Newer
Older
// Copyright 2018 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/>.
//! Bridge between the network and consensus service for getting collations to it.
use polkadot_primitives::{AccountId, Hash};
use polkadot_primitives::parachain::{Id as ParaId, Collation};
use futures::sync::oneshot;
use std::collections::hash_map::{HashMap, Entry};
use std::time::{Duration, Instant};
const COLLATION_LIFETIME: Duration = Duration::from_secs(60 * 5);
/// The role of the collator. Whether they're the primary or backup for this parachain.
#[derive(PartialEq, Debug, Clone, Copy, Encode, Decode)]
pub enum Role {
/// Primary collators should send collations whenever it's time.
/// Backup collators should not.
38
39
40
41
42
43
44
45
46
47
48
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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
/// A maintenance action for the collator set.
#[derive(PartialEq, Debug)]
#[allow(dead_code)]
pub enum Action {
/// Disconnect the given collator.
Disconnect(AccountId),
/// Give the collator a new role.
NewRole(AccountId, Role),
}
struct CollationSlot {
live_at: Instant,
entries: SlotEntries,
}
impl CollationSlot {
fn blank_now() -> Self {
CollationSlot {
live_at: Instant::now(),
entries: SlotEntries::Blank,
}
}
fn stay_alive(&self, now: Instant) -> bool {
self.live_at + COLLATION_LIFETIME > now
}
}
enum SlotEntries {
Blank,
// not queried yet
Pending(Vec<Collation>),
// waiting for next to arrive.
Awaiting(Vec<oneshot::Sender<Collation>>),
}
impl SlotEntries {
fn received_collation(&mut self, collation: Collation) {
*self = match ::std::mem::replace(self, SlotEntries::Blank) {
SlotEntries::Blank => SlotEntries::Pending(vec![collation]),
SlotEntries::Pending(mut cs) => {
cs.push(collation);
SlotEntries::Pending(cs)
}
SlotEntries::Awaiting(senders) => {
for sender in senders {
let _ = sender.send(collation.clone());
}
SlotEntries::Blank
}
};
}
fn await_with(&mut self, sender: oneshot::Sender<Collation>) {
*self = match ::std::mem::replace(self, SlotEntries::Blank) {
SlotEntries::Blank => SlotEntries::Awaiting(vec![sender]),
SlotEntries::Awaiting(mut senders) => {
senders.push(sender);
SlotEntries::Awaiting(senders)
}
SlotEntries::Pending(mut cs) => {
let next_collation = cs.pop().expect("empty variant is always `Blank`; qed");
let _ = sender.send(next_collation);
if cs.is_empty() {
SlotEntries::Blank
} else {
SlotEntries::Pending(cs)
}
}
};
}
}
struct ParachainCollators {
primary: AccountId,
backup: Vec<AccountId>,
}
/// Manages connected collators and role assignments from the perspective of a validator.
pub struct CollatorPool {
collators: HashMap<AccountId, ParaId>,
parachain_collators: HashMap<ParaId, ParachainCollators>,
collations: HashMap<(Hash, ParaId), CollationSlot>,
}
impl CollatorPool {
/// Create a new `CollatorPool` object.
pub fn new() -> Self {
CollatorPool {
collators: HashMap::new(),
parachain_collators: HashMap::new(),
collations: HashMap::new(),
}
}
/// Call when a new collator is authenticated. Returns the role.
pub fn on_new_collator(&mut self, account_id: AccountId, para_id: ParaId) -> Role {
self.collators.insert(account_id.clone(), para_id);
match self.parachain_collators.entry(para_id) {
Entry::Vacant(vacant) => {
vacant.insert(ParachainCollators {
primary: account_id,
backup: Vec::new(),
});
Role::Primary
},
Entry::Occupied(mut occupied) => {
occupied.get_mut().backup.push(account_id);
Role::Backup
}
}
}
/// Called when a collator disconnects. If it was the primary, returns a new primary for that
/// parachain.
pub fn on_disconnect(&mut self, account_id: AccountId) -> Option<AccountId> {
self.collators.remove(&account_id).and_then(|para_id| match self.parachain_collators.entry(para_id) {
Entry::Vacant(_) => None,
Entry::Occupied(mut occ) => {
if occ.get().primary == account_id {
if occ.get().backup.is_empty() {
occ.remove();
None
} else {
let mut collators = occ.get_mut();
collators.primary = collators.backup.pop().expect("backup non-empty; qed");
Some(collators.primary)
}
} else {
let pos = occ.get().backup.iter().position(|a| a == &account_id)
.expect("registered collator always present in backup if not primary; qed");
occ.get_mut().backup.remove(pos);
None
}
}
})
}
/// Called when a collation is received.
/// The collator should be registered for the parachain of the collation as a precondition of this function.
/// The collation should have been checked for integrity of signature before passing to this function.
pub fn on_collation(&mut self, account_id: AccountId, relay_parent: Hash, collation: Collation) {
if let Some(para_id) = self.collators.get(&account_id) {
debug_assert_eq!(para_id, &collation.receipt.parachain_index);
// TODO: punish if not primary?
self.collations.entry((relay_parent, para_id.clone()))
.or_insert_with(CollationSlot::blank_now)
.entries
.received_collation(collation);
}
}
/// Wait for a collation from a parachain.
pub fn await_collation(&mut self, relay_parent: Hash, para_id: ParaId, sender: oneshot::Sender<Collation>) {
self.collations.entry((relay_parent, para_id))
.or_insert_with(CollationSlot::blank_now)
.entries
.await_with(sender);
}
/// Call periodically to perform collator set maintenance.
/// Returns a set of actions to perform on the network level.
pub fn maintain_peers(&mut self) -> Vec<Action> {
// TODO: rearrange periodically to new primary, evaluate based on latency etc.
Vec::new()
}
/// called when a block with given hash has been imported.
pub fn collect_garbage(&mut self, chain_head: Option<&Hash>) {
let now = Instant::now();
self.collations.retain(|&(ref h, _), slot| chain_head != Some(h) && slot.stay_alive(now));
}
}
#[cfg(test)]
mod tests {
use super::*;
use polkadot_primitives::parachain::{CandidateReceipt, BlockData, HeadData};
use substrate_primitives::H512;
use futures::Future;
#[test]
fn disconnect_primary_gives_new_primary() {
let mut pool = CollatorPool::new();
let para_id: ParaId = 5.into();
let bad_primary = [0; 32].into();
let good_backup = [1; 32].into();
assert_eq!(pool.on_new_collator(bad_primary, para_id.clone()), Role::Primary);
assert_eq!(pool.on_new_collator(good_backup, para_id.clone()), Role::Backup);
assert_eq!(pool.on_disconnect(bad_primary), Some(good_backup));
assert_eq!(pool.on_disconnect(good_backup), None);
}
#[test]
fn disconnect_backup_removes_from_pool() {
let mut pool = CollatorPool::new();
let para_id: ParaId = 5.into();
let primary = [0; 32].into();
let backup = [1; 32].into();
assert_eq!(pool.on_new_collator(primary, para_id.clone()), Role::Primary);
assert_eq!(pool.on_new_collator(backup, para_id.clone()), Role::Backup);
assert_eq!(pool.on_disconnect(backup), None);
assert!(pool.parachain_collators.get(¶_id).unwrap().backup.is_empty());
}
#[test]
fn await_before_collation() {
let mut pool = CollatorPool::new();
let para_id: ParaId = 5.into();
let primary = [0; 32].into();
let relay_parent = [1; 32].into();
assert_eq!(pool.on_new_collator(primary, para_id.clone()), Role::Primary);
let (tx1, rx1) = oneshot::channel();
let (tx2, rx2) = oneshot::channel();
pool.await_collation(relay_parent, para_id, tx1);
pool.await_collation(relay_parent, para_id, tx2);
pool.on_collation(primary, relay_parent, Collation {
receipt: CandidateReceipt {
parachain_index: para_id,
collator: primary.into(),
signature: H512::from([2; 64]).into(),
head_data: HeadData(vec![1, 2, 3]),
balance_uploads: vec![],
egress_queue_roots: vec![],
fees: 0,
block_data_hash: [3; 32].into(),
},
block_data: BlockData(vec![4, 5, 6]),
});
rx1.wait().unwrap();
rx2.wait().unwrap();
}
#[test]
fn collate_before_await() {
let mut pool = CollatorPool::new();
let para_id: ParaId = 5.into();
let primary = [0; 32].into();
let relay_parent = [1; 32].into();
assert_eq!(pool.on_new_collator(primary, para_id.clone()), Role::Primary);
pool.on_collation(primary, relay_parent, Collation {
receipt: CandidateReceipt {
parachain_index: para_id,
collator: primary.into(),
signature: H512::from([2; 64]).into(),
head_data: HeadData(vec![1, 2, 3]),
balance_uploads: vec![],
egress_queue_roots: vec![],
fees: 0,
block_data_hash: [3; 32].into(),
},
block_data: BlockData(vec![4, 5, 6]),
});
let (tx, rx) = oneshot::channel();
pool.await_collation(relay_parent, para_id, tx);
rx.wait().unwrap();
}
#[test]
fn slot_stay_alive() {
let slot = CollationSlot::blank_now();
let now = slot.live_at;
assert!(slot.stay_alive(now));
assert!(slot.stay_alive(now + Duration::from_secs(10)));
assert!(!slot.stay_alive(now + COLLATION_LIFETIME));
assert!(!slot.stay_alive(now + COLLATION_LIFETIME + Duration::from_secs(10)));
}
}