ethers-rs/ethers-providers/src/stream.rs

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#![allow(clippy::return_self_not_must_use)]
use crate::{JsonRpcClient, Middleware, PinBoxFut, Provider, ProviderError};
use ethers_core::types::{Transaction, TxHash, U256};
use futures_core::{stream::Stream, Future};
use futures_util::{stream, stream::FuturesUnordered, FutureExt, StreamExt};
use pin_project::pin_project;
use serde::{de::DeserializeOwned, Serialize};
use std::{
collections::VecDeque,
fmt::Debug,
pin::Pin,
task::{Context, Poll},
time::Duration,
vec::IntoIter,
};
#[cfg(not(target_arch = "wasm32"))]
use futures_timer::Delay;
#[cfg(target_arch = "wasm32")]
use wasm_timer::Delay;
// https://github.com/tomusdrw/rust-web3/blob/befcb2fb8f3ca0a43e3081f68886fa327e64c8e6/src/api/eth_filter.rs#L20
pub fn interval(duration: Duration) -> impl Stream<Item = ()> + Send + Unpin {
stream::unfold((), move |_| Delay::new(duration).map(|_| Some(((), ())))).map(drop)
}
/// The default polling interval for filters and pending transactions
pub const DEFAULT_POLL_INTERVAL: Duration = Duration::from_millis(7000);
2022-08-03 16:21:55 +00:00
/// The polling interval to use for local endpoints, See [`crate::is_local_endpoint()`]
pub const DEFAULT_LOCAL_POLL_INTERVAL: Duration = Duration::from_millis(100);
enum FilterWatcherState<'a, R> {
WaitForInterval,
GetFilterChanges(PinBoxFut<'a, Vec<R>>),
NextItem(IntoIter<R>),
}
#[must_use = "filters do nothing unless you stream them"]
/// Streams data from an installed filter via `eth_getFilterChanges`
#[pin_project]
pub struct FilterWatcher<'a, P, R> {
/// The filter's installed id on the ethereum node
pub id: U256,
provider: &'a Provider<P>,
// The polling interval
interval: Box<dyn Stream<Item = ()> + Send + Unpin>,
/// statemachine driven by the Stream impl
state: FilterWatcherState<'a, R>,
}
impl<'a, P, R> FilterWatcher<'a, P, R>
where
P: JsonRpcClient,
R: Send + Sync + DeserializeOwned,
{
/// Creates a new watcher with the provided factory and filter id.
pub fn new<T: Into<U256>>(id: T, provider: &'a Provider<P>) -> Self {
Self {
id: id.into(),
interval: Box::new(interval(DEFAULT_POLL_INTERVAL)),
state: FilterWatcherState::WaitForInterval,
provider,
}
}
/// Sets the stream's polling interval
pub fn interval(mut self, duration: Duration) -> Self {
self.interval = Box::new(interval(duration));
self
}
/// Alias for Box::pin, must be called in order to pin the stream and be able
/// to call `next` on it.
pub fn stream(self) -> Pin<Box<Self>> {
Box::pin(self)
}
}
// Advances the filter's state machine
impl<'a, P, R> Stream for FilterWatcher<'a, P, R>
where
P: JsonRpcClient,
R: Serialize + Send + Sync + DeserializeOwned + Debug + 'a,
{
type Item = R;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
let mut this = self.project();
let id = *this.id;
loop {
*this.state = match &mut this.state {
FilterWatcherState::WaitForInterval => {
// Wait the polling period
let _ready = futures_util::ready!(this.interval.poll_next_unpin(cx));
let fut = Box::pin(this.provider.get_filter_changes(id));
FilterWatcherState::GetFilterChanges(fut)
}
FilterWatcherState::GetFilterChanges(fut) => {
// NOTE: If the provider returns an error, this will return an empty
// 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> =
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,
// the next call will immediately go to this branch instead of trying to get
// filter changes again. Once the whole vector is consumed, it will poll again
// for new logs
FilterWatcherState::NextItem(iter) => {
if let item @ Some(_) = iter.next() {
return Poll::Ready(item)
}
FilterWatcherState::WaitForInterval
}
};
}
}
}
impl<'a, P> FilterWatcher<'a, P, TxHash>
where
P: JsonRpcClient,
{
/// Returns a stream that yields the `Transaction`s for the transaction hashes this stream
/// yields.
///
/// This internally calls `Provider::get_transaction` with every new transaction.
/// No more than n futures will be buffered at any point in time, and less than n may also be
/// buffered depending on the state of each future.
pub fn transactions_unordered(self, n: usize) -> TransactionStream<'a, P, Self> {
TransactionStream::new(self.provider, self, n)
}
}
/// Errors `TransactionStream` can throw
#[derive(Debug, thiserror::Error)]
pub enum GetTransactionError {
#[error("Failed to get transaction `{0}`: {1}")]
ProviderError(TxHash, ProviderError),
/// `get_transaction` resulted in a `None`
#[error("Transaction `{0}` not found")]
NotFound(TxHash),
}
impl From<GetTransactionError> for ProviderError {
fn from(err: GetTransactionError) -> Self {
match err {
GetTransactionError::ProviderError(_, err) => err,
err @ GetTransactionError::NotFound(_) => ProviderError::CustomError(err.to_string()),
}
}
}
#[cfg(not(target_arch = "wasm32"))]
type TransactionFut<'a> = Pin<Box<dyn Future<Output = TransactionResult> + Send + 'a>>;
#[cfg(target_arch = "wasm32")]
type TransactionFut<'a> = Pin<Box<dyn Future<Output = TransactionResult> + 'a>>;
type TransactionResult = Result<Transaction, GetTransactionError>;
/// Drains a stream of transaction hashes and yields entire `Transaction`.
#[must_use = "streams do nothing unless polled"]
pub struct TransactionStream<'a, P, St> {
/// Currently running futures pending completion.
pending: FuturesUnordered<TransactionFut<'a>>,
/// Temporary buffered transaction that get started as soon as another future finishes.
buffered: VecDeque<TxHash>,
/// The provider that gets the transaction
provider: &'a Provider<P>,
/// A stream of transaction hashes.
stream: St,
/// max allowed futures to execute at once.
max_concurrent: usize,
}
impl<'a, P: JsonRpcClient, St> TransactionStream<'a, P, St> {
/// Create a new `TransactionStream` instance
pub fn new(provider: &'a Provider<P>, stream: St, max_concurrent: usize) -> Self {
Self {
pending: Default::default(),
buffered: Default::default(),
provider,
stream,
max_concurrent,
}
}
/// Push a future into the set
fn push_tx(&mut self, tx: TxHash) {
let fut = self.provider.get_transaction(tx).then(move |res| match res {
Ok(Some(tx)) => futures_util::future::ok(tx),
Ok(None) => futures_util::future::err(GetTransactionError::NotFound(tx)),
Err(err) => futures_util::future::err(GetTransactionError::ProviderError(tx, err)),
});
self.pending.push(Box::pin(fut));
}
}
impl<'a, P, St> Stream for TransactionStream<'a, P, St>
where
P: JsonRpcClient,
St: Stream<Item = TxHash> + Unpin + 'a,
{
type Item = TransactionResult;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = self.get_mut();
// drain buffered transactions first
while this.pending.len() < this.max_concurrent {
if let Some(tx) = this.buffered.pop_front() {
this.push_tx(tx);
} else {
break
}
}
let mut stream_done = false;
loop {
match Stream::poll_next(Pin::new(&mut this.stream), cx) {
Poll::Ready(Some(tx)) => {
if this.pending.len() < this.max_concurrent {
this.push_tx(tx);
} else {
this.buffered.push_back(tx);
}
}
Poll::Ready(None) => {
stream_done = true;
break
}
_ => break,
}
}
// poll running futures
if let tx @ Poll::Ready(Some(_)) = this.pending.poll_next_unpin(cx) {
return tx
}
if stream_done && this.pending.is_empty() {
// all done
return Poll::Ready(None)
}
Poll::Pending
}
}
#[cfg(test)]
#[cfg(not(target_arch = "wasm32"))]
mod tests {
use super::*;
use crate::{Http, Ws};
use ethers_core::{
types::{TransactionReceipt, TransactionRequest},
utils::Anvil,
};
use futures_util::{FutureExt, StreamExt};
use std::{collections::HashSet, convert::TryFrom};
#[tokio::test]
async fn can_stream_pending_transactions() {
let num_txs = 5;
let geth = Anvil::new().block_time(2u64).spawn();
let provider = Provider::<Http>::try_from(geth.endpoint())
.unwrap()
.interval(Duration::from_millis(1000));
let ws = Ws::connect(geth.ws_endpoint()).await.unwrap();
let ws_provider = Provider::new(ws);
let accounts = provider.get_accounts().await.unwrap();
let tx = TransactionRequest::new().from(accounts[0]).to(accounts[0]).value(1e18 as u64);
let mut sending = futures_util::future::join_all(
std::iter::repeat(tx.clone())
.take(num_txs)
.enumerate()
.map(|(nonce, tx)| tx.nonce(nonce))
.map(|tx| async {
provider.send_transaction(tx, None).await.unwrap().await.unwrap().unwrap()
}),
)
.fuse();
let mut watch_tx_stream = provider
.watch_pending_transactions()
.await
.unwrap()
.transactions_unordered(num_txs)
.fuse();
let mut sub_tx_stream =
ws_provider.subscribe_pending_txs().await.unwrap().transactions_unordered(2).fuse();
let mut sent: Option<Vec<TransactionReceipt>> = None;
let mut watch_received: Vec<Transaction> = Vec::with_capacity(num_txs);
let mut sub_received: Vec<Transaction> = Vec::with_capacity(num_txs);
loop {
futures_util::select! {
txs = sending => {
sent = Some(txs)
},
tx = watch_tx_stream.next() => watch_received.push(tx.unwrap().unwrap()),
tx = sub_tx_stream.next() => sub_received.push(tx.unwrap().unwrap()),
};
if watch_received.len() == num_txs && sub_received.len() == num_txs {
if let Some(ref sent) = sent {
assert_eq!(sent.len(), watch_received.len());
let sent_txs =
sent.iter().map(|tx| tx.transaction_hash).collect::<HashSet<_>>();
assert_eq!(sent_txs, watch_received.iter().map(|tx| tx.hash).collect());
assert_eq!(sent_txs, sub_received.iter().map(|tx| tx.hash).collect());
break
}
}
}
}
#[tokio::test]
async fn can_stream_transactions() {
let anvil = Anvil::new().block_time(2u64).spawn();
let provider =
Provider::<Http>::try_from(anvil.endpoint()).unwrap().with_sender(anvil.addresses()[0]);
let accounts = provider.get_accounts().await.unwrap();
let tx = TransactionRequest::new().from(accounts[0]).to(accounts[0]).value(1e18 as u64);
let txs = vec![tx.clone().nonce(0u64), tx.clone().nonce(1u64), tx.clone().nonce(2u64)];
let txs =
futures_util::future::join_all(txs.into_iter().map(|tx| async {
provider.send_transaction(tx, None).await.unwrap().await.unwrap()
}))
.await;
let stream = TransactionStream::new(
&provider,
stream::iter(txs.iter().cloned().map(|tx| tx.unwrap().transaction_hash)),
10,
);
let res =
stream.collect::<Vec<_>>().await.into_iter().collect::<Result<Vec<_>, _>>().unwrap();
assert_eq!(res.len(), txs.len());
assert_eq!(
res.into_iter().map(|tx| tx.hash).collect::<HashSet<_>>(),
txs.into_iter().map(|tx| tx.unwrap().transaction_hash).collect()
);
}
}