hermez-node/txselector/txselector.go
txselector/txselector.goRaw
1package txselector
2
3// current: very simple version of TxSelector
4
5import (
6 "bytes"
7 "fmt"
8 "math/big"
9 "sort"
10
11 ethCommon "github.com/ethereum/go-ethereum/common"
12 "github.com/hermeznetwork/hermez-node/common"
13 "github.com/hermeznetwork/hermez-node/db/l2db"
14 "github.com/hermeznetwork/hermez-node/db/statedb"
15 "github.com/hermeznetwork/hermez-node/log"
16 "github.com/hermeznetwork/hermez-node/txprocessor"
17 "github.com/hermeznetwork/tracerr"
18 "github.com/iden3/go-iden3-crypto/babyjub"
19)
20
21// txs implements the interface Sort for an array of Tx
22type txs []common.PoolL2Tx
23
24func (t txs) Len() int {
25 return len(t)
26}
27func (t txs) Swap(i, j int) {
28 t[i], t[j] = t[j], t[i]
29}
30func (t txs) Less(i, j int) bool {
31 return t[i].AbsoluteFee > t[j].AbsoluteFee
32}
33
34// CoordAccount contains the data of the Coordinator account, that will be used
35// to create new transactions of CreateAccountDeposit type to add new TokenID
36// accounts for the Coordinator to receive the fees.
37type CoordAccount struct {
38 Addr ethCommon.Address
39 BJJ babyjub.PublicKeyComp
40 AccountCreationAuth []byte // signature in byte array format
41}
42
43// SelectionConfig contains the parameters of configuration of the selection of
44// transactions for the next batch
45type SelectionConfig struct {
46 // MaxL1UserTxs is the maximum L1-user-tx for a batch
47 MaxL1UserTxs uint64
48
49 // TxProcessorConfig contains the config for ProcessTxs
50 TxProcessorConfig txprocessor.Config
51}
52
53// TxSelector implements all the functionalities to select the txs for the next
54// batch
55type TxSelector struct {
56 l2db *l2db.L2DB
57 localAccountsDB *statedb.LocalStateDB
58
59 coordAccount *CoordAccount
60}
61
62// NewTxSelector returns a *TxSelector
63func NewTxSelector(coordAccount *CoordAccount, dbpath string,
64 synchronizerStateDB *statedb.StateDB, l2 *l2db.L2DB) (*TxSelector, error) {
65 localAccountsDB, err := statedb.NewLocalStateDB(dbpath, 128,
66 synchronizerStateDB, statedb.TypeTxSelector, 0) // without merkletree
67 if err != nil {
68 return nil, tracerr.Wrap(err)
69 }
70
71 return &TxSelector{
72 l2db: l2,
73 localAccountsDB: localAccountsDB,
74 coordAccount: coordAccount,
75 }, nil
76}
77
78// LocalAccountsDB returns the LocalStateDB of the TxSelector
79func (txsel *TxSelector) LocalAccountsDB() *statedb.LocalStateDB {
80 return txsel.localAccountsDB
81}
82
83// Reset tells the TxSelector to get it's internal AccountsDB
84// from the required `batchNum`
85func (txsel *TxSelector) Reset(batchNum common.BatchNum) error {
86 err := txsel.localAccountsDB.Reset(batchNum, true)
87 if err != nil {
88 return tracerr.Wrap(err)
89 }
90 return nil
91}
92
93func (txsel *TxSelector) getCoordIdx(tokenID common.TokenID) (common.Idx, error) {
94 return txsel.localAccountsDB.GetIdxByEthAddrBJJ(txsel.coordAccount.Addr,
95 txsel.coordAccount.BJJ, tokenID)
96}
97
98// coordAccountForTokenID creates a new L1CoordinatorTx to create a new
99// Coordinator account for the given TokenID in the case that the account does
100// not exist yet in the db, and does not exist a L1CoordinatorTx to creat that
101// account in the given array of L1CoordinatorTxs. If a new Coordinator account
102// needs to be created, a new L1CoordinatorTx will be returned from this
103// function. After calling this method, if the l1CoordinatorTx is added to the
104// selection, positionL1 must be increased 1.
105func (txsel *TxSelector) coordAccountForTokenID(l1CoordinatorTxs []common.L1Tx,
106 tokenID common.TokenID, positionL1 int) (*common.L1Tx, int, error) {
107 // check if CoordinatorAccount for TokenID is already pending to create
108 if checkAlreadyPendingToCreate(l1CoordinatorTxs, tokenID,
109 txsel.coordAccount.Addr, txsel.coordAccount.BJJ) {
110 return nil, positionL1, nil
111 }
112 _, err := txsel.getCoordIdx(tokenID)
113 if tracerr.Unwrap(err) == statedb.ErrIdxNotFound {
114 // create L1CoordinatorTx to create new CoordAccount for
115 // TokenID
116 l1CoordinatorTx := common.L1Tx{
117 Position: positionL1,
118 UserOrigin: false,
119 FromEthAddr: txsel.coordAccount.Addr,
120 FromBJJ: txsel.coordAccount.BJJ,
121 TokenID: tokenID,
122 Amount: big.NewInt(0),
123 DepositAmount: big.NewInt(0),
124 Type: common.TxTypeCreateAccountDeposit,
125 }
126
127 return &l1CoordinatorTx, positionL1, nil
128 }
129 if err != nil {
130 return nil, positionL1, tracerr.Wrap(err)
131 }
132 // CoordAccount for TokenID already exists
133 return nil, positionL1, nil
134}
135
136// GetL2TxSelection returns the L1CoordinatorTxs and a selection of the L2Txs
137// for the next batch, from the L2DB pool.
138// It returns: the CoordinatorIdxs used to receive the fees of the selected
139// L2Txs. An array of bytearrays with the signatures of the
140// AccountCreationAuthorization of the accounts of the users created by the
141// Coordinator with L1CoordinatorTxs of those accounts that does not exist yet
142// but there is a transactions to them and the authorization of account
143// creation exists. The L1UserTxs, L1CoordinatorTxs, PoolL2Txs that will be
144// included in the next batch.
145func (txsel *TxSelector) GetL2TxSelection(selectionConfig *SelectionConfig,
146 batchNum common.BatchNum) ([]common.Idx, [][]byte, []common.L1Tx,
147 []common.PoolL2Tx, error) {
148 coordIdxs, accCreationAuths, _, l1CoordinatorTxs, l2Txs, err :=
149 txsel.GetL1L2TxSelection(selectionConfig, batchNum, []common.L1Tx{})
150 return coordIdxs, accCreationAuths, l1CoordinatorTxs, l2Txs, tracerr.Wrap(err)
151}
152
153// GetL1L2TxSelection returns the selection of L1 + L2 txs.
154// It returns: the CoordinatorIdxs used to receive the fees of the selected
155// L2Txs. An array of bytearrays with the signatures of the
156// AccountCreationAuthorization of the accounts of the users created by the
157// Coordinator with L1CoordinatorTxs of those accounts that does not exist yet
158// but there is a transactions to them and the authorization of account
159// creation exists. The L1UserTxs, L1CoordinatorTxs, PoolL2Txs that will be
160// included in the next batch.
161func (txsel *TxSelector) GetL1L2TxSelection(selectionConfig *SelectionConfig,
162 batchNum common.BatchNum, l1UserTxs []common.L1Tx) ([]common.Idx, [][]byte,
163 []common.L1Tx, []common.L1Tx, []common.PoolL2Tx, error) {
164 // TODO input parameter 'batchNum' is not used, delete
165
166 // WIP.0: the TxSelector is not optimized and will need a redesign. The
167 // current version is implemented in order to have a functional
168 // implementation that can be used asap.
169 //
170 // WIP.1: this method uses a 'cherry-pick' of internal calls of the
171 // StateDB, a refactor of the StateDB to reorganize it internally is
172 // planned once the main functionallities are covered, with that
173 // refactor the TxSelector will be updated also.
174
175 // get pending l2-tx from tx-pool
176 l2TxsRaw, err := txsel.l2db.GetPendingTxs()
177 if err != nil {
178 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
179 }
180
181 txselStateDB := txsel.localAccountsDB.StateDB
182 tp := txprocessor.NewTxProcessor(txselStateDB, selectionConfig.TxProcessorConfig)
183
184 // Process L1UserTxs
185 for i := 0; i < len(l1UserTxs); i++ {
186 // assumption: l1usertx are sorted by L1Tx.Position
187 _, _, _, _, err := tp.ProcessL1Tx(nil, &l1UserTxs[i])
188 if err != nil {
189 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
190 }
191 }
192
193 var l1CoordinatorTxs []common.L1Tx
194 positionL1 := len(l1UserTxs)
195 var accAuths [][]byte
196
197 // sort l2TxsRaw (cropping at MaxTx at this point)
198 l2Txs0 := txsel.getL2Profitable(l2TxsRaw, selectionConfig.TxProcessorConfig.MaxTx)
199
200 noncesMap := make(map[common.Idx]common.Nonce)
201 var l2Txs []common.PoolL2Tx
202 // iterate over l2Txs
203 // - if tx.TokenID does not exist at CoordsIdxDB
204 // - create new L1CoordinatorTx creating a CoordAccount, for
205 // Coordinator to receive the fee of the new TokenID
206 for i := 0; i < len(l2Txs0); i++ {
207 accSender, err := tp.StateDB().GetAccount(l2Txs0[i].FromIdx)
208 if err != nil {
209 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
210 }
211 // populate the noncesMap used at the next iteration
212 noncesMap[l2Txs0[i].FromIdx] = accSender.Nonce
213
214 // if TokenID does not exist yet, create new L1CoordinatorTx to
215 // create the CoordinatorAccount for that TokenID, to receive
216 // the fees. Only in the case that there does not exist yet a
217 // pending L1CoordinatorTx to create the account for the
218 // Coordinator for that TokenID
219 var newL1CoordTx *common.L1Tx
220 newL1CoordTx, positionL1, err =
221 txsel.coordAccountForTokenID(l1CoordinatorTxs,
222 accSender.TokenID, positionL1)
223 if err != nil {
224 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
225 }
226 if newL1CoordTx != nil {
227 // if there is no space for the L1CoordinatorTx, discard the L2Tx
228 if len(l1CoordinatorTxs) >= int(selectionConfig.MaxL1UserTxs)-len(l1UserTxs) {
229 // discard L2Tx
230 continue
231 }
232 // increase positionL1
233 positionL1++
234 l1CoordinatorTxs = append(l1CoordinatorTxs, *newL1CoordTx)
235 accAuths = append(accAuths, txsel.coordAccount.AccountCreationAuth)
236 }
237 l2Txs = append(l2Txs, l2Txs0[i])
238 }
239
240 var validTxs []common.PoolL2Tx
241 // iterate over l2TxsRaw
242 // - check Nonces
243 // - if needed, create new L1CoordinatorTxs for unexisting ToIdx
244 // - keep used accAuths
245 // - put the valid txs into validTxs array
246 for i := 0; i < len(l2Txs); i++ {
247 // check if Nonce is correct
248 nonce := noncesMap[l2Txs[i].FromIdx]
249 if l2Txs[i].Nonce == nonce {
250 noncesMap[l2Txs[i].FromIdx]++
251 } else {
252 // not valid Nonce at tx
253 continue
254 }
255
256 // If tx.ToIdx>=256, tx.ToIdx should exist to localAccountsDB,
257 // if so, tx is used. If tx.ToIdx==0, for an L2Tx will be the
258 // case of TxToEthAddr or TxToBJJ, check if
259 // tx.ToEthAddr/tx.ToBJJ exist in localAccountsDB, if yes tx is
260 // used; if not, check if tx.ToEthAddr is in
261 // AccountCreationAuthDB, if so, tx is used and L1CoordinatorTx
262 // of CreateAccountAndDeposit is created. If tx.ToIdx==1, is a
263 // Exit type and is used.
264 if l2Txs[i].ToIdx == 0 { // ToEthAddr/ToBJJ case
265 validL2Tx, l1CoordinatorTx, accAuth, err :=
266 txsel.processTxToEthAddrBJJ(validTxs, selectionConfig,
267 len(l1UserTxs), l1CoordinatorTxs, positionL1, l2Txs[i])
268 if err != nil {
269 log.Debug(err)
270 continue
271 }
272 if accAuth != nil && l1CoordinatorTx != nil {
273 accAuths = append(accAuths, accAuth.Signature)
274 l1CoordinatorTxs = append(l1CoordinatorTxs, *l1CoordinatorTx)
275 positionL1++
276 }
277 if validL2Tx != nil {
278 validTxs = append(validTxs, *validL2Tx)
279 }
280 } else if l2Txs[i].ToIdx >= common.IdxUserThreshold {
281 _, err = txsel.localAccountsDB.GetAccount(l2Txs[i].ToIdx)
282 if err != nil {
283 // tx not valid
284 log.Debugw("invalid L2Tx: ToIdx not found in StateDB",
285 "ToIdx", l2Txs[i].ToIdx)
286 continue
287 }
288 // TODO if EthAddr!=0 or BJJ!=0, check that ToIdxAccount.EthAddr or BJJ
289
290 // Account found in the DB, include the l2Tx in the selection
291 validTxs = append(validTxs, l2Txs[i])
292 } else if l2Txs[i].ToIdx == common.Idx(1) {
293 // valid txs (of Exit type)
294 validTxs = append(validTxs, l2Txs[i])
295 }
296 }
297
298 // Process L1CoordinatorTxs
299 for i := 0; i < len(l1CoordinatorTxs); i++ {
300 _, _, _, _, err := tp.ProcessL1Tx(nil, &l1CoordinatorTxs[i])
301 if err != nil {
302 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
303 }
304 }
305
306 // get CoordIdxsMap for the TokenIDs
307 coordIdxsMap := make(map[common.TokenID]common.Idx)
308 for i := 0; i < len(l2Txs); i++ {
309 // get TokenID from tx.Sender
310 accSender, err := tp.StateDB().GetAccount(l2Txs[i].FromIdx)
311 if err != nil {
312 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
313 }
314 tokenID := accSender.TokenID
315
316 coordIdx, err := txsel.getCoordIdx(tokenID)
317 if err != nil {
318 // if err is db.ErrNotFound, should not happen, as all
319 // the l2Txs.TokenID should have a CoordinatorIdx
320 // created in the DB at this point
321 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
322 }
323 coordIdxsMap[tokenID] = coordIdx
324 }
325
326 var coordIdxs []common.Idx
327 tp.AccumulatedFees = make(map[common.Idx]*big.Int)
328 for _, idx := range coordIdxsMap {
329 tp.AccumulatedFees[idx] = big.NewInt(0)
330 coordIdxs = append(coordIdxs, idx)
331 }
332 // sort CoordIdxs
333 sort.SliceStable(coordIdxs, func(i, j int) bool {
334 return coordIdxs[i] < coordIdxs[j]
335 })
336
337 // get most profitable L2-tx
338 maxL2Txs := selectionConfig.TxProcessorConfig.MaxTx -
339 uint32(len(l1UserTxs)) - uint32(len(l1CoordinatorTxs))
340
341 selectedL2Txs := txsel.getL2Profitable(l2Txs, maxL2Txs) // TODO this will only need to crop the lasts, as are already sorted
342 for i := 0; i < len(selectedL2Txs); i++ {
343 _, _, _, err = tp.ProcessL2Tx(coordIdxsMap, nil, nil, &selectedL2Txs[i])
344 if err != nil {
345 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
346 }
347 }
348
349 // distribute the AccumulatedFees from the processed L2Txs into the
350 // Coordinator Idxs
351 for idx, accumulatedFee := range tp.AccumulatedFees {
352 cmp := accumulatedFee.Cmp(big.NewInt(0))
353 if cmp == 1 { // accumulatedFee>0
354 // send the fee to the Idx of the Coordinator for the TokenID
355 accCoord, err := txsel.localAccountsDB.GetAccount(idx)
356 if err != nil {
357 log.Errorw("Can not distribute accumulated fees to coordinator account: No coord Idx to receive fee", "idx", idx)
358 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
359 }
360 accCoord.Balance = new(big.Int).Add(accCoord.Balance, accumulatedFee)
361 _, err = txsel.localAccountsDB.UpdateAccount(idx, accCoord)
362 if err != nil {
363 log.Error(err)
364 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
365 }
366 }
367 }
368
369 err = tp.StateDB().MakeCheckpoint()
370 if err != nil {
371 return nil, nil, nil, nil, nil, tracerr.Wrap(err)
372 }
373
374 return coordIdxs, accAuths, l1UserTxs, l1CoordinatorTxs, selectedL2Txs, nil
375}
376
377// processTxsToEthAddrBJJ process the common.PoolL2Tx in the case where
378// ToIdx==0, which can be the tx type of ToEthAddr or ToBJJ. If the receiver
379// does not have an account yet, a new L1CoordinatorTx of type
380// CreateAccountDeposit (with 0 as DepositAmount) is created and added to the
381// l1CoordinatorTxs array, and then the PoolL2Tx is added into the validTxs
382// array.
383func (txsel *TxSelector) processTxToEthAddrBJJ(validTxs []common.PoolL2Tx,
384 selectionConfig *SelectionConfig, nL1UserTxs int, l1CoordinatorTxs []common.L1Tx,
385 positionL1 int, l2Tx common.PoolL2Tx) (*common.PoolL2Tx, *common.L1Tx,
386 *common.AccountCreationAuth, error) {
387 accSender, err := txsel.localAccountsDB.GetAccount(l2Tx.FromIdx)
388 if err != nil {
389 return nil, nil, nil, err
390 }
391 l2Tx.TokenID = accSender.TokenID // TODO rm and add it before at GetL1L2TxsSelection
392
393 // if L2Tx needs a new L1CoordinatorTx of CreateAccount type, and a
394 // previous L2Tx in the current process already created a
395 // L1CoordinatorTx of this type, in the DB there still seem that needs
396 // to create a new L1CoordinatorTx, but as is already created, the tx
397 // is valid
398 if checkAlreadyPendingToCreate(l1CoordinatorTxs, l2Tx.TokenID, l2Tx.ToEthAddr, l2Tx.ToBJJ) {
399 return &l2Tx, nil, nil, nil
400 }
401
402 var l1CoordinatorTx *common.L1Tx
403 var accAuth *common.AccountCreationAuth
404 if !bytes.Equal(l2Tx.ToEthAddr.Bytes(), common.EmptyAddr.Bytes()) &&
405 !bytes.Equal(l2Tx.ToEthAddr.Bytes(), common.FFAddr.Bytes()) {
406 // case: ToEthAddr != 0x00 neither 0xff
407 if l2Tx.ToBJJ != common.EmptyBJJComp {
408 // case: ToBJJ!=0:
409 // if idx exist for EthAddr&BJJ use it
410 _, err := txsel.localAccountsDB.GetIdxByEthAddrBJJ(l2Tx.ToEthAddr,
411 l2Tx.ToBJJ, l2Tx.TokenID)
412 if err == nil {
413 // account for ToEthAddr&ToBJJ already exist,
414 // there is no need to create a new one.
415 // tx valid, StateDB will use the ToIdx==0 to define the AuxToIdx
416 return &l2Tx, nil, nil, nil
417 }
418 // if not, check if AccountCreationAuth exist for that
419 // ToEthAddr
420 accAuth, err = txsel.l2db.GetAccountCreationAuth(l2Tx.ToEthAddr)
421 if err != nil {
422 // not found, l2Tx will not be added in the selection
423 return nil, nil, nil, tracerr.Wrap(fmt.Errorf("invalid L2Tx: ToIdx not found in StateDB, neither ToEthAddr found in AccountCreationAuths L2DB. ToIdx: %d, ToEthAddr: %s",
424 l2Tx.ToIdx, l2Tx.ToEthAddr.Hex()))
425 }
426 if accAuth.BJJ != l2Tx.ToBJJ {
427 // if AccountCreationAuth.BJJ is not the same
428 // than in the tx, tx is not accepted
429 return nil, nil, nil, tracerr.Wrap(fmt.Errorf("invalid L2Tx: ToIdx not found in StateDB, neither ToEthAddr & ToBJJ found in AccountCreationAuths L2DB. ToIdx: %d, ToEthAddr: %s, ToBJJ: %s",
430 l2Tx.ToIdx, l2Tx.ToEthAddr.Hex(), l2Tx.ToBJJ.String()))
431 }
432 } else {
433 // case: ToBJJ==0:
434 // if idx exist for EthAddr use it
435 _, err := txsel.localAccountsDB.GetIdxByEthAddr(l2Tx.ToEthAddr, l2Tx.TokenID)
436 if err == nil {
437 // account for ToEthAddr already exist,
438 // there is no need to create a new one.
439 // tx valid, StateDB will use the ToIdx==0 to define the AuxToIdx
440 return &l2Tx, nil, nil, nil
441 }
442 // if not, check if AccountCreationAuth exist for that ToEthAddr
443 accAuth, err = txsel.l2db.GetAccountCreationAuth(l2Tx.ToEthAddr)
444 if err != nil {
445 // not found, l2Tx will not be added in the selection
446 return nil, nil, nil, tracerr.Wrap(fmt.Errorf("invalid L2Tx: ToIdx not found in StateDB, neither ToEthAddr found in AccountCreationAuths L2DB. ToIdx: %d, ToEthAddr: %s",
447 l2Tx.ToIdx, l2Tx.ToEthAddr))
448 }
449 }
450 // create L1CoordinatorTx for the accountCreation
451 l1CoordinatorTx = &common.L1Tx{
452 Position: positionL1,
453 UserOrigin: false,
454 FromEthAddr: accAuth.EthAddr,
455 FromBJJ: accAuth.BJJ,
456 TokenID: l2Tx.TokenID,
457 Amount: big.NewInt(0),
458 DepositAmount: big.NewInt(0),
459 Type: common.TxTypeCreateAccountDeposit,
460 }
461 } else if bytes.Equal(l2Tx.ToEthAddr.Bytes(), common.FFAddr.Bytes()) &&
462 l2Tx.ToBJJ != common.EmptyBJJComp {
463 // if idx exist for EthAddr&BJJ use it
464 _, err := txsel.localAccountsDB.GetIdxByEthAddrBJJ(l2Tx.ToEthAddr, l2Tx.ToBJJ,
465 l2Tx.TokenID)
466 if err == nil {
467 // account for ToEthAddr&ToBJJ already exist, (where ToEthAddr==0xff)
468 // there is no need to create a new one.
469 // tx valid, StateDB will use the ToIdx==0 to define the AuxToIdx
470 return &l2Tx, nil, nil, nil
471 }
472 // if idx don't exist for EthAddr&BJJ, coordinator can create a
473 // new account without L1Authorization, as ToEthAddr==0xff
474 // create L1CoordinatorTx for the accountCreation
475 l1CoordinatorTx = &common.L1Tx{
476 Position: positionL1,
477 UserOrigin: false,
478 FromEthAddr: l2Tx.ToEthAddr,
479 FromBJJ: l2Tx.ToBJJ,
480 TokenID: l2Tx.TokenID,
481 Amount: big.NewInt(0),
482 DepositAmount: big.NewInt(0),
483 Type: common.TxTypeCreateAccountDeposit,
484 }
485 }
486 if len(l1CoordinatorTxs) >= int(selectionConfig.MaxL1UserTxs)-nL1UserTxs {
487 // L2Tx discarded
488 return nil, nil, nil, tracerr.Wrap(fmt.Errorf("L2Tx discarded due not slots for L1CoordinatorTx to create a new account for receiver of L2Tx"))
489 }
490
491 return &l2Tx, l1CoordinatorTx, accAuth, nil
492}
493
494func checkAlreadyPendingToCreate(l1CoordinatorTxs []common.L1Tx, tokenID common.TokenID,
495 addr ethCommon.Address, bjj babyjub.PublicKeyComp) bool {
496 for i := 0; i < len(l1CoordinatorTxs); i++ {
497 if bytes.Equal(l1CoordinatorTxs[i].FromEthAddr.Bytes(), addr.Bytes()) &&
498 l1CoordinatorTxs[i].TokenID == tokenID &&
499 l1CoordinatorTxs[i].FromBJJ == bjj {
500 return true
501 }
502 }
503 return false
504}
505
506// getL2Profitable returns the profitable selection of L2Txssorted by Nonce
507func (txsel *TxSelector) getL2Profitable(l2Txs []common.PoolL2Tx, max uint32) []common.PoolL2Tx {
508 sort.Sort(txs(l2Txs))
509 if len(l2Txs) < int(max) {
510 return l2Txs
511 }
512 l2Txs = l2Txs[:max]
513
514 // sort l2Txs by Nonce. This can be done in many different ways, what
515 // is needed is to output the l2Txs where the Nonce of l2Txs for each
516 // Account is sorted, but the l2Txs can not be grouped by sender Account
517 // neither by Fee. This is because later on the Nonces will need to be
518 // sequential for the zkproof generation.
519 sort.SliceStable(l2Txs, func(i, j int) bool {
520 return l2Txs[i].Nonce < l2Txs[j].Nonce
521 })
522
523 return l2Txs
524}