1// Copyright 2019 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
17package core
18
19import (
20	"sync"
21
22	"github.com/ethereum/go-ethereum/common"
23	"github.com/ethereum/go-ethereum/core/state"
24)
25
26// txNoncer is a tiny virtual state database to manage the executable nonces of
27// accounts in the pool, falling back to reading from a real state database if
28// an account is unknown.
29type txNoncer struct {
30	fallback *state.StateDB
31	nonces   map[common.Address]uint64
32	lock     sync.Mutex
33}
34
35// newTxNoncer creates a new virtual state database to track the pool nonces.
36func newTxNoncer(statedb *state.StateDB) *txNoncer {
37	return &txNoncer{
38		fallback: statedb.Copy(),
39		nonces:   make(map[common.Address]uint64),
40	}
41}
42
43// get returns the current nonce of an account, falling back to a real state
44// database if the account is unknown.
45func (txn *txNoncer) get(addr common.Address) uint64 {
46	// We use mutex for get operation is the underlying
47	// state will mutate db even for read access.
48	txn.lock.Lock()
49	defer txn.lock.Unlock()
50
51	if _, ok := txn.nonces[addr]; !ok {
52		txn.nonces[addr] = txn.fallback.GetNonce(addr)
53	}
54	return txn.nonces[addr]
55}
56
57// set inserts a new virtual nonce into the virtual state database to be returned
58// whenever the pool requests it instead of reaching into the real state database.
59func (txn *txNoncer) set(addr common.Address, nonce uint64) {
60	txn.lock.Lock()
61	defer txn.lock.Unlock()
62
63	txn.nonces[addr] = nonce
64}
65
66// setIfLower updates a new virtual nonce into the virtual state database if the
67// the new one is lower.
68func (txn *txNoncer) setIfLower(addr common.Address, nonce uint64) {
69	txn.lock.Lock()
70	defer txn.lock.Unlock()
71
72	if _, ok := txn.nonces[addr]; !ok {
73		txn.nonces[addr] = txn.fallback.GetNonce(addr)
74	}
75	if txn.nonces[addr] <= nonce {
76		return
77	}
78	txn.nonces[addr] = nonce
79}
80
81// setAll sets the nonces for all accounts to the given map.
82func (txn *txNoncer) setAll(all map[common.Address]uint64) {
83	txn.lock.Lock()
84	defer txn.lock.Unlock()
85
86	txn.nonces = all
87}
88