Apparently not enough votes on macro blocks about core-rs-albatross

[jgraef]

I took a look at block #46720, which showed not enough votes in the Demo. As you can see below, when tried calculating the votes from the slots, the public key of validator 31 is missing from slots.

The following method counts votes:

    pub fn votes(&self, validators: &GroupedList<LazyPublicKey>) -> u16 {
        // sum up votes of signers that signed prepare and commit
        (&self.prepare.signers & &self.commit.signers)
            .iter()
            .map(|s|
                validators.groups().get(s)
                    .map(|Group (count, _)| *count)
                    .unwrap_or(0)
            )
            .sum()
    }

Note the unwrap_or. We should return an AggregateProofError here. I checked that MacroHeader::validators is correct and Blockchain verifies that fact.

Slots is dervied from CompressedList<_> by turning it into an iterator.

Block

{
  "type": "macro",
  "hash": "a1645ad6b696742421494e4b6146c33e6e56101f4072bd2bd03ba5e7b595bf38",
  "blockNumber": 46720,
  "viewNumber": 0,
  "epoch": 365,
  "parentMacroHash": "b805c1024df2a9e5630ea62d2ff1c2aa8b4903ae0d251311460d7b491047aba6",
  "parentHash": "29cac6d1e3fc2d774e4da41b9b758ca4d48b8750a20089f36e6c54e4dbee900a",
  "seed": "84ec9d8d200a23d4c9db4a109a2e7761e98ba04e43f2b358cbc448c0338a8d222e07bba6991778cda134888cb4e414f6",
  "stateRoot": "8e205e7cd8065e241e23877590ecd9e33cc6251a76964677bf13a9af67f00ee0",
  "extrinsicsRoot": "ffa4f40bc65f22180a8fd7ead157857a7a2b8a4014f4dfc360ae9cee7c081d63",
  "timestamp": 1573572053,
  "timestampMillis": 1573572053044,
  "slashFine": 310229,
  "justification": {
    "votes": 319,
    "prepare": {
      "signature": "96bdc11d37094d24e57b4e659dca44fdce34a027785f0e89c0c6e631890b060ca7043f9793380bd7960ef8d6a7fc6ede",
      "signers": [0, 1, 2, 3, 4, 5, 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]
    },
    "commit": {
      "signature": "abf7d350884c7d4888b712676440c1f858ee187f80b41c559ca20a977e895a9721756a6c7ed2b5e2ba94ec12aabe4718",
      "signers": [0, 1, 2, 3, 7, 8, 9, 10, 11, 12, 13, 14, 16, 21, 23, 25, 26, 27, 29, 30, 31]
    }
  }
}

Slot allocation

Found 31 unique validator keys in slots

• Validator 0 - b84a37ba: 17
• Validator 1 - b79d17a2: 18
• Validator 2 - b6a23ab8: 14
• Validator 3 - b3ea5eae: 17
• Validator 4 - b21846a4: 18
• Validator 5 - b19553a4: 18
• Validator 6 - afbadc8c: 22
• Validator 7 - ae9b7c4b: 20
• Validator 8 - ad271d2a: 19
• Validator 9 - acc6bcd7: 16
• Validator 10 - ab800b4c: 17
• Validator 11 - a5ed1821: 14
• Validator 12 - a4963031: 24
• Validator 13 - a20b1ce6: 18
• Validator 14 - a1d9100f: 17
• Validator 15 - a16c34fe: 14
• Validator 16 - a0465a40: 13
• Validator 17 - 94f1e18e: 25
• Validator 18 - 92e2dfe8: 14
• Validator 19 - 91188fe5: 17
• Validator 20 - 8eecc4e7: 22
• Validator 21 - 8dee007d: 11
• Validator 22 - 8b4b103b: 14
• Validator 23 - 8a7e4dc3: 15
• Validator 24 - 8a77af51: 19
• Validator 25 - 8961b960: 12
• Validator 26 - 8820dc9e: 18
• Validator 27 - 8576fe01: 16
• Validator 28 - 8502eac8: 10
• Validator 29 - 835287fc: 15
• Validator 30 - 811112a5: 8

Votes

ERROR: No public key for: 31
ERROR: No public key for: 31
ERROR: No public key for: 31

• Prepare: 498
• Commit: 327
• Both: 327

[jgraef]

Counting the votes over slots returns 327 votes, whereas the value reported by the RPC server is 319. So the RPC server is reporting even 8 less votes than the slots can count. That corresponds to the 30th validators slot amount.