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506 lines
14 KiB
506 lines
14 KiB
package types
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import (
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"bytes"
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"fmt"
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"strings"
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"sync"
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. "github.com/tendermint/go-common"
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)
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/*
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VoteSet helps collect signatures from validators at each height+round for a
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predefined vote type.
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We need VoteSet to be able to keep track of conflicting votes when validators
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double-sign. Yet, we can't keep track of *all* the votes seen, as that could
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be a DoS attack vector.
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There are two storage areas for votes.
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1. voteSet.votes
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2. voteSet.votesByBlock
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`.votes` is the "canonical" list of votes. It always has at least one vote,
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if a vote from a validator had been seen at all. Usually it keeps track of
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the first vote seen, but when a 2/3 majority is found, votes for that get
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priority and are copied over from `.votesByBlock`.
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`.votesByBlock` keeps track of a list of votes for a particular block. There
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are two ways a &blockVotes{} gets created in `.votesByBlock`.
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1. the first vote seen by a validator was for the particular block.
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2. a peer claims to have seen 2/3 majority for the particular block.
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Since the first vote from a validator will always get added in `.votesByBlock`
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, all votes in `.votes` will have a corresponding entry in `.votesByBlock`.
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When a &blockVotes{} in `.votesByBlock` reaches a 2/3 majority quorum, its
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votes are copied into `.votes`.
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All this is memory bounded because conflicting votes only get added if a peer
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told us to track that block, each peer only gets to tell us 1 such block, and,
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there's only a limited number of peers.
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NOTE: Assumes that the sum total of voting power does not exceed MaxUInt64.
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*/
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type VoteSet struct {
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chainID string
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height int
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round int
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type_ byte
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mtx sync.Mutex
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valSet *ValidatorSet
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votesBitArray *BitArray
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votes []*Vote // Primary votes to share
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sum int64 // Sum of voting power for seen votes, discounting conflicts
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maj23 *BlockID // First 2/3 majority seen
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votesByBlock map[string]*blockVotes // string(blockHash|blockParts) -> blockVotes
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peerMaj23s map[string]BlockID // Maj23 for each peer
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}
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// Constructs a new VoteSet struct used to accumulate votes for given height/round.
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func NewVoteSet(chainID string, height int, round int, type_ byte, valSet *ValidatorSet) *VoteSet {
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if height == 0 {
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PanicSanity("Cannot make VoteSet for height == 0, doesn't make sense.")
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}
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return &VoteSet{
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chainID: chainID,
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height: height,
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round: round,
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type_: type_,
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valSet: valSet,
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votesBitArray: NewBitArray(valSet.Size()),
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votes: make([]*Vote, valSet.Size()),
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sum: 0,
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maj23: nil,
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votesByBlock: make(map[string]*blockVotes, valSet.Size()),
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peerMaj23s: make(map[string]BlockID),
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}
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}
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func (voteSet *VoteSet) ChainID() string {
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return voteSet.chainID
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}
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func (voteSet *VoteSet) Height() int {
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if voteSet == nil {
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return 0
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} else {
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return voteSet.height
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}
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}
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func (voteSet *VoteSet) Round() int {
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if voteSet == nil {
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return -1
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} else {
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return voteSet.round
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}
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}
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func (voteSet *VoteSet) Type() byte {
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if voteSet == nil {
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return 0x00
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} else {
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return voteSet.type_
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}
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}
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func (voteSet *VoteSet) Size() int {
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if voteSet == nil {
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return 0
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} else {
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return voteSet.valSet.Size()
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}
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}
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// Returns added=true if vote is valid and new.
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// Otherwise returns err=ErrVote[
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// UnexpectedStep | InvalidIndex | InvalidAddress |
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// InvalidSignature | InvalidBlockHash | ConflictingVotes ]
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// Duplicate votes return added=false, err=nil.
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// Conflicting votes return added=*, err=ErrVoteConflictingVotes.
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// NOTE: vote should not be mutated after adding.
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func (voteSet *VoteSet) AddVote(vote *Vote) (added bool, err error) {
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.addVote(vote)
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}
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// NOTE: Validates as much as possible before attempting to verify the signature.
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func (voteSet *VoteSet) addVote(vote *Vote) (added bool, err error) {
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valIndex := vote.ValidatorIndex
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valAddr := vote.ValidatorAddress
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blockKey := vote.BlockID.Key()
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// Ensure that validator index was set
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if valIndex < 0 || len(valAddr) == 0 {
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panic("Validator index or address was not set in vote.")
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}
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// Make sure the step matches.
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if (vote.Height != voteSet.height) ||
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(vote.Round != voteSet.round) ||
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(vote.Type != voteSet.type_) {
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return false, ErrVoteUnexpectedStep
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}
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// Ensure that signer is a validator.
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lookupAddr, val := voteSet.valSet.GetByIndex(valIndex)
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if val == nil {
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return false, ErrVoteInvalidValidatorIndex
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}
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// Ensure that the signer has the right address
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if !bytes.Equal(valAddr, lookupAddr) {
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return false, ErrVoteInvalidValidatorAddress
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}
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// If we already know of this vote, return false.
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if existing, ok := voteSet.getVote(valIndex, blockKey); ok {
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if existing.Signature.Equals(vote.Signature) {
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return false, nil // duplicate
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} else {
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return false, ErrVoteInvalidSignature // NOTE: assumes deterministic signatures
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}
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}
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// Check signature.
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if !val.PubKey.VerifyBytes(SignBytes(voteSet.chainID, vote), vote.Signature) {
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// Bad signature.
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return false, ErrVoteInvalidSignature
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}
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// Add vote and get conflicting vote if any
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added, conflicting := voteSet.addVerifiedVote(vote, blockKey, val.VotingPower)
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if conflicting != nil {
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return added, &ErrVoteConflictingVotes{
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VoteA: conflicting,
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VoteB: vote,
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}
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} else {
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if !added {
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PanicSanity("Expected to add non-conflicting vote")
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}
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return added, nil
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}
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}
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// Returns (vote, true) if vote exists for valIndex and blockKey
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func (voteSet *VoteSet) getVote(valIndex int, blockKey string) (vote *Vote, ok bool) {
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if existing := voteSet.votes[valIndex]; existing != nil && existing.BlockID.Key() == blockKey {
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return existing, true
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}
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if existing := voteSet.votesByBlock[blockKey].getByIndex(valIndex); existing != nil {
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return existing, true
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}
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return nil, false
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}
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// Assumes signature is valid.
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// If conflicting vote exists, returns it.
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func (voteSet *VoteSet) addVerifiedVote(vote *Vote, blockKey string, votingPower int64) (added bool, conflicting *Vote) {
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valIndex := vote.ValidatorIndex
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// Already exists in voteSet.votes?
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if existing := voteSet.votes[valIndex]; existing != nil {
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if existing.BlockID.Equals(vote.BlockID) {
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PanicSanity("addVerifiedVote does not expect duplicate votes")
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} else {
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conflicting = existing
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}
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// Replace vote if blockKey matches voteSet.maj23.
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if voteSet.maj23 != nil && voteSet.maj23.Key() == blockKey {
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voteSet.votes[valIndex] = vote
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voteSet.votesBitArray.SetIndex(valIndex, true)
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}
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// Otherwise don't add it to voteSet.votes
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} else {
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// Add to voteSet.votes and incr .sum
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voteSet.votes[valIndex] = vote
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voteSet.votesBitArray.SetIndex(valIndex, true)
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voteSet.sum += votingPower
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}
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votesByBlock, ok := voteSet.votesByBlock[blockKey]
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if ok {
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if conflicting != nil && !votesByBlock.peerMaj23 {
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// There's a conflict and no peer claims that this block is special.
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return false, conflicting
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}
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// We'll add the vote in a bit.
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} else {
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// .votesByBlock doesn't exist...
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if conflicting != nil {
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// ... and there's a conflicting vote.
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// We're not even tracking this blockKey, so just forget it.
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return false, conflicting
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} else {
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// ... and there's no conflicting vote.
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// Start tracking this blockKey
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votesByBlock = newBlockVotes(false, voteSet.valSet.Size())
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voteSet.votesByBlock[blockKey] = votesByBlock
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// We'll add the vote in a bit.
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}
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}
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// Before adding to votesByBlock, see if we'll exceed quorum
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origSum := votesByBlock.sum
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quorum := voteSet.valSet.TotalVotingPower()*2/3 + 1
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// Add vote to votesByBlock
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votesByBlock.addVerifiedVote(vote, votingPower)
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// If we just crossed the quorum threshold and have 2/3 majority...
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if origSum < quorum && quorum <= votesByBlock.sum {
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// Only consider the first quorum reached
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if voteSet.maj23 == nil {
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maj23BlockID := vote.BlockID
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voteSet.maj23 = &maj23BlockID
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// And also copy votes over to voteSet.votes
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for i, vote := range votesByBlock.votes {
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if vote != nil {
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voteSet.votes[i] = vote
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}
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}
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}
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}
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return true, conflicting
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}
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// If a peer claims that it has 2/3 majority for given blockKey, call this.
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// NOTE: if there are too many peers, or too much peer churn,
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// this can cause memory issues.
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// TODO: implement ability to remove peers too
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func (voteSet *VoteSet) SetPeerMaj23(peerID string, blockID BlockID) {
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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blockKey := blockID.Key()
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// Make sure peer hasn't already told us something.
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if existing, ok := voteSet.peerMaj23s[peerID]; ok {
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if existing.Equals(blockID) {
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return // Nothing to do
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} else {
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return // TODO bad peer!
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}
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}
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voteSet.peerMaj23s[peerID] = blockID
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// Create .votesByBlock entry if needed.
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votesByBlock, ok := voteSet.votesByBlock[blockKey]
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if ok {
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if votesByBlock.peerMaj23 {
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return // Nothing to do
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} else {
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votesByBlock.peerMaj23 = true
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// No need to copy votes, already there.
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}
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} else {
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votesByBlock = newBlockVotes(true, voteSet.valSet.Size())
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voteSet.votesByBlock[blockKey] = votesByBlock
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// No need to copy votes, no votes to copy over.
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}
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}
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func (voteSet *VoteSet) BitArray() *BitArray {
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if voteSet == nil {
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return nil
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.votesBitArray.Copy()
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}
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func (voteSet *VoteSet) BitArrayByBlockID(blockID BlockID) *BitArray {
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if voteSet == nil {
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return nil
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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votesByBlock, ok := voteSet.votesByBlock[blockID.Key()]
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if ok {
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return votesByBlock.bitArray.Copy()
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}
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return nil
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}
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// NOTE: if validator has conflicting votes, returns "canonical" vote
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func (voteSet *VoteSet) GetByIndex(valIndex int) *Vote {
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.votes[valIndex]
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}
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func (voteSet *VoteSet) GetByAddress(address []byte) *Vote {
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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valIndex, val := voteSet.valSet.GetByAddress(address)
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if val == nil {
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PanicSanity("GetByAddress(address) returned nil")
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}
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return voteSet.votes[valIndex]
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}
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func (voteSet *VoteSet) HasTwoThirdsMajority() bool {
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if voteSet == nil {
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return false
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.maj23 != nil
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}
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func (voteSet *VoteSet) IsCommit() bool {
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if voteSet == nil {
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return false
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}
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if voteSet.type_ != VoteTypePrecommit {
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return false
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.maj23 != nil
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}
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func (voteSet *VoteSet) HasTwoThirdsAny() bool {
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if voteSet == nil {
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return false
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return voteSet.sum > voteSet.valSet.TotalVotingPower()*2/3
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}
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// Returns either a blockhash (or nil) that received +2/3 majority.
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// If there exists no such majority, returns (nil, PartSetHeader{}, false).
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func (voteSet *VoteSet) TwoThirdsMajority() (blockID BlockID, ok bool) {
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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if voteSet.maj23 != nil {
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return *voteSet.maj23, true
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} else {
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return BlockID{}, false
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}
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}
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func (voteSet *VoteSet) String() string {
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if voteSet == nil {
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return "nil-VoteSet"
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}
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return voteSet.StringIndented("")
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}
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func (voteSet *VoteSet) StringIndented(indent string) string {
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voteStrings := make([]string, len(voteSet.votes))
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for i, vote := range voteSet.votes {
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if vote == nil {
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voteStrings[i] = "nil-Vote"
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} else {
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voteStrings[i] = vote.String()
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}
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}
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return fmt.Sprintf(`VoteSet{
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%s H:%v R:%v T:%v
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%s %v
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%s %v
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%s %v
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%s}`,
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indent, voteSet.height, voteSet.round, voteSet.type_,
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indent, strings.Join(voteStrings, "\n"+indent+" "),
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indent, voteSet.votesBitArray,
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indent, voteSet.peerMaj23s,
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indent)
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}
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func (voteSet *VoteSet) StringShort() string {
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if voteSet == nil {
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return "nil-VoteSet"
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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return fmt.Sprintf(`VoteSet{H:%v R:%v T:%v +2/3:%v %v %v}`,
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voteSet.height, voteSet.round, voteSet.type_, voteSet.maj23, voteSet.votesBitArray, voteSet.peerMaj23s)
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}
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//--------------------------------------------------------------------------------
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// Commit
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func (voteSet *VoteSet) MakeCommit() *Commit {
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if voteSet.type_ != VoteTypePrecommit {
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PanicSanity("Cannot MakeCommit() unless VoteSet.Type is VoteTypePrecommit")
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}
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voteSet.mtx.Lock()
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defer voteSet.mtx.Unlock()
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// Make sure we have a 2/3 majority
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if voteSet.maj23 == nil {
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PanicSanity("Cannot MakeCommit() unless a blockhash has +2/3")
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}
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// For every validator, get the precommit
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votesCopy := make([]*Vote, len(voteSet.votes))
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copy(votesCopy, voteSet.votes)
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return &Commit{
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BlockID: *voteSet.maj23,
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Precommits: votesCopy,
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}
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}
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//--------------------------------------------------------------------------------
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/*
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Votes for a particular block
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There are two ways a *blockVotes gets created for a blockKey.
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1. first (non-conflicting) vote of a validator w/ blockKey (peerMaj23=false)
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2. A peer claims to have a 2/3 majority w/ blockKey (peerMaj23=true)
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*/
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type blockVotes struct {
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peerMaj23 bool // peer claims to have maj23
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bitArray *BitArray // valIndex -> hasVote?
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votes []*Vote // valIndex -> *Vote
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sum int64 // vote sum
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}
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func newBlockVotes(peerMaj23 bool, numValidators int) *blockVotes {
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return &blockVotes{
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peerMaj23: peerMaj23,
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bitArray: NewBitArray(numValidators),
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votes: make([]*Vote, numValidators),
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sum: 0,
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}
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}
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func (vs *blockVotes) addVerifiedVote(vote *Vote, votingPower int64) {
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valIndex := vote.ValidatorIndex
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if existing := vs.votes[valIndex]; existing == nil {
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vs.bitArray.SetIndex(valIndex, true)
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vs.votes[valIndex] = vote
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vs.sum += votingPower
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}
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}
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func (vs *blockVotes) getByIndex(index int) *Vote {
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if vs == nil {
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return nil
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}
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return vs.votes[index]
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}
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//--------------------------------------------------------------------------------
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// Common interface between *consensus.VoteSet and types.Commit
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type VoteSetReader interface {
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Height() int
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Round() int
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Type() byte
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Size() int
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BitArray() *BitArray
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GetByIndex(int) *Vote
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IsCommit() bool
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}
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