database/contract_view.go

   1 package database
   2
   3 import (
   4         "bytes"
   5
   6         dbm "github.com/bytom/bytom/database/leveldb"
   7         "github.com/bytom/bytom/errors"
   8         "github.com/bytom/bytom/protocol/state"
   9 )
  10
  11 // ContractPrefix contract prefix
  12 var ContractPrefix = []byte("C:")
  13
  14 // CalcContractKey calculate contract key
  15 func CalcContractKey(hash [32]byte) []byte {
  16         return append(ContractPrefix, hash[:]...)
  17 }
  18
  19 func saveContractView(db dbm.DB, batch dbm.Batch, view *state.ContractViewpoint) error {
  20         for hash, value := range view.AttachEntries {
  21                 data := db.Get(CalcContractKey(hash))
  22                 // contract is not exist
  23                 if data == nil {
  24                         // key:"c:sha256(program.Code)" value:"txID+program.Code"
  25                         batch.Set(CalcContractKey(hash), value)
  26                 }
  27                 // contract is deleted in the same batch
  28                 if v, ok := view.DetachEntries[hash]; ok && bytes.Equal(data, v) {
  29                         batch.Set(CalcContractKey(hash), value)
  30                 }
  31         }
  32         return nil
  33 }
  34
  35 func deleteContractView(db dbm.DB, batch dbm.Batch, view *state.ContractViewpoint) error {
  36         for hash, value := range view.DetachEntries {
  37                 // rollback is forbidden if contract register transaction id is different
  38                 if bytes.Equal(db.Get(CalcContractKey(hash)), value) {
  39                         batch.Delete(CalcContractKey(hash))
  40                 }
  41         }
  42         return nil
  43 }
  44
  45 func getContract(db dbm.DB, hash [32]byte) ([]byte, error) {
  46         data := db.Get(CalcContractKey(hash))
  47         if data == nil {
  48                 return nil, errors.New("can't find the registered contract by contract hash")
  49         }
  50
  51         // data:"txID+program.Code" len(txID) == 32
  52         if len(data) <= 32 {
  53                 return nil, errors.New("registered contract format error")
  54         }
  55
  56         return data[32:], nil
  57 }