Newer
Older
// 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 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),
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
}
/// 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),
)
)).await?;
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, revoke) = connect_to_authorities(ctx, authorities).await?;
Ok(ConnectionRequest {
validator_map,
connections,
revoke,
})
}
async fn connect_to_authorities<Context: SubsystemContext>(
ctx: &mut Context,
validator_ids: Vec<AuthorityDiscoveryId>,
) -> Result<(mpsc::Receiver<(AuthorityDiscoveryId, PeerId)>, oneshot::Sender<()>), Error> {
const PEERS_CAPACITY: usize = 8;
let (revoke_tx, revoke) = oneshot::channel();
let (connected, connected_rx) = mpsc::channel(PEERS_CAPACITY);
ctx.send_message(AllMessages::NetworkBridge(
NetworkBridgeMessage::ConnectToValidators {
validator_ids,
connected,
revoke,
}
)).await?;
Ok((connected_rx, revoke_tx))
}
/// A pending connection request to validators.
/// This struct implements `Stream` to allow for asynchronous
/// discovery of validator addresses.
///
/// NOTE: you should call `revoke` on this struct
/// when you're no longer interested in the requested validators.
#[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)>,
#[must_use = "a request should be revoked at some point"]
revoke: oneshot::Sender<()>,
}
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
}
}
impl ConnectionRequest {
/// By revoking the request the caller allows the network to
/// free some peer slots thus freeing the resources.
/// It doesn't necessarily lead to peers disconnection though.
/// The revokation is enacted on in the next connection request.
///
/// This can be done either by calling this function or dropping the request.
pub fn revoke(self) {
if let Err(_) = self.revoke.send(()) {
log::warn!(
"Failed to revoke a validator connection request",
);
}
}
}