forked from Sadzeih/go-reddit
/
stream.go
209 lines (170 loc) · 5.01 KB
/
stream.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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
package reddit
import (
"context"
"sync"
"time"
)
// StreamService allows streaming new content from Reddit as it appears.
type StreamService struct {
client *Client
}
// Posts streams posts from the specified subreddit.
// It returns 2 channels and a function:
// - a channel into which new posts will be sent
// - a channel into which any errors will be sent
// - a function that the client can call once to stop the streaming and close the channels
//
// Because of the 100 post limit imposed by Reddit when fetching posts, some high-traffic
// streams might drop submissions between API requests, such as when streaming r/all.
func (s *StreamService) Posts(subreddit string, opts ...StreamOpt) (<-chan *Post, <-chan error, func()) {
streamConfig := &streamConfig{
Interval: defaultStreamInterval,
DiscardInitial: false,
MaxRequests: 0,
}
for _, opt := range opts {
opt(streamConfig)
}
ticker := time.NewTicker(streamConfig.Interval)
postsCh := make(chan *Post)
errsCh := make(chan error)
var once sync.Once
stop := func() {
once.Do(func() {
ticker.Stop()
close(postsCh)
close(errsCh)
})
}
// originally used the "before" parameter, but if that post gets deleted, subsequent requests
// would just return empty listings; easier to just keep track of all post ids encountered
ids := set{}
go func() {
defer stop()
var n int
infinite := streamConfig.MaxRequests == 0
for ; ; <-ticker.C {
n++
posts, err := s.getPosts(subreddit)
if err != nil {
errsCh <- err
if !infinite && n >= streamConfig.MaxRequests {
break
}
continue
}
for _, post := range posts {
id := post.FullID
// if this post id is already part of the set, it means that it and the ones
// after it in the list have already been streamed, so break out of the loop
if ids.Exists(id) {
break
}
ids.Add(id)
// skip this post because we are discarding initial fetch of posts
if streamConfig.DiscardInitial {
continue
}
postsCh <- post
}
// setting discard initial to false, since we the loop has run once already
streamConfig.DiscardInitial = false
if !infinite && n >= streamConfig.MaxRequests {
break
}
}
}()
return postsCh, errsCh, stop
}
// Comments streams comments from the specified subreddit.
// It returns 2 channels and a function:
// - a channel into which new comments will be sent
// - a channel into which any errors will be sent
// - a function that the client can call once to stop the streaming and close the channels
//
// Because of the 100 post limit imposed by Reddit when fetching posts, some high-traffic
// streams might drop submissions between API requests, such as when streaming r/all.
func (s *StreamService) Comments(subreddit string, opts ...StreamOpt) (<-chan *Comment, <-chan error, func()) {
streamConfig := &streamConfig{
Interval: defaultStreamInterval,
DiscardInitial: false,
MaxRequests: 0,
}
for _, opt := range opts {
opt(streamConfig)
}
ticker := time.NewTicker(streamConfig.Interval)
commentsCh := make(chan *Comment)
errsCh := make(chan error)
var once sync.Once
stop := func() {
once.Do(func() {
ticker.Stop()
close(commentsCh)
close(errsCh)
})
}
// originally used the "before" parameter, but if that post gets deleted, subsequent requests
// would just return empty listings; easier to just keep track of all post ids encountered
ids := set{}
go func() {
defer stop()
var n int
infinite := streamConfig.MaxRequests == 0
for ; ; <-ticker.C {
n++
comments, err := s.getComments(subreddit)
if err != nil {
errsCh <- err
if !infinite && n >= streamConfig.MaxRequests {
break
}
continue
}
for _, comment := range comments {
id := comment.FullID
// if this post id is already part of the set, it means that it and the ones
// after it in the list have already been streamed, so break out of the loop
if ids.Exists(id) {
break
}
ids.Add(id)
// skip this post because we are discarding initial fetch of posts
if streamConfig.DiscardInitial {
continue
}
commentsCh <- comment
}
// setting discard initial to false, since we the loop has run once already
streamConfig.DiscardInitial = false
if !infinite && n >= streamConfig.MaxRequests {
break
}
}
}()
return commentsCh, errsCh, stop
}
func (s *StreamService) getPosts(subreddit string) ([]*Post, error) {
posts, _, err := s.client.Subreddit.NewPosts(context.Background(), subreddit, &ListOptions{Limit: 100})
return posts, err
}
func (s *StreamService) getComments(subreddit string) ([]*Comment, error) {
opts := &ListCommentsOptions{}
opts.Limit = 100
comments, _, err := s.client.Subreddit.NewComments(context.Background(), subreddit, opts)
return comments, err
}
type set map[string]struct{}
func (s set) Add(v string) {
s[v] = struct{}{}
}
func (s set) Delete(v string) {
delete(s, v)
}
func (s set) Len() int {
return len(s)
}
func (s set) Exists(v string) bool {
_, ok := s[v]
return ok
}