// Copyright 2015 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 (
"context"
"errors"
"fmt"
"math/big"
"sync"
"time"
"github.com/ava-labs/coreth/accounts/abi/bind"
"github.com/ava-labs/coreth/consensus/ethash"
"github.com/ava-labs/coreth/core"
"github.com/ava-labs/coreth/core/bloombits"
"github.com/ava-labs/coreth/core/rawdb"
"github.com/ava-labs/coreth/core/state"
"github.com/ava-labs/coreth/core/types"
"github.com/ava-labs/coreth/core/vm"
"github.com/ava-labs/coreth/params"
"github.com/ava-labs/coreth/rpc"
"github.com/ava-labs/go-ethereum"
"github.com/ava-labs/go-ethereum/common"
"github.com/ava-labs/go-ethereum/common/math"
"github.com/ava-labs/go-ethereum/eth/filters"
"github.com/ava-labs/go-ethereum/ethdb"
"github.com/ava-labs/go-ethereum/event"
)
// This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
var _ bind.ContractBackend = (*SimulatedBackend)(nil)
var (
errBlockNumberUnsupported = errors.New("simulatedBackend cannot access blocks other than the latest block")
errGasEstimationFailed = errors.New("gas required exceeds allowance or always failing transaction")
)
// 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
mu sync.Mutex
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
events *filters.EventSystem // Event system for filtering log events live
config *params.ChainConfig
}
// NewSimulatedBackendWithDatabase creates a new binding backend based on the given database
// and uses a simulated blockchain for testing purposes.
func NewSimulatedBackendWithDatabase(database ethdb.Database, alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
genesis := core.Genesis{Config: params.AllEthashProtocolChanges, GasLimit: gasLimit, Alloc: alloc}
genesis.MustCommit(database)
blockchain, _ := core.NewBlockChain(database, nil, genesis.Config, ethash.NewFaker(), vm.Config{}, nil)
backend := &SimulatedBackend{
database: database,
blockchain: blockchain,
config: genesis.Config,
events: filters.NewEventSystem(new(event.TypeMux), &filterBackend{database, blockchain}, false),
}
backend.rollback()
return backend
}
// NewSimulatedBackend creates a new binding backend using a simulated blockchain
// for testing purposes.
func NewSimulatedBackend(alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
return NewSimulatedBackendWithDatabase(rawdb.NewMemoryDatabase(), alloc, gasLimit)
}
// Close terminates the underlying blockchain's update loop.
func (b *SimulatedBackend) Close() error {
b.blockchain.Stop()
return nil
}
// Commit imports all the pending transactions as a single block and starts a
// fresh new state.
func (b *SimulatedBackend) Commit() {
b.mu.Lock()
defer b.mu.Unlock()
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() {
b.mu.Lock()
defer b.mu.Unlock()
b.rollback()
}
func (b *SimulatedBackend) rollback() {
blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(int, *core.BlockGen) {})
statedb, _ := b.blockchain.State()
b.pendingBlock = blocks[0]
b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database())
}
// CodeAt returns the code associated with a certain account in the blockchain.
func (b *SimulatedBackend) CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error) {
b.mu.Lock()
defer b.mu.Unlock()
if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
return nil, errBlockNumberUnsupported
}
statedb, _ := b.blockchain.State()
return statedb.GetCode(contract), nil
}
// BalanceAt returns the wei balance of a certain account in the blockchain.
func (b *SimulatedBackend) BalanceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (*big.Int, error) {
b.mu.Lock()
defer b.mu.Unlock()
if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
return nil, errBlockNumberUnsupported
}
statedb, _ := b.blockchain.State()
return statedb.GetBalance(contract), nil
}
// NonceAt returns the nonce of a certain account in the blockchain.
func (b *SimulatedBackend) NonceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (uint64, error) {
b.mu.Lock()
defer b.mu.Unlock()
if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
return 0, errBlockNumberUnsupported
}
statedb, _ := b.blockchain.State()
return statedb.GetNonce(contract), nil
}
// StorageAt returns the value of key in the storage of an account in the blockchain.
func (b *SimulatedBackend) StorageAt(ctx context.Context, contract common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
b.mu.Lock()
defer b.mu.Unlock()
if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
return nil, errBlockNumberUnsupported
}
statedb, _ := b.blockchain.State()
val := statedb.GetState(contract, key)
return val[:], nil
}
// TransactionReceipt returns the receipt of a transaction.
func (b *SimulatedBackend) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
receipt, _, _, _ := rawdb.ReadReceipt(b.database, txHash, b.config)
return receipt, nil
}
// TransactionByHash checks the pool of pending transactions in addition to the
// blockchain. The isPending return value indicates whether the transaction has been
// mined yet. Note that the transaction may not be part of the canonical chain even if
// it's not pending.
func (b *SimulatedBackend) TransactionByHash(ctx context.Context, txHash common.Hash) (*types.Transaction, bool, error) {
b.mu.Lock()
defer b.mu.Unlock()
tx := b.pendingBlock.Transaction(txHash)
if tx != nil {
return tx, true, nil
}
tx, _, _, _ = rawdb.ReadTransaction(b.database, txHash)
if tx != nil {
return tx, false, nil
}
return nil, false, ethereum.NotFound
}
// PendingCodeAt returns the code associated with an account in the pending state.
func (b *SimulatedBackend)