feat: use the scaled power for winning tickets (#375)

This brings us in-line with the FIP.

Author: Stebalien

gpbft/gpbft.go

@@ -460,7 +460,7 @@ func (i *instance) tryCurrentPhase() error {
 // It must be safe for concurrent use.
 func ValidateMessage(powerTable *PowerTable, beacon []byte, host Host, msg *GMessage) error {
 	// Check sender is eligible.
-	senderPower, _, senderPubKey := powerTable.Get(msg.Sender)
+	senderPower, senderPubKey := powerTable.Get(msg.Sender)
 	if senderPower == 0 {
 		return xerrors.Errorf("sender %d with zero power or not in power table", msg.Sender)
 	}
@@ -1150,7 +1150,7 @@ func (q *quorumState) receiveSender(sender ActorID) (uint16, bool) {
 		return 0, false
 	}
 	q.senders[sender] = struct{}{}
-	senderPower, _, _ := q.powerTable.Get(sender)
+	senderPower, _ := q.powerTable.Get(sender)
 	q.sendersTotalPower += senderPower
 	return senderPower, true
 }
@@ -1433,9 +1433,9 @@ func (c *convergeState) FindMaxTicketProposal(table PowerTable) ConvergeValue {
 
 	for key, value := range c.values {
 		for _, ticket := range c.tickets[key] {
-			_, senderPower, _ := table.Get(ticket.Sender)
+			senderPower, _ := table.Get(ticket.Sender)
 			ticketAsInt := new(big.Int).SetBytes(ticket.Ticket)
-			weightedTicket := new(big.Int).Mul(ticketAsInt, senderPower)
+			weightedTicket := new(big.Int).Mul(ticketAsInt, big.NewInt(int64(senderPower)))
 			if maxTicket == nil || weightedTicket.Cmp(maxTicket) > 0 {
 				maxTicket = weightedTicket
 				maxValue = value

gpbft/message_builder.go

@@ -2,7 +2,6 @@ package gpbft
 
 import (
 	"errors"
-	"math/big"
 
 	xerrors "golang.org/x/xerrors"
 )
@@ -68,7 +67,7 @@ func (mb *MessageBuilder) SetSigningMarshaler(sm SigningMarshaler) {
 }
 
 type powerTableAccessor interface {
-	Get(ActorID) (uint16, *big.Int, PubKey)
+	Get(ActorID) (uint16, PubKey)
 }
 
 type SignerWithMarshaler interface {
@@ -105,7 +104,7 @@ type SignatureBuilder struct {
 }
 
 func (mb *MessageBuilder) PrepareSigningInputs(id ActorID) (*SignatureBuilder, error) {
-	effectivePower, _, pubKey := mb.powerTable.Get(id)
+	effectivePower, pubKey := mb.powerTable.Get(id)
 	if pubKey == nil || effectivePower == 0 {
 		return nil, xerrors.Errorf("could not find pubkey for actor %d: %w", id, ErrNoPower)
 	}

gpbft/powertable.go

@@ -132,13 +132,13 @@ func (p *PowerTable) rescale() error {
 
 // Get retrieves the scaled power, unscaled StoragePower and PubKey for the given id, if present in
 // the table. Otherwise, returns 0/nil.
-func (p *PowerTable) Get(id ActorID) (uint16, *StoragePower, PubKey) {
+func (p *PowerTable) Get(id ActorID) (uint16, PubKey) {
 	if index, ok := p.Lookup[id]; ok {
-		entry := p.Entries[index]
+		key := p.Entries[index].PubKey
 		scaledPower := p.ScaledPower[index]
-		return scaledPower, entry.Power, entry.PubKey
+		return scaledPower, key
 	}
-	return 0, nil, nil
+	return 0, nil
 }
 
 // Has check whether this PowerTable contains an entry for the given id.

gpbft/powertable_test.go

@@ -26,8 +26,8 @@ func TestPowerTable(t *testing.T) {
 		})
 		t.Run("gets nil", func(t *testing.T) {
 			subject := gpbft.NewPowerTable()
-			_, gotPower, gotKey := subject.Get(1413)
-			require.Nil(t, gotPower)
+			gotPower, gotKey := subject.Get(1413)
+			require.Zero(t, gotPower)
 			require.Nil(t, gotKey)
 		})
 	})
@@ -199,7 +199,8 @@ func TestPowerTable(t *testing.T) {
 func requireAddedToPowerTable(t *testing.T, subject *gpbft.PowerTable, entry gpbft.PowerEntry) {
 	t.Helper()
 	require.True(t, subject.Has(entry.ID))
-	_, gotPower, gotKey := subject.Get(entry.ID)
+	_, gotKey := subject.Get(entry.ID)
+	gotPower := subject.Entries[subject.Lookup[entry.ID]].Power
 	require.Equal(t, entry.Power, gotPower)
 	require.Equal(t, entry.PubKey, gotKey)
 }

sim/adversary/decide.go

@@ -61,7 +61,7 @@ func (i *ImmediateDecide) StartInstance(instance uint64) error {
 		SupplementalData: *supplementalData,
 	}
 	sigPayload := i.host.MarshalPayloadForSigning(i.host.NetworkName(), &justificationPayload)
-	_, _, pubkey := powertable.Get(i.id)
+	_, pubkey := powertable.Get(i.id)
 	sig, err := i.host.Sign(pubkey, sigPayload)
 	if err != nil {
 		panic(err)