parent
fea3569956
commit
073c5bfdaa
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package signal
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import (
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"sync"
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)
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// Signal lets goroutines signal that some event has occurred. Other goroutines can wait for the signal.
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type Signal struct {
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ch chan struct{}
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once sync.Once
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}
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// New wraps a channel and turns it into a signal for a one-time event.
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func New(ch chan struct{}) *Signal {
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return &Signal{
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ch: ch,
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once: sync.Once{},
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}
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}
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// Notify alerts any goroutines waiting on this signal that the event has occurred.
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// After the first call to Notify(), future calls are no-op.
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func (s *Signal) Notify() {
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s.once.Do(func() {
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close(s.ch)
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})
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}
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// Wait returns a channel which will be written to when Notify() is called for the first time.
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// This channel will never be written to a second time.
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func (s *Signal) Wait() <-chan struct{} {
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return s.ch
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}
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@ -0,0 +1,25 @@
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package signal
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import (
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"testing"
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)
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func TestMultiNotifyDoesntCrash(t *testing.T) {
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sig := New(make(chan struct{}))
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sig.Notify()
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sig.Notify()
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// If code has reached here without crashing, the test has passed.
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}
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func TestWait(t *testing.T) {
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sig := New(make(chan struct{}))
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sig.Notify()
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select {
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case <-sig.Wait():
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// Test succeeds
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return
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default:
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// sig.Wait() should have been read from, because sig.Notify() wrote to it.
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t.Fail()
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}
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}
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