forked from lightningnetwork/lnd
-
Notifications
You must be signed in to change notification settings - Fork 1
/
witness_beacon.go
147 lines (117 loc) · 3.99 KB
/
witness_beacon.go
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
package main
import (
"sync"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/contractcourt"
"github.com/lightningnetwork/lnd/invoices"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwallet"
)
// preimageSubscriber reprints an active subscription to be notified once the
// daemon discovers new preimages, either on chain or off-chain.
type preimageSubscriber struct {
updateChan chan lntypes.Preimage
quit chan struct{}
}
// preimageBeacon is an implementation of the contractcourt.WitnessBeacon
// interface, and the lnwallet.PreimageCache interface. This implementation is
// concerned with a single witness type: sha256 hahsh preimages.
type preimageBeacon struct {
sync.RWMutex
invoices *invoices.InvoiceRegistry
wCache *channeldb.WitnessCache
clientCounter uint64
subscribers map[uint64]*preimageSubscriber
}
// SubscribeUpdates returns a channel that will be sent upon *each* time a new
// preimage is discovered.
func (p *preimageBeacon) SubscribeUpdates() *contractcourt.WitnessSubscription {
p.Lock()
defer p.Unlock()
clientID := p.clientCounter
client := &preimageSubscriber{
updateChan: make(chan lntypes.Preimage, 10),
quit: make(chan struct{}),
}
p.subscribers[p.clientCounter] = client
p.clientCounter++
srvrLog.Debugf("Creating new witness beacon subscriber, id=%v",
p.clientCounter)
return &contractcourt.WitnessSubscription{
WitnessUpdates: client.updateChan,
CancelSubscription: func() {
p.Lock()
defer p.Unlock()
delete(p.subscribers, clientID)
close(client.quit)
},
}
}
// LookupPreImage attempts to lookup a preimage in the global cache. True is
// returned for the second argument if the preimage is found.
func (p *preimageBeacon) LookupPreimage(
payHash lntypes.Hash) (lntypes.Preimage, bool) {
p.RLock()
defer p.RUnlock()
// First, we'll check the invoice registry to see if we already know of
// the preimage as it's on that we created ourselves.
invoice, _, err := p.invoices.LookupInvoice(payHash)
switch {
case err == channeldb.ErrInvoiceNotFound:
// If we get this error, then it simply means that this invoice
// wasn't found, so we don't treat it as a critical error.
case err != nil:
return lntypes.Preimage{}, false
}
// If we've found the invoice, then we can return the preimage
// directly.
if err != channeldb.ErrInvoiceNotFound &&
invoice.Terms.PaymentPreimage != channeldb.UnknownPreimage {
return invoice.Terms.PaymentPreimage, true
}
// Otherwise, we'll perform a final check using the witness cache.
preimage, err := p.wCache.LookupSha256Witness(payHash)
if err != nil {
ltndLog.Errorf("Unable to lookup witness: %v", err)
return lntypes.Preimage{}, false
}
return preimage, true
}
// AddPreimages adds a batch of newly discovered preimages to the global cache,
// and also signals any subscribers of the newly discovered witness.
func (p *preimageBeacon) AddPreimages(preimages ...lntypes.Preimage) error {
// Exit early if no preimages are presented.
if len(preimages) == 0 {
return nil
}
// Copy the preimages to ensure the backing area can't be modified by
// the caller when delivering notifications.
preimageCopies := make([]lntypes.Preimage, 0, len(preimages))
for _, preimage := range preimages {
srvrLog.Infof("Adding preimage=%v to witness cache", preimage)
preimageCopies = append(preimageCopies, preimage)
}
// First, we'll add the witness to the decaying witness cache.
err := p.wCache.AddSha256Witnesses(preimages...)
if err != nil {
return err
}
p.Lock()
defer p.Unlock()
// With the preimage added to our state, we'll now send a new
// notification to all subscribers.
for _, client := range p.subscribers {
go func(c *preimageSubscriber) {
for _, preimage := range preimageCopies {
select {
case c.updateChan <- preimage:
case <-c.quit:
return
}
}
}(client)
}
return nil
}
var _ contractcourt.WitnessBeacon = (*preimageBeacon)(nil)
var _ lnwallet.PreimageCache = (*preimageBeacon)(nil)