accounts/abi/bind: use ethereum interfaces
In this commit, contract bindings and their backend start using the Ethereum Go API interfaces offered by ethclient. This makes ethclient a suitable replacement for the old remote backend and gets us one step closer to the final stable Go API that is planned for go-ethereum 1.5. The changes in detail: * Pending state is optional for read only contract bindings. BoundContract attempts to discover the Pending* methods via an interface assertion. There are a couple of advantages to this: ContractCaller is just two methods and can be implemented on top of pretty much anything that provides Ethereum data. Since the backend interfaces are now disjoint, ContractBackend can simply be declared as a union of the reader and writer side. * Caching of HasCode is removed. The caching could go wrong in case of chain reorganisations and removing it simplifies the code a lot. We'll figure out a performant way of providing ErrNoCode before the 1.5 release. * BoundContract now ensures that the backend receives a non-nil context with every call.
This commit is contained in:
Felix Lange
@ -17,8 +17,10 @@
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package backends
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import (
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"fmt"
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"math/big"
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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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@ -79,58 +81,44 @@ func (b *SimulatedBackend) Rollback() {
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b.pendingState, _ = state.New(b.pendingBlock.Root(), b.database)
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}
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// HasCode implements ContractVerifier.HasCode, checking whether there is any
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// code associated with a certain account in the blockchain.
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func (b *SimulatedBackend) HasCode(ctx context.Context, contract common.Address, pending bool) (bool, error) {
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if pending {
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return len(b.pendingState.GetCode(contract)) > 0, nil
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// CodeAt implements ChainStateReader.CodeAt, returning the code associated with
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// a certain account at a given block number 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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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, fmt.Errorf("SimulatedBackend cannot access blocks other than the latest block")
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}
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statedb, _ := b.blockchain.State()
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return len(statedb.GetCode(contract)) > 0, nil
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return statedb.GetCode(contract), nil
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}
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// ContractCall implements ContractCaller.ContractCall, executing the specified
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// contract with the given input data.
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func (b *SimulatedBackend) ContractCall(ctx context.Context, contract common.Address, data []byte, pending bool) ([]byte, error) {
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// Create a copy of the current state db to screw around with
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var (
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block *types.Block
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statedb *state.StateDB
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)
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if pending {
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block, statedb = b.pendingBlock, b.pendingState.Copy()
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} else {
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block = b.blockchain.CurrentBlock()
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statedb, _ = b.blockchain.State()
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}
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// If there's no code to interact with, respond with an appropriate error
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if code := statedb.GetCode(contract); len(code) == 0 {
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return nil, bind.ErrNoCode
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}
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// Set infinite balance to the a fake caller account
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from := statedb.GetOrNewStateObject(common.Address{})
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from.SetBalance(common.MaxBig)
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// Assemble the call invocation to measure the gas usage
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msg := callmsg{
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from: from,
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to: &contract,
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gasPrice: new(big.Int),
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gasLimit: common.MaxBig,
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value: new(big.Int),
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data: data,
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}
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// Execute the call and return
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vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), vm.Config{})
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gaspool := new(core.GasPool).AddGas(common.MaxBig)
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out, _, err := core.ApplyMessage(vmenv, msg, gaspool)
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return out, err
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// PendingCodeAt implements PendingStateReader.PendingCodeAt, returning the
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// code associated with a certain account in the pending state of the blockchain.
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func (b *SimulatedBackend) PendingCodeAt(ctx context.Context, contract common.Address) ([]byte, error) {
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return b.pendingState.GetCode(contract), nil
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}
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// PendingAccountNonce implements ContractTransactor.PendingAccountNonce, retrieving
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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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if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
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return nil, fmt.Errorf("SimulatedBackend cannot access blocks other than the latest block")
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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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rval, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState.Copy())
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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) PendingAccountNonce(ctx context.Context, account common.Address) (uint64, error) {
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func (b *SimulatedBackend) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
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return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
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}
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@ -140,45 +128,49 @@ 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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// EstimateGasLimit implements ContractTransactor.EstimateGasLimit, executing the
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// requested code against the currently pending block/state and returning the used
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// gas.
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func (b *SimulatedBackend) EstimateGasLimit(ctx context.Context, sender common.Address, contract *common.Address, value *big.Int, data []byte) (*big.Int, error) {
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// Create a copy of the currently pending state db to screw around with
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var (
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block = b.pendingBlock
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statedb = b.pendingState.Copy()
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)
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// If there's no code to interact with, respond with an appropriate error
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if contract != nil {
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if code := statedb.GetCode(*contract); len(code) == 0 {
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return nil, bind.ErrNoCode
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}
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}
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// Set infinite balance to the a fake caller account
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from := statedb.GetOrNewStateObject(sender)
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from.SetBalance(common.MaxBig)
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// Assemble the call invocation to measure the gas usage
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msg := callmsg{
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from: from,
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to: contract,
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gasPrice: new(big.Int),
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gasLimit: common.MaxBig,
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value: value,
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data: data,
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}
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// Execute the call and return
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vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), vm.Config{})
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gaspool := new(core.GasPool).AddGas(common.MaxBig)
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_, gas, _, err := core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
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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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_, gas, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState.Copy())
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return gas, err
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}
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// SendTransaction implements ContractTransactor.SendTransaction, delegating the raw
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// transaction injection to the remote node.
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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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vmenv := core.NewEnv(statedb, chainConfig, b.blockchain, msg, block.Header(), 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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sender, err := tx.From()
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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(nil, 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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@ -187,26 +179,20 @@ func (b *SimulatedBackend) SendTransaction(ctx context.Context, tx *types.Transa
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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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from *state.StateObject
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to *common.Address
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gasLimit *big.Int
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gasPrice *big.Int
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value *big.Int
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data []byte
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ethereum.CallMsg
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}
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func (m callmsg) From() (common.Address, error) { return m.from.Address(), nil }
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func (m callmsg) FromFrontier() (common.Address, error) { return m.from.Address(), nil }
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func (m callmsg) From() (common.Address, error) { return m.CallMsg.From, nil }
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func (m callmsg) FromFrontier() (common.Address, error) { return m.CallMsg.From, nil }
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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.to }
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func (m callmsg) GasPrice() *big.Int { return m.gasPrice }
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func (m callmsg) Gas() *big.Int { return m.gasLimit }
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func (m callmsg) Value() *big.Int { return m.value }
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func (m callmsg) Data() []byte { return m.data }
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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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