54 lines
1.5 KiB
Go
54 lines
1.5 KiB
Go
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package signal
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import (
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"log"
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"os"
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gosignal "os/signal"
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"sync/atomic"
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"syscall"
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)
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// Trap sets up a simplified signal "trap", appropriate for common
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// behavior expected from a vanilla unix command-line tool in general
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// (and the Docker engine in particular).
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//
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// * If SIGINT or SIGTERM are received, `cleanup` is called, then the process is terminated.
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// * If SIGINT or SIGTERM are repeated 3 times before cleanup is complete, then cleanup is
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// skipped and the process terminated directly.
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// * If "DEBUG" is set in the environment, SIGQUIT causes an exit without cleanup.
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//
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func Trap(cleanup func()) {
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c := make(chan os.Signal, 1)
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signals := []os.Signal{os.Interrupt, syscall.SIGTERM}
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if os.Getenv("DEBUG") == "" {
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signals = append(signals, syscall.SIGQUIT)
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}
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gosignal.Notify(c, signals...)
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go func() {
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interruptCount := uint32(0)
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for sig := range c {
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go func(sig os.Signal) {
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log.Printf("Received signal '%v', starting shutdown of docker...\n", sig)
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switch sig {
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case os.Interrupt, syscall.SIGTERM:
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// If the user really wants to interrupt, let him do so.
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if atomic.LoadUint32(&interruptCount) < 3 {
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atomic.AddUint32(&interruptCount, 1)
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// Initiate the cleanup only once
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if atomic.LoadUint32(&interruptCount) == 1 {
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// Call cleanup handler
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cleanup()
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} else {
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return
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}
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} else {
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log.Printf("Force shutdown of docker, interrupting cleanup\n")
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}
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case syscall.SIGQUIT:
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}
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os.Exit(128 + int(sig.(syscall.Signal)))
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}(sig)
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}
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}()
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}
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