feat(examples): add basic event filtering example (#2137)

CHANGELOG.md

@@ -114,6 +114,7 @@
   Added `twos_complement` function for I256.
 - [#1934](https://github.com/gakonst/ethers-rs/pull/1934) Allow 16 calls in multicall.
 - [#1941](https://github.com/gakonst/ethers-rs/pull/1941) Add `add_calls` and `call_array` for `Multicall`.
+- Added basic event log filtering example.
 
 ## ethers-contract-abigen
 

examples/README.md

@@ -22,7 +22,7 @@
     - [x] Events with meta
     - [ ] Methods
 - [ ] Events
-  - [ ] Logs and filtering
+  - [x] Logs and filtering
   - [ ] Solidity topics
 - [ ] Middleware
   - [x] Builder

examples/events/examples/filtering.rs

@@ -0,0 +1,48 @@
+use ethers::{
+    core::types::{Address, Filter, H160, H256, U256},
+    providers::{Http, Middleware, Provider},
+};
+use eyre::Result;
+use std::sync::Arc;
+use tokio;
+
+const HTTP_URL: &str = "https://mainnet.infura.io/v3/c60b0bb42f8a4c6481ecd229eddaca27";
+const V3FACTORY_ADDRESS: &str = "0x1F98431c8aD98523631AE4a59f267346ea31F984";
+const DAI_ADDRESS: &str = "0x6B175474E89094C44Da98b954EedeAC495271d0F";
+const USDC_ADDRESS: &str = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
+const USDT_ADDRESS: &str = "0xdAC17F958D2ee523a2206206994597C13D831ec7";
+
+/// This example demonstrates filtering and parsing event logs by fetching all Uniswap V3 pools
+/// where both tokens are in the set [USDC, USDT, DAI].
+///
+/// V3 factory reference: https://github.com/Uniswap/v3-core/blob/main/contracts/interfaces/IUniswapV3Factory.sol
+#[tokio::main]
+async fn main() -> Result<()> {
+    let provider = Provider::<Http>::try_from(HTTP_URL)?;
+    let client = Arc::new(provider);
+    let token_topics = vec![
+        H256::from(USDC_ADDRESS.parse::<H160>()?),
+        H256::from(USDT_ADDRESS.parse::<H160>()?),
+        H256::from(DAI_ADDRESS.parse::<H160>()?),
+    ];
+    let filter = Filter::new()
+        .address(V3FACTORY_ADDRESS.parse::<Address>()?)
+        .event("PoolCreated(address,address,uint24,int24,address)")
+        .topic1(token_topics.to_vec())
+        .topic2(token_topics.to_vec())
+        .from_block(0);
+    let logs = client.get_logs(&filter).await?;
+    println!("{} pools found!", logs.iter().len());
+    for log in logs.iter() {
+        let token0 = Address::from(log.topics[1]);
+        let token1 = Address::from(log.topics[2]);
+        let fee_tier = U256::from_big_endian(&log.topics[3].as_bytes()[29..32]);
+        let tick_spacing = U256::from_big_endian(&log.data[29..32]);
+        let pool = Address::from(&log.data[44..64].try_into()?);
+        println!(
+            "pool = {}, token0 = {}, token1 = {}, fee = {}, spacing = {}",
+            pool, token0, token1, fee_tier, tick_spacing,
+        );
+    }
+    Ok(())
+}