Fix sorting of l2txs nonces in TxSelector

txprocessor/txprocessor.go

@@ -32,11 +32,13 @@ type TxProcessor struct {
 
 // Config contains the TxProcessor configuration parameters
 type Config struct {
-	NLevels  uint32
+	NLevels uint32
+	// MaxFeeTx is the maximum number of coordinator accounts that can receive fees
 	MaxFeeTx uint32
 	MaxTx    uint32
 	MaxL1Tx  uint32
-	ChainID  uint16
+	// ChainID of the blockchain
+	ChainID uint16
 }
 
 type processedExit struct {

txselector/txselector.go

@@ -18,7 +18,8 @@ import (
 	"github.com/iden3/go-iden3-crypto/babyjub"
 )
 
-// txs implements the interface Sort for an array of Tx
+// txs implements the interface Sort for an array of Tx, and sorts the txs by
+// absolute fee
 type txs []common.PoolL2Tx
 
 func (t txs) Len() int {
@@ -590,11 +591,12 @@ func checkAlreadyPendingToCreate(l1CoordinatorTxs []common.L1Tx, tokenID common.
 
 // getL2Profitable returns the profitable selection of L2Txssorted by Nonce
 func (txsel *TxSelector) getL2Profitable(l2Txs []common.PoolL2Tx, max uint32) []common.PoolL2Tx {
+	// Sort by absolute fee
 	sort.Sort(txs(l2Txs))
-	if len(l2Txs) < int(max) {
-		return l2Txs
+
+	if len(l2Txs) > int(max) {
+		l2Txs = l2Txs[:max]
 	}
-	l2Txs = l2Txs[:max]
 
 	// sort l2Txs by Nonce. This can be done in many different ways, what
 	// is needed is to output the l2Txs where the Nonce of l2Txs for each

txselector/txselector_test.go

@@ -538,7 +538,8 @@ func TestTransferToBjj(t *testing.T) {
 		MaxL1UserTxs:      5,
 		TxProcessorConfig: tpc,
 	}
-	// batch1 to create some accounts with positive balance
+	// batch1 to freeze L1UserTxs that will create some accounts with
+	// positive balance
 	l1UserTxs := []common.L1Tx{}
 	_, _, _, _, _, _, err = txsel.GetL1L2TxSelection(selectionConfig, l1UserTxs)
 	require.NoError(t, err)
@@ -628,3 +629,78 @@ func TestTransferToBjj(t *testing.T) {
 	err = txsel.l2db.StartForging(common.TxIDsFromPoolL2Txs(oL2Txs), txsel.localAccountsDB.CurrentBatch())
 	require.NoError(t, err)
 }
+
+func TestTransferManyFromSameAccount(t *testing.T) {
+	set := `
+		Type: Blockchain
+
+		CreateAccountDeposit(0) Coord: 0
+		CreateAccountDeposit(0) A: 1000
+		CreateAccountDeposit(0) B: 1000
+
+		> batchL1 // freeze L1User{1}
+		> batchL1 // forge L1User{1}
+		> block
+	`
+
+	chainID := uint16(0)
+	tc := til.NewContext(chainID, common.RollupConstMaxL1UserTx)
+	blocks, err := tc.GenerateBlocks(set)
+	assert.NoError(t, err)
+
+	hermezContractAddr := ethCommon.HexToAddress("0xc344E203a046Da13b0B4467EB7B3629D0C99F6E6")
+	txsel := initTest(t, chainID, hermezContractAddr, tc.Users["Coord"])
+
+	// restart nonces of TilContext, as will be set by generating directly
+	// the PoolL2Txs for each specific batch with tc.GeneratePoolL2Txs
+	tc.RestartNonces()
+
+	tpc := txprocessor.Config{
+		NLevels:  16,
+		MaxFeeTx: 10,
+		MaxTx:    20,
+		MaxL1Tx:  10,
+		ChainID:  chainID,
+	}
+	selectionConfig := &SelectionConfig{
+		MaxL1UserTxs:      5,
+		TxProcessorConfig: tpc,
+	}
+	// batch1 to freeze L1UserTxs
+	l1UserTxs := []common.L1Tx{}
+	_, _, _, _, _, _, err = txsel.GetL1L2TxSelection(selectionConfig, l1UserTxs)
+	require.NoError(t, err)
+
+	// 8 transfers from the same account
+
+	batchPoolL2 := `
+	Type: PoolL2
+	PoolTransfer(0) A-B: 10 (126) // 1
+	PoolTransfer(0) A-B: 10 (126) // 2
+	PoolTransfer(0) A-B: 10 (126) // 3
+	PoolTransfer(0) A-B: 10 (126) // 4
+	PoolTransfer(0) A-B: 10 (126) // 5
+	PoolTransfer(0) A-B: 10 (126) // 6
+	PoolTransfer(0) A-B: 10 (126) // 7
+	PoolTransfer(0) A-B: 10 (126) // 8
+	`
+	poolL2Txs, err := tc.GeneratePoolL2Txs(batchPoolL2)
+	require.NoError(t, err)
+
+	// reorder poolL2Txs so that nonces are not sorted
+	poolL2Txs[0], poolL2Txs[7] = poolL2Txs[7], poolL2Txs[0]
+	poolL2Txs[1], poolL2Txs[6] = poolL2Txs[6], poolL2Txs[1]
+
+	// add the PoolL2Txs to the l2DB
+	addL2Txs(t, txsel, poolL2Txs)
+	// batch 2 to crate some accounts with positive balance, and do 8 L2Tx transfers from account A
+	l1UserTxs = til.L1TxsToCommonL1Txs(tc.Queues[*blocks[0].Rollup.Batches[1].Batch.ForgeL1TxsNum])
+	_, _, oL1UserTxs, oL1CoordTxs, oL2Txs, discardedL2Txs, err := txsel.GetL1L2TxSelection(selectionConfig, l1UserTxs)
+	require.NoError(t, err)
+	assert.Equal(t, 3, len(oL1UserTxs))
+	require.Equal(t, 0, len(oL1CoordTxs))
+	assert.Equal(t, 8, len(oL2Txs))
+	assert.Equal(t, 0, len(discardedL2Txs))
+	err = txsel.l2db.StartForging(common.TxIDsFromPoolL2Txs(oL2Txs), txsel.localAccountsDB.CurrentBatch())
+	require.NoError(t, err)
+}