ethers-rs/ethers-middleware/src/gas_oracle/etherchain.rs

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use ethers_core::types::U256;
use async_trait::async_trait;
use reqwest::Client;
use serde::Deserialize;
use serde_aux::prelude::*;
use url::Url;
use crate::gas_oracle::{GasCategory, GasOracle, GasOracleError, GWEI_TO_WEI};
const ETHERCHAIN_URL: &str = "https://www.etherchain.org/api/gasPriceOracle";
/// A client over HTTP for the [Etherchain](https://www.etherchain.org/api/gasPriceOracle) gas tracker API
/// that implements the `GasOracle` trait
#[derive(Debug)]
pub struct Etherchain {
client: Client,
url: Url,
gas_category: GasCategory,
}
impl Default for Etherchain {
fn default() -> Self {
Self::new()
}
}
#[derive(Deserialize)]
struct EtherchainResponse {
#[serde(deserialize_with = "deserialize_number_from_string")]
#[serde(rename = "safeLow")]
safe_low: f32,
#[serde(deserialize_with = "deserialize_number_from_string")]
standard: f32,
#[serde(deserialize_with = "deserialize_number_from_string")]
fast: f32,
#[serde(deserialize_with = "deserialize_number_from_string")]
fastest: f32,
}
impl Etherchain {
pub fn new() -> Self {
let url = Url::parse(ETHERCHAIN_URL).expect("invalid url");
Etherchain {
client: Client::new(),
url,
gas_category: GasCategory::Standard,
}
}
pub fn category(mut self, gas_category: GasCategory) -> Self {
self.gas_category = gas_category;
self
}
}
#[async_trait]
impl GasOracle for Etherchain {
async fn fetch(&self) -> Result<U256, GasOracleError> {
let res = self
.client
.get(self.url.as_ref())
.send()
.await?
.json::<EtherchainResponse>()
.await?;
let gas_price = match self.gas_category {
GasCategory::SafeLow => U256::from((res.safe_low as u64) * GWEI_TO_WEI),
GasCategory::Standard => U256::from((res.standard as u64) * GWEI_TO_WEI),
GasCategory::Fast => U256::from((res.fast as u64) * GWEI_TO_WEI),
GasCategory::Fastest => U256::from((res.fastest as u64) * GWEI_TO_WEI),
};
Ok(gas_price)
}
}