f64,
15    max_price: Option<U256>,
16}
17
18impl GeometricGasPrice {
19    /// Constructor
20    ///
21    /// Note: Providing `None` to `max_price` requires giving it a type-hint, so you'll need
22    /// to call this like `GeometricGasPrice::new(1.125, 60u64, None::<u64>)`.
23    pub fn new<T: Into<U256>, K: Into<u64>>(
24        coefficient: f64,
25        every_secs: K,
26        max_price: Option<T>,
27    ) -> Self {
28        GeometricGasPrice {
29            every_secs: every_secs.into(),
30            coefficient,
31            max_price: max_price.map(Into::into),
32        }
33    }
34}
35
36impl GasEscalator for GeometricGasPrice {
37    fn get_gas_price(&self, initial_price: U256, time_elapsed: u64) -> U256 {
38        let mut result = initial_price.as_u64() as f64;
39
40        if time_elapsed >= self.every_secs {
41            let iters = time_elapsed / self.every_secs;
42            for _ in 0..iters {
43                result *= self.coefficient;
44            }
45        }
46
47        let mut result = U256::from(result.ceil() as u64);
48        if let Some(max_price) = self.max_price {
49            result = std::cmp::min(result, max_price);
50        }
51        result
52    }
53}
54
55#[cfg(test)]
56// https://github.com/makerdao/pymaker/blob/master/tests/test_gas.py#L165
57mod tests {
58    use super::*;
59
60    #[test]
61    fn gas_price_increases_with_time() {
62        let oracle = GeometricGasPrice::new(1.125, 10u64, None::<u64>);
63        let initial_price = U256::from(100);
64
65        assert_eq!(oracle.get_gas_price(initial_price, 0), 100.into());
66        assert_eq!(oracle.get_gas_price(initial_price, 1), 100.into());
67        assert_eq!(oracle.get_gas_price(initial_price, 10), 113.into());
68        assert_eq!(oracle.get_gas_price(initial_price, 15), 113.into());
69        assert_eq!(oracle.get_gas_price(initial_price, 20), 127.into());
70        assert_eq!(oracle.get_gas_price(initial_price, 30), 143.into());
71        assert_eq!(oracle.get_gas_price(initial_price, 50), 181.into());
72        assert_eq!(oracle.get_gas_price(initial_price, 100), 325.into());
73    }
74
75    #[test]
76    fn gas_price_should_obey_max_value() {
77        let oracle = GeometricGasPrice::new(1.125, 60u64, Some(2500));
78        let initial_price = U256::from(1000);
79
80        assert_eq!(oracle.get_gas_price(initial_price, 0), 1000.into());
81        assert_eq!(oracle.get_gas_price(initial_price, 1), 1000.into());
82        assert_eq!(oracle.get_gas_price(initial_price, 59), 1000.into());
83        assert_eq!(oracle.get_gas_price(initial_price, 60), 1125.into());
84        assert_eq!(oracle.get_gas_price(initial_price, 119), 1125.into());
85        assert_eq!(oracle.get_gas_price(initial_price, 120), 1266.into());
86        assert_eq!(oracle.get_gas_price(initial_price, 1200), 2500.into());
87        assert_eq!(oracle.get_gas_price(initial_price, 3000), 2500.into());
88        assert_eq!(oracle.get_gas_price(initial_price, 1000000), 2500.into());
89    }
90
91    #[test]
92    #[allow(clippy::float_cmp)]
93    fn behaves_with_realistic_values() {
94        let oracle = GeometricGasPrice::new(1.25, 10u64, None::<u64>);
95        const GWEI: f64 = 1000000000.0;
96        let initial_price = U256::from(100 * GWEI as u64);
97
98        for seconds in &[0u64, 1, 10, 12, 30, 60] {
99            println!(
100                "gas price after {} seconds is {}",
101                seconds,
102                oracle.get_gas_price(initial_price, *seconds).as_u64() as f64 / GWEI
103            );
104        }
105
106        let normalized = |time| oracle.get_gas_price(initial_price, time).as_u64() as f64 / GWEI;
107
108        assert_eq!(normalized(0), 100.0);
109        assert_eq!(normalized(1), 100.0);
110        assert_eq!(normalized(10), 125.0);
111        assert_eq!(normalized(12), 125.0);
112        assert_eq!(normalized(30), 195.3125);
113        assert_eq!(normalized(60), 381.469726563);
114    }
115}
ethers_middleware/gas_escalator/geometric.rs

ethers_middleware/gas_escalator/
geometric.rs
