/
main.go
96 lines (76 loc) · 1.44 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
package main
import (
"context"
"fmt"
"os"
"os/signal"
"strconv"
"syscall"
"time"
"golang.org/x/sync/errgroup"
)
func main() {
eg, ctx := errgroup.WithContext(context.Background()) // ~ context.WithCancel() + waitGroup
eg.Go(func() error {
return RunWorkers(ctx)
})
//go RunWorkers(ctx)
sigQuit := make(chan os.Signal, 1)
signal.Notify(sigQuit, syscall.SIGINT, syscall.SIGTERM)
eg.Go(func() error {
select {
case s := <-sigQuit:
return fmt.Errorf("captured signal: %v", s)
case <-ctx.Done():
return nil
}
})
if err := eg.Wait(); err != nil {
fmt.Printf("gracefully shutting down the server: %s\n", err.Error())
}
fmt.Println("graceful shutdown service")
}
// bad code. only for mock
func generator() chan int {
out := make(chan int)
go func() {
defer close(out)
i := 0
for {
out <- i
time.Sleep(time.Second)
i += 1
}
}()
return out
}
func RunWorkers(ctx context.Context) error {
wn1Chan := workerNode1(ctx)
return workerNode2(wn1Chan)
}
func workerNode1(ctx context.Context) chan string {
input := generator()
out := make(chan string)
go func() {
defer func() {
fmt.Println("workerNode1 stop")
close(out)
}()
for {
select {
case <-ctx.Done():
return
case msg := <-input:
out <- strconv.Itoa(msg)
}
}
}()
return out
}
func workerNode2(input chan string) error {
for msg := range input {
fmt.Println(msg)
}
fmt.Println("workerNode2 stop")
return nil
}