-
Notifications
You must be signed in to change notification settings - Fork 646
/
pubsub_server.go
276 lines (229 loc) · 6.37 KB
/
pubsub_server.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
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package json
import (
"errors"
"net/http"
"sync"
"time"
"github.com/gorilla/websocket"
"github.com/ava-labs/avalanchego/snow"
)
const (
// Size of the ws read buffer
readBufferSize = 1024
// Size of the ws write buffer
writeBufferSize = 1024
// Time allowed to write a message to the peer.
writeWait = 10 * time.Second
// Time allowed to read the next pong message from the peer.
pongWait = 60 * time.Second
// Send pings to peer with this period. Must be less than pongWait.
pingPeriod = (pongWait * 9) / 10
// Maximum message size allowed from peer.
maxMessageSize = 512 // bytes
// Maximum number of pending messages to send to a peer.
maxPendingMessages = 256 // messages
)
var upgrader = websocket.Upgrader{
ReadBufferSize: readBufferSize,
WriteBufferSize: writeBufferSize,
CheckOrigin: func(*http.Request) bool { return true },
}
var (
errDuplicateChannel = errors.New("duplicate channel")
)
// PubSubServer maintains the set of active clients and sends messages to the clients.
type PubSubServer struct {
ctx *snow.Context
lock sync.Mutex
conns map[*Connection]map[string]struct{}
channels map[string]map[*Connection]struct{}
}
// NewPubSubServer ...
func NewPubSubServer(ctx *snow.Context) *PubSubServer {
return &PubSubServer{
ctx: ctx,
conns: make(map[*Connection]map[string]struct{}),
channels: make(map[string]map[*Connection]struct{}),
}
}
func (s *PubSubServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
wsConn, err := upgrader.Upgrade(w, r, nil)
if err != nil {
s.ctx.Log.Debug("Failed to upgrade %s", err)
return
}
conn := &Connection{s: s, conn: wsConn, send: make(chan interface{}, maxPendingMessages)}
s.addConnection(conn)
}
// Publish ...
func (s *PubSubServer) Publish(channel string, msg interface{}) {
s.lock.Lock()
defer s.lock.Unlock()
conns, exists := s.channels[channel]
if !exists {
s.ctx.Log.Warn("attempted to publush to an unknown channel %s", channel)
return
}
pubMsg := &publish{
Channel: channel,
Value: msg,
}
for conn := range conns {
select {
case conn.send <- pubMsg:
default:
s.ctx.Log.Verbo("dropping message to subscribed connection due to too many pending messages")
}
}
}
// Register ...
func (s *PubSubServer) Register(channel string) error {
s.lock.Lock()
defer s.lock.Unlock()
if _, exists := s.channels[channel]; exists {
return errDuplicateChannel
}
s.channels[channel] = make(map[*Connection]struct{})
return nil
}
func (s *PubSubServer) addConnection(conn *Connection) {
s.lock.Lock()
defer s.lock.Unlock()
s.conns[conn] = make(map[string]struct{})
go conn.writePump()
go conn.readPump()
}
func (s *PubSubServer) removeConnection(conn *Connection) {
s.lock.Lock()
defer s.lock.Unlock()
channels, exists := s.conns[conn]
if !exists {
s.ctx.Log.Warn("attempted to remove an unknown connection")
return
}
for channel := range channels {
delete(s.channels[channel], conn)
}
}
func (s *PubSubServer) addChannel(conn *Connection, channel string) {
s.lock.Lock()
defer s.lock.Unlock()
channels, exists := s.conns[conn]
if !exists {
return
}
conns, exists := s.channels[channel]
if !exists {
return
}
channels[channel] = struct{}{}
conns[conn] = struct{}{}
}
func (s *PubSubServer) removeChannel(conn *Connection, channel string) {
s.lock.Lock()
defer s.lock.Unlock()
channels, exists := s.conns[conn]
if !exists {
return
}
conns, exists := s.channels[channel]
if !exists {
return
}
delete(channels, channel)
delete(conns, conn)
}
type publish struct {
Channel string `json:"channel"`
Value interface{} `json:"value"`
}
type subscribe struct {
Channel string `json:"channel"`
Unsubscribe bool `json:"unsubscribe"`
}
// Connection is a representation of the websocket connection.
type Connection struct {
s *PubSubServer
// The websocket connection.
conn *websocket.Conn
// Buffered channel of outbound messages.
send chan interface{}
}
// readPump pumps messages from the websocket connection to the hub.
//
// The application runs readPump in a per-connection goroutine. The application
// ensures that there is at most one reader on a connection by executing all
// reads from this goroutine.
func (c *Connection) readPump() {
defer func() {
c.s.removeConnection(c)
// close is called by both the writePump and the readPump so one of them
// will always error
_ = c.conn.Close()
}()
c.conn.SetReadLimit(maxMessageSize)
// SetReadDeadline returns an error if the connection is corrupted
if err := c.conn.SetReadDeadline(time.Now().Add(pongWait)); err != nil {
return
}
c.conn.SetPongHandler(func(string) error {
return c.conn.SetReadDeadline(time.Now().Add(pongWait))
})
for {
msg := subscribe{}
err := c.conn.ReadJSON(&msg)
if err != nil {
if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
c.s.ctx.Log.Debug("Unexpected close in websockets: %s", err)
}
break
}
if msg.Unsubscribe {
c.s.removeChannel(c, msg.Channel)
} else {
c.s.addChannel(c, msg.Channel)
}
}
}
// writePump pumps messages from the hub to the websocket connection.
//
// A goroutine running writePump is started for each connection. The
// application ensures that there is at most one writer to a connection by
// executing all writes from this goroutine.
func (c *Connection) writePump() {
ticker := time.NewTicker(pingPeriod)
defer func() {
ticker.Stop()
// close is called by both the writePump and the readPump so one of them
// will always error
_ = c.conn.Close()
}()
for {
select {
case message, ok := <-c.send:
if err := c.conn.SetWriteDeadline(time.Now().Add(writeWait)); err != nil {
c.s.ctx.Log.Debug("failed to set the write deadline, closing the connection due to %s", err)
return
}
if !ok {
// The hub closed the channel. Attempt to close the connection
// gracefully.
_ = c.conn.WriteMessage(websocket.CloseMessage, []byte{})
return
}
if err := c.conn.WriteJSON(message); err != nil {
return
}
case <-ticker.C:
if err := c.conn.SetWriteDeadline(time.Now().Add(writeWait)); err != nil {
c.s.ctx.Log.Debug("failed to set the write deadline, closing the connection due to %s", err)
return
}
if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
return
}
}
}
}