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