      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     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
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345

    // Copyright 2015-2017 Parity Technologies (UK) Ltd.
    // This file is part of Parity.

    // Parity 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.

    // Parity 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 Parity.  If not, see <http://www.gnu.org/licenses/>.

    //! Collects votes on hashes at each Message::Round.

    use std::fmt::Debug;
    use util::*;
    use rlp::Encodable;

    pub trait Message: Clone + PartialEq + Eq + Hash + Encodable + Debug {
    	type Round: Clone + PartialEq + Eq + Hash + Default + Debug + Ord;

    	fn signature(&self) -> H520;

    	fn block_hash(&self) -> Option<H256>;

    	fn round(&self) -> &Self::Round;

    	fn is_broadcastable(&self) -> bool;
    }

    /// Storing all Proposals, Prevotes and Precommits.
    #[derive(Debug)]
    pub struct VoteCollector<M: Message> {
    	votes: RwLock<BTreeMap<M::Round, StepCollector<M>>>,
    }

    #[derive(Debug, Default)]
    struct StepCollector<M: Message> {
    	voted: HashSet<Address>,
    	pub block_votes: HashMap<Option<H256>, HashMap<H520, Address>>,
    	messages: HashSet<M>,
    }

    impl <M: Message> StepCollector<M> {
    	/// Returns Some(&Address) when validator is double voting.
    	fn insert<'a>(&mut self, message: M, address: &'a Address) -> Option<&'a Address> {
    		// Do nothing when message was seen.
    		if self.messages.insert(message.clone()) {
    			if self.voted.insert(address.clone()) {
    				self
    					.block_votes
    					.entry(message.block_hash())
    					.or_insert_with(HashMap::new)
    					.insert(message.signature(), address.clone());
    			} else {
    				// Bad validator sent a different message.
    				return Some(address);
    			}
    		}
    		None
    	}

    	/// Count all votes for the given block hash at this round.
    	fn count_block(&self, block_hash: &Option<H256>) -> usize {
    		self.block_votes.get(block_hash).map_or(0, HashMap::len)
    	}

    	/// Count all votes collected for the given round.
    	fn count(&self) -> usize {
    		self.block_votes.values().map(HashMap::len).sum()
    	}
    }

    #[derive(Debug)]
    pub struct SealSignatures {
    	pub proposal: H520,
    	pub votes: Vec<H520>,
    }

    impl PartialEq for SealSignatures {
    	fn eq(&self, other: &SealSignatures) -> bool {
    		self.proposal == other.proposal
    			&& self.votes.iter().collect::<HashSet<_>>() == other.votes.iter().collect::<HashSet<_>>()
    	}
    }

    impl Eq for SealSignatures {}

    impl <M: Message + Default> Default for VoteCollector<M> {
    	fn default() -> Self {
    		let mut collector = BTreeMap::new();
    		// Insert dummy entry to fulfill invariant: "only messages newer than the oldest are inserted".
    		collector.insert(Default::default(), Default::default());
    		VoteCollector { votes: RwLock::new(collector) }
    	}
    }

    impl <M: Message + Default + Encodable + Debug> VoteCollector<M> {
    	/// Insert vote if it is newer than the oldest one.
    	pub fn vote<'a>(&self, message: M, voter: &'a Address) -> Option<&'a Address> {
    		self
    			.votes
    			.write()
    			.entry(message.round().clone())
    			.or_insert_with(Default::default)
    			.insert(message, voter)
    	}

    	/// Checks if the message should be ignored.
    	pub fn is_old_or_known(&self, message: &M) -> bool {
    		self
    			.votes
    			.read()
    			.get(&message.round())
    			.map_or(false, |c| {
    				let is_known = c.messages.contains(message);
    				if is_known { trace!(target: "poa", "Known message: {:?}.", message); }
    				is_known
    			})
    		|| {
    			let guard = self.votes.read();
    			let is_old = guard.keys().next().map_or(true, |oldest| message.round() <= oldest);
    			if is_old { trace!(target: "poa", "Old message {:?}.", message); }
    			is_old
    		}
    	}

    	/// Throws out messages older than message, leaves message as marker for the oldest.
    	pub fn throw_out_old(&self, vote_round: &M::Round) {
    		let mut guard = self.votes.write();
    		let new_collector = guard.split_off(vote_round);
    		*guard = new_collector;
    	}

    	/// Collects the signatures used to seal a block.
    	pub fn seal_signatures(&self, proposal_round: M::Round, commit_round: M::Round, block_hash: &H256) -> Option<SealSignatures> {
    		let ref bh = Some(*block_hash);
    		let maybe_seal = {
    			let guard = self.votes.read();
    			guard
    				.get(&proposal_round)
    				.and_then(|c| c.block_votes.get(bh))
    				.and_then(|proposals| proposals.keys().next())
    				.map(|proposal| SealSignatures {
    					proposal: proposal.clone(),
    					votes: guard
    						.get(&commit_round)
    						.and_then(|c| c.block_votes.get(bh))
    						.map(|precommits| precommits.keys().cloned().collect())
    						.unwrap_or_else(Vec::new),
    				})
    				.and_then(|seal| if seal.votes.is_empty() { None } else { Some(seal) })
    		};
    		if maybe_seal.is_some() {
    				// Remove messages that are no longer relevant.
    				self.throw_out_old(&commit_round);
    		}
    		maybe_seal
    	}

    	/// Count votes which agree with the given message.
    	pub fn count_aligned_votes(&self, message: &M) -> usize {
    		self
    			.votes
    			.read()
    			.get(&message.round())
    			.map_or(0, |m| m.count_block(&message.block_hash()))
    	}

    	/// Count all votes collected for a given round.
    	pub fn count_round_votes(&self, vote_round: &M::Round) -> usize {
    		self.votes.read().get(vote_round).map_or(0, StepCollector::count)
    	}

    	/// Get all messages older than the round.
    	pub fn get_up_to(&self, round: &M::Round) -> Vec<Bytes> {
    		let guard = self.votes.read();
    		guard
    			.iter()
    			.take_while(|&(r, _)| r <= round)
    			.map(|(_, c)| c.messages.iter().filter(|m| m.is_broadcastable()).map(|m| ::rlp::encode(m).to_vec()).collect::<Vec<_>>())
    			.fold(Vec::new(), |mut acc, mut messages| { acc.append(&mut messages); acc })
    	}

    	/// Retrieve address from which the message was sent from cache.
    	pub fn get(&self, message: &M) -> Option<Address> {
    		let guard = self.votes.read();
    		guard.get(&message.round()).and_then(|c| c.block_votes.get(&message.block_hash())).and_then(|origins| origins.get(&message.signature()).cloned())
    	}

    	/// Count the number of total rounds kept track of.
    	#[cfg(test)]
    	pub fn len(&self) -> usize {
    		self.votes.read().len()
    	}
    }

    #[cfg(test)]
    mod tests {
    	use util::*;
    	use rlp::*;
    	use super::*;

    	#[derive(Debug, PartialEq, Eq, Clone, Hash, Default)]
    	struct TestMessage {
    		step: TestStep,
    		block_hash: Option<H256>,
    		signature: H520,
    	}

    	type TestStep = u64;

    	impl Message for TestMessage {
    		type Round = TestStep;

    		fn signature(&self) -> H520 { self.signature }

    		fn block_hash(&self) -> Option<H256> { self.block_hash }

    		fn round(&self) -> &TestStep { &self.step }

    		fn is_broadcastable(&self) -> bool { true }
    	}

    	impl Encodable for TestMessage {
    		fn rlp_append(&self, s: &mut RlpStream) {
    			s.begin_list(3)
    				.append(&self.signature)
    				.append(&self.step)
    				.append(&self.block_hash.unwrap_or_else(H256::zero));
    		}
    	}

    	fn random_vote(collector: &VoteCollector<TestMessage>, signature: H520, step: TestStep, block_hash: Option<H256>) -> bool {
    		full_vote(collector, signature, step, block_hash, &H160::random()).is_none()
    	}

    	fn full_vote<'a>(collector: &VoteCollector<TestMessage>, signature: H520, step: TestStep, block_hash: Option<H256>, address: &'a Address) -> Option<&'a Address> {
    		collector.vote(TestMessage { signature: signature, step: step, block_hash: block_hash }, address)
    	}

    	#[test]
    	fn seal_retrieval() {
    		let collector = VoteCollector::default();
    		let bh = Some("1".sha3());
    		let mut signatures = Vec::new();
    		for _ in 0..5 {
    			signatures.push(H520::random());
    		}
    		let propose_round = 3;
    		let commit_round = 5;
    		// Wrong round.
    		random_vote(&collector, signatures[4].clone(), 1, bh.clone());
    		// Good proposal
    		random_vote(&collector, signatures[0].clone(), propose_round.clone(), bh.clone());
    		// Wrong block proposal.
    		random_vote(&collector, signatures[0].clone(), propose_round.clone(), Some("0".sha3()));
    		// Wrong block commit.
    		random_vote(&collector, signatures[3].clone(), commit_round.clone(), Some("0".sha3()));
    		// Wrong round.
    		random_vote(&collector, signatures[0].clone(), 6, bh.clone());
    		// Wrong round.
    		random_vote(&collector, signatures[0].clone(), 4, bh.clone());
    		// Relevant commit.
    		random_vote(&collector, signatures[2].clone(), commit_round.clone(), bh.clone());
    		// Replicated vote.
    		random_vote(&collector, signatures[2].clone(), commit_round.clone(), bh.clone());
    		// Wrong round.
    		random_vote(&collector, signatures[4].clone(), 6, bh.clone());
    		// Relevant precommit.
    		random_vote(&collector, signatures[1].clone(), commit_round.clone(), bh.clone());
    		// Wrong round, same signature.
    		random_vote(&collector, signatures[1].clone(), 7, bh.clone());
    		let seal = SealSignatures {
    			proposal: signatures[0],
    			votes: signatures[1..3].to_vec()
    		};
    		assert_eq!(seal, collector.seal_signatures(propose_round, commit_round, &bh.unwrap()).unwrap());
    	}

    	#[test]
    	fn count_votes() {
    		let collector = VoteCollector::default();
    		let round1 = 1;
    		let round3 = 3;
    		// good 1
    		random_vote(&collector, H520::random(), round1, Some("0".sha3()));
    		random_vote(&collector, H520::random(), 0, Some("0".sha3()));
    		// good 3
    		random_vote(&collector, H520::random(), round3, Some("0".sha3()));
    		random_vote(&collector, H520::random(), 2, Some("0".sha3()));
    		// good prevote
    		random_vote(&collector, H520::random(), round1, Some("1".sha3()));
    		// good prevote
    		let same_sig = H520::random();
    		random_vote(&collector, same_sig.clone(), round1, Some("1".sha3()));
    		random_vote(&collector, same_sig, round1, Some("1".sha3()));
    		// good precommit
    		random_vote(&collector, H520::random(), round3, Some("1".sha3()));
    		// good prevote
    		random_vote(&collector, H520::random(), round1, Some("0".sha3()));
    		random_vote(&collector, H520::random(), 4, Some("2".sha3()));

    		assert_eq!(collector.count_round_votes(&round1), 4);
    		assert_eq!(collector.count_round_votes(&round3), 2);

    		let message = TestMessage {
    			signature: H520::default(),
    			step: round1,
    			block_hash: Some("1".sha3())
    		};
    		assert_eq!(collector.count_aligned_votes(&message), 2);
    	}

    	#[test]
    	fn remove_old() {
    		let collector = VoteCollector::default();
    		let vote = |round, hash| {
    			random_vote(&collector, H520::random(), round, hash);
    		};
    		vote(6, Some("0".sha3()));
    		vote(3, Some("0".sha3()));
    		vote(7, Some("0".sha3()));
    		vote(8, Some("1".sha3()));
    		vote(1, Some("1".sha3()));

    		collector.throw_out_old(&7);
    		assert_eq!(collector.len(), 2);
    	}

    	#[test]
    	fn malicious_authority() {
    		let collector = VoteCollector::default();
    		let round = 3;
    		// Vote is inserted fine.
    		assert!(full_vote(&collector, H520::random(), round, Some("0".sha3()), &Address::default()).is_none());
    		// Returns the double voting address.
    		full_vote(&collector, H520::random(), round, Some("1".sha3()), &Address::default()).unwrap();
    		assert_eq!(collector.count_round_votes(&round), 1);
    	}
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result
+
  Collapse/expand all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)