Add transparent multicall middleware

ethers-contract/src/base.rs

@@ -200,7 +200,8 @@ impl BaseContract {
         decode_function_data_raw(function, bytes, false)
     }
 
-    fn get_fn_from_input(&self, input: &[u8]) -> Result<&Function, AbiError> {
+    /// Returns the function from the input bytes (useful for going from tx.data to function)
+    pub fn get_fn_from_input(&self, input: &[u8]) -> Result<&Function, AbiError> {
         let sig: [u8; 4] = input
             .get(0..4)
             .ok_or(AbiError::WrongSelector)?

ethers-contract/src/call.rs

@@ -176,6 +176,30 @@ pub struct FunctionCall<B, M, D> {
     pub(crate) _m: PhantomData<M>,
 }
 
+impl<B, M, D> FunctionCall<B, M, D>
+where
+    B: Borrow<M>,
+    M: Middleware,
+    D: Detokenize,
+{
+    /// Creates a new function call object
+    pub fn new(
+        tx: TypedTransaction,
+        function: Function,
+        client: B,
+        block: Option<BlockId>,
+    ) -> Self {
+        Self {
+            tx,
+            function,
+            client,
+            block,
+            datatype: PhantomData,
+            _m: PhantomData,
+        }
+    }
+}
+
 impl<B, M, D> Clone for FunctionCall<B, M, D>
 where
     B: Clone,

ethers-contract/src/lib.rs

@@ -30,7 +30,7 @@ pub mod stream;
 
 #[cfg(feature = "abigen")]
 #[cfg_attr(docsrs, doc(cfg(feature = "abigen")))]
-mod multicall;
+pub mod multicall;
 #[cfg(feature = "abigen")]
 #[cfg_attr(docsrs, doc(cfg(feature = "abigen")))]
 pub use multicall::{

ethers-contract/src/multicall/constants.rs

@@ -1,5 +1,14 @@
 use ethers_core::types::{Chain, H160};
 
+/// presigned tx that will deploy multicall3
+pub const SIGNED_DEPLOY_MULTICALL_TX: &str = "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+
+/// address to be funded for `SIGNED_DEPLOY_MULTICALL_TX` to succeed
+pub const DEPLOYER_ADDRESS: H160 = H160([
+    0x05, 0xf3, 0x2B, 0x3c, 0xC3, 0x88, 0x84, 0x53, 0xff, 0x71, 0xB0, 0x11, 0x35, 0xB3, 0x4F, 0xF8,
+    0xe4, 0x12, 0x63, 0xF2,
+]);
+
 /// The Multicall3 contract address that is deployed in [`MULTICALL_SUPPORTED_CHAIN_IDS`]:
 /// [`0xcA11bde05977b3631167028862bE2a173976CA11`](https://etherscan.io/address/0xcA11bde05977b3631167028862bE2a173976CA11)
 pub const MULTICALL_ADDRESS: H160 = H160([

ethers-contract/src/multicall/middleware.rs

@@ -202,6 +202,7 @@ impl<M: Middleware> Multicall<M> {
         let address: Address = match address {
             Some(addr) => addr,
             None => {
+                // TODO: replace with eth_getCode?
                 let chain_id = client
                     .get_chainid()
                     .await

ethers-contract/src/multicall/mod.rs

@@ -1,14 +1,18 @@
+//! Contains the `Multicall` contract which enables batching `eth_call` RPC requests
+
 use std::result::Result as StdResult;
 
 /// The Multicall contract bindings. Auto-generated with `abigen`.
 pub mod contract;
 
+/// vendored constants from [Multicall repo](https://github.com/mds1/multicall#new-deployments)
 pub mod constants;
 
 if_providers! {
     mod middleware;
     pub use middleware::{Call, Multicall, MulticallContract};
 
+    /// The Multicall error types.
     pub mod error;
 }
 

ethers-middleware/README.md

@@ -18,6 +18,8 @@ For more information, please refer to the [book](https://gakonst.com/ethers-rs).
 -   [`Transformer`](./transformer/trait.Transformer.html): Allows intercepting and
     transforming a transaction to be broadcasted via a proxy wallet, e.g.
     [`DSProxy`](./transformer/struct.DsProxy.html).
+-   [`MultiCall`](./multicall/struct.MulticallMiddleware.html): transparently batches multiple `eth_call` requests into a single
+    `eth_call` request, reducing the number of round trips to the RPC and saving API CU usage.
 
 ## Examples
 

ethers-middleware/src/lib.rs

@@ -41,6 +41,11 @@ pub use policy::{
 pub mod timelag;
 pub use timelag::TimeLag;
 
+/// The [MulticallMiddleware] provides a way to batch multiple calls into a single call
+pub mod multicall;
+#[cfg(not(target_arch = "wasm32"))]
+pub use multicall::MulticallMiddleware;
+
 /// [MiddlewareBuilder] provides a way to compose many [`Middleware`]s in a concise way.
 pub mod builder;
 pub use builder::MiddlewareBuilder;