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// Copyright 2020 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
//! Utility function to make it easier to connect to validators.
use std::collections::HashMap;
use std::pin::Pin;
use futures::{
channel::{mpsc, oneshot},
task::{Poll, self},
stream,
};
use streamunordered::{StreamUnordered, StreamYield};
use polkadot_node_subsystem::{
errors::RuntimeApiError, SubsystemError,
messages::{AllMessages, RuntimeApiMessage, RuntimeApiRequest, NetworkBridgeMessage},
SubsystemContext,
};
use polkadot_primitives::v1::{Hash, ValidatorId, AuthorityDiscoveryId};
use sc_network::PeerId;
/// Error when making a request to connect to validators.
pub enum Error {
/// Attempted to send or receive on a oneshot channel which had been canceled
#[error(transparent)]
Oneshot(#[from] oneshot::Canceled),
/// A subsystem error.
#[error(transparent)]
Subsystem(#[from] SubsystemError),
/// An error in the Runtime API.
#[error(transparent)]
RuntimeApi(#[from] RuntimeApiError),
}
/// Utility function to make it easier to connect to validators.
pub async fn connect_to_validators<Context: SubsystemContext>(
ctx: &mut Context,
relay_parent: Hash,
validators: Vec<ValidatorId>,
) -> Result<ConnectionRequest, Error> {
// ValidatorId -> AuthorityDiscoveryId
let (tx, rx) = oneshot::channel();
ctx.send_message(AllMessages::RuntimeApi(
RuntimeApiMessage::Request(
relay_parent,
RuntimeApiRequest::ValidatorDiscovery(validators.clone(), tx),
)
let maybe_authorities = rx.await??;
let authorities: Vec<_> = maybe_authorities.iter()
.cloned()
.filter_map(|id| id)
.collect();
let validator_map = validators.into_iter()
.zip(maybe_authorities.into_iter())
.filter_map(|(k, v)| v.map(|v| (v, k)))
.collect::<HashMap<AuthorityDiscoveryId, ValidatorId>>();
let connections = connect_to_authorities(ctx, authorities).await?;
Ok(ConnectionRequest {
validator_map,
connections,
})
}
async fn connect_to_authorities<Context: SubsystemContext>(
ctx: &mut Context,
validator_ids: Vec<AuthorityDiscoveryId>,
) -> Result<mpsc::Receiver<(AuthorityDiscoveryId, PeerId)>, Error> {
const PEERS_CAPACITY: usize = 8;
let (connected, connected_rx) = mpsc::channel(PEERS_CAPACITY);
ctx.send_message(AllMessages::NetworkBridge(
NetworkBridgeMessage::ConnectToValidators {
validator_ids,
connected,
}
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/// A struct that assists performing multiple concurrent connection requests.
///
/// This allows concurrent connections to validator sets at different `relay_parents`
/// and multiplexes their results into a single `Stream`.
#[derive(Default)]
pub struct ConnectionRequests {
// added connection requests relay_parent -> StreamUnordered token
id_map: HashMap<Hash, usize>,
// Connection requests themselves.
requests: StreamUnordered<ConnectionRequest>,
}
impl ConnectionRequests {
/// Insert a new connection request.
///
/// If a `ConnectionRequest` under a given `relay_parent` already exists it will
/// be revoked and substituted with a new one.
pub fn put(&mut self, relay_parent: Hash, request: ConnectionRequest) {
self.remove(&relay_parent);
let token = self.requests.push(request);
self.id_map.insert(relay_parent, token);
}
/// Remove a connection request by a given `relay_parent`.
pub fn remove(&mut self, relay_parent: &Hash) {
if let Some(token) = self.id_map.remove(relay_parent) {
Pin::new(&mut self.requests).remove(token);
}
}
}
impl stream::Stream for ConnectionRequests {
/// (relay_parent, validator_id, peer_id).
type Item = (Hash, ValidatorId, PeerId);
fn poll_next(mut self: Pin<&mut Self>, cx: &mut task::Context) -> Poll<Option<Self::Item>> {
// If there are currently no requests going on, pend instead of
// polling `StreamUnordered` which would lead to it terminating
// and returning `Poll::Ready(None)`.
if self.requests.is_empty() {
return Poll::Pending;
}
match Pin::new(&mut self.requests).poll_next(cx) {
Poll::Ready(Some((yielded, token))) => {
match yielded {
StreamYield::Item(item) => {
if let Some((relay_parent, _)) = self.id_map.iter()
.find(|(_, &val)| val == token)
{
return Poll::Ready(Some((*relay_parent, item.0, item.1)));
}
}
StreamYield::Finished(_) => {
// `ConnectionRequest` is fullfilled, but not revoked
}
}
},
_ => {},
}
Poll::Pending
}
}
/// A pending connection request to validators.
/// This struct implements `Stream` to allow for asynchronous
/// discovery of validator addresses.
///
/// NOTE: the request will be revoked on drop.
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#[must_use = "dropping a request will result in its immediate revokation"]
pub struct ConnectionRequest {
validator_map: HashMap<AuthorityDiscoveryId, ValidatorId>,
#[must_use = "streams do nothing unless polled"]
connections: mpsc::Receiver<(AuthorityDiscoveryId, PeerId)>,
}
impl stream::Stream for ConnectionRequest {
type Item = (ValidatorId, PeerId);
fn poll_next(mut self: Pin<&mut Self>, cx: &mut task::Context) -> Poll<Option<Self::Item>> {
if self.validator_map.is_empty() {
return Poll::Ready(None);
}
match Pin::new(&mut self.connections).poll_next(cx) {
Poll::Ready(Some((id, peer_id))) => {
if let Some(validator_id) = self.validator_map.remove(&id) {
return Poll::Ready(Some((validator_id, peer_id)));
} else {
// unknown authority_id
// should be unreachable
}
}
_ => {},
}
Poll::Pending
}
}
#[cfg(test)]
mod tests {
use super::*;
use polkadot_primitives::v1::ValidatorPair;
use sp_core::{Pair, Public};
use futures::{executor, poll, StreamExt, SinkExt};
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#[test]
fn adding_a_connection_request_works() {
let mut connection_requests = ConnectionRequests::default();
executor::block_on(async move {
assert_eq!(poll!(Pin::new(&mut connection_requests).next()), Poll::Pending);
let validator_1 = ValidatorPair::generate().0.public();
let validator_2 = ValidatorPair::generate().0.public();
let auth_1 = AuthorityDiscoveryId::from_slice(&[1; 32]);
let auth_2 = AuthorityDiscoveryId::from_slice(&[2; 32]);
let mut validator_map = HashMap::new();
validator_map.insert(auth_1.clone(), validator_1.clone());
validator_map.insert(auth_2.clone(), validator_2.clone());
let (mut rq1_tx, rq1_rx) = mpsc::channel(8);
let peer_id_1 = PeerId::random();
let peer_id_2 = PeerId::random();
let connection_request_1 = ConnectionRequest {
validator_map,
connections: rq1_rx,
};
let relay_parent_1 = Hash::repeat_byte(1);
connection_requests.put(relay_parent_1.clone(), connection_request_1);
rq1_tx.send((auth_1, peer_id_1.clone())).await.unwrap();
rq1_tx.send((auth_2, peer_id_2.clone())).await.unwrap();
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent_1, validator_1, peer_id_1));
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent_1, validator_2, peer_id_2));
assert_eq!(
poll!(Pin::new(&mut connection_requests).next()),
Poll::Pending,
);
});
}
#[test]
fn adding_two_connection_requests_works() {
let mut connection_requests = ConnectionRequests::default();
executor::block_on(async move {
assert_eq!(poll!(Pin::new(&mut connection_requests).next()), Poll::Pending);
let validator_1 = ValidatorPair::generate().0.public();
let validator_2 = ValidatorPair::generate().0.public();
let auth_1 = AuthorityDiscoveryId::from_slice(&[1; 32]);
let auth_2 = AuthorityDiscoveryId::from_slice(&[2; 32]);
let mut validator_map_1 = HashMap::new();
let mut validator_map_2 = HashMap::new();
validator_map_1.insert(auth_1.clone(), validator_1.clone());
validator_map_2.insert(auth_2.clone(), validator_2.clone());
let (mut rq1_tx, rq1_rx) = mpsc::channel(8);
let (mut rq2_tx, rq2_rx) = mpsc::channel(8);
let peer_id_1 = PeerId::random();
let peer_id_2 = PeerId::random();
let connection_request_1 = ConnectionRequest {
validator_map: validator_map_1,
connections: rq1_rx,
};
let connection_request_2 = ConnectionRequest {
validator_map: validator_map_2,
connections: rq2_rx,
};
let relay_parent_1 = Hash::repeat_byte(1);
let relay_parent_2 = Hash::repeat_byte(2);
connection_requests.put(relay_parent_1.clone(), connection_request_1);
connection_requests.put(relay_parent_2.clone(), connection_request_2);
rq1_tx.send((auth_1, peer_id_1.clone())).await.unwrap();
rq2_tx.send((auth_2, peer_id_2.clone())).await.unwrap();
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent_1, validator_1, peer_id_1));
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent_2, validator_2, peer_id_2));
assert_eq!(
poll!(Pin::new(&mut connection_requests).next()),
Poll::Pending,
);
});
}
#[test]
fn replacing_a_connection_request_works() {
let mut connection_requests = ConnectionRequests::default();
executor::block_on(async move {
assert_eq!(poll!(Pin::new(&mut connection_requests).next()), Poll::Pending);
let validator_1 = ValidatorPair::generate().0.public();
let validator_2 = ValidatorPair::generate().0.public();
let auth_1 = AuthorityDiscoveryId::from_slice(&[1; 32]);
let auth_2 = AuthorityDiscoveryId::from_slice(&[2; 32]);
let mut validator_map_1 = HashMap::new();
let mut validator_map_2 = HashMap::new();
validator_map_1.insert(auth_1.clone(), validator_1.clone());
validator_map_2.insert(auth_2.clone(), validator_2.clone());
let (mut rq1_tx, rq1_rx) = mpsc::channel(8);
let (mut rq2_tx, rq2_rx) = mpsc::channel(8);
let peer_id_1 = PeerId::random();
let peer_id_2 = PeerId::random();
let connection_request_1 = ConnectionRequest {
validator_map: validator_map_1,
connections: rq1_rx,
};
let connection_request_2 = ConnectionRequest {
validator_map: validator_map_2,
connections: rq2_rx,
};
let relay_parent = Hash::repeat_byte(3);
connection_requests.put(relay_parent.clone(), connection_request_1);
rq1_tx.send((auth_1.clone(), peer_id_1.clone())).await.unwrap();
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent, validator_1, peer_id_1.clone()));
connection_requests.put(relay_parent.clone(), connection_request_2);
assert!(rq1_tx.send((auth_1, peer_id_1.clone())).await.is_err());
rq2_tx.send((auth_2, peer_id_2.clone())).await.unwrap();
let res = Pin::new(&mut connection_requests).next().await.unwrap();
assert_eq!(res, (relay_parent, validator_2, peer_id_2));
assert_eq!(
poll!(Pin::new(&mut connection_requests).next()),
Poll::Pending,
);
});
}
}