Properly support replace by fee for the data poster (untested)

arbnode/dataposter/dbstorage/storage.go

@@ -58,6 +58,18 @@ func (s *Storage) FetchContents(_ context.Context, startingIndex uint64, maxResu
 	return res, it.Error()
 }
 
+func (s *Storage) Get(_ context.Context, index uint64) (*storage.QueuedTransaction, error) {
+	key := idxToKey(index)
+	value, err := s.db.Get(key)
+	if err != nil {
+		if errors.Is(err, leveldb.ErrNotFound) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	return s.encDec().Decode(value)
+}
+
 func (s *Storage) lastItemIdx(context.Context) ([]byte, error) {
 	return s.db.Get(lastItemIdxKey)
 }

arbnode/dataposter/noop/storage.go

@@ -16,6 +16,10 @@ func (s *Storage) FetchContents(_ context.Context, _, _ uint64) ([]*storage.Queu
 	return nil, nil
 }
 
+func (s *Storage) Get(_ context.Context, _ uint64) (*storage.QueuedTransaction, error) {
+	return nil, nil
+}
+
 func (s *Storage) FetchLast(ctx context.Context) (*storage.QueuedTransaction, error) {
 	return nil, nil
 }

arbnode/dataposter/redis/redisstorage.go

@@ -78,6 +78,20 @@ func (s *Storage) FetchContents(ctx context.Context, startingIndex uint64, maxRe
 	return items, nil
 }
 
+func (s *Storage) Get(ctx context.Context, index uint64) (*storage.QueuedTransaction, error) {
+	contents, err := s.FetchContents(ctx, index, 1)
+	if err != nil {
+		return nil, err
+	}
+	if len(contents) == 0 {
+		return nil, nil
+	} else if len(contents) == 1 {
+		return contents[0], nil
+	} else {
+		return nil, fmt.Errorf("expected only one return value for Get but got %v", len(contents))
+	}
+}
+
 func (s *Storage) FetchLast(ctx context.Context) (*storage.QueuedTransaction, error) {
 	query := redis.ZRangeArgs{
 		Key:   s.key,

arbnode/dataposter/slice/slicestorage.go

@@ -45,6 +45,13 @@ func (s *Storage) FetchContents(_ context.Context, startingIndex uint64, maxResu
 	return res, nil
 }
 
+func (s *Storage) Get(_ context.Context, index uint64) (*storage.QueuedTransaction, error) {
+	if index >= s.firstNonce+uint64(len(s.queue)) || index < s.firstNonce {
+		return nil, nil
+	}
+	return s.encDec().Decode(s.queue[index-s.firstNonce])
+}
+
 func (s *Storage) FetchLast(context.Context) (*storage.QueuedTransaction, error) {
 	if len(s.queue) == 0 {
 		return nil, nil

arbnode/dataposter/storage/storage.go

@@ -26,31 +26,34 @@ var (
 )
 
 type QueuedTransaction struct {
-	FullTx          *types.Transaction
-	DeprecatedData  types.DynamicFeeTx // FullTx should be used instead
-	Meta            []byte
-	Sent            bool
-	Created         time.Time // may be earlier than the tx was given to the tx poster
-	NextReplacement time.Time
+	FullTx           *types.Transaction
+	DeprecatedData   types.DynamicFeeTx // FullTx should be used instead
+	Meta             []byte
+	Sent             bool
+	Created          time.Time // may be earlier than the tx was given to the tx poster
+	NextReplacement  time.Time
+	CumulativeWeight uint64 // a rough estimate of the total number of batches submitted at this point, not guaranteed to be exact
 }
 
 type queuedTransactionForEncoding struct {
-	FullTx          *types.Transaction
-	Data            types.DynamicFeeTx
-	Meta            []byte
-	Sent            bool
-	Created         RlpTime
-	NextReplacement RlpTime
+	FullTx           *types.Transaction
+	Data             types.DynamicFeeTx
+	Meta             []byte
+	Sent             bool
+	Created          RlpTime
+	NextReplacement  RlpTime
+	CumulativeWeight *uint64 `rlp:"optional"`
 }
 
 func (qt *QueuedTransaction) EncodeRLP(w io.Writer) error {
 	return rlp.Encode(w, queuedTransactionForEncoding{
-		FullTx:          qt.FullTx,
-		Data:            qt.DeprecatedData,
-		Meta:            qt.Meta,
-		Sent:            qt.Sent,
-		Created:         (RlpTime)(qt.Created),
-		NextReplacement: (RlpTime)(qt.NextReplacement),
+		FullTx:           qt.FullTx,
+		Data:             qt.DeprecatedData,
+		Meta:             qt.Meta,
+		Sent:             qt.Sent,
+		Created:          (RlpTime)(qt.Created),
+		NextReplacement:  (RlpTime)(qt.NextReplacement),
+		CumulativeWeight: &qt.CumulativeWeight,
 	})
 }
 
@@ -65,6 +68,11 @@ func (qt *QueuedTransaction) DecodeRLP(s *rlp.Stream) error {
 	qt.Sent = qtEnc.Sent
 	qt.Created = time.Time(qtEnc.Created)
 	qt.NextReplacement = time.Time(qtEnc.NextReplacement)
+	if qtEnc.CumulativeWeight != nil {
+		qt.CumulativeWeight = *qtEnc.CumulativeWeight
+	} else {
+		qt.CumulativeWeight = qt.FullTx.Nonce()
+	}
 	return nil
 }
 

util/arbmath/bips.go

@@ -36,3 +36,10 @@ func UintMulByBips(value uint64, bips Bips) uint64 {
 func SaturatingCastToBips(value uint64) Bips {
 	return Bips(SaturatingCast(value))
 }
+
+// BigDivToBips returns dividend/divisor as bips, saturating if out of bounds
+func BigDivToBips(dividend, divisor *big.Int) Bips {
+	value := BigMulByInt(dividend, int64(OneInBips))
+	value.Div(value, divisor)
+	return Bips(BigToUintSaturating(value))
+}