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davecgh merged 3 commits into from
Oct 7, 2026
+272 −39
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mempool: Prune old vote metadata. #3805

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e8f47dc
mempool: Modernize pool membership test helper.
davecgh Sep 23, 2026
d54099a
mempool: Prune old vote metadata.
davecgh Sep 23, 2026
cd33677
mempool: Add vote pruning tests.
davecgh Sep 23, 2026
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78 changes: 55 additions & 23 deletions internal/mempool/mempool.go
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Original file line number Diff line number Diff line change
Expand Up @@ -255,6 +255,15 @@ type VerboseTxDesc struct {
Depends []*TxDesc
}

// trackedVotes houses metadata about recent votes that vote on the same block.
type trackedVotes struct {
// blockHeight specifies the known good height for the associated block.
blockHeight int64

// votes houses the metadata about the votes.
votes []mining.VoteDesc
}

// voteTracker houses information related to votes that may or may not also be
// in the mempool.
type voteTracker struct {
Expand All @@ -270,14 +279,14 @@ type voteTracker struct {
// regardless of their current membership in the pool.
//
// It is protected by the embedded mtx.
votes map[chainhash.Hash][]mining.VoteDesc
votes map[chainhash.Hash]trackedVotes
}

// newVoteTracker returns an initialized [voteTracker] instance.
func newVoteTracker(cfg *Config) *voteTracker {
return &voteTracker{
cfg: cfg,
votes: make(map[chainhash.Hash][]mining.VoteDesc),
votes: make(map[chainhash.Hash]trackedVotes),
}
}

Expand All @@ -293,12 +302,16 @@ func (t *voteTracker) AddVote(vote *dcrutil.Tx) {
ticketHash := &voteTx.TxIn[1].PreviousOutPoint.Hash

// Nothing to do if a vote for the ticket is already known.
vts := t.votes[votedHash]
tracked, ok := t.votes[votedHash]
vts := tracked.votes
for _, vt := range vts {
if vt.TicketHash == *ticketHash {
return
}
}
if !ok {
tracked.blockHeight = int64(votedHeight)
}

// Append the vote and update the maps.
voteHash := vote.Hash()
Expand All @@ -313,7 +326,8 @@ func (t *voteTracker) AddVote(vote *dcrutil.Tx) {
vts = make([]mining.VoteDesc, 0, t.cfg.ChainParams.TicketsPerBlock)
}
vts = append(vts, voteTxDesc)
t.votes[votedHash] = vts
tracked.votes = vts
t.votes[votedHash] = tracked

approves := func() string {
if approvesParent {
Expand All @@ -334,14 +348,14 @@ func (t *voteTracker) VoteHashesForBlock(blockHash *chainhash.Hash) []chainhash.
defer t.mtx.RUnlock()

// Lookup the vote metadata for the block.
vts, exists := t.votes[*blockHash]
if !exists || len(vts) == 0 {
tracked, exists := t.votes[*blockHash]
if !exists || len(tracked.votes) == 0 {
return nil
}

// Copy the vote hashes from the vote metadata.
hashes := make([]chainhash.Hash, 0, len(vts))
for _, vt := range vts {
hashes := make([]chainhash.Hash, 0, len(tracked.votes))
for _, vt := range tracked.votes {
hashes = append(hashes, vt.VoteHash)
}

Expand All @@ -357,14 +371,30 @@ func (t *voteTracker) VotesForBlocks(hashes []chainhash.Hash) [][]mining.VoteDes

t.mtx.RLock()
for _, hash := range hashes {
votes := t.votes[hash]
result = append(result, votes)
result = append(result, t.votes[hash].votes)
}
t.mtx.RUnlock()

return result
}

// PruneOldVotes prunes vote metadata for blocks that are sufficiently old
// relative to the provided best chain height.
//
// This function is safe for concurrent access.
func (t *voteTracker) PruneOldVotes(height int64) {
t.mtx.Lock()
defer t.mtx.Unlock()

for blockHash, tracked := range t.votes {
if tracked.blockHeight+heightDiffToPruneVotes < height {
log.Debugf("Pruning %d tracked votes for block %v (height %v)",
len(tracked.votes), blockHash, tracked.blockHeight)
delete(t.votes, blockHash)
}
}
}

// orphanTx is a normal transaction that references an ancestor transaction
// that is not yet available. It also contains additional information related
// to it such as an expiration time to help prevent caching the orphan forever.
Expand Down Expand Up @@ -422,8 +452,6 @@ func (mp *TxPool) VotesForBlocks(hashes []chainhash.Hash) [][]mining.VoteDesc {
return mp.voteTrack.VotesForBlocks(hashes)
}

// TODO Pruning of the votes map DECRED

// TSpendHashes returns hashes of all existing tracked tspends. This function
// is safe for concurrent access.
func (mp *TxPool) TSpendHashes() []chainhash.Hash {
Expand Down Expand Up @@ -503,7 +531,6 @@ func (mp *TxPool) RemoveOrphan(tx *dcrutil.Tx) {
//
// This function is safe for concurrent access.
func (mp *TxPool) RemoveOrphansByTag(tag Tag) uint64 {

var numEvicted uint64
mp.mtx.Lock()
for _, otx := range mp.orphans {
Expand Down Expand Up @@ -1047,7 +1074,7 @@ func (mp *TxPool) checkVoteDoubleSpend(vote *dcrutil.Tx) error {
ticketSpent := voteTx.TxIn[1].PreviousOutPoint.Hash
hashVotedOn, heightVotedOn := stake.SSGenBlockVotedOn(voteTx)
mp.voteTrack.mtx.RLock()
for _, existingVote := range mp.voteTrack.votes[hashVotedOn] {
for _, existingVote := range mp.voteTrack.votes[hashVotedOn].votes {
if existingVote.TicketHash == ticketSpent {
// Ensure the vote is still actually in the mempool. This is needed
// because the votes map is not currently kept in sync with the
Expand Down Expand Up @@ -1186,7 +1213,7 @@ func (mp *TxPool) IsRegTxTreeKnownDisapproved(hash *chainhash.Hash) bool {

// There are not possibly enough votes to tell if the regular transaction
// tree is approved or not, so assume it's valid.
vts := mp.voteTrack.votes[*hash]
vts := mp.voteTrack.votes[*hash].votes
if len(vts) <= int(mp.cfg.ChainParams.TicketsPerBlock/2) {
return false
}
Expand Down Expand Up @@ -2180,8 +2207,8 @@ func (mp *TxPool) processOrphans(acceptedTx *dcrutil.Tx, checkTxFlags blockchain
return acceptedTxns
}

// pruneStakeTx is the internal function which implements the public
// PruneStakeTx. See the comment for PruneStakeTx for more details.
// pruneStakeTx is an internal function which implements [TxPool.PruneStakeTx].
// See its comment for more details.
//
// This function MUST be called with the mempool lock held (for writes).
func (mp *TxPool) pruneStakeTx(requiredStakeDifficulty, height int64, isAutoRevocationsEnabled bool) {
Expand Down Expand Up @@ -2238,14 +2265,19 @@ func (mp *TxPool) pruneStakeTx(requiredStakeDifficulty, height int64, isAutoRevo
continue
}
}

// Prune old votes from the map of per-block votes.
mp.voteTrack.PruneOldVotes(height)
}

// PruneStakeTx is the function which is called every time a new block is
// processed. The idea is any outstanding SStx that hasn't been mined in a
// certain period of time (CoinbaseMaturity) and the submitted SStx's
// stake difficulty is below the current required stake difficulty should be
// pruned from mempool since they will never be mined. The same idea stands
// for SSGen and SSRtx.
// PruneStakeTx prunes stake transactions that are no longer deemed relevant for
// the given parameters. It is intended to be called every time a new block is
// added to the main chain. Therefore, the provided parameters are expected to
// be relative to the best chain tip.
//
// For example, it prunes outstanding ticket purchases that have exceeded the
// coinbase maturity or are now below the given required stake difficulty (aka
// ticket price). Similar pruning applies to votes and revocations.
func (mp *TxPool) PruneStakeTx(requiredStakeDifficulty, height int64) {
isAutoRevocationsEnabled, err := mp.cfg.IsAutoRevocationsAgendaActive()
if err != nil {
Expand Down
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