Improve Stream performance (#25)

* perf(provider): remove infinite loop and rely on the runtime to poll the stream

* chore: cargo fmt

ethers-providers/src/stream.rs

@@ -104,7 +104,6 @@ where
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         let mut this = self.project();
 
-        loop {
         *this.state = match this.state {
             FilterWatcherState::WaitForInterval => {
                 // Wait the polling period
@@ -122,8 +121,7 @@ where
                 // vector. Should we make this return a Result instead? Ideally if we're
                 // in a streamed loop we wouldn't want the loop to terminate if an error
                 // is encountered (since it might be a temporary error).
-                    let items: Vec<R> =
+                let items: Vec<R> = futures_util::ready!(fut.as_mut().poll(cx)).unwrap_or_default();
-                        futures_util::ready!(fut.as_mut().poll(cx)).unwrap_or_default();
                 FilterWatcherState::NextItem(items.into_iter())
             }
             // Consume 1 element from the vector. If more elements are in the vector,
@@ -135,7 +133,8 @@ where
                 None => FilterWatcherState::WaitForInterval,
             },
         };
-        }
+
+        Poll::Pending
     }
 }
 

ethers/examples/get_logs.rs

@@ -1,19 +0,0 @@
-use anyhow::Result;
-use ethers::prelude::*;
-use std::convert::TryFrom;
-
-#[tokio::main]
-async fn main() -> Result<()> {
-    // connect to the network
-    let provider = Provider::<Http>::try_from("http://localhost:8545")?;
-
-    let filter = Filter::new()
-        .address_str("f817796F60D268A36a57b8D2dF1B97B14C0D0E1d")?
-        .event("ValueChanged(address,string,string)") // event name
-        .topic0("9729a6fbefefc8f6005933898b13dc45c3a2c8b7".parse::<Address>()?); // indexed param
-
-    let logs = provider.get_logs(&filter).await?;
-    println!("Got logs: {}", serde_json::to_string(&logs).unwrap());
-
-    Ok(())
-}

ethers/examples/watch_blocks.rs

@@ -0,0 +1,13 @@
+use ethers::prelude::*;
+use std::convert::TryFrom;
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    let provider = Provider::<Http>::try_from("http://localhost:8545")?;
+    let mut stream = provider.watch_blocks().await?.interval(2000u64).stream();
+    while let Some(block) = stream.next().await {
+        dbg!(block);
+    }
+
+    Ok(())
+}