gitlab.com/yannislg/go-pulse@v0.0.0-20210722055913-a3e24e95638d/accounts/abi/bind/backends/simulated.go (about)

     1  // Copyright 2015 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package backends
    18  
    19  import (
    20  	"context"
    21  	"errors"
    22  	"fmt"
    23  	"math/big"
    24  	"sync"
    25  	"time"
    26  
    27  	"github.com/ethereum/go-ethereum"
    28  	"github.com/ethereum/go-ethereum/accounts/abi/bind"
    29  	"github.com/ethereum/go-ethereum/common"
    30  	"github.com/ethereum/go-ethereum/common/math"
    31  	"github.com/ethereum/go-ethereum/consensus/ethash"
    32  	"github.com/ethereum/go-ethereum/core"
    33  	"github.com/ethereum/go-ethereum/core/bloombits"
    34  	"github.com/ethereum/go-ethereum/core/rawdb"
    35  	"github.com/ethereum/go-ethereum/core/state"
    36  	"github.com/ethereum/go-ethereum/core/types"
    37  	"github.com/ethereum/go-ethereum/core/vm"
    38  	"github.com/ethereum/go-ethereum/eth/filters"
    39  	"github.com/ethereum/go-ethereum/ethdb"
    40  	"github.com/ethereum/go-ethereum/event"
    41  	"github.com/ethereum/go-ethereum/params"
    42  	"github.com/ethereum/go-ethereum/rpc"
    43  )
    44  
    45  // This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
    46  var _ bind.ContractBackend = (*SimulatedBackend)(nil)
    47  
    48  var (
    49  	errBlockNumberUnsupported  = errors.New("simulatedBackend cannot access blocks other than the latest block")
    50  	errBlockDoesNotExist       = errors.New("block does not exist in blockchain")
    51  	errTransactionDoesNotExist = errors.New("transaction does not exist")
    52  	errGasEstimationFailed     = errors.New("gas required exceeds allowance or always failing transaction")
    53  )
    54  
    55  // SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
    56  // the background. Its main purpose is to allow easily testing contract bindings.
    57  // Simulated backend implements the following interfaces:
    58  // ChainReader, ChainStateReader, ContractBackend, ContractCaller, ContractFilterer, ContractTransactor,
    59  // DeployBackend, GasEstimator, GasPricer, LogFilterer, PendingContractCaller, TransactionReader, and TransactionSender
    60  type SimulatedBackend struct {
    61  	database   ethdb.Database   // In memory database to store our testing data
    62  	blockchain *core.BlockChain // Ethereum blockchain to handle the consensus
    63  
    64  	mu           sync.Mutex
    65  	pendingBlock *types.Block   // Currently pending block that will be imported on request
    66  	pendingState *state.StateDB // Currently pending state that will be the active on on request
    67  
    68  	events *filters.EventSystem // Event system for filtering log events live
    69  
    70  	config *params.ChainConfig
    71  }
    72  
    73  // NewSimulatedBackendWithDatabase creates a new binding backend based on the given database
    74  // and uses a simulated blockchain for testing purposes.
    75  func NewSimulatedBackendWithDatabase(database ethdb.Database, alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
    76  	genesis := core.Genesis{Config: params.AllEthashProtocolChanges, GasLimit: gasLimit, Alloc: alloc}
    77  	genesis.MustCommit(database)
    78  	blockchain, _ := core.NewBlockChain(database, nil, genesis.Config, ethash.NewFaker(), vm.Config{}, nil)
    79  
    80  	backend := &SimulatedBackend{
    81  		database:   database,
    82  		blockchain: blockchain,
    83  		config:     genesis.Config,
    84  		events:     filters.NewEventSystem(&filterBackend{database, blockchain}, false),
    85  	}
    86  	backend.rollback()
    87  	return backend
    88  }
    89  
    90  // NewSimulatedBackend creates a new binding backend using a simulated blockchain
    91  // for testing purposes.
    92  func NewSimulatedBackend(alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
    93  	return NewSimulatedBackendWithDatabase(rawdb.NewMemoryDatabase(), alloc, gasLimit)
    94  }
    95  
    96  // Close terminates the underlying blockchain's update loop.
    97  func (b *SimulatedBackend) Close() error {
    98  	b.blockchain.Stop()
    99  	return nil
   100  }
   101  
   102  // Commit imports all the pending transactions as a single block and starts a
   103  // fresh new state.
   104  func (b *SimulatedBackend) Commit() {
   105  	b.mu.Lock()
   106  	defer b.mu.Unlock()
   107  
   108  	if _, err := b.blockchain.InsertChain([]*types.Block{b.pendingBlock}); err != nil {
   109  		panic(err) // This cannot happen unless the simulator is wrong, fail in that case
   110  	}
   111  	b.rollback()
   112  }
   113  
   114  // Rollback aborts all pending transactions, reverting to the last committed state.
   115  func (b *SimulatedBackend) Rollback() {
   116  	b.mu.Lock()
   117  	defer b.mu.Unlock()
   118  
   119  	b.rollback()
   120  }
   121  
   122  func (b *SimulatedBackend) rollback() {
   123  	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(int, *core.BlockGen) {})
   124  	statedb, _ := b.blockchain.State()
   125  
   126  	b.pendingBlock = blocks[0]
   127  	b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database(), nil)
   128  }
   129  
   130  // stateByBlockNumber retrieves a state by a given blocknumber.
   131  func (b *SimulatedBackend) stateByBlockNumber(ctx context.Context, blockNumber *big.Int) (*state.StateDB, error) {
   132  	if blockNumber == nil || blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) == 0 {
   133  		return b.blockchain.State()
   134  	}
   135  	block, err := b.BlockByNumber(ctx, blockNumber)
   136  	if err != nil {
   137  		return nil, err
   138  	}
   139  	return b.blockchain.StateAt(block.Hash())
   140  }
   141  
   142  // CodeAt returns the code associated with a certain account in the blockchain.
   143  func (b *SimulatedBackend) CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error) {
   144  	b.mu.Lock()
   145  	defer b.mu.Unlock()
   146  
   147  	statedb, err := b.stateByBlockNumber(ctx, blockNumber)
   148  	if err != nil {
   149  		return nil, err
   150  	}
   151  
   152  	return statedb.GetCode(contract), nil
   153  }
   154  
   155  // BalanceAt returns the wei balance of a certain account in the blockchain.
   156  func (b *SimulatedBackend) BalanceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (*big.Int, error) {
   157  	b.mu.Lock()
   158  	defer b.mu.Unlock()
   159  
   160  	statedb, err := b.stateByBlockNumber(ctx, blockNumber)
   161  	if err != nil {
   162  		return nil, err
   163  	}
   164  
   165  	return statedb.GetBalance(contract), nil
   166  }
   167  
   168  // NonceAt returns the nonce of a certain account in the blockchain.
   169  func (b *SimulatedBackend) NonceAt(ctx context.Context, contract common.Address, blockNumber *big.Int) (uint64, error) {
   170  	b.mu.Lock()
   171  	defer b.mu.Unlock()
   172  
   173  	statedb, err := b.stateByBlockNumber(ctx, blockNumber)
   174  	if err != nil {
   175  		return 0, err
   176  	}
   177  
   178  	return statedb.GetNonce(contract), nil
   179  }
   180  
   181  // StorageAt returns the value of key in the storage of an account in the blockchain.
   182  func (b *SimulatedBackend) StorageAt(ctx context.Context, contract common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error) {
   183  	b.mu.Lock()
   184  	defer b.mu.Unlock()
   185  
   186  	statedb, err := b.stateByBlockNumber(ctx, blockNumber)
   187  	if err != nil {
   188  		return nil, err
   189  	}
   190  
   191  	val := statedb.GetState(contract, key)
   192  	return val[:], nil
   193  }
   194  
   195  // TransactionReceipt returns the receipt of a transaction.
   196  func (b *SimulatedBackend) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
   197  	b.mu.Lock()
   198  	defer b.mu.Unlock()
   199  
   200  	receipt, _, _, _ := rawdb.ReadReceipt(b.database, txHash, b.config)
   201  	return receipt, nil
   202  }
   203  
   204  // TransactionByHash checks the pool of pending transactions in addition to the
   205  // blockchain. The isPending return value indicates whether the transaction has been
   206  // mined yet. Note that the transaction may not be part of the canonical chain even if
   207  // it's not pending.
   208  func (b *SimulatedBackend) TransactionByHash(ctx context.Context, txHash common.Hash) (*types.Transaction, bool, error) {
   209  	b.mu.Lock()
   210  	defer b.mu.Unlock()
   211  
   212  	tx := b.pendingBlock.Transaction(txHash)
   213  	if tx != nil {
   214  		return tx, true, nil
   215  	}
   216  	tx, _, _, _ = rawdb.ReadTransaction(b.database, txHash)
   217  	if tx != nil {
   218  		return tx, false, nil
   219  	}
   220  	return nil, false, ethereum.NotFound
   221  }
   222  
   223  // BlockByHash retrieves a block based on the block hash
   224  func (b *SimulatedBackend) BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
   225  	b.mu.Lock()
   226  	defer b.mu.Unlock()
   227  
   228  	if hash == b.pendingBlock.Hash() {
   229  		return b.pendingBlock, nil
   230  	}
   231  
   232  	block := b.blockchain.GetBlockByHash(hash)
   233  	if block != nil {
   234  		return block, nil
   235  	}
   236  
   237  	return nil, errBlockDoesNotExist
   238  }
   239  
   240  // BlockByNumber retrieves a block from the database by number, caching it
   241  // (associated with its hash) if found.
   242  func (b *SimulatedBackend) BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error) {
   243  	b.mu.Lock()
   244  	defer b.mu.Unlock()
   245  
   246  	if number == nil || number.Cmp(b.pendingBlock.Number()) == 0 {
   247  		return b.blockchain.CurrentBlock(), nil
   248  	}
   249  
   250  	block := b.blockchain.GetBlockByNumber(uint64(number.Int64()))
   251  	if block == nil {
   252  		return nil, errBlockDoesNotExist
   253  	}
   254  
   255  	return block, nil
   256  }
   257  
   258  // HeaderByHash returns a block header from the current canonical chain.
   259  func (b *SimulatedBackend) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
   260  	b.mu.Lock()
   261  	defer b.mu.Unlock()
   262  
   263  	if hash == b.pendingBlock.Hash() {
   264  		return b.pendingBlock.Header(), nil
   265  	}
   266  
   267  	header := b.blockchain.GetHeaderByHash(hash)
   268  	if header == nil {
   269  		return nil, errBlockDoesNotExist
   270  	}
   271  
   272  	return header, nil
   273  }
   274  
   275  // HeaderByNumber returns a block header from the current canonical chain. If number is
   276  // nil, the latest known header is returned.
   277  func (b *SimulatedBackend) HeaderByNumber(ctx context.Context, block *big.Int) (*types.Header, error) {
   278  	b.mu.Lock()
   279  	defer b.mu.Unlock()
   280  
   281  	if block == nil || block.Cmp(b.pendingBlock.Number()) == 0 {
   282  		return b.blockchain.CurrentHeader(), nil
   283  	}
   284  
   285  	return b.blockchain.GetHeaderByNumber(uint64(block.Int64())), nil
   286  }
   287  
   288  // TransactionCount returns the number of transactions in a given block
   289  func (b *SimulatedBackend) TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error) {
   290  	b.mu.Lock()
   291  	defer b.mu.Unlock()
   292  
   293  	if blockHash == b.pendingBlock.Hash() {
   294  		return uint(b.pendingBlock.Transactions().Len()), nil
   295  	}
   296  
   297  	block := b.blockchain.GetBlockByHash(blockHash)
   298  	if block == nil {
   299  		return uint(0), errBlockDoesNotExist
   300  	}
   301  
   302  	return uint(block.Transactions().Len()), nil
   303  }
   304  
   305  // TransactionInBlock returns the transaction for a specific block at a specific index
   306  func (b *SimulatedBackend) TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error) {
   307  	b.mu.Lock()
   308  	defer b.mu.Unlock()
   309  
   310  	if blockHash == b.pendingBlock.Hash() {
   311  		transactions := b.pendingBlock.Transactions()
   312  		if uint(len(transactions)) < index+1 {
   313  			return nil, errTransactionDoesNotExist
   314  		}
   315  
   316  		return transactions[index], nil
   317  	}
   318  
   319  	block := b.blockchain.GetBlockByHash(blockHash)
   320  	if block == nil {
   321  		return nil, errBlockDoesNotExist
   322  	}
   323  
   324  	transactions := block.Transactions()
   325  	if uint(len(transactions)) < index+1 {
   326  		return nil, errTransactionDoesNotExist
   327  	}
   328  
   329  	return transactions[index], nil
   330  }
   331  
   332  // PendingCodeAt returns the code associated with an account in the pending state.
   333  func (b *SimulatedBackend) PendingCodeAt(ctx context.Context, contract common.Address) ([]byte, error) {
   334  	b.mu.Lock()
   335  	defer b.mu.Unlock()
   336  
   337  	return b.pendingState.GetCode(contract), nil
   338  }
   339  
   340  // CallContract executes a contract call.
   341  func (b *SimulatedBackend) CallContract(ctx context.Context, call ethereum.CallMsg, blockNumber *big.Int) ([]byte, error) {
   342  	b.mu.Lock()
   343  	defer b.mu.Unlock()
   344  
   345  	if blockNumber != nil && blockNumber.Cmp(b.blockchain.CurrentBlock().Number()) != 0 {
   346  		return nil, errBlockNumberUnsupported
   347  	}
   348  	state, err := b.blockchain.State()
   349  	if err != nil {
   350  		return nil, err
   351  	}
   352  	rval, _, _, err := b.callContract(ctx, call, b.blockchain.CurrentBlock(), state)
   353  	return rval, err
   354  }
   355  
   356  // PendingCallContract executes a contract call on the pending state.
   357  func (b *SimulatedBackend) PendingCallContract(ctx context.Context, call ethereum.CallMsg) ([]byte, error) {
   358  	b.mu.Lock()
   359  	defer b.mu.Unlock()
   360  	defer b.pendingState.RevertToSnapshot(b.pendingState.Snapshot())
   361  
   362  	rval, _, _, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
   363  	return rval, err
   364  }
   365  
   366  // PendingNonceAt implements PendingStateReader.PendingNonceAt, retrieving
   367  // the nonce currently pending for the account.
   368  func (b *SimulatedBackend) PendingNonceAt(ctx context.Context, account common.Address) (uint64, error) {
   369  	b.mu.Lock()
   370  	defer b.mu.Unlock()
   371  
   372  	return b.pendingState.GetOrNewStateObject(account).Nonce(), nil
   373  }
   374  
   375  // SuggestGasPrice implements ContractTransactor.SuggestGasPrice. Since the simulated
   376  // chain doesn't have miners, we just return a gas price of 1 for any call.
   377  func (b *SimulatedBackend) SuggestGasPrice(ctx context.Context) (*big.Int, error) {
   378  	return big.NewInt(1), nil
   379  }
   380  
   381  // EstimateGas executes the requested code against the currently pending block/state and
   382  // returns the used amount of gas.
   383  func (b *SimulatedBackend) EstimateGas(ctx context.Context, call ethereum.CallMsg) (uint64, error) {
   384  	b.mu.Lock()
   385  	defer b.mu.Unlock()
   386  
   387  	// Determine the lowest and highest possible gas limits to binary search in between
   388  	var (
   389  		lo  uint64 = params.TxGas - 1
   390  		hi  uint64
   391  		cap uint64
   392  	)
   393  	if call.Gas >= params.TxGas {
   394  		hi = call.Gas
   395  	} else {
   396  		hi = b.pendingBlock.GasLimit()
   397  	}
   398  	cap = hi
   399  
   400  	// Create a helper to check if a gas allowance results in an executable transaction
   401  	executable := func(gas uint64) bool {
   402  		call.Gas = gas
   403  
   404  		snapshot := b.pendingState.Snapshot()
   405  		_, _, failed, err := b.callContract(ctx, call, b.pendingBlock, b.pendingState)
   406  		b.pendingState.RevertToSnapshot(snapshot)
   407  
   408  		if err != nil || failed {
   409  			return false
   410  		}
   411  		return true
   412  	}
   413  	// Execute the binary search and hone in on an executable gas limit
   414  	for lo+1 < hi {
   415  		mid := (hi + lo) / 2
   416  		if !executable(mid) {
   417  			lo = mid
   418  		} else {
   419  			hi = mid
   420  		}
   421  	}
   422  	// Reject the transaction as invalid if it still fails at the highest allowance
   423  	if hi == cap {
   424  		if !executable(hi) {
   425  			return 0, errGasEstimationFailed
   426  		}
   427  	}
   428  	return hi, nil
   429  }
   430  
   431  // callContract implements common code between normal and pending contract calls.
   432  // state is modified during execution, make sure to copy it if necessary.
   433  func (b *SimulatedBackend) callContract(ctx context.Context, call ethereum.CallMsg, block *types.Block, statedb *state.StateDB) ([]byte, uint64, bool, error) {
   434  	// Ensure message is initialized properly.
   435  	if call.GasPrice == nil {
   436  		call.GasPrice = big.NewInt(1)
   437  	}
   438  	if call.Gas == 0 {
   439  		call.Gas = 50000000
   440  	}
   441  	if call.Value == nil {
   442  		call.Value = new(big.Int)
   443  	}
   444  	// Set infinite balance to the fake caller account.
   445  	from := statedb.GetOrNewStateObject(call.From)
   446  	from.SetBalance(math.MaxBig256)
   447  	// Execute the call.
   448  	msg := callmsg{call}
   449  
   450  	evmContext := core.NewEVMContext(msg, block.Header(), b.blockchain, nil)
   451  	// Create a new environment which holds all relevant information
   452  	// about the transaction and calling mechanisms.
   453  	vmenv := vm.NewEVM(evmContext, statedb, b.config, vm.Config{})
   454  	gaspool := new(core.GasPool).AddGas(math.MaxUint64)
   455  
   456  	return core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
   457  }
   458  
   459  // SendTransaction updates the pending block to include the given transaction.
   460  // It panics if the transaction is invalid.
   461  func (b *SimulatedBackend) SendTransaction(ctx context.Context, tx *types.Transaction) error {
   462  	b.mu.Lock()
   463  	defer b.mu.Unlock()
   464  
   465  	sender, err := types.Sender(types.NewEIP155Signer(b.config.ChainID), tx)
   466  	if err != nil {
   467  		panic(fmt.Errorf("invalid transaction: %v", err))
   468  	}
   469  	nonce := b.pendingState.GetNonce(sender)
   470  	if tx.Nonce() != nonce {
   471  		panic(fmt.Errorf("invalid transaction nonce: got %d, want %d", tx.Nonce(), nonce))
   472  	}
   473  
   474  	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
   475  		for _, tx := range b.pendingBlock.Transactions() {
   476  			block.AddTxWithChain(b.blockchain, tx)
   477  		}
   478  		block.AddTxWithChain(b.blockchain, tx)
   479  	})
   480  	statedb, _ := b.blockchain.State()
   481  
   482  	b.pendingBlock = blocks[0]
   483  	b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database(), nil)
   484  	return nil
   485  }
   486  
   487  // FilterLogs executes a log filter operation, blocking during execution and
   488  // returning all the results in one batch.
   489  //
   490  // TODO(karalabe): Deprecate when the subscription one can return past data too.
   491  func (b *SimulatedBackend) FilterLogs(ctx context.Context, query ethereum.FilterQuery) ([]types.Log, error) {
   492  	var filter *filters.Filter
   493  	if query.BlockHash != nil {
   494  		// Block filter requested, construct a single-shot filter
   495  		filter = filters.NewBlockFilter(&filterBackend{b.database, b.blockchain}, *query.BlockHash, query.Addresses, query.Topics)
   496  	} else {
   497  		// Initialize unset filter boundaried to run from genesis to chain head
   498  		from := int64(0)
   499  		if query.FromBlock != nil {
   500  			from = query.FromBlock.Int64()
   501  		}
   502  		to := int64(-1)
   503  		if query.ToBlock != nil {
   504  			to = query.ToBlock.Int64()
   505  		}
   506  		// Construct the range filter
   507  		filter = filters.NewRangeFilter(&filterBackend{b.database, b.blockchain}, from, to, query.Addresses, query.Topics, false)
   508  	}
   509  	// Run the filter and return all the logs
   510  	logs, err := filter.Logs(ctx)
   511  	if err != nil {
   512  		return nil, err
   513  	}
   514  	res := make([]types.Log, len(logs))
   515  	for i, log := range logs {
   516  		res[i] = *log
   517  	}
   518  	return res, nil
   519  }
   520  
   521  // SubscribeFilterLogs creates a background log filtering operation, returning a
   522  // subscription immediately, which can be used to stream the found events.
   523  func (b *SimulatedBackend) SubscribeFilterLogs(ctx context.Context, query ethereum.FilterQuery, ch chan<- types.Log) (ethereum.Subscription, error) {
   524  	// Subscribe to contract events
   525  	sink := make(chan []*types.Log)
   526  
   527  	sub, err := b.events.SubscribeLogs(query, sink)
   528  	if err != nil {
   529  		return nil, err
   530  	}
   531  	// Since we're getting logs in batches, we need to flatten them into a plain stream
   532  	return event.NewSubscription(func(quit <-chan struct{}) error {
   533  		defer sub.Unsubscribe()
   534  		for {
   535  			select {
   536  			case logs := <-sink:
   537  				for _, log := range logs {
   538  					select {
   539  					case ch <- *log:
   540  					case err := <-sub.Err():
   541  						return err
   542  					case <-quit:
   543  						return nil
   544  					}
   545  				}
   546  			case err := <-sub.Err():
   547  				return err
   548  			case <-quit:
   549  				return nil
   550  			}
   551  		}
   552  	}), nil
   553  }
   554  
   555  // SubscribeNewHead returns an event subscription for a new header
   556  func (b *SimulatedBackend) SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (ethereum.Subscription, error) {
   557  	// subscribe to a new head
   558  	sink := make(chan *types.Header)
   559  	sub := b.events.SubscribeNewHeads(sink)
   560  
   561  	return event.NewSubscription(func(quit <-chan struct{}) error {
   562  		defer sub.Unsubscribe()
   563  		for {
   564  			select {
   565  			case head := <-sink:
   566  				select {
   567  				case ch <- head:
   568  				case err := <-sub.Err():
   569  					return err
   570  				case <-quit:
   571  					return nil
   572  				}
   573  			case err := <-sub.Err():
   574  				return err
   575  			case <-quit:
   576  				return nil
   577  			}
   578  		}
   579  	}), nil
   580  }
   581  
   582  // AdjustTime adds a time shift to the simulated clock.
   583  func (b *SimulatedBackend) AdjustTime(adjustment time.Duration) error {
   584  	b.mu.Lock()
   585  	defer b.mu.Unlock()
   586  
   587  	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
   588  		for _, tx := range b.pendingBlock.Transactions() {
   589  			block.AddTx(tx)
   590  		}
   591  		block.OffsetTime(int64(adjustment.Seconds()))
   592  	})
   593  	statedb, _ := b.blockchain.State()
   594  
   595  	b.pendingBlock = blocks[0]
   596  	b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database(), nil)
   597  
   598  	return nil
   599  }
   600  
   601  // Blockchain returns the underlying blockchain.
   602  func (b *SimulatedBackend) Blockchain() *core.BlockChain {
   603  	return b.blockchain
   604  }
   605  
   606  // callmsg implements core.Message to allow passing it as a transaction simulator.
   607  type callmsg struct {
   608  	ethereum.CallMsg
   609  }
   610  
   611  func (m callmsg) From() common.Address { return m.CallMsg.From }
   612  func (m callmsg) Nonce() uint64        { return 0 }
   613  func (m callmsg) CheckNonce() bool     { return false }
   614  func (m callmsg) To() *common.Address  { return m.CallMsg.To }
   615  func (m callmsg) GasPrice() *big.Int   { return m.CallMsg.GasPrice }
   616  func (m callmsg) Gas() uint64          { return m.CallMsg.Gas }
   617  func (m callmsg) Value() *big.Int      { return m.CallMsg.Value }
   618  func (m callmsg) Data() []byte         { return m.CallMsg.Data }
   619  
   620  // filterBackend implements filters.Backend to support filtering for logs without
   621  // taking bloom-bits acceleration structures into account.
   622  type filterBackend struct {
   623  	db ethdb.Database
   624  	bc *core.BlockChain
   625  }
   626  
   627  func (fb *filterBackend) ChainDb() ethdb.Database  { return fb.db }
   628  func (fb *filterBackend) EventMux() *event.TypeMux { panic("not supported") }
   629  
   630  func (fb *filterBackend) HeaderByNumber(ctx context.Context, block rpc.BlockNumber) (*types.Header, error) {
   631  	if block == rpc.LatestBlockNumber {
   632  		return fb.bc.CurrentHeader(), nil
   633  	}
   634  	return fb.bc.GetHeaderByNumber(uint64(block.Int64())), nil
   635  }
   636  
   637  func (fb *filterBackend) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
   638  	return fb.bc.GetHeaderByHash(hash), nil
   639  }
   640  
   641  func (fb *filterBackend) GetReceipts(ctx context.Context, hash common.Hash) (types.Receipts, error) {
   642  	number := rawdb.ReadHeaderNumber(fb.db, hash)
   643  	if number == nil {
   644  		return nil, nil
   645  	}
   646  	return rawdb.ReadReceipts(fb.db, hash, *number, fb.bc.Config()), nil
   647  }
   648  
   649  func (fb *filterBackend) GetLogs(ctx context.Context, hash common.Hash) ([][]*types.Log, error) {
   650  	number := rawdb.ReadHeaderNumber(fb.db, hash)
   651  	if number == nil {
   652  		return nil, nil
   653  	}
   654  	receipts := rawdb.ReadReceipts(fb.db, hash, *number, fb.bc.Config())
   655  	if receipts == nil {
   656  		return nil, nil
   657  	}
   658  	logs := make([][]*types.Log, len(receipts))
   659  	for i, receipt := range receipts {
   660  		logs[i] = receipt.Logs
   661  	}
   662  	return logs, nil
   663  }
   664  
   665  func (fb *filterBackend) SubscribeNewTxsEvent(ch chan<- core.NewTxsEvent) event.Subscription {
   666  	return nullSubscription()
   667  }
   668  
   669  func (fb *filterBackend) SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription {
   670  	return fb.bc.SubscribeChainEvent(ch)
   671  }
   672  
   673  func (fb *filterBackend) SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription {
   674  	return fb.bc.SubscribeRemovedLogsEvent(ch)
   675  }
   676  
   677  func (fb *filterBackend) SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription {
   678  	return fb.bc.SubscribeLogsEvent(ch)
   679  }
   680  
   681  func (fb *filterBackend) SubscribePendingLogsEvent(ch chan<- []*types.Log) event.Subscription {
   682  	return nullSubscription()
   683  }
   684  
   685  func (fb *filterBackend) BloomStatus() (uint64, uint64) { return 4096, 0 }
   686  
   687  func (fb *filterBackend) ServiceFilter(ctx context.Context, ms *bloombits.MatcherSession) {
   688  	panic("not supported")
   689  }
   690  
   691  func nullSubscription() event.Subscription {
   692  	return event.NewSubscription(func(quit <-chan struct{}) error {
   693  		<-quit
   694  		return nil
   695  	})
   696  }