/
watcher.go
129 lines (107 loc) · 3.49 KB
/
watcher.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
// Copyright 2022-2023 Tigris Data, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package realtime
import (
"context"
"github.com/rs/zerolog/log"
"github.com/tigrisdata/tigris/store/cache"
)
// Watch is called when an event is received by ChannelWatcher.
type Watch func(*cache.StreamMessages, error) ([]string, error)
// ChannelWatcher is to watch events for a single channel. It accepts a watch that will be notified when a new event
// is read from the stream. As ChannelWatcher is mapped to a consumer group on a stream therefore the state is restored
// from the cache during restart which means a watcher is only created if it doesn’t exist otherwise the existing one
// is returned.
type ChannelWatcher struct {
ctx context.Context
name string
watch Watch
stream cache.Stream
sigStop chan struct{}
sigDisconnect chan struct{}
}
func CreateWatcher(ctx context.Context, name string, pos string, existingPos string, stream cache.Stream) (*ChannelWatcher, error) {
w := newWatcher(ctx, name, stream)
if len(pos) == 0 {
// just use the existing id
err := w.move(ctx, existingPos)
return w, err
}
if pos > existingPos {
log.Warn().Msgf("new position '%s' is greater than existing pos '%s' for watch '%s'", pos, existingPos, name)
}
if err := w.move(ctx, pos); err != nil {
return nil, err
}
return w, nil
}
func CreateAndRegisterWatcher(ctx context.Context, name string, pos string, stream cache.Stream) (*ChannelWatcher, error) {
if len(pos) == 0 {
pos = cache.ConsumerGroupDefaultCurrentPos
}
if err := stream.CreateConsumerGroup(ctx, name, pos); err != nil {
return nil, err
}
return newWatcher(ctx, name, stream), nil
}
func newWatcher(ctx context.Context, id string, stream cache.Stream) *ChannelWatcher {
return &ChannelWatcher{
ctx: ctx,
name: id,
stream: stream,
sigStop: make(chan struct{}),
sigDisconnect: make(chan struct{}),
}
}
func (watcher *ChannelWatcher) StartWatching(watch Watch) {
watcher.watch = watch
go watcher.watchEvents()
}
func (watcher *ChannelWatcher) move(ctx context.Context, newPos string) error {
if len(newPos) == 0 {
return nil
}
return watcher.stream.SetID(ctx, watcher.name, newPos)
}
func (watcher *ChannelWatcher) Stop() {
close(watcher.sigStop)
}
func (watcher *ChannelWatcher) Disconnect() {
close(watcher.sigDisconnect)
}
func (watcher *ChannelWatcher) watchEvents() {
for {
select {
case <-watcher.sigStop:
return
case <-watcher.sigDisconnect:
_ = watcher.stream.RemoveConsumerGroup(watcher.ctx, watcher.name)
return
default:
resp, hasData, err := watcher.stream.ReadGroup(watcher.ctx, watcher.name, cache.ReadGroupPosCurrent)
if err != nil {
continue
}
if !hasData {
continue
}
if ids, err := watcher.watch(resp, nil); err == nil {
_ = watcher.ack(watcher.ctx, ids)
}
}
}
}
func (watcher *ChannelWatcher) ack(ctx context.Context, ids []string) error {
return watcher.stream.Ack(ctx, watcher.name, ids...)
}