add optional swap limit logic

pkg/source/kyber-pmm/pool_simulator.go

@@ -135,7 +135,7 @@ func (p *PoolSimulator) CalcAmountOut(
 		inventoryLimit = limit.GetLimit(p.baseToken.Address)
 	}
 
-	if result.TokenAmountOut.Amount.Cmp(inventoryLimit) > 0 {
+	if inventoryLimit != nil && result.TokenAmountOut.Amount.Cmp(inventoryLimit) > 0 {
 		return nil, errors.New("not enough inventory")
 	}
 	return result, nil
@@ -349,12 +349,13 @@ func NewInventory(balance map[string]*big.Int) *Inventory {
 }
 
 // GetLimit returns a copy of balance for the token in Inventory
+// return nil if there is no limit
 func (i *Inventory) GetLimit(tokenAddress string) *big.Int {
 	i.lock.RLock()
 	defer i.lock.RUnlock()
 	balance, avail := i.Balance[tokenAddress]
 	if !avail {
-		return big.NewInt(0)
+		return nil
 	}
 	return big.NewInt(0).Set(balance)
 }

pkg/source/pool/swap_limit.go

@@ -6,6 +6,7 @@ import "math/big"
 // i.e: SwapLimit must be something affect multiple pools once it is change.
 type SwapLimit interface {
 	// GetLimit return a limit for a certain key. Normally each dex will have different limit values
+	// return nil in case there is no limit
 	// For example: PMM's key is token's string and its value is the inventory's balance of that token
 	GetLimit(key string) *big.Int
 	// UpdateLimit update both limits for a trade (assuming each trade is from 1 token to another token)

pkg/source/synthetix/pool_simulator.go

@@ -110,7 +110,7 @@ func (p *PoolSimulator) CalcAmountOut(
 	if synthetixTradeVolume != nil {
 		allowedVol := limit.GetLimit(strconv.FormatUint(p.poolState.BlockTimestamp, 10))
 
-		if allowedVol.Cmp(synthetixTradeVolume) < 0 {
+		if allowedVol != nil && allowedVol.Cmp(synthetixTradeVolume) < 0 {
 			return nil, ErrSurpassedVolumeLimit
 		}
 	}
@@ -230,6 +230,9 @@ func (p *PoolSimulator) GetPoolStateVersion() PoolStateVersion {
 }
 
 func (p *PoolSimulator) CalculateLimit() map[string]*big.Int {
+	if p.poolState.AtomicMaxVolumePerBlock == nil {
+		return nil
+	}
 	var (
 		s      = p.poolState
 		maxVol = big.NewInt(0).Set(p.poolState.AtomicMaxVolumePerBlock)
@@ -259,12 +262,13 @@ func NewLimits(atomicMaxVolumePerBlocks map[string]*big.Int) pool.SwapLimit {
 }
 
 // GetLimit returns a copy of balance for the token in Inventory
+
 func (i *AtomicLimits) GetLimit(blockTimeStamp string) *big.Int {
 	i.lock.RLock()
 	defer i.lock.RUnlock()
 	balance, avail := i.Limits[blockTimeStamp]
 	if !avail {
-		return big.NewInt(0)
+		return nil
 	}
 	return big.NewInt(0).Set(balance)
 }