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
|
package main
import (
"bufio"
"fmt"
"log"
"os"
"path/filepath"
"regexp"
"strings"
"time"
"github.com/robfig/cron/v3"
)
type inputLine struct {
Schedule string
Task string
}
var lastSeenInput = map[inputLine]struct{}{}
func main() {
p, err := inputFilePath()
if err != nil {
log.Fatalf("getting input file: %s", err)
}
c := cron.New()
for {
input, err := readInput(p)
if err != nil {
log.Printf("reading input: %s", err)
}
changed := inputChanged(lastSeenInput, input)
if changed {
fmt.Println("changed!")
lastSeenInput = input
c.Stop()
c := cron.New()
err := addJobs(c)
if err != nil {
log.Printf("adding jobs: %s", err)
}
c.Start()
} else {
fmt.Println("not changed!")
}
time.Sleep(time.Minute) // re-read the input file every minute
}
}
func inputFilePath() (string, error) {
args := os.Args
if len(args) != 2 {
return "", fmt.Errorf("expected one argument (input file path), got %d", len(args)-1)
}
p := filepath.Clean(args[1])
// While we're here, check that the input path actually exists and
// is stat-able.
if _, err := os.Stat(p); err != nil {
return "", fmt.Errorf("cannot stat input file: %w", err)
}
return p, nil
}
var inputFileRe = regexp.MustCompile(`([^\s]+\s+[^\s]+\s+[^\s]+\s+[^\s]+\s+[^\s]+)\s+(.*)`)
func readInput(p string) (map[inputLine]struct{}, error) {
input := map[inputLine]struct{}{}
f, err := os.Open(p)
if err != nil {
return nil, fmt.Errorf("opening '%s': %w", p, err)
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := strings.TrimSpace(scanner.Text())
if line == "" {
continue
}
matches := inputFileRe.FindStringSubmatch(line)
if matches == nil || len(matches) != 1+2 {
log.Printf("failed to parse input line: '%s'", line)
}
input[inputLine{Schedule: matches[1], Task: matches[2]}] = struct{}{}
}
if err := scanner.Err(); err != nil {
return nil, fmt.Errorf("scanning: %w", err)
}
return input, nil
}
func inputChanged(old, new map[inputLine]struct{}) bool {
if len(new) != len(old) {
return true
}
for k := range old {
if _, ok := new[k]; !ok {
return true
}
}
return false
}
func addJobs(c *cron.Cron) error { return nil }
|
