bbc4ea4ae8
The run loop, which previously contained custom opcode executes have been removed and has been simplified to a few checks. Each operation consists of 4 elements: execution function, gas cost function, stack validation function and memory size function. The execution function implements the operation's runtime behaviour, the gas cost function implements the operation gas costs function and greatly depends on the memory and stack, the stack validation function validates the stack and makes sure that enough items can be popped off and pushed on and the memory size function calculates the memory required for the operation and returns it. This commit also allows the EVM to go unmetered. This is helpful for offline operations such as contract calls.
277 lines
10 KiB
Go
277 lines
10 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package backends
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import (
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"errors"
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"fmt"
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"math/big"
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"sync"
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"github.com/ethereum/go-ethereum"
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"github.com/ethereum/go-ethereum/accounts/abi/bind"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/state"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/core/vm"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/params"
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"golang.org/x/net/context"
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)
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// Default chain configuration which sets homestead phase at block 0 (i.e. no frontier)
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var chainConfig = ¶ms.ChainConfig{HomesteadBlock: big.NewInt(0), EIP150Block: new(big.Int), EIP158Block: new(big.Int)}
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// This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
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var _ bind.ContractBackend = (*SimulatedBackend)(nil)
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var errBlockNumberUnsupported = errors.New("SimulatedBackend cannot access blocks other than the latest block")
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// SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
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// the background. Its main purpose is to allow easily testing contract bindings.
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type SimulatedBackend struct {
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database ethdb.Database // In memory database to store our testing data
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blockchain *core.BlockChain // Ethereum blockchain to handle the consensus
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mu sync.Mutex
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pendingBlock *types.Block // Currently pending block that will be imported on request
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pendingState *state.StateDB // Currently pending state that will be the active on on request
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config *params.ChainConfig
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}
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// NewSimulatedBackend creates a new binding backend using a simulated blockchain
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// for testing purposes.
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func NewSimulatedBackend(accounts ...core.GenesisAccount) *SimulatedBackend {
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database, _ := ethdb.NewMemDatabase()
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core.WriteGenesisBlockForTesting(database, accounts...)
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blockchain, _ := core.NewBlockChain(database, chainConfig, new(core.FakePow), new(event.TypeMux))
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backend := &SimulatedBackend{database: database, blockchain: blockchain}
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backend.rollback()
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return backend
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}
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// Commit imports all the pending transactions as a single block and starts a
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// fresh new state.
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func (b *SimulatedBackend) Commit() {
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b.mu.Lock()
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defer b.mu.Unlock()
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if _, err := b.blockchain.InsertChain([]*types.Block{b.pendingBlock}); err != nil {
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panic(err) // This cannot happen unless the simulator is wrong, fail in that case
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}
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b.rollback()
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}
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// Rollback aborts all pending transactions, reverting to the last committed state.
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func (b *SimulatedBackend) Rollback() {
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b.mu.Lock()
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defer b.mu.Unlock()
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b.rollback()
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}
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func (b *SimulatedBackend) rollback() {
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blocks, _ := core.GenerateChain(chainConfig, b.blockchain.CurrentBlock(), b.database, 1, func(int, *core.BlockGen) {})
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b.pendingBlock = blocks[0]
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b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
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}
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// CodeAt returns the code associated with a certain account in the blockchain.
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func (b *SimulatedBackend) CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetCode(contract), nil
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}
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// BalanceAt returns the wei balance of a certain account in the blockchain.
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func (b *SimulatedBackend) BalanceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (*big.Int, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetBalance(contract), nil
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}
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// NonceAt returns the nonce of a certain account in the blockchain.
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func (b *SimulatedBackend) NonceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (uint64, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return 0, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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return statedb.GetNonce(contract), nil
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}
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// StorageAt returns the value of key in the storage of an account in the blockchain.
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func (b *SimulatedBackend) StorageAt(ctx context.Context, contract common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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statedb, _ := b.blockchain.State()
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val := statedb.GetState(contract, key)
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return val[:], nil
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}
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// TransactionReceipt returns the receipt of a transaction.
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func (b *SimulatedBackend) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
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return core.GetReceipt(b.database, txHash), nil
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}
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// PendingCodeAt returns the code associated with an account in the pending state.
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func (b *SimulatedBackend) PendingCodeAt(ctx context.Context, contract common.Address) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.pendingState.GetCode(contract), nil
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}
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// CallContract executes a contract call.
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func (b *SimulatedBackend) CallContract(ctx context.Context, call ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, errBlockNumberUnsupported
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}
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state, err := b.blockchain.State()
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if err != nil {
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return nil, err
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}
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rval, _, err := b.callContract(ctx, call, b.blockchain.CurrentBlock(), state)
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return rval, err
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}
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// PendingCallContract executes a contract call on the pending state.
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func (b *SimulatedBackend) PendingCallContract(ctx context.Context, call ethereum.CallMsg) ([]byte, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
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rval, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
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return rval, err
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}
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// PendingNonceAt implements PendingStateReader.PendingNonceAt, retrieving
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// the nonce currently pending for the account.
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func (b *SimulatedBackend) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
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}
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// SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated
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// chain doens't have miners, we just return a gas price of 1 for any call.
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func (b *SimulatedBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
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return big.NewInt(1), nil
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}
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// EstimateGas executes the requested code against the currently pending block/state and
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// returns the used amount of gas.
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func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMsg) (*big.Int, error) {
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b.mu.Lock()
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defer b.mu.Unlock()
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defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
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_, gas, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
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return gas, err
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}
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// callContract implemens common code between normal and pending contract calls.
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// state is modified during execution, make sure to copy it if necessary.
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func (b *SimulatedBackend) callContract(ctx context.Context, call ethereum.CallMsg, block *types.Block, statedb *state.StateDB) ([]byte, *big.Int, error) {
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// Ensure message is initialized properly.
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if call.GasPrice == nil {
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call.GasPrice = big.NewInt(1)
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}
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if call.Gas == nil || call.Gas.BitLen() == 0 {
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call.Gas = big.NewInt(50000000)
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}
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if call.Value == nil {
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call.Value = new(big.Int)
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}
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// Set infinite balance to the fake caller account.
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from := statedb.GetOrNewStateObject(call.From)
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from.SetBalance(common.MaxBig)
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// Execute the call.
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msg := callmsg{call}
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evmContext := core.NewEVMContext(msg, block.Header(), b.blockchain)
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// Create a new environment which holds all relevant information
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// about the transaction and calling mechanisms.
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vmenv := vm.NewEVM(evmContext, statedb, chainConfig, vm.Config{})
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gaspool := new(core.GasPool).AddGas(common.MaxBig)
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ret, gasUsed, _, err := core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
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return ret, gasUsed, err
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}
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// SendTransaction updates the pending block to include the given transaction.
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// It panics if the transaction is invalid.
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func (b *SimulatedBackend) SendTransaction(ctx context.Context, tx *types.Transaction) error {
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b.mu.Lock()
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defer b.mu.Unlock()
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sender, err := types.Sender(types.HomesteadSigner{}, tx)
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if err != nil {
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panic(fmt.Errorf("invalid transaction: %v", err))
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}
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nonce := b.pendingState.GetNonce(sender)
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if tx.Nonce() != nonce {
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panic(fmt.Errorf("invalid transaction nonce: got %d, want %d", tx.Nonce(), nonce))
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}
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blocks, _ := core.GenerateChain(chainConfig, b.blockchain.CurrentBlock(), b.database, 1, func(number int, block *core.BlockGen) {
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for _, tx := range b.pendingBlock.Transactions() {
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block.AddTx(tx)
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}
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block.AddTx(tx)
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})
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b.pendingBlock = blocks[0]
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b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
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return nil
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}
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// callmsg implements core.Message to allow passing it as a transaction simulator.
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type callmsg struct {
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ethereum.CallMsg
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}
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func (m callmsg) From() common.Address { return m.CallMsg.From }
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func (m callmsg) Nonce() uint64 { return 0 }
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func (m callmsg) CheckNonce() bool { return false }
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func (m callmsg) To() *common.Address { return m.CallMsg.To }
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func (m callmsg) GasPrice() *big.Int { return m.CallMsg.GasPrice }
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func (m callmsg) Gas() *big.Int { return m.CallMsg.Gas }
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func (m callmsg) Value() *big.Int { return m.CallMsg.Value }
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func (m callmsg) Data() []byte { return m.CallMsg.Data }
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