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accounts/abi/bind: use ethereum interfaces

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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
2016-08-22 14:01:28 +02:00
parent 056f15aa53
commit d62d5fe59a
4 changed files with 212 additions and 228 deletions
Download Patch File Download Diff File Expand all files Collapse all files

75
accounts/abi/bind/base.go
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@ -20,8 +20,8 @@ import (
"errors"
"fmt"
"math/big"
"sync/atomic"
"github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
@ -62,9 +62,6 @@ type BoundContract struct {
abi abi.ABI // Reflect based ABI to access the correct Ethereum methods
caller ContractCaller // Read interface to interact with the blockchain
transactor ContractTransactor // Write interface to interact with the blockchain
latestHasCode uint32 // Cached verification that the latest state contains code for this contract
pendingHasCode uint32 // Cached verification that the pending state contains code for this contract
}
// NewBoundContract creates a low level contract interface through which calls
@ -105,25 +102,42 @@ func (c *BoundContract) Call(opts *CallOpts, result interface{}, method string,
if opts == nil {
opts = new(CallOpts)
}
// Make sure we have a contract to operate on, and bail out otherwise
if (opts.Pending && atomic.LoadUint32(&c.pendingHasCode) == 0) || (!opts.Pending && atomic.LoadUint32(&c.latestHasCode) == 0) {
if code, err := c.caller.HasCode(opts.Context, c.address, opts.Pending); err != nil {
return err
} else if !code {
return ErrNoCode
}
if opts.Pending {
atomic.StoreUint32(&c.pendingHasCode, 1)
} else {
atomic.StoreUint32(&c.latestHasCode, 1)
}
}
// Pack the input, call and unpack the results
input, err := c.abi.Pack(method, params...)
if err != nil {
return err
}
output, err := c.caller.ContractCall(opts.Context, c.address, input, opts.Pending)
var (
msg = ethereum.CallMsg{To: &c.address, Data: input}
ctx = ensureContext(opts.Context)
code []byte
output []byte
)
if opts.Pending {
pb, ok := c.caller.(PendingContractCaller)
if !ok {
return ErrNoPendingState
}
output, err = pb.PendingCallContract(ctx, msg)
if err == nil && len(output) == 0 {
// Make sure we have a contract to operate on, and bail out otherwise.
if code, err = pb.PendingCodeAt(ctx, c.address); err != nil {
return err
} else if len(code) == 0 {
return ErrNoCode
}
}
} else {
output, err = c.caller.CallContract(ctx, msg, nil)
if err == nil && len(output) == 0 {
// Make sure we have a contract to operate on, and bail out otherwise.
if code, err = c.caller.CodeAt(ctx, c.address, nil); err != nil {
return err
} else if len(code) == 0 {
return ErrNoCode
}
}
}
if err != nil {
return err
}
@ -158,7 +172,7 @@ func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, i
}
nonce := uint64(0)
if opts.Nonce == nil {
nonce, err = c.transactor.PendingAccountNonce(opts.Context, opts.From)
nonce, err = c.transactor.PendingNonceAt(ensureContext(opts.Context), opts.From)
if err != nil {
return nil, fmt.Errorf("failed to retrieve account nonce: %v", err)
}
@ -168,7 +182,7 @@ func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, i
// Figure out the gas allowance and gas price values
gasPrice := opts.GasPrice
if gasPrice == nil {
gasPrice, err = c.transactor.SuggestGasPrice(opts.Context)
gasPrice, err = c.transactor.SuggestGasPrice(ensureContext(opts.Context))
if err != nil {
return nil, fmt.Errorf("failed to suggest gas price: %v", err)
}
@ -176,18 +190,18 @@ func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, i
gasLimit := opts.GasLimit
if gasLimit == nil {
// Gas estimation cannot succeed without code for method invocations
if contract != nil && atomic.LoadUint32(&c.pendingHasCode) == 0 {
if code, err := c.transactor.HasCode(opts.Context, c.address, true); err != nil {
if contract != nil {
if code, err := c.transactor.PendingCodeAt(ensureContext(opts.Context), c.address); err != nil {
return nil, err
} else if !code {
} else if len(code) == 0 {
return nil, ErrNoCode
}
atomic.StoreUint32(&c.pendingHasCode, 1)
}
// If the contract surely has code (or code is not needed), estimate the transaction
gasLimit, err = c.transactor.EstimateGasLimit(opts.Context, opts.From, contract, value, input)
msg := ethereum.CallMsg{From: opts.From, To: contract, Value: value, Data: input}
gasLimit, err = c.transactor.EstimateGas(ensureContext(opts.Context), msg)
if err != nil {
return nil, fmt.Errorf("failed to exstimate gas needed: %v", err)
return nil, fmt.Errorf("failed to estimate gas needed: %v", err)
}
}
// Create the transaction, sign it and schedule it for execution
@ -204,8 +218,15 @@ func (c *BoundContract) transact(opts *TransactOpts, contract *common.Address, i
if err != nil {
return nil, err
}
if err := c.transactor.SendTransaction(opts.Context, signedTx); err != nil {
if err := c.transactor.SendTransaction(ensureContext(opts.Context), signedTx); err != nil {
return nil, err
}
return signedTx, nil
}
func ensureContext(ctx context.Context) context.Context {
if ctx == nil {
return context.TODO()
}
return ctx
}