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
|
package cron
import (
"fmt"
"runtime"
"sync"
"time"
)
// JobWrapper decorates the given Job with some behavior.
type JobWrapper func(Job) Job
// Chain is a sequence of JobWrappers that decorates submitted jobs with
// cross-cutting behaviors like logging or synchronization.
type Chain struct {
wrappers []JobWrapper
}
// NewChain returns a Chain consisting of the given JobWrappers.
func NewChain(c ...JobWrapper) Chain {
return Chain{c}
}
// Then decorates the given job with all JobWrappers in the chain.
//
// This:
// NewChain(m1, m2, m3).Then(job)
// is equivalent to:
// m1(m2(m3(job)))
func (c Chain) Then(j Job) Job {
for i := range c.wrappers {
j = c.wrappers[len(c.wrappers)-i-1](j)
}
return j
}
// Recover panics in wrapped jobs and log them with the provided logger.
func Recover(logger Logger) JobWrapper {
return func(j Job) Job {
return FuncJob(func() {
defer func() {
if r := recover(); r != nil {
const size = 64 << 10
buf := make([]byte, size)
buf = buf[:runtime.Stack(buf, false)]
err, ok := r.(error)
if !ok {
err = fmt.Errorf("%v", r)
}
logger.Error(err, "panic", "stack", "...\n"+string(buf))
}
}()
j.Run()
})
}
}
// DelayIfStillRunning serializes jobs, delaying subsequent runs until the
// previous one is complete. Jobs running after a delay of more than a minute
// have the delay logged at Info.
func DelayIfStillRunning(logger Logger) JobWrapper {
return func(j Job) Job {
var mu sync.Mutex
return FuncJob(func() {
start := time.Now()
mu.Lock()
defer mu.Unlock()
if dur := time.Since(start); dur > time.Minute {
logger.Info("delay", "duration", dur)
}
j.Run()
})
}
}
// SkipIfStillRunning skips an invocation of the Job if a previous invocation is
// still running. It logs skips to the given logger at Info level.
func SkipIfStillRunning(logger Logger) JobWrapper {
return func(j Job) Job {
var ch = make(chan struct{}, 1)
ch <- struct{}{}
return FuncJob(func() {
select {
case v := <-ch:
j.Run()
ch <- v
default:
logger.Info("skip")
}
})
}
}
|
