consensus: remove unused offline tracker (#9178)

substrate/primitives/consensus/common/src/lib.rs

@@ -39,7 +39,6 @@ use futures::prelude::*;
 use sp_state_machine::StorageProof;
 
 pub mod block_validation;
-pub mod offline_tracker;
 pub mod error;
 pub mod block_import;
 mod select_chain;

substrate/primitives/consensus/common/src/offline_tracker.rs

@@ -1,137 +0,0 @@
-// This file is part of Substrate.
-
-// Copyright (C) 2018-2021 Parity Technologies (UK) Ltd.
-// SPDX-License-Identifier: Apache-2.0
-
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// 	http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//! Tracks offline validators.
-
-use std::collections::HashMap;
-use std::time::Duration;
-use wasm_timer::Instant;
-
-// time before we report a validator.
-const REPORT_TIME: Duration = Duration::from_secs(60 * 5);
-
-struct Observed {
-	last_round_end: Instant,
-	offline_since: Instant,
-}
-
-impl Observed {
-	fn new() -> Observed {
-		let now = Instant::now();
-		Observed {
-			last_round_end: now,
-			offline_since: now,
-		}
-	}
-
-	fn note_round_end(&mut self, was_online: bool) {
-		let now = Instant::now();
-
-		self.last_round_end = now;
-		if was_online {
-			self.offline_since = now;
-		}
-	}
-
-	fn is_active(&self) -> bool {
-		// can happen if clocks are not monotonic
-		if self.offline_since > self.last_round_end { return true }
-		self.last_round_end.duration_since(self.offline_since) < REPORT_TIME
-	}
-}
-
-/// Tracks offline validators and can issue a report for those offline.
-pub struct OfflineTracker<AuthorityId> {
-	observed: HashMap<AuthorityId, Observed>,
-}
-
-impl<AuthorityId: Eq + Clone + std::hash::Hash> OfflineTracker<AuthorityId> {
-	/// Create a new tracker.
-	pub fn new() -> Self {
-		OfflineTracker { observed: HashMap::new() }
-	}
-
-	/// Note new consensus is starting with the given set of validators.
-	pub fn note_new_block(&mut self, validators: &[AuthorityId]) {
-		use std::collections::HashSet;
-
-		let set: HashSet<_> = validators.iter().cloned().collect();
-		self.observed.retain(|k, _| set.contains(k));
-	}
-
-	/// Note that a round has ended.
-	pub fn note_round_end(&mut self, validator: AuthorityId, was_online: bool) {
-		self.observed.entry(validator)
-			.or_insert_with(Observed::new)
-			.note_round_end(was_online);
-	}
-
-	/// Generate a vector of indices for offline account IDs.
-	pub fn reports(&self, validators: &[AuthorityId]) -> Vec<u32> {
-		validators.iter()
-			.enumerate()
-			.filter_map(|(i, v)| if self.is_online(v) {
-				None
-			} else {
-				Some(i as u32)
-			})
-			.collect()
-	}
-
-	/// Whether reports on a validator set are consistent with our view of things.
-	pub fn check_consistency(&self, validators: &[AuthorityId], reports: &[u32]) -> bool {
-		reports.iter().cloned().all(|r| {
-			let v = match validators.get(r as usize) {
-				Some(v) => v,
-				None => return false,
-			};
-
-			// we must think all validators reported externally are offline.
-			let thinks_online = self.is_online(v);
-			!thinks_online
-		})
-	}
-
-	fn is_online(&self, v: &AuthorityId) -> bool {
-		self.observed.get(v).map(Observed::is_active).unwrap_or(true)
-	}
-}
-
-#[cfg(test)]
-mod tests {
-	use super::*;
-
-	#[test]
-	fn validator_offline() {
-		let mut tracker = OfflineTracker::<u64>::new();
-		let v1 = 1;
-		let v2 = 2;
-		let v3 = 3;
-		tracker.note_round_end(v1, true);
-		tracker.note_round_end(v2, true);
-		tracker.note_round_end(v3, true);
-
-		let slash_time = REPORT_TIME + Duration::from_secs(5);
-		tracker.observed.get_mut(&v1).unwrap().offline_since -= slash_time;
-		tracker.observed.get_mut(&v2).unwrap().offline_since -= slash_time;
-
-		assert_eq!(tracker.reports(&[v1, v2, v3]), vec![0, 1]);
-
-		tracker.note_new_block(&[v1, v3]);
-		assert_eq!(tracker.reports(&[v1, v2, v3]), vec![0]);
-	}
-}