blockchain/txbuilder/estimate.go

   1 package txbuilder
   2
   3 import (
   4         "github.com/vapor/consensus"
   5         "github.com/vapor/consensus/segwit"
   6         "github.com/vapor/protocol/bc/types"
   7 )
   8
   9 // EstimateTxGasInfo estimate transaction consumed gas
  10 type EstimateTxGasInfo struct {
  11         TotalNeu    int64 `json:"total_neu"`
  12         FlexibleNeu int64 `json:"flexible_neu"`
  13         StorageNeu  int64 `json:"storage_neu"`
  14         VMNeu       int64 `json:"vm_neu"`
  15 }
  16
  17 // EstimateTxGas estimate consumed neu for transaction
  18 func EstimateTxGas(template Template) (*EstimateTxGasInfo, error) {
  19         var baseP2WSHSize, totalWitnessSize, baseP2WSHGas, totalP2WPKHGas, totalP2WSHGas int64
  20         baseSize := int64(176) // inputSize(112) + outputSize(64)
  21         baseP2WPKHSize := int64(98)
  22         baseP2WPKHGas := int64(1409)
  23         for pos, input := range template.Transaction.TxData.Inputs {
  24                 switch input.InputType() {
  25                 case types.SpendInputType:
  26                         controlProgram := input.ControlProgram()
  27                         if segwit.IsP2WPKHScript(controlProgram) {
  28                                 totalWitnessSize += baseP2WPKHSize
  29                                 totalP2WPKHGas += baseP2WPKHGas
  30                         } else if segwit.IsP2WSHScript(controlProgram) {
  31                                 baseP2WSHSize, baseP2WSHGas = estimateP2WSHGas(template.SigningInstructions[pos])
  32                                 totalWitnessSize += baseP2WSHSize
  33                                 totalP2WSHGas += baseP2WSHGas
  34                         }
  35                 }
  36         }
  37
  38         flexibleGas := int64(0)
  39         if totalP2WPKHGas > 0 {
  40                 flexibleGas += baseP2WPKHGas + (baseSize+baseP2WPKHSize)*consensus.ActiveNetParams.StorageGasRate
  41         } else if totalP2WSHGas > 0 {
  42                 flexibleGas += baseP2WSHGas + (baseSize+baseP2WSHSize)*consensus.ActiveNetParams.StorageGasRate
  43         }
  44
  45         // the total transaction storage gas
  46         totalTxSizeGas := (int64(template.Transaction.TxData.SerializedSize) + totalWitnessSize) * consensus.ActiveNetParams.StorageGasRate
  47
  48         // the total transaction gas is composed of storage and virtual machines
  49         totalGas := totalTxSizeGas + totalP2WPKHGas + totalP2WSHGas + flexibleGas
  50         if totalGas > consensus.ActiveNetParams.DefaultGasCredit {
  51                 totalGas -= consensus.ActiveNetParams.DefaultGasCredit
  52         } else {
  53                 totalGas = 0
  54         }
  55
  56         return &EstimateTxGasInfo{
  57                 TotalNeu:    totalGas * consensus.ActiveNetParams.VMGasRate,
  58                 FlexibleNeu: flexibleGas * consensus.ActiveNetParams.VMGasRate,
  59                 StorageNeu:  totalTxSizeGas * consensus.ActiveNetParams.VMGasRate,
  60                 VMNeu:       (totalP2WPKHGas + totalP2WSHGas) * consensus.ActiveNetParams.VMGasRate,
  61         }, nil
  62 }
  63
  64 // estimateP2WSH return the witness size and the gas consumed to execute the virtual machine for P2WSH program
  65 func estimateP2WSHGas(sigInst *SigningInstruction) (int64, int64) {
  66         var witnessSize, gas int64
  67         for _, witness := range sigInst.WitnessComponents {
  68                 switch t := witness.(type) {
  69                 case *SignatureWitness:
  70                         witnessSize += 33*int64(len(t.Keys)) + 65*int64(t.Quorum)
  71                         gas += 1131*int64(len(t.Keys)) + 72*int64(t.Quorum) + 659
  72                         if int64(len(t.Keys)) == 1 && int64(t.Quorum) == 1 {
  73                                 gas += 27
  74                         }
  75                 case *RawTxSigWitness:
  76                         witnessSize += 33*int64(len(t.Keys)) + 65*int64(t.Quorum)
  77                         gas += 1131*int64(len(t.Keys)) + 72*int64(t.Quorum) + 659
  78                         if int64(len(t.Keys)) == 1 && int64(t.Quorum) == 1 {
  79                                 gas += 27
  80                         }
  81                 }
  82         }
  83         return witnessSize, gas
  84 }