More gas oracles (#1251)

* Deriver auto_impls for GasOracle

* Provider as GasOracle

* impl fill_transaction in GasOracleMiddleware

Cargo.lock

@@ -135,6 +135,18 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "auto_impl"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7862e21c893d65a1650125d157eaeec691439379a1cee17ee49031b79236ada4"
+dependencies = [
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "auto_impl"
 version = "1.0.1"
@@ -1365,6 +1377,7 @@ name = "ethers-middleware"
 version = "0.17.0"
 dependencies = [
  "async-trait",
+ "auto_impl 0.5.0",
  "ethers-contract",
  "ethers-core",
  "ethers-etherscan",
@@ -1393,7 +1406,7 @@ name = "ethers-providers"
 version = "0.17.0"
 dependencies = [
  "async-trait",
- "auto_impl",
+ "auto_impl 1.0.1",
  "base64 0.13.0",
  "bytes",
  "ethers-core",
@@ -1547,7 +1560,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "089263294bb1c38ac73649a6ad563dd9a5142c8dc0482be15b8b9acb22a1611e"
 dependencies = [
  "arrayvec 0.7.2",
- "auto_impl",
+ "auto_impl 1.0.1",
  "bytes",
  "ethereum-types",
  "fastrlp-derive",

ethers-middleware/Cargo.toml

@@ -21,6 +21,7 @@ ethers-providers = { version = "^0.17.0", path = "../ethers-providers", default-
 ethers-signers = { version = "^0.17.0", path = "../ethers-signers", default-features = false }
 
 async-trait = { version = "0.1.50", default-features = false }
+auto_impl = { version = "0.5.0", default-features = false }
 serde = { version = "1.0.124", default-features = false, features = ["derive"] }
 thiserror = { version = "1.0", default-features = false }
 futures-util = { version = "^0.3" }

ethers-middleware/src/gas_oracle/gas_now.rs

@@ -23,7 +23,7 @@ struct GasNowResponseWrapper {
     data: GasNowResponse,
 }
 
-#[derive(Clone, Debug, Deserialize, PartialEq, PartialOrd)]
+#[derive(Clone, Debug, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
 pub struct GasNowResponse {
     pub rapid: u64,
     pub fast: u64,
@@ -41,7 +41,7 @@ impl GasNow {
     pub fn with_client(client: Client) -> Self {
         let url = Url::parse(GAS_NOW_URL).expect("invalid url");
 
-        Self { url, gas_category: GasCategory::Standard }
+        Self { client, url, gas_category: GasCategory::Standard }
     }
 
     /// Sets the gas price category to be used when fetching the gas price.
@@ -64,7 +64,7 @@ impl GasNow {
 
 impl Default for GasNow {
     fn default() -> Self {
-        Self::new(Client::new())
+        Self::new()
     }
 }
 

ethers-middleware/src/gas_oracle/middleware.rs

@@ -56,24 +56,11 @@ where
         &self.inner
     }
 
-    async fn get_gas_price(&self) -> Result<U256, Self::Error> {
-        Ok(self.gas_oracle.fetch().await?)
-    }
-
-    async fn estimate_eip1559_fees(
+    async fn fill_transaction(
         &self,
-        _: Option<fn(U256, Vec<Vec<U256>>) -> (U256, U256)>,
-    ) -> Result<(U256, U256), Self::Error> {
-        Ok(self.gas_oracle.estimate_eip1559_fees().await?)
-    }
-
-    async fn send_transaction<T: Into<TypedTransaction> + Send + Sync>(
-        &self,
-        tx: T,
+        tx: &mut TypedTransaction,
         block: Option<BlockId>,
-    ) -> Result<PendingTransaction<'_, Self::Provider>, Self::Error> {
-        let mut tx = tx.into();
-
+    ) -> Result<(), Self::Error> {
         match tx {
             TypedTransaction::Legacy(ref mut tx) => {
                 if tx.gas_price.is_none() {
@@ -98,6 +85,28 @@ where
                 }
             }
         };
+
+        self.inner().fill_transaction(tx, block).await.map_err(FromErr::from)
+    }
+
+    async fn get_gas_price(&self) -> Result<U256, Self::Error> {
+        Ok(self.gas_oracle.fetch().await?)
+    }
+
+    async fn estimate_eip1559_fees(
+        &self,
+        _: Option<fn(U256, Vec<Vec<U256>>) -> (U256, U256)>,
+    ) -> Result<(U256, U256), Self::Error> {
+        Ok(self.gas_oracle.estimate_eip1559_fees().await?)
+    }
+
+    async fn send_transaction<T: Into<TypedTransaction> + Send + Sync>(
+        &self,
+        tx: T,
+        block: Option<BlockId>,
+    ) -> Result<PendingTransaction<'_, Self::Provider>, Self::Error> {
+        let mut tx = tx.into();
+        self.fill_transaction(&mut tx, block).await?;
         self.inner.send_transaction(tx, block).await.map_err(MiddlewareError::MiddlewareError)
     }
 }

ethers-middleware/src/gas_oracle/mod.rs

@@ -22,10 +22,18 @@ pub use cache::Cache;
 mod polygon;
 pub use polygon::Polygon;
 
+mod gas_now;
+pub use gas_now::GasNow;
+
+mod provider_oracle;
+pub use provider_oracle::ProviderOracle;
+
 use ethers_core::types::U256;
 
 use async_trait::async_trait;
+use auto_impl::auto_impl;
 use reqwest::Error as ReqwestError;
+use std::error::Error;
 use thiserror::Error;
 
 const GWEI_TO_WEI: u64 = 1000000000;
@@ -73,6 +81,10 @@ pub enum GasOracleError {
 
     #[error("Chain is not supported by the oracle")]
     UnsupportedChain,
+
+    /// Error thrown when the provider failed.
+    #[error("Chain is not supported by the oracle")]
+    ProviderError(#[from] Box<dyn Error + Send + Sync>),
 }
 
 /// `GasOracle` is a trait that an underlying gas oracle needs to implement.
@@ -95,6 +107,7 @@ pub enum GasOracleError {
 /// ```
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
+#[auto_impl(&, Box, Arc)]
 pub trait GasOracle: Send + Sync + std::fmt::Debug {
     /// Makes an asynchronous HTTP query to the underlying `GasOracle`
     ///

ethers-middleware/src/gas_oracle/provider_oracle.rs

@@ -0,0 +1,40 @@
+use crate::gas_oracle::{GasOracle, GasOracleError};
+use async_trait::async_trait;
+use ethers_core::types::U256;
+use ethers_providers::Middleware;
+use std::fmt::Debug;
+
+/// Gas oracle from a [`Middleware`] implementation such as an
+/// Ethereum RPC provider.
+#[derive(Debug)]
+pub struct ProviderOracle<M: Middleware> {
+    provider: M,
+}
+
+impl<M: Middleware> ProviderOracle<M> {
+    pub fn new(provider: M) -> Self {
+        Self { provider }
+    }
+}
+
+#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
+impl<M: Middleware> GasOracle for ProviderOracle<M>
+where
+    <M as Middleware>::Error: 'static,
+{
+    async fn fetch(&self) -> Result<U256, GasOracleError> {
+        self.provider
+            .get_gas_price()
+            .await
+            .map_err(|err| GasOracleError::ProviderError(Box::new(err)))
+    }
+
+    async fn estimate_eip1559_fees(&self) -> Result<(U256, U256), GasOracleError> {
+        // TODO: Allow configuring different estimation functions.
+        self.provider
+            .estimate_eip1559_fees(None)
+            .await
+            .map_err(|err| GasOracleError::ProviderError(Box::new(err)))
+    }
+}