Skip rehashing function signatures (#965)

`ethercontract-rs` is computing and storing all the function signature
hashes when generating the contract bindings.
Unfortunately we used `ethabi::function::encode_inputs()` which does not
memoize the hash and therefore has to recompute it every time.
This PR makes simply makes sure that we don't rehash the signature every
time.

### Test Plan
Unit tests still work and I was able to continue running the backend
services using this patched version

ethcontract-common/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ethcontract-common"
-version = "0.25.3"
+version = "0.25.4"
 authors = ["Gnosis developers <developers@gnosis.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"

ethcontract-derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ethcontract-derive"
-version = "0.25.3"
+version = "0.25.4"
 authors = ["Gnosis developers <developers@gnosis.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"
@@ -20,8 +20,8 @@ proc-macro = true
 
 [dependencies]
 anyhow = "1.0"
-ethcontract-common = { version = "0.25.3", path = "../ethcontract-common" }
-ethcontract-generate = { version = "0.25.3", path = "../ethcontract-generate", default-features = false }
+ethcontract-common = { version = "0.25.4", path = "../ethcontract-common" }
+ethcontract-generate = { version = "0.25.4", path = "../ethcontract-generate", default-features = false }
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = "2.0"

ethcontract-generate/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ethcontract-generate"
-version = "0.25.3"
+version = "0.25.4"
 authors = ["Gnosis developers <developers@gnosis.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"
@@ -18,7 +18,7 @@ http = ["curl"]
 [dependencies]
 anyhow = "1.0"
 curl = { version = "0.4", optional = true }
-ethcontract-common = { version = "0.25.3", path = "../ethcontract-common" }
+ethcontract-common = { version = "0.25.4", path = "../ethcontract-common" }
 Inflector = "0.11"
 proc-macro2 = "1.0"
 quote = "1.0"

ethcontract-mock/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ethcontract-mock"
-version = "0.25.3"
+version = "0.25.4"
 authors = ["Gnosis developers <developers@gnosis.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"
@@ -12,12 +12,12 @@ Tools for mocking ethereum contracts.
 """
 
 [dependencies]
-ethcontract = { version = "0.25.3", path = "../ethcontract", default-features = false, features = ["derive"] }
+ethcontract = { version = "0.25.4", path = "../ethcontract", default-features = false, features = ["derive"] }
 hex = "0.4"
 mockall = "0.11"
 rlp = "0.5"
 predicates = "3.0"
 
 [dev-dependencies]
 tokio = { version = "1.6", features = ["macros", "rt"] }
-ethcontract-derive = { version = "0.25.3", path = "../ethcontract-derive", default-features = false }
+ethcontract-derive = { version = "0.25.4", path = "../ethcontract-derive", default-features = false }

ethcontract/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ethcontract"
-version = "0.25.3"
+version = "0.25.4"
 authors = ["Gnosis developers <developers@gnosis.io>"]
 edition = "2021"
 license = "MIT OR Apache-2.0"
@@ -35,8 +35,8 @@ ws-tokio = ["web3/ws-tokio"]
 aws-config = { version = "0.55", optional = true }
 aws-sdk-kms = { version = "0.28", optional = true }
 arrayvec = "0.7"
-ethcontract-common = { version = "0.25.3", path = "../ethcontract-common" }
-ethcontract-derive = { version = "0.25.3", path = "../ethcontract-derive", optional = true, default-features = false }
+ethcontract-common = { version = "0.25.4", path = "../ethcontract-common" }
+ethcontract-derive = { version = "0.25.4", path = "../ethcontract-derive", optional = true, default-features = false }
 futures = "0.3"
 futures-timer = "3.0"
 hex = "0.4"

ethcontract/src/contract.rs

@@ -10,7 +10,7 @@ use crate::{
     errors::{DeployError, LinkError},
     tokens::Tokenize,
 };
-use ethcontract_common::abi::{Error as AbiError, Result as AbiResult};
+use ethcontract_common::abi::{encode, Error as AbiError, Result as AbiResult};
 use ethcontract_common::abiext::FunctionExt;
 use ethcontract_common::hash::H32;
 use ethcontract_common::{Abi, Bytecode, Contract, DeploymentInformation};
@@ -202,17 +202,17 @@ impl<T: Transport> Instance<T> {
         R: Tokenize,
     {
         let signature = signature.into().into_inner();
-        let signature = signature.as_ref();
         let function = self
             .methods
-            .get(signature)
+            .get(&signature)
             .map(|(name, index)| &self.abi.functions[name][*index])
             .ok_or_else(|| AbiError::InvalidName(hex::encode(signature)))?;
         let tokens = match params.into_token() {
             ethcontract_common::abi::Token::Tuple(tokens) => tokens,
             _ => unreachable!("function arguments are always tuples"),
         };
-        let data = function.encode_input(&tokens)?;
+
+        let data = signature.iter().copied().chain(encode(&tokens)).collect();
 
         // take ownership here as it greatly simplifies dealing with futures
         // lifetime as it would require the contract Instance to live until