feat: derives &, Arc and Box for Middleware (#109)

* test: can stack Middlewares with Arcs

* feat: derive &, Box and Arc impls for Middleware

* chore: fix spacing

Cargo.lock

@@ -266,6 +266,18 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "065374052e7df7ee4047b1160cca5e1467a12351a40b3da123c870ba0b8eda2a"
 
+[[package]]
+name = "auto_impl"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42cbf586c80ada5e5ccdecae80d3ef0854f224e2dd74435f8d87e6831b8d0a38"
+dependencies = [
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.0.1"
@@ -874,6 +886,7 @@ dependencies = [
  "async-tls",
  "async-trait",
  "async-tungstenite",
+ "auto_impl",
  "ethers",
  "ethers-core",
  "futures-channel",
@@ -1884,6 +1897,30 @@ dependencies = [
  "uint",
 ]
 
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
 [[package]]
 name = "proc-macro-hack"
 version = "0.5.19"

ethers-contract/tests/contract.rs

@@ -387,10 +387,7 @@ mod celo_tests {
         let call = contract
             .method::<_, H256>("setValue", "hi".to_owned())
             .unwrap();
-        let pending_tx = call
-            .send()
-            .await
-            .unwrap();
+        let pending_tx = call.send().await.unwrap();
         let _receipt = pending_tx.await.unwrap();
 
         let value: String = contract

ethers-middleware/tests/stack.rs

@@ -57,7 +57,7 @@ mod tests {
         let address = signer.address();
 
         // the base provider
-        let provider = Provider::<Http>::try_from(ganache.endpoint()).unwrap();
+        let provider = Arc::new(Provider::<Http>::try_from(ganache.endpoint()).unwrap());
 
         // the Gas Price escalator middleware is the first middleware above the provider,
         // so that it receives the transaction last, after all the other middleware
@@ -69,7 +69,8 @@ mod tests {
         let provider = GasOracleMiddleware::new(provider, gas_oracle);
 
         // The signing middleware signs txs
-        let provider = SignerMiddleware::new(provider, signer);
+        use std::sync::Arc;
+        let provider = Arc::new(SignerMiddleware::new(provider, signer));
 
         // The nonce manager middleware MUST be above the signing middleware so that it overrides
         // the nonce and the signer does not make any eth_getTransaction count calls

ethers-providers/Cargo.toml

@@ -41,6 +41,7 @@ async-tls = { version = "0.7.0", optional = true }
 
 # needed for parsing while deserialization in gas oracles
 serde-aux = "0.6.1"
+auto_impl = "0.4.1"
 
 [dev-dependencies]
 ethers = { version = "0.1.3", path = "../ethers" }

ethers-providers/src/lib.rs

@@ -118,6 +118,7 @@ mod pubsub;
 pub use pubsub::{PubsubClient, SubscriptionStream};
 
 use async_trait::async_trait;
+use auto_impl::auto_impl;
 use serde::{de::DeserializeOwned, Serialize};
 use std::{error::Error, fmt::Debug, future::Future, pin::Pin};
 
@@ -128,6 +129,7 @@ pub(crate) type PinBoxFut<'a, T> =
     Pin<Box<dyn Future<Output = Result<T, ProviderError>> + Send + 'a>>;
 
 #[async_trait]
+#[auto_impl(&, Box, Arc)]
 /// Trait which must be implemented by data transports to be used with the Ethereum
 /// JSON-RPC provider.
 pub trait JsonRpcClient: Debug + Send + Sync {
@@ -147,6 +149,7 @@ pub trait FromErr<T> {
 }
 
 #[async_trait]
+#[auto_impl(&, Box, Arc)]
 pub trait Middleware: Sync + Send + Debug {
     type Error: Sync + Send + Error + FromErr<<Self::Inner as Middleware>::Error>;
     type Provider: JsonRpcClient;