/
live.go
104 lines (89 loc) · 2.08 KB
/
live.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
package events
import (
"fmt"
)
// LiveEventLog combines an EventLog and a ChainStreamer to make a new Streamer
// that streams first from the EventLog, and then from the ChainStreamer. When
// streaming from the ChainStreamer the messages are both sent to the EventLog
// and the subscriber.
type LiveEventLog struct {
eventlog EventLog
streamer ChainStreamer
}
func NewLiveEventLog(e EventLog, s ChainStreamer) *LiveEventLog {
return &LiveEventLog{
eventlog: e,
streamer: s,
}
}
func (l *LiveEventLog) Stream(done chan struct{}, from uint64) (*Subscription, error) {
if from < l.eventlog.FirstBlock() {
return nil, fmt.Errorf("got from=%d; want from >= %d", from, l.eventlog.FirstBlock())
}
c := make(chan *Message)
errc := make(chan error, 1)
go func() {
err := l.stream(c, done, from)
errc <- err
close(c)
}()
return &Subscription{
C: c,
Err: errc,
Done: done,
}, nil
}
func (l *LiveEventLog) stream(c chan *Message, done chan struct{}, from uint64) error {
nextBlock := from
// 1. Stream all events from the eventlog.
elSub, err := l.eventlog.Stream(done, nextBlock)
if err != nil {
return err
}
for m := range elSub.C {
if m.Action == Rollback {
return fmt.Errorf("got unexpected Rollback from eventlog")
}
switch m.Action {
case Append:
nextBlock = m.Block.Number + 1
case SetNext:
nextBlock = m.Number
}
if err := sendOrDone(c, done, m); err != nil {
return err
}
}
if err := <-elSub.Err; err != nil {
return err
}
// 2. Start streaming from chain.
l.streamer.Filter = l.eventlog.Filter()
chSub, err := l.streamer.Stream(done, nextBlock)
if err != nil {
return err
}
for m := range chSub.C {
switch m.Action {
case Append:
if err := l.eventlog.Append(m.Block); err != nil {
return err
}
case Rollback:
if err := l.eventlog.Rollback(m.Number); err != nil {
return err
}
case SetNext:
if err := l.eventlog.SetNext(m.Number); err != nil {
return err
}
}
if err := sendOrDone(c, done, m); err != nil {
return err
}
}
if err := <-chSub.Err; err != nil {
return err
}
return nil
}