75 lines
3.3 KiB
Markdown
75 lines
3.3 KiB
Markdown
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order: 2
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# State
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## Signing Info (Liveness)
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Every block includes a set of precommits by the validators for the previous block,
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known as the `LastCommitInfo` provided by Tendermint. A `LastCommitInfo` is valid so
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long as it contains precommits from +2/3 of total voting power.
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Proposers are incentivized to include precommits from all validators in the `LastCommitInfo`
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by receiving additional fees proportional to the difference between the voting
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power included in the `LastCommitInfo` and +2/3 (see [TODO](https://github.com/cosmos/cosmos-sdk/issues/967)).
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Validators are penalized for failing to be included in the `LastCommitInfo` for some
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number of blocks by being automatically jailed, potentially slashed, and unbonded.
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Information about validator's liveness activity is tracked through `ValidatorSigningInfo`.
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It is indexed in the store as follows:
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- ValidatorSigningInfo: ` 0x01 | ConsAddress -> amino(valSigningInfo)`
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- MissedBlocksBitArray: ` 0x02 | ConsAddress | LittleEndianUint64(signArrayIndex) -> VarInt(didMiss)`
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The first mapping allows us to easily lookup the recent signing info for a
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validator based on the validator's consensus address. The second mapping acts
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as a bit-array of size `SignedBlocksWindow` that tells us if the validator missed
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the block for a given index in the bit-array. The index in the bit-array is given
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as little endian uint64.
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The result is a `varint` that takes on `0` or `1`, where `0` indicates the
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validator did not miss (did sign) the corresponding block, and `1` indicates
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they missed the block (did not sign).
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Note that the `MissedBlocksBitArray` is not explicitly initialized up-front. Keys
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are added as we progress through the first `SignedBlocksWindow` blocks for a newly
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bonded validator. The `SignedBlocksWindow` parameter defines the size
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(number of blocks) of the sliding window used to track validator liveness.
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The information stored for tracking validator liveness is as follows:
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```protobuf
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// ValidatorSigningInfo defines a validator's signing info for monitoring their
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// liveness activity.
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message ValidatorSigningInfo {
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string address = 1;
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// height at which validator was first a candidate OR was unjailed
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int64 start_height = 2;
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// index offset into signed block bit array
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int64 index_offset = 3;
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// timestamp validator cannot be unjailed until
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google.protobuf.Timestamp jailed_until = 4;
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// whether or not a validator has been tombstoned (killed out of validator
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// set)
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bool tombstoned = 5;
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// missed blocks counter (to avoid scanning the array every time)
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int64 missed_blocks_counter = 6;
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}
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```
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Where:
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- **Address**: The validator's consensus address.
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- **StartHeight**: The height that the candidate became an active validator
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(with non-zero voting power).
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- **IndexOffset**: Index which is incremented each time the validator was a bonded
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in a block and may have signed a precommit or not. This in conjunction with the
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`SignedBlocksWindow` param determines the index in the `MissedBlocksBitArray`.
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- **JailedUntil**: Time for which the validator is jailed until due to liveness downtime.
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- **Tombstoned**: Desribes if the validator is tombstoned or not. It is set once the
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validator commits an equivocation or for any other configured misbehiavor.
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- **MissedBlocksCounter**: A counter kept to avoid unnecessary array reads. Note
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that `Sum(MissedBlocksBitArray)` equals `MissedBlocksCounter` always.
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