6 "github.com/bytom/vapor/application/mov/common"
7 "github.com/bytom/vapor/application/mov/contract"
8 "github.com/bytom/vapor/consensus/segwit"
9 "github.com/bytom/vapor/errors"
10 vprMath "github.com/bytom/vapor/math"
11 "github.com/bytom/vapor/protocol/bc"
12 "github.com/bytom/vapor/protocol/bc/types"
13 "github.com/bytom/vapor/protocol/vm"
16 // Engine is used to generate math transactions
19 feeStrategy FeeStrategy
23 // NewEngine return a new Engine
24 func NewEngine(orderBook *OrderBook, rewardProgram []byte) *Engine {
25 return &Engine{orderBook: orderBook, feeStrategy: NewDefaultFeeStrategy(), rewardProgram: rewardProgram}
28 // HasMatchedTx check does the input trade pair can generate a match deal
29 func (e *Engine) HasMatchedTx(tradePairs ...*common.TradePair) bool {
30 if err := validateTradePairs(tradePairs); err != nil {
34 orders := e.orderBook.PeekOrders(tradePairs)
39 return IsMatched(orders)
42 // NextMatchedTx return the next matchable transaction by the specified trade pairs
43 // the size of trade pairs at least 2, and the sequence of trade pairs can form a loop
44 // for example, [assetA -> assetB, assetB -> assetC, assetC -> assetA]
45 func (e *Engine) NextMatchedTx(tradePairs ...*common.TradePair) (*types.Tx, error) {
46 if !e.HasMatchedTx(tradePairs...) {
47 return nil, errors.New("the specified trade pairs can not be matched")
50 tx, partialOrders, err := e.buildMatchTx(sortOrders(e.orderBook.PeekOrders(tradePairs)))
55 for _, tradePair := range tradePairs {
56 e.orderBook.PopOrder(tradePair)
59 if err := e.addReOrder(partialOrders, tx); err != nil {
65 func addMatchTxFeeOutput(txData *types.TxData, fees []*bc.AssetAmount, rewardProgram []byte) {
66 for _, feeAmount := range fees {
67 if feeAmount.Amount != 0 {
68 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*feeAmount.AssetId, feeAmount.Amount, rewardProgram))
73 func (e *Engine) addReOrder(partialOrders []*common.Order, tx *types.Tx) error {
75 for i, output := range tx.Outputs {
76 if !segwit.IsP2WMCScript(output.ControlProgram()) || output.AssetAmount().Amount == 0 {
80 partialOrder := partialOrders[index]
81 order, err := common.NewOrderFromOutput(tx, i, partialOrder.BlockHeight, partialOrder.TxIndex)
87 e.orderBook.AddOrder(order)
92 func addRefundOutput(txData *types.TxData, orders []*common.Order) {
93 refundAmount := map[bc.AssetID]uint64{}
94 var assetIDs []bc.AssetID
95 var refundScript [][]byte
96 for i, input := range txData.Inputs {
97 refundAmount[input.AssetID()] += input.Amount()
98 assetIDs = append(assetIDs, input.AssetID())
99 refundScript = append(refundScript, orders[i].ContractArgs.SellerProgram)
102 for _, output := range txData.Outputs {
103 assetAmount := output.AssetAmount()
104 refundAmount[*assetAmount.AssetId] -= assetAmount.Amount
107 refundCount := len(refundScript)
108 for _, assetID := range assetIDs {
109 amount := refundAmount[assetID]
110 averageAmount := amount / uint64(refundCount)
111 if averageAmount == 0 {
115 for i := 0; i < refundCount && amount > 0; i++ {
116 if i == refundCount-1 {
117 averageAmount = amount
119 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(assetID, averageAmount, refundScript[i]))
120 amount -= averageAmount
125 func addTakerOutput(txData *types.TxData, orders []*common.Order, priceDiffs []*bc.AssetAmount, makerFlags []*MakerFlag) {
126 for i := range orders {
127 if makerFlags[i].IsMaker {
130 for _, priceDiff := range priceDiffs {
131 if priceDiff.Amount == 0 {
135 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*priceDiff.AssetId, priceDiff.Amount, orders[i].ContractArgs.SellerProgram))
141 func (e *Engine) buildMatchTx(orders []*common.Order) (*types.Tx, []*common.Order, error) {
142 txData := &types.TxData{Version: 1}
143 for _, order := range orders {
144 input := types.NewSpendInput(nil, *order.Utxo.SourceID, *order.FromAssetID, order.Utxo.Amount, order.Utxo.SourcePos, order.Utxo.ControlProgram)
145 txData.Inputs = append(txData.Inputs, input)
148 isMakers := MakerFlags(orders)
149 receivedAmounts, priceDiffs := CalcReceivedAmount(orders)
150 allocatedAssets := e.feeStrategy.Allocate(receivedAmounts, priceDiffs, isMakers)
152 partialOrders, err := addMatchTxOutput(txData, orders, receivedAmounts, allocatedAssets, isMakers)
157 addMatchTxFeeOutput(txData, allocatedAssets.Fees, e.rewardProgram)
158 addTakerOutput(txData, orders, priceDiffs, isMakers)
159 addRefundOutput(txData, orders)
161 byteData, err := txData.MarshalText()
166 txData.SerializedSize = uint64(len(byteData))
167 return types.NewTx(*txData), partialOrders, nil
170 func addMatchTxOutput(txData *types.TxData, orders []*common.Order, receivedAmounts []*bc.AssetAmount, allocatedAssets *AllocatedAssets, makerFlags []*MakerFlag) ([]*common.Order, error) {
171 var partialOrders []*common.Order
172 for i, order := range orders {
173 contractArgs := order.ContractArgs
174 receivedAmount := receivedAmounts[i].Amount
175 shouldPayAmount := calcShouldPayAmount(receivedAmount, contractArgs.RatioNumerator, contractArgs.RatioDenominator)
177 requestAmount := CalcRequestAmount(order.Utxo.Amount, order.RatioNumerator, order.RatioDenominator)
178 exchangeAmount := order.Utxo.Amount - shouldPayAmount
179 isPartialTrade := requestAmount > receivedAmount && CalcRequestAmount(exchangeAmount, contractArgs.RatioNumerator, contractArgs.RatioDenominator) >= 1
181 setMatchTxArguments(txData.Inputs[i], isPartialTrade, len(txData.Outputs), receivedAmount, makerFlags[i].IsMaker, contractArgs.Version)
183 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.ToAssetID, allocatedAssets.Receives[i].Amount, contractArgs.SellerProgram))
185 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.FromAssetID, exchangeAmount, order.Utxo.ControlProgram))
186 partialOrders = append(partialOrders, order)
189 return partialOrders, nil
192 func calcOppositeIndex(size int, selfIdx int) int {
193 return (selfIdx + 1) % size
196 // CalcRequestAmount is from amount * numerator / ratioDenominator
197 func CalcRequestAmount(fromAmount uint64, ratioNumerator, ratioDenominator int64) uint64 {
198 res := big.NewInt(0).SetUint64(fromAmount)
199 res.Mul(res, big.NewInt(ratioNumerator)).Quo(res, big.NewInt(ratioDenominator))
206 func calcShouldPayAmount(receiveAmount uint64, ratioNumerator, ratioDenominator int64) uint64 {
207 res := big.NewInt(0).SetUint64(receiveAmount)
208 res.Mul(res, big.NewInt(ratioDenominator)).Quo(res, big.NewInt(ratioNumerator))
215 // CalcReceivedAmount return amount of assets received by each participant in the matching transaction and the price difference
216 func CalcReceivedAmount(orders []*common.Order) ([]*bc.AssetAmount, []*bc.AssetAmount) {
217 var receivedAmounts, priceDiffs, shouldPayAmounts []*bc.AssetAmount
218 for i, order := range orders {
219 requestAmount := CalcRequestAmount(order.Utxo.Amount, order.RatioNumerator, order.RatioDenominator)
220 oppositeOrder := orders[calcOppositeIndex(len(orders), i)]
221 receiveAmount := vprMath.MinUint64(oppositeOrder.Utxo.Amount, requestAmount)
222 shouldPayAmount := calcShouldPayAmount(receiveAmount, order.RatioNumerator, order.RatioDenominator)
223 receivedAmounts = append(receivedAmounts, &bc.AssetAmount{AssetId: order.ToAssetID, Amount: receiveAmount})
224 shouldPayAmounts = append(shouldPayAmounts, &bc.AssetAmount{AssetId: order.FromAssetID, Amount: shouldPayAmount})
227 for i, receivedAmount := range receivedAmounts {
228 oppositeShouldPayAmount := shouldPayAmounts[calcOppositeIndex(len(orders), i)]
229 priceDiffs = append(priceDiffs, &bc.AssetAmount{AssetId: oppositeShouldPayAmount.AssetId, Amount: 0})
230 if oppositeShouldPayAmount.Amount > receivedAmount.Amount {
231 priceDiffs[i].Amount = oppositeShouldPayAmount.Amount - receivedAmount.Amount
234 return receivedAmounts, priceDiffs
237 // IsMatched check does the orders can be exchange
238 func IsMatched(orders []*common.Order) bool {
239 sortedOrders := sortOrders(orders)
240 if len(sortedOrders) == 0 {
244 product := big.NewRat(1, 1)
245 for _, order := range orders {
246 product.Mul(product, big.NewRat(order.RatioNumerator, order.RatioDenominator))
248 one := big.NewRat(1, 1)
249 return product.Cmp(one) <= 0
252 // MakerFlag represent whether the order is isMaker and include the contract version of order
253 type MakerFlag struct {
258 // MakerFlags return a slice of array indicate whether orders[i] is maker
259 func MakerFlags(orders []*common.Order) []*MakerFlag {
260 makerFlags := make([]*MakerFlag, len(orders))
261 for i, order := range orders {
262 makerFlags[i].IsMaker = isMaker(order, orders[calcOppositeIndex(len(orders), i)])
263 makerFlags[i].ContractVersion = order.ContractArgs.Version
268 func isMaker(order, oppositeOrder *common.Order) bool {
269 // old version of order's block height and tx sequence is 0
270 if order.BlockHeight == 0 && oppositeOrder.BlockHeight != 0 {
273 if order.BlockHeight != 0 && oppositeOrder.BlockHeight == 0 {
276 if order.BlockHeight == oppositeOrder.BlockHeight {
277 if order.TxIndex == oppositeOrder.TxIndex {
278 return order.UTXOHash().String() < oppositeOrder.UTXOHash().String()
280 return order.TxIndex < oppositeOrder.TxIndex
282 return order.BlockHeight < oppositeOrder.BlockHeight
285 func setMatchTxArguments(txInput *types.TxInput, isPartialTrade bool, position int, receiveAmounts uint64, isMaker bool, contractVersion int) {
286 feeRate := TakerFeeRate
288 feeRate = MakerFeeRate
291 var arguments [][]byte
293 arguments = [][]byte{vm.Int64Bytes(int64(receiveAmounts))}
294 if contractVersion == segwit.MagneticV2 {
295 arguments = append(arguments, vm.Int64Bytes(feeRate))
297 arguments = append(arguments, vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.PartialTradeClauseSelector))
299 if contractVersion == segwit.MagneticV2 {
300 arguments = append(arguments, vm.Int64Bytes(feeRate))
302 arguments = [][]byte{vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.FullTradeClauseSelector)}
304 txInput.SetArguments(arguments)
307 func sortOrders(orders []*common.Order) []*common.Order {
308 if len(orders) == 0 {
312 orderMap := make(map[bc.AssetID]*common.Order)
313 firstOrder := orders[0]
314 for i := 1; i < len(orders); i++ {
315 orderMap[*orders[i].FromAssetID] = orders[i]
318 sortedOrders := []*common.Order{firstOrder}
319 for order := firstOrder; *order.ToAssetID != *firstOrder.FromAssetID; {
320 nextOrder, ok := orderMap[*order.ToAssetID]
325 sortedOrders = append(sortedOrders, nextOrder)
331 func validateTradePairs(tradePairs []*common.TradePair) error {
332 if len(tradePairs) < 2 {
333 return errors.New("size of trade pairs at least 2")
336 assetMap := make(map[string]bool)
337 for _, tradePair := range tradePairs {
338 assetMap[tradePair.FromAssetID.String()] = true
339 if *tradePair.FromAssetID == *tradePair.ToAssetID {
340 return errors.New("from asset id can't equal to asset id")
344 for _, tradePair := range tradePairs {
345 key := tradePair.ToAssetID.String()
346 if _, ok := assetMap[key]; !ok {
347 return errors.New("invalid trade pairs")
349 delete(assetMap, key)