ethers-rs/ethers-middleware/README.md

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Markdown

Ethers uses a middleware-based architecture. You start the middleware stack with
a [`Provider`](ethers_providers::Provider), and wrap it with additional
middleware functionalities that you need.
## Available Middleware
- [`Signer`](./signer/struct.SignerMiddleware.html): Signs transactions locally,
with a private key or a hardware wallet
- [`Nonce Manager`](./nonce_manager/struct.NonceManagerMiddleware.html): Manages
nonces locally, allowing the rapid broadcast of transactions without having to
wait for them to be submitted
- [`Gas Escalator`](./gas_escalator/struct.GasEscalatorMiddleware.html): Bumps
transaction gas prices in the background
- [`Gas Oracle`](./gas_oracle/struct.GasOracleMiddleware.html): Allows getting
your gas price estimates from places other than `eth_gasPrice`.
- [`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).
## Example of a middleware stack
```rust no_run
use ethers_providers::{Provider, Http};
use ethers_signers::{LocalWallet, Signer};
use ethers_middleware::{
gas_escalator::{GasEscalatorMiddleware, GeometricGasPrice, Frequency},
gas_oracle::{GasOracleMiddleware, EthGasStation, GasCategory},
signer::SignerMiddleware,
nonce_manager::NonceManagerMiddleware,
};
use ethers_core::rand;
use std::convert::TryFrom;
// Start the stack
let provider = Provider::<Http>::try_from("http://localhost:8545").unwrap();
// Escalate gas prices
let escalator = GeometricGasPrice::new(1.125, 60u64, None::<u64>);
let provider =
GasEscalatorMiddleware::new(provider, escalator, Frequency::PerBlock);
// Sign transactions with a private key
let signer = LocalWallet::new(&mut rand::thread_rng());
let address = signer.address();
let provider = SignerMiddleware::new(provider, signer);
// Use EthGasStation as the gas oracle
let gas_oracle = EthGasStation::new(None);
let provider = GasOracleMiddleware::new(provider, gas_oracle);
// Manage nonces locally
let provider = NonceManagerMiddleware::new(provider, address);
// ... do something with the provider
```
## Example of a middleware stack using a builder
Each [`Middleware`](ethers_providers::Middleware) implements the trait [MiddlewareBuilder](crate::MiddlewareBuilder) to help composition of a [`Middleware`](ethers_providers::Middleware) stack. As usual the composition acts in a wrapping fashion. Adding a new layer results in wrapping its predecessor.
Builder can be used as follows:
```rust
use ethers_providers::{Middleware, Provider, Http};
use std::sync::Arc;
use std::convert::TryFrom;
use ethers_signers::{LocalWallet, Signer};
use ethers_middleware::{*,gas_escalator::*,gas_oracle::*};
fn builder_example() {
let key = "fdb33e2105f08abe41a8ee3b758726a31abdd57b7a443f470f23efce853af169";
let signer = key.parse::<LocalWallet>().unwrap();
let address = signer.address();
let escalator = GeometricGasPrice::new(1.125, 60_u64, None::<u64>);
let gas_oracle = EthGasStation::new(None);
let provider = Provider::<Http>::try_from("http://localhost:8545")
.unwrap()
.wrap_into(|p| GasEscalatorMiddleware::new(p, escalator, Frequency::PerBlock))
.gas_oracle(gas_oracle)
.with_signer(signer)
.nonce_manager(address); // Outermost layer
}
fn builder_example_raw_wrap() {
let key = "fdb33e2105f08abe41a8ee3b758726a31abdd57b7a443f470f23efce853af169";
let signer = key.parse::<LocalWallet>().unwrap();
let address = signer.address();
let escalator = GeometricGasPrice::new(1.125, 60_u64, None::<u64>);
let provider = Provider::<Http>::try_from("http://localhost:8545")
.unwrap()
.wrap_into(|p| GasEscalatorMiddleware::new(p, escalator, Frequency::PerBlock))
.wrap_into(|p| SignerMiddleware::new(p, signer))
.wrap_into(|p| GasOracleMiddleware::new(p, EthGasStation::new(None)))
.wrap_into(|p| NonceManagerMiddleware::new(p, address)); // Outermost layer
}
```