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118 lines
2.8 KiB
118 lines
2.8 KiB
package graceful
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import (
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"os"
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"os/signal"
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"sync"
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"sync/atomic"
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"github.com/zenazn/goji/graceful/listener"
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)
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var mu sync.Mutex // protects everything that follows
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var listeners = make([]*listener.T, 0)
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var prehooks = make([]func(), 0)
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var posthooks = make([]func(), 0)
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var closing int32
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var wait = make(chan struct{})
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var stdSignals = []os.Signal{os.Interrupt}
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var sigchan = make(chan os.Signal, 1)
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func init() {
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go waitForSignal()
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}
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// HandleSignals installs signal handlers for a set of standard signals. By
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// default, this set only includes keyboard interrupts, however when the package
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// detects that it is running under Einhorn, a SIGUSR2 handler is installed as
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// well.
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func HandleSignals() {
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AddSignal(stdSignals...)
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}
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// AddSignal adds the given signal to the set of signals that trigger a graceful
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// shutdown.
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func AddSignal(sig ...os.Signal) {
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signal.Notify(sigchan, sig...)
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}
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// ResetSignals resets the list of signals that trigger a graceful shutdown.
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func ResetSignals() {
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signal.Stop(sigchan)
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}
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type userShutdown struct{}
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func (u userShutdown) String() string {
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return "application initiated shutdown"
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}
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func (u userShutdown) Signal() {}
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// Shutdown manually triggers a shutdown from your application. Like Wait(),
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// blocks until all connections have gracefully shut down.
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func Shutdown() {
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sigchan <- userShutdown{}
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<-wait
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}
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// PreHook registers a function to be called before any of this package's normal
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// shutdown actions. All listeners will be called in the order they were added,
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// from a single goroutine.
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func PreHook(f func()) {
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mu.Lock()
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defer mu.Unlock()
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prehooks = append(prehooks, f)
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}
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// PostHook registers a function to be called after all of this package's normal
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// shutdown actions. All listeners will be called in the order they were added,
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// from a single goroutine, and are guaranteed to be called after all listening
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// connections have been closed, but before Wait() returns.
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//
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// If you've Hijacked any connections that must be gracefully shut down in some
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// other way (since this library disowns all hijacked connections), it's
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// reasonable to use a PostHook to signal and wait for them.
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func PostHook(f func()) {
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mu.Lock()
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defer mu.Unlock()
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posthooks = append(posthooks, f)
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}
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func waitForSignal() {
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<-sigchan
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mu.Lock()
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defer mu.Unlock()
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for _, f := range prehooks {
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f()
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}
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atomic.StoreInt32(&closing, 1)
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var wg sync.WaitGroup
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wg.Add(len(listeners))
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for _, l := range listeners {
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go func(l *listener.T) {
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defer wg.Done()
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l.Close()
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l.Drain()
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}(l)
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}
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wg.Wait()
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for _, f := range posthooks {
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f()
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}
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close(wait)
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}
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// Wait for all connections to gracefully shut down. This is commonly called at
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// the bottom of the main() function to prevent the program from exiting
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// prematurely.
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func Wait() {
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<-wait
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}
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