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
|
// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus 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 dexon-consensus 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 dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.
package core
import (
"fmt"
"math/big"
"sync"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/crypto"
"github.com/dexon-foundation/dexon-consensus/core/types"
)
// Errors for leader module.
var (
ErrIncorrectCRSSignature = fmt.Errorf("incorrect CRS signature")
)
type validLeaderFn func(*types.Block) (bool, error)
// Some constant value.
var (
maxHash *big.Int
one *big.Rat
)
func init() {
hash := make([]byte, common.HashLength)
for i := range hash {
hash[i] = 0xff
}
maxHash = big.NewInt(0).SetBytes(hash)
one = big.NewRat(1, 1)
}
type leaderSelector struct {
hashCRS common.Hash
numCRS *big.Int
minCRSBlock *big.Int
minBlockHash common.Hash
pendingBlocks []*types.Block
validLeader validLeaderFn
lock sync.Mutex
logger common.Logger
}
func newLeaderSelector(
validLeader validLeaderFn, logger common.Logger) *leaderSelector {
return &leaderSelector{
minCRSBlock: maxHash,
validLeader: validLeader,
logger: logger,
}
}
func (l *leaderSelector) distance(sig crypto.Signature) *big.Int {
hash := crypto.Keccak256Hash(sig.Signature[:])
num := big.NewInt(0)
num.SetBytes(hash[:])
num.Abs(num.Sub(l.numCRS, num))
return num
}
func (l *leaderSelector) probability(sig crypto.Signature) float64 {
dis := l.distance(sig)
prob := big.NewRat(1, 1).SetFrac(dis, maxHash)
p, _ := prob.Sub(one, prob).Float64()
return p
}
func (l *leaderSelector) restart(crs common.Hash) {
numCRS := big.NewInt(0)
numCRS.SetBytes(crs[:])
l.lock.Lock()
defer l.lock.Unlock()
l.numCRS = numCRS
l.hashCRS = crs
l.minCRSBlock = maxHash
l.minBlockHash = common.Hash{}
l.pendingBlocks = []*types.Block{}
}
func (l *leaderSelector) leaderBlockHash() common.Hash {
l.lock.Lock()
defer l.lock.Unlock()
newPendingBlocks := []*types.Block{}
for _, b := range l.pendingBlocks {
ok, dist := l.potentialLeader(b)
if !ok {
continue
}
ok, err := l.validLeader(b)
if err != nil {
l.logger.Error("Error checking validLeader", "error", err, "block", b)
continue
}
if ok {
l.updateLeader(b, dist)
} else {
newPendingBlocks = append(newPendingBlocks, b)
}
}
l.pendingBlocks = newPendingBlocks
return l.minBlockHash
}
func (l *leaderSelector) processBlock(block *types.Block) error {
ok, err := verifyCRSSignature(block, l.hashCRS)
if err != nil {
return err
}
if !ok {
return ErrIncorrectCRSSignature
}
l.lock.Lock()
defer l.lock.Unlock()
ok, dist := l.potentialLeader(block)
if !ok {
return nil
}
ok, err = l.validLeader(block)
if err != nil {
return err
}
if !ok {
l.pendingBlocks = append(l.pendingBlocks, block)
return nil
}
l.updateLeader(block, dist)
return nil
}
func (l *leaderSelector) potentialLeader(block *types.Block) (bool, *big.Int) {
dist := l.distance(block.CRSSignature)
cmp := l.minCRSBlock.Cmp(dist)
if cmp > 0 || (cmp == 0 && block.Hash.Less(l.minBlockHash)) {
return true, dist
}
return false, dist
}
func (l *leaderSelector) updateLeader(block *types.Block, dist *big.Int) {
l.minCRSBlock = dist
l.minBlockHash = block.Hash
}
|
