Files
go-ethereum/accounts/abi/bind/backends/simulated.go
Felix Lange 46a527d014 [release/1.4.16] core/state: implement reverts by journaling all changes
This commit replaces the deep-copy based state revert mechanism with a
linear complexity journal. This commit also hides several internal
StateDB methods to limit the number of ways in which calling code can
use the journal incorrectly.

As usual consultation and bug fixes to the initial implementation were
provided by @karalabe, @obscuren and @Arachnid. Thank you!

(cherry picked from commit 1f1ea18b54)
2016-10-06 16:25:17 +02:00

215 lines
8.0 KiB
Go

// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package backends
import (
"math/big"
"github.com/ethereum/go-ethereum/accounts/abi/bind"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
)
// Default chain configuration which sets homestead phase at block 0 (i.e. no frontier)
var chainConfig = &core.ChainConfig{HomesteadBlock: big.NewInt(0)}
// This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
var _ bind.ContractBackend = (*SimulatedBackend)(nil)
// SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
// the background. Its main purpose is to allow easily testing contract bindings.
type SimulatedBackend struct {
database ethdb.Database // In memory database to store our testing data
blockchain *core.BlockChain // Ethereum blockchain to handle the consensus
pendingBlock *types.Block // Currently pending block that will be imported on request
pendingState *state.StateDB // Currently pending state that will be the active on on request
}
// NewSimulatedBackend creates a new binding backend using a simulated blockchain
// for testing purposes.
func NewSimulatedBackend(accounts ...core.GenesisAccount) *SimulatedBackend {
database, _ := ethdb.NewMemDatabase()
core.WriteGenesisBlockForTesting(database, accounts...)
blockchain, _ := core.NewBlockChain(database, chainConfig, new(core.FakePow), new(event.TypeMux))
backend := &SimulatedBackend{
database: database,
blockchain: blockchain,
}
backend.Rollback()
return backend
}
// Commit imports all the pending transactions as a single block and starts a
// fresh new state.
func (b *SimulatedBackend) Commit() {
if _, err := b.blockchain.InsertChain([]*types.Block{b.pendingBlock}); err != nil {
panic(err) // This cannot happen unless the simulator is wrong, fail in that case
}
b.Rollback()
}
// Rollback aborts all pending transactions, reverting to the last committed state.
func (b *SimulatedBackend) Rollback() {
blocks, _ := core.GenerateChain(nil, b.blockchain.CurrentBlock(), b.database, 1, func(int, *core.BlockGen) {})
b.pendingBlock = blocks[0]
b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
}
// HasCode implements ContractVerifier.HasCode, checking whether there is any
// code associated with a certain account in the blockchain.
func (b *SimulatedBackend) HasCode(contract common.Address, pending bool) (bool, error) {
if pending {
return len(b.pendingState.GetCode(contract)) > 0, nil
}
statedb, _ := b.blockchain.State()
return len(statedb.GetCode(contract)) > 0, nil
}
// ContractCall implements ContractCaller.ContractCall, executing the specified
// contract with the given input data.
func (b *SimulatedBackend) ContractCall(contract common.Address, data []byte, pending bool) ([]byte, error) {
// Create a copy of the current state db to screw around with
var (
block *types.Block
statedb *state.StateDB
)
if pending {
block, statedb = b.pendingBlock, b.pendingState
defer statedb.RevertToSnapshot(statedb.Snapshot())
} else {
block = b.blockchain.CurrentBlock()
statedb, _ = b.blockchain.State()
}
// If there's no code to interact with, respond with an appropriate error
if code := statedb.GetCode(contract); len(code) == 0 {
return nil, bind.ErrNoCode
}
// Set infinite balance to the a fake caller account
from := statedb.GetOrNewStateObject(common.Address{})
from.SetBalance(common.MaxBig)
// Assemble the call invocation to measure the gas usage
msg := callmsg{
from: from,
to: &contract,
gasPrice: new(big.Int),
gasLimit: common.MaxBig,
value: new(big.Int),
data: data,
}
// Execute the call and return
vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), vm.Config{})
gaspool := new(core.GasPool).AddGas(common.MaxBig)
out, _, err := core.ApplyMessage(vmenv, msg, gaspool)
return out, err
}
// PendingAccountNonce implements ContractTransactor.PendingAccountNonce, retrieving
// the nonce currently pending for the account.
func (b *SimulatedBackend) PendingAccountNonce(account common.Address) (uint64, error) {
return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
}
// SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated
// chain doens't have miners, we just return a gas price of 1 for any call.
func (b *SimulatedBackend) SuggestGasPrice() (*big.Int, error) {
return big.NewInt(1), nil
}
// EstimateGasLimit implements ContractTransactor.EstimateGasLimit, executing the
// requested code against the currently pending block/state and returning the used
// gas.
func (b *SimulatedBackend) EstimateGasLimit(sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
// Create a copy of the currently pending state db to screw around with
var (
block = b.pendingBlock
statedb = b.pendingState
)
defer statedb.RevertToSnapshot(statedb.Snapshot())
// If there's no code to interact with, respond with an appropriate error
if contract != nil {
if code := statedb.GetCode(*contract); len(code) == 0 {
return nil, bind.ErrNoCode
}
}
// Set infinite balance to the a fake caller account
from := statedb.GetOrNewStateObject(sender)
from.SetBalance(common.MaxBig)
// Assemble the call invocation to measure the gas usage
msg := callmsg{
from: from,
to: contract,
gasPrice: new(big.Int),
gasLimit: common.MaxBig,
value: value,
data: data,
}
// Execute the call and return
vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), vm.Config{})
gaspool := new(core.GasPool).AddGas(common.MaxBig)
_, gas, _, err := core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
return gas, err
}
// SendTransaction implements ContractTransactor.SendTransaction, delegating the raw
// transaction injection to the remote node.
func (b *SimulatedBackend) SendTransaction(tx *types.Transaction) error {
blocks, _ := core.GenerateChain(nil, b.blockchain.CurrentBlock(), b.database, 1, func(number int, block *core.BlockGen) {
for _, tx := range b.pendingBlock.Transactions() {
block.AddTx(tx)
}
block.AddTx(tx)
})
b.pendingBlock = blocks[0]
b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
return nil
}
// callmsg implements core.Message to allow passing it as a transaction simulator.
type callmsg struct {
from *state.StateObject
to *common.Address
gasLimit *big.Int
gasPrice *big.Int
value *big.Int
data []byte
}
func (m callmsg) From() (common.Address, error) { return m.from.Address(), nil }
func (m callmsg) FromFrontier() (common.Address, error) { return m.from.Address(), nil }
func (m callmsg) Nonce() uint64 { return m.from.Nonce() }
func (m callmsg) To() *common.Address { return m.to }
func (m callmsg) GasPrice() *big.Int { return m.gasPrice }
func (m callmsg) Gas() *big.Int { return m.gasLimit }
func (m callmsg) Value() *big.Int { return m.value }
func (m callmsg) Data() []byte { return m.data }