aboutsummaryrefslogtreecommitdiffstats
path: root/interfaces.go
blob: 921d0261643f4d99599da7aed0669178dfdffe90 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
// 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)
}