forked from nats-io/nats.go
-
Notifications
You must be signed in to change notification settings - Fork 0
/
main.go
135 lines (112 loc) · 3.38 KB
/
main.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
// Copyright 2012-2022 The NATS Authors
// 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 main
import (
"flag"
"log"
"os"
"os/signal"
"time"
"github.com/ybm2dyd/nats.go"
)
// NOTE: Can test with demo servers.
// nats-qsub -s demo.nats.io <subject> <queue>
func usage() {
log.Printf("Usage: nats-qsub [-s server] [-creds file] [-nkey file] [-t] <subject> <queue>\n")
flag.PrintDefaults()
}
func showUsageAndExit(exitcode int) {
usage()
os.Exit(exitcode)
}
func printMsg(m *nats.Msg, i int) {
log.Printf("[#%d] Received on [%s] Queue[%s] Pid[%d]: '%s'", i, m.Subject, m.Sub.Queue, os.Getpid(), string(m.Data))
}
func main() {
var urls = flag.String("s", nats.DefaultURL, "The nats server URLs (separated by comma)")
var userCreds = flag.String("creds", "", "User Credentials File")
var nkeyFile = flag.String("nkey", "", "NKey Seed File")
var showTime = flag.Bool("t", false, "Display timestamps")
var showHelp = flag.Bool("h", false, "Show help message")
log.SetFlags(0)
flag.Usage = usage
flag.Parse()
if *showHelp {
showUsageAndExit(0)
}
args := flag.Args()
if len(args) != 2 {
showUsageAndExit(1)
}
// Connect Options.
opts := []nats.Option{nats.Name("NATS Sample Queue Subscriber")}
opts = setupConnOptions(opts)
if *userCreds != "" && *nkeyFile != "" {
log.Fatal("specify -seed or -creds")
}
// Use UserCredentials
if *userCreds != "" {
opts = append(opts, nats.UserCredentials(*userCreds))
}
// Use Nkey authentication.
if *nkeyFile != "" {
opt, err := nats.NkeyOptionFromSeed(*nkeyFile)
if err != nil {
log.Fatal(err)
}
opts = append(opts, opt)
}
// Connect to NATS
nc, err := nats.Connect(*urls, opts...)
if err != nil {
log.Fatal(err)
}
subj, queue, i := args[0], args[1], 0
nc.QueueSubscribe(subj, queue, func(msg *nats.Msg) {
i++
printMsg(msg, i)
})
nc.Flush()
if err := nc.LastError(); err != nil {
log.Fatal(err)
}
log.Printf("Listening on [%s], queue group [%s]", subj, queue)
if *showTime {
log.SetFlags(log.LstdFlags)
}
// Setup the interrupt handler to drain so we don't miss
// requests when scaling down.
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
<-c
log.Println()
log.Printf("Draining...")
nc.Drain()
log.Fatalf("Exiting")
}
func setupConnOptions(opts []nats.Option) []nats.Option {
totalWait := 10 * time.Minute
reconnectDelay := time.Second
opts = append(opts, nats.ReconnectWait(reconnectDelay))
opts = append(opts, nats.MaxReconnects(int(totalWait/reconnectDelay)))
opts = append(opts, nats.DisconnectErrHandler(func(nc *nats.Conn, err error) {
log.Printf("Disconnected due to: %s, will attempt reconnects for %.0fm", err, totalWait.Minutes())
}))
opts = append(opts, nats.ReconnectHandler(func(nc *nats.Conn) {
log.Printf("Reconnected [%s]", nc.ConnectedUrl())
}))
opts = append(opts, nats.ClosedHandler(func(nc *nats.Conn) {
log.Fatalf("Exiting: %v", nc.LastError())
}))
return opts
}