ethereum: add new Go API interfaces

interfaces.go

+// Copyright 2016 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 ethereum defines interfaces for interacting with Ethereum.
+package ethereum
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"golang.org/x/net/context"
+)
+
+// TODO: move subscription to package event
+
+// Subscription represents an event subscription where events are
+// delivered on a data channel.
+type Subscription interface {
+	// Unsubscribe cancels the sending of events to the data channel
+	// and closes the error channel.
+	Unsubscribe()
+	// Err returns the subscription error channel. The error channel receives
+	// a value if there is an issue with the subscription (e.g. the network connection
+	// delivering the events has been closed). Only one value will ever be sent.
+	// The error channel is closed by Unsubscribe.
+	Err() <-chan error
+}
+
+// ChainReader provides access to the blockchain. The methods in this interface access raw
+// data from either the canonical chain (when requesting by block number) or any
+// blockchain fork that was previously downloaded and processed by the node. The block
+// number argument can be nil to select the latest canonical block. Reading block headers
+// should be preferred over full blocks whenever possible.
+type ChainReader interface {
+	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
+	BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error)
+	HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error)
+	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
+	TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error)
+	TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error)
+	TransactionByHash(ctx context.Context, txHash common.Hash) (*types.Transaction, error)
+	TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
+}
+
+// ChainStateReader wraps access to the state trie of the canonical blockchain. Note that
+// implementations of the interface may be unable to return state values for old blocks.
+// In many cases, using CallContract can be preferable to reading raw contract storage.
+type ChainStateReader interface {
+	BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error)
+	StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error)
+	CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error)
+	NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error)
+}
+
+// A ChainHeadEventer returns notifications whenever the canonical head block is updated.
+type ChainHeadEventer interface {
+	SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (Subscription, error)
+}
+
+// CallMsg contains parameters for contract calls.
+type CallMsg struct {
+	From     common.Address  // the sender of the 'transaction'
+	To       *common.Address // the destination contract (nil for contract creation)
+	Gas      *big.Int        // if nil, the call executes with near-infinite gas
+	GasPrice *big.Int        // wei <-> gas exchange ratio
+	Value    *big.Int        // amount of wei sent along with the call
+	Data     []byte          // input data, usually an ABI-encoded contract method invocation
+}
+
+// A ContractCaller provides contract calls, essentially transactions that are executed by
+// the EVM but not mined into the blockchain. ContractCall is a low-level method to
+// execute such calls. For applications which are structured around specific contracts,
+// the abigen tool provides a nicer, properly typed way to perform calls.
+type ContractCaller interface {
+	CallContract(ctx context.Context, call CallMsg, blockNumber *big.Int) ([]byte, error)
+}
+
+// FilterQuery contains options for contact log filtering.
+type FilterQuery struct {
+	FromBlock *big.Int         // beginning of the queried range, nil means genesis block
+	ToBlock   *big.Int         // end of the range, nil means latest block
+	Addresses []common.Address // restricts matches to events created by specific contracts
+
+	// The Topic list restricts matches to particular event topics. Each event has a list
+	// of topics. Topics matches a prefix of that list. An empty element slice matches any
+	// topic. Non-empty elements represent an alternative that matches any of the
+	// contained topics.
+	//
+	// Examples:
+	// {} or nil          matches any topic list
+	// {{A}}              matches topic A in first position
+	// {{}, {B}}          matches any topic in first position, B in second position
+	// {{A}}, {B}}        matches topic A in first position, B in second position
+	// {{A, B}}, {C, D}}  matches topic (A OR B) in first position, (C OR D) in second position
+	Topics [][]common.Hash
+}
+
+// LogFilterer provides access to contract log events using a one-off query or continuous
+// event subscription.
+type LogFilterer interface {
+	FilterLogs(ctx context.Context, q FilterQuery) ([]vm.Log, error)
+	SubscribeFilterLogs(ctx context.Context, q FilterQuery, ch chan<- vm.Log) (Subscription, error)
+}
+
+// TransactionSender wraps transaction sending. The SendTransaction method injects a
+// signed transaction into the pending transaction pool for execution. If the transaction
+// was a contract creation, the TransactionReceipt method can be used to retrieve the
+// contract address after the transaction has been mined.
+//
+// The transaction must be signed and have a valid nonce to be included. Consumers of the
+// API can use package accounts to maintain local private keys and need can retrieve the
+// next available nonce using PendingNonceAt.
+type TransactionSender interface {
+	SendTransaction(ctx context.Context, tx *types.Transaction) error
+}
+
+// GasPricer wraps the gas price oracle, which monitors the blockchain to determine the
+// optimal gas price given current fee market conditions.
+type GasPricer interface {
+	SuggestGasPrice(ctx context.Context) (*big.Int, error)
+}
+
+// A PendingStateReader provides access to the pending state, which is the result of all
+// known executable transactions which have not yet been included in the blockchain. It is
+// commonly used to display the result of ’unconfirmed’ actions (e.g. wallet value
+// transfers) initiated by the user. The PendingNonceAt operation is a good way to
+// retrieve the next available transaction nonce for a specific account.
+type PendingStateReader interface {
+	PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error)
+	PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error)
+	PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error)
+	PendingNonceAt(ctx context.Context, account common.Address) (uint64, error)
+	PendingTransactionCount(ctx context.Context) (uint, error)
+}
+
+// PendingContractCaller can be used to perform calls against the pending state.
+type PendingContractCaller interface {
+	PendingCallContract(ctx context.Context, call CallMsg) ([]byte, error)
+}
+
+// GasEstimator wraps EstimateGas, which tries to estimate the gas needed to execute a
+// specific transaction based on the pending state. There is no guarantee that this is the
+// true gas limit requirement as other transactions may be added or removed by miners, but
+// it should provide a basis for setting a reasonable default.
+type GasEstimator interface {
+	EstimateGas(ctx context.Context, call CallMsg) (usedGas *big.Int, err error)
+}
+
+// A PendingStateEventer provides access to real time notifications about changes to the
+// pending state.
+type PendingStateEventer interface {
+	SubscribePendingTransactions(ctx context.Context, ch chan<- *types.Transaction) (Subscription, error)
+}