Refactor "lite" to handle delayed validator set changes.

Also, fix consensus liveness issue.

lite/dbprovider.go

@@ -0,0 +1,168 @@
+package lite
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+
+	amino "github.com/tendermint/go-amino"
+	crypto "github.com/tendermint/tendermint/crypto"
+	lerr "github.com/tendermint/tendermint/lite/errors"
+	"github.com/tendermint/tendermint/types"
+	dbm "github.com/tendermint/tmlibs/db"
+)
+
+func signedHeaderKey(chainID string, height int64) []byte {
+	return []byte(fmt.Sprintf("%s/%010d/sh", chainID, height))
+}
+
+var signedHeaderKeyPattern = regexp.MustCompile(`([^/]+)/([0-9]*)/sh`)
+
+func parseSignedHeaderKey(key []byte) (chainID string, height int64, ok bool) {
+	submatch := signedHeaderKeyPattern.FindSubmatch(key)
+	if submatch == nil {
+		return "", 0, false
+	}
+	chainID = string(submatch[1])
+	heightStr := string(submatch[2])
+	heightInt, err := strconv.Atoi(heightStr)
+	if err != nil {
+		return "", 0, false
+	}
+	height = int64(heightInt)
+	ok = true // good!
+	return
+}
+
+func validatorSetKey(chainID string, height int64) []byte {
+	return []byte(fmt.Sprintf("%s/%010d/vs", chainID, height))
+}
+
+type DBProvider struct {
+	chainID string
+	db      dbm.DB
+	cdc     *amino.Codec
+}
+
+func NewDBProvider(db dbm.DB) *DBProvider {
+	//db = dbm.NewDebugDB("db provider "+cmn.RandStr(4), db)
+	cdc := amino.NewCodec()
+	crypto.RegisterAmino(cdc)
+	dbp := &DBProvider{db: db, cdc: cdc}
+	return dbp
+}
+
+// Implements PersistentProvider.
+func (dbp *DBProvider) SaveFullCommit(fc FullCommit) error {
+
+	batch := dbp.db.NewBatch()
+
+	// Save the fc.validators.
+	// We might be overwriting what we already have, but
+	// it makes the logic easier for now.
+	vsKey := validatorSetKey(fc.ChainID(), fc.Height())
+	vsBz, err := dbp.cdc.MarshalBinary(fc.Validators)
+	if err != nil {
+		return err
+	}
+	batch.Set(vsKey, vsBz)
+
+	// Save the fc.NextValidators.
+	nvsKey := validatorSetKey(fc.ChainID(), fc.Height()+1)
+	nvsBz, err := dbp.cdc.MarshalBinary(fc.NextValidators)
+	if err != nil {
+		return err
+	}
+	batch.Set(nvsKey, nvsBz)
+
+	// Save the fc.SignedHeader
+	shKey := signedHeaderKey(fc.ChainID(), fc.Height())
+	shBz, err := dbp.cdc.MarshalBinary(fc.SignedHeader)
+	if err != nil {
+		return err
+	}
+	batch.Set(shKey, shBz)
+
+	// And write sync.
+	batch.WriteSync()
+	return nil
+}
+
+// Implements Provider.
+func (dbp *DBProvider) LatestFullCommit(chainID string, minHeight, maxHeight int64) (
+	FullCommit, error) {
+
+	if minHeight <= 0 {
+		minHeight = 1
+	}
+	if maxHeight == 0 {
+		maxHeight = 1<<63 - 1
+	}
+
+	itr := dbp.db.ReverseIterator(
+		signedHeaderKey(chainID, maxHeight),
+		signedHeaderKey(chainID, minHeight-1),
+	)
+	defer itr.Close()
+
+	for itr.Valid() {
+		key := itr.Key()
+		_, _, ok := parseSignedHeaderKey(key)
+		if !ok {
+			// Skip over other keys.
+			itr.Next()
+			continue
+		} else {
+			// Found the latest full commit signed header.
+			shBz := itr.Value()
+			sh := types.SignedHeader{}
+			err := dbp.cdc.UnmarshalBinary(shBz, &sh)
+			if err != nil {
+				return FullCommit{}, err
+			} else {
+				return dbp.fillFullCommit(sh)
+			}
+		}
+	}
+	return FullCommit{}, lerr.ErrCommitNotFound()
+}
+
+func (dbp *DBProvider) ValidatorSet(chainID string, height int64) (valset *types.ValidatorSet, err error) {
+	return dbp.getValidatorSet(chainID, height)
+}
+
+func (dbp *DBProvider) getValidatorSet(chainID string, height int64) (valset *types.ValidatorSet, err error) {
+	vsBz := dbp.db.Get(validatorSetKey(chainID, height))
+	if vsBz == nil {
+		err = lerr.ErrMissingValidators(chainID, height)
+		return
+	}
+	err = dbp.cdc.UnmarshalBinary(vsBz, &valset)
+	if err != nil {
+		return
+	}
+	valset.TotalVotingPower() // to test deep equality.
+	return
+}
+
+func (dbp *DBProvider) fillFullCommit(sh types.SignedHeader) (FullCommit, error) {
+	var chainID = sh.ChainID
+	var height = sh.Height
+	var valset, nvalset *types.ValidatorSet
+	// Load the validator set.
+	valset, err := dbp.getValidatorSet(chainID, height)
+	if err != nil {
+		return FullCommit{}, err
+	}
+	// Load the next validator set.
+	nvalset, err = dbp.getValidatorSet(chainID, height+1)
+	if err != nil {
+		return FullCommit{}, err
+	}
+	// Return filled FullCommit.
+	return FullCommit{
+		SignedHeader:   sh,
+		Validators:     valset,
+		NextValidators: nvalset,
+	}, nil
+}