114 lines
2.2 KiB
Go
114 lines
2.2 KiB
Go
package goshutdowner
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import (
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"context"
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"os"
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"os/signal"
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"sync"
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"syscall"
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)
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// Simple struct, use like a sync.Mutex
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//
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// var s goshutdowner.Shutdowner
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// s.Add(func() {
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// log.Println("Shutting down")
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// })
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type Shutdowner struct {
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initializer sync.Once
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shutdown bool
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quit chan os.Signal
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funcs []ShutdownFunc
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wg sync.WaitGroup
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mutex sync.Mutex
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cancelContext context.Context
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cancelFunc context.CancelFunc
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}
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type ShutdownFunc func()
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// Internal method
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func (f ShutdownFunc) execute(c context.Context) {
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done := make(chan interface{})
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// Execute ShutdownFunc in goroutine and close channel when finished
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go func() {
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f()
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close(done)
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}()
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// Check if context canceled or ShutdownFunc finished
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select {
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case <-c.Done():
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// Context canceled, return
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return
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case <-done:
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// ShutdownFunc finished, return
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return
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}
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}
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// Internal method
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func (s *Shutdowner) init() {
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s.initializer.Do(func() {
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s.mutex.Lock()
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defer s.mutex.Unlock()
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// Initialize cancel context and signal channel
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s.cancelContext, s.cancelFunc = context.WithCancel(context.Background())
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s.quit = make(chan os.Signal, 2)
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signal.Notify(s.quit,
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os.Interrupt,
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syscall.SIGINT,
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syscall.SIGTERM, // e.g. Docker stop
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)
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go func() {
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for range s.quit {
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s.Shutdown()
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}
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}()
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})
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}
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// Add a func, that should be called with s.Shutdown() or when receiving a shutdown signal
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func (s *Shutdowner) Add(f ShutdownFunc) {
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s.init()
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s.mutex.Lock()
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defer s.mutex.Unlock()
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s.wg.Add(1)
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s.funcs = append(s.funcs, f)
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}
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// Trigger shutdown directly
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func (s *Shutdowner) Shutdown() {
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s.init()
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s.mutex.Lock()
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defer s.mutex.Unlock()
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if !s.shutdown {
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// First time shutdown is called
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for _, f := range s.funcs {
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go func(f ShutdownFunc) {
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defer s.wg.Done()
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f.execute(s.cancelContext)
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}(f)
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}
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s.shutdown = true
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} else {
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// Second time shutdown is called
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// Cancel graceful shutdown
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s.cancelFunc()
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}
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}
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// Wait till all functions finished
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func (s *Shutdowner) Wait() {
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s.init()
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s.wg.Wait()
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}
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// Shutdown and wait till shutdown finished. Shorthand for:
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//
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// s.Shutdown()
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// s.Wait()
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func (s *Shutdowner) ShutdownAndWait() {
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s.Shutdown()
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s.Wait()
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}
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