TxProc merge multiple exits into single ExitInfo

Fix #497

txprocessor/txprocessor.go

@@ -328,7 +328,8 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 			if i < int(tp.config.MaxTx)-1 {
 				tp.zki.ISOutIdx[i] = tp.s.CurrentIdx().BigInt()
 				tp.zki.ISStateRoot[i] = tp.s.MT.Root().BigInt()
-				tp.zki.ISAccFeeOut[i] = formatAccumulatedFees(collectedFees, tp.zki.FeePlanTokens, coordIdxs)
+				tp.zki.ISAccFeeOut[i] = formatAccumulatedFees(collectedFees,
+					tp.zki.FeePlanTokens, coordIdxs)
 				tp.zki.ISExitRoot[i] = exitTree.Root().BigInt()
 			}
 			if i >= tp.i {
@@ -396,6 +397,7 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 	// once all txs processed (exitTree root frozen), for each Exit,
 	// generate common.ExitInfo data
 	var exitInfos []common.ExitInfo
+	exitInfosByIdx := make(map[common.Idx]*common.ExitInfo)
 	for i := 0; i < nTx; i++ {
 		if !exits[i].exit {
 			continue
@@ -415,7 +417,12 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 			MerkleProof: p,
 			Balance:     exitAccount.Balance,
 		}
-		exitInfos = append(exitInfos, ei)
+		if prevExit, ok := exitInfosByIdx[exitIdx]; !ok {
+			exitInfos = append(exitInfos, ei)
+			exitInfosByIdx[exitIdx] = &exitInfos[len(exitInfos)-1]
+		} else {
+			*prevExit = ei
+		}
 	}
 
 	if tp.s.Typ == statedb.TypeSynchronizer {

txprocessor/txprocessor_test.go

@@ -3,7 +3,6 @@ package txprocessor
 import (
 	"encoding/binary"
 	"encoding/hex"
-	"fmt"
 	"io/ioutil"
 	"math/big"
 	"os"
@@ -463,7 +462,7 @@ func TestProcessTxsSynchronizer(t *testing.T) {
 		blocks[1].Rollup.Batches[1].L1CoordinatorTxs, l2Txs)
 	require.NoError(t, err)
 
-	assert.Equal(t, 2, len(ptOut.ExitInfos)) // 2, as previous batch was without L1UserTxs, and has pending the 'ForceExit(1) A: 5'
+	assert.Equal(t, 1, len(ptOut.ExitInfos)) // 1, as previous batch was without L1UserTxs, and has pending the 'ForceExit(1) A: 5', and the 2 exit transactions get grouped under 1 ExitInfo
 	assert.Equal(t, 1, len(ptOut.CreatedAccounts))
 	assert.Equal(t, 4, len(ptOut.CollectedFees))
 	assert.Equal(t, "0", ptOut.CollectedFees[common.TokenID(0)].String())
@@ -842,10 +841,8 @@ func TestTwoExits(t *testing.T) {
 	ptOuts := []*ProcessTxOutput{}
 	for _, block := range blocks {
 		for _, batch := range block.Rollup.Batches {
-			// fmt.Printf("Batch %v\n%#v\n", batch.Batch.BatchNum, batch.L1UserTxs)
 			ptOut, err := tp.ProcessTxs(nil, batch.L1UserTxs, nil, nil)
 			require.NoError(t, err)
-			fmt.Printf("Exits (batch %v)\n%#v\n", batch.Batch.BatchNum, ptOut.ExitInfos)
 			ptOuts = append(ptOuts, ptOut)
 		}
 	}