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package evidence
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import (
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"errors"
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"fmt"
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"sync"
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"time"
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"github.com/gogo/protobuf/proto"
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gogotypes "github.com/gogo/protobuf/types"
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dbm "github.com/tendermint/tm-db"
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clist "github.com/tendermint/tendermint/libs/clist"
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"github.com/tendermint/tendermint/libs/log"
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tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
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sm "github.com/tendermint/tendermint/state"
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"github.com/tendermint/tendermint/types"
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)
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const (
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baseKeyCommitted = byte(0x00)
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baseKeyPending = byte(0x01)
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)
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// Pool maintains a pool of valid evidence to be broadcasted and committed
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type Pool struct {
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logger log.Logger
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evidenceStore dbm.DB
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evidenceList *clist.CList // concurrent linked-list of evidence
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// needed to load validators to verify evidence
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stateDB StateStore
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// needed to load headers to verify evidence
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blockStore BlockStore
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mtx sync.Mutex
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// latest state
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state sm.State
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}
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// NewPool creates an evidence pool. If using an existing evidence store,
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// it will add all pending evidence to the concurrent list.
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func NewPool(evidenceDB dbm.DB, stateDB StateStore, blockStore BlockStore) (*Pool, error) {
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var (
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state = stateDB.LoadState()
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)
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pool := &Pool{
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stateDB: stateDB,
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blockStore: blockStore,
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state: state,
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logger: log.NewNopLogger(),
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evidenceStore: evidenceDB,
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evidenceList: clist.New(),
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}
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// if pending evidence already in db, in event of prior failure, then load it back to the evidenceList
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evList := pool.AllPendingEvidence()
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for _, ev := range evList {
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pool.evidenceList.PushBack(ev)
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}
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return pool, nil
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}
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// PendingEvidence is used primarily as part of block proposal and returns up to maxNum of uncommitted evidence.
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// If maxNum is -1, all evidence is returned. Pending evidence is prioritized based on time.
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func (evpool *Pool) PendingEvidence(maxNum uint32) []types.Evidence {
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evpool.removeExpiredPendingEvidence()
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evidence, err := evpool.listEvidence(baseKeyPending, int64(maxNum))
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if err != nil {
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evpool.logger.Error("Unable to retrieve pending evidence", "err", err)
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}
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return evidence
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}
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// AllPendingEvidence returns all evidence ready to be proposed and committed.
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func (evpool *Pool) AllPendingEvidence() []types.Evidence {
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evpool.removeExpiredPendingEvidence()
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evidence, err := evpool.listEvidence(baseKeyPending, -1)
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if err != nil {
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evpool.logger.Error("Unable to retrieve pending evidence", "err", err)
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}
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return evidence
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}
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// Update uses the latest block & state to update any evidence that has been committed, to prune all expired evidence
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func (evpool *Pool) Update(block *types.Block, state sm.State) {
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// sanity check
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if state.LastBlockHeight != block.Height {
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panic(fmt.Sprintf("Failed EvidencePool.Update sanity check: got state.Height=%d with block.Height=%d",
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state.LastBlockHeight,
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block.Height,
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),
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)
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}
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// update the state
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evpool.updateState(state)
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// remove evidence from pending and mark committed
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evpool.MarkEvidenceAsCommitted(block.Height, block.Evidence.Evidence)
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// prune pending, committed and potential evidence and polc's periodically
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if block.Height%state.ConsensusParams.Evidence.MaxAgeNumBlocks == 0 {
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evpool.logger.Debug("Pruning expired evidence")
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// NOTE: As this is periodic, this implies that there may be some pending evidence in the
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// db that have already expired. However, expired evidence will also be removed whenever
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// PendingEvidence() is called ensuring that no expired evidence is proposed.
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evpool.removeExpiredPendingEvidence()
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}
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}
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// AddEvidence checks the evidence is valid and adds it to the pool.
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func (evpool *Pool) AddEvidence(ev types.Evidence) error {
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evpool.logger.Debug("Attempting to add evidence", "ev", ev)
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if evpool.Has(ev) {
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return nil
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}
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// 1) Verify against state.
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if err := evpool.verify(ev); err != nil {
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return types.NewErrEvidenceInvalid(ev, err)
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}
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// 2) Save to store.
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if err := evpool.addPendingEvidence(ev); err != nil {
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return fmt.Errorf("database error when adding evidence: %v", err)
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}
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// 3) Add evidence to clist.
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evpool.evidenceList.PushBack(ev)
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evpool.logger.Info("Verified new evidence of byzantine behavior", "evidence", ev)
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return nil
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}
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// Verify verifies the evidence against the node's (or evidence pool's) state. More specifically, to validate
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// evidence against state is to validate it against the nodes own header and validator set for that height. This ensures
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// as well as meeting the evidence's own validation rules, that the evidence hasn't expired, that the validator is still
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// bonded and that the evidence can be committed to the chain.
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func (evpool *Pool) Verify(evidence types.Evidence) error {
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if evpool.IsCommitted(evidence) {
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return errors.New("evidence was already committed")
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}
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// We have already verified this piece of evidence - no need to do it again
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if evpool.IsPending(evidence) {
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return nil
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}
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return evpool.verify(evidence)
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}
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func (evpool *Pool) verify(evidence types.Evidence) error {
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return VerifyEvidence(evidence, evpool.State(), evpool.stateDB, evpool.blockStore)
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}
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// MarkEvidenceAsCommitted marks all the evidence as committed and removes it
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// from the queue.
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func (evpool *Pool) MarkEvidenceAsCommitted(height int64, evidence []types.Evidence) {
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// make a map of committed evidence to remove from the clist
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blockEvidenceMap := make(map[string]struct{})
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for _, ev := range evidence {
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// As the evidence is stored in the block store we only need to record the height that it was saved at.
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key := keyCommitted(ev)
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h := gogotypes.Int64Value{Value: height}
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evBytes, err := proto.Marshal(&h)
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if err != nil {
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panic(err)
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}
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if err := evpool.evidenceStore.Set(key, evBytes); err != nil {
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evpool.logger.Error("Unable to add committed evidence", "err", err)
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// if we can't move evidence to committed then don't remove the evidence from pending
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continue
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}
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// if pending, remove from that bucket, remember not all evidence has been seen before
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if evpool.IsPending(ev) {
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evpool.removePendingEvidence(ev)
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blockEvidenceMap[evMapKey(ev)] = struct{}{}
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}
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}
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// remove committed evidence from the clist
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if len(blockEvidenceMap) != 0 {
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evpool.removeEvidenceFromList(blockEvidenceMap)
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}
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}
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// Has checks whether the evidence exists either pending or already committed
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func (evpool *Pool) Has(evidence types.Evidence) bool {
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return evpool.IsPending(evidence) || evpool.IsCommitted(evidence)
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}
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// IsEvidenceExpired checks whether evidence is past the maximum age where it can be used
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func (evpool *Pool) IsEvidenceExpired(evidence types.Evidence) bool {
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return evpool.IsExpired(evidence.Height(), evidence.Time())
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}
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// IsExpired checks whether evidence or a polc is expired by checking whether a height and time is older
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// than set by the evidence consensus parameters
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func (evpool *Pool) IsExpired(height int64, time time.Time) bool {
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var (
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params = evpool.State().ConsensusParams.Evidence
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ageDuration = evpool.State().LastBlockTime.Sub(time)
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ageNumBlocks = evpool.State().LastBlockHeight - height
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)
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return ageNumBlocks > params.MaxAgeNumBlocks &&
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ageDuration > params.MaxAgeDuration
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}
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// IsCommitted returns true if we have already seen this exact evidence and it is already marked as committed.
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func (evpool *Pool) IsCommitted(evidence types.Evidence) bool {
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key := keyCommitted(evidence)
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ok, err := evpool.evidenceStore.Has(key)
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if err != nil {
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evpool.logger.Error("Unable to find committed evidence", "err", err)
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}
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return ok
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}
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// IsPending checks whether the evidence is already pending. DB errors are passed to the logger.
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func (evpool *Pool) IsPending(evidence types.Evidence) bool {
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key := keyPending(evidence)
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ok, err := evpool.evidenceStore.Has(key)
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if err != nil {
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evpool.logger.Error("Unable to find pending evidence", "err", err)
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}
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return ok
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}
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// EvidenceFront goes to the first evidence in the clist
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func (evpool *Pool) EvidenceFront() *clist.CElement {
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return evpool.evidenceList.Front()
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}
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// EvidenceWaitChan is a channel that closes once the first evidence in the list is there. i.e Front is not nil
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func (evpool *Pool) EvidenceWaitChan() <-chan struct{} {
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return evpool.evidenceList.WaitChan()
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}
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// SetLogger sets the Logger.
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func (evpool *Pool) SetLogger(l log.Logger) {
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evpool.logger = l
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}
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// State returns the current state of the evpool.
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func (evpool *Pool) State() sm.State {
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evpool.mtx.Lock()
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defer evpool.mtx.Unlock()
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return evpool.state
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}
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func (evpool *Pool) addPendingEvidence(evidence types.Evidence) error {
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evi, err := types.EvidenceToProto(evidence)
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if err != nil {
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return fmt.Errorf("unable to convert to proto, err: %w", err)
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}
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evBytes, err := proto.Marshal(evi)
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if err != nil {
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return fmt.Errorf("unable to marshal evidence: %w", err)
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}
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key := keyPending(evidence)
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return evpool.evidenceStore.Set(key, evBytes)
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}
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func (evpool *Pool) removePendingEvidence(evidence types.Evidence) {
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key := keyPending(evidence)
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if err := evpool.evidenceStore.Delete(key); err != nil {
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evpool.logger.Error("Unable to delete pending evidence", "err", err)
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} else {
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evpool.logger.Info("Deleted pending evidence", "evidence", evidence)
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}
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}
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// listEvidence lists up to maxNum pieces of evidence for the given prefix key.
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// If maxNum is -1, there's no cap on the size of returned evidence.
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func (evpool *Pool) listEvidence(prefixKey byte, maxNum int64) ([]types.Evidence, error) {
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var count int64
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var evidence []types.Evidence
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iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{prefixKey})
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if err != nil {
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return nil, fmt.Errorf("database error: %v", err)
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}
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defer iter.Close()
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for ; iter.Valid(); iter.Next() {
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if count == maxNum {
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return evidence, nil
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}
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count++
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val := iter.Value()
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var (
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ev types.Evidence
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evpb tmproto.Evidence
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)
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err := proto.Unmarshal(val, &evpb)
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if err != nil {
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return nil, err
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}
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ev, err = types.EvidenceFromProto(&evpb)
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if err != nil {
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return nil, err
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}
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evidence = append(evidence, ev)
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}
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return evidence, nil
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}
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func (evpool *Pool) removeExpiredPendingEvidence() {
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iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{baseKeyPending})
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if err != nil {
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evpool.logger.Error("Unable to iterate over pending evidence", "err", err)
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return
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}
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defer iter.Close()
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blockEvidenceMap := make(map[string]struct{})
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for ; iter.Valid(); iter.Next() {
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evBytes := iter.Value()
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var (
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ev types.Evidence
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evpb tmproto.Evidence
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)
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err := proto.Unmarshal(evBytes, &evpb)
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if err != nil {
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evpool.logger.Error("Unable to unmarshal Evidence", "err", err)
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continue
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}
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ev, err = types.EvidenceFromProto(&evpb)
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if err != nil {
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evpool.logger.Error("Error in transition evidence from protobuf", "err", err)
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continue
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}
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if !evpool.IsExpired(ev.Height()-1, ev.Time()) {
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if len(blockEvidenceMap) != 0 {
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evpool.removeEvidenceFromList(blockEvidenceMap)
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}
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return
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}
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evpool.removePendingEvidence(ev)
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blockEvidenceMap[evMapKey(ev)] = struct{}{}
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}
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}
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func (evpool *Pool) removeEvidenceFromList(
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blockEvidenceMap map[string]struct{}) {
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for e := evpool.evidenceList.Front(); e != nil; e = e.Next() {
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// Remove from clist
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ev := e.Value.(types.Evidence)
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if _, ok := blockEvidenceMap[evMapKey(ev)]; ok {
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evpool.evidenceList.Remove(e)
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e.DetachPrev()
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}
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}
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}
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func (evpool *Pool) updateState(state sm.State) {
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evpool.mtx.Lock()
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defer evpool.mtx.Unlock()
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evpool.state = state
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}
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func evMapKey(ev types.Evidence) string {
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return string(ev.Hash())
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}
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// big endian padded hex
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func bE(h int64) string {
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return fmt.Sprintf("%0.16X", h)
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}
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func keyCommitted(evidence types.Evidence) []byte {
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return append([]byte{baseKeyCommitted}, keySuffix(evidence)...)
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}
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func keyPending(evidence types.Evidence) []byte {
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return append([]byte{baseKeyPending}, keySuffix(evidence)...)
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}
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func keySuffix(evidence types.Evidence) []byte {
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return []byte(fmt.Sprintf("%s/%X", bE(evidence.Height()), evidence.Hash()))
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}
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