Save prev signature on db only if chained mode is enabled

chain/beacon/chain.go

@@ -41,12 +41,19 @@ type chainStore struct {
 func newChainStore(l log.Logger, cf *Config, cl net.ProtocolClient, c *cryptoStore, store chain.Store, t *ticker) *chainStore {
 	// we make sure the chain is increasing monotically
 	as := newAppendStore(store)
+
+	//
+	ss := newSchemeStore(as, cf.Group.Scheme)
+
 	// we write some stats about the timing when new beacon is saved
-	ds := newDiscrepancyStore(as, l, c.GetGroup())
+	ds := newDiscrepancyStore(ss, l, c.GetGroup())
+
 	// we can register callbacks on it
 	cbs := NewCallbackStore(ds)
+
 	// we give the final append store to the syncer
 	syncer := NewSyncer(l, cbs, c.chain, cl)
+
 	//
 	verifier := chain.NewVerifier(cf.Group.Scheme)
 
@@ -152,11 +159,13 @@ func (c *chainStore) runAggregator() {
 				break
 			}
 			cache.FlushRounds(partial.p.GetRound())
+
 			newBeacon := &chain.Beacon{
 				Round:       roundCache.round,
 				PreviousSig: roundCache.prev,
 				Signature:   finalSig,
 			}
+
 			c.l.Infow("", "beacon_id", beaconID, "aggregated_beacon", newBeacon.Round)
 			if c.tryAppend(lastBeacon, newBeacon) {
 				lastBeacon = newBeacon

chain/beacon/store.go

@@ -7,6 +7,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/drand/drand/common/scheme"
+
 	"github.com/drand/drand/chain"
 	"github.com/drand/drand/key"
 	"github.com/drand/drand/log"
@@ -43,12 +45,44 @@ func (a *appendStore) Put(b *chain.Beacon) error {
 	if b.Round != a.last.Round+1 {
 		return fmt.Errorf("invalid round inserted: last %d, new %d", a.last.Round, b.Round)
 	}
-	if !bytes.Equal(a.last.Signature, b.PreviousSig) {
+	if err := a.Store.Put(b); err != nil {
+		return err
+	}
+	a.last = b
+	return nil
+}
+
+// schemeStore is a store that run different checks depending on what scheme is being used.
+type schemeStore struct {
+	chain.Store
+	sch  scheme.Scheme
+	last *chain.Beacon
+	sync.Mutex
+}
+
+func newSchemeStore(s chain.Store, sch scheme.Scheme) chain.Store {
+	last, _ := s.Last()
+	return &schemeStore{
+		Store: s,
+		last:  last,
+		sch:   sch,
+	}
+}
+
+func (a *schemeStore) Put(b *chain.Beacon) error {
+	a.Lock()
+	defer a.Unlock()
+
+	if a.sch.DecouplePrevSig {
+		b.PreviousSig = nil
+	} else if !bytes.Equal(a.last.Signature, b.PreviousSig) {
 		return fmt.Errorf("invalid previous signature")
 	}
+
 	if err := a.Store.Put(b); err != nil {
 		return err
 	}
+
 	a.last = b
 	return nil
 }