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package latch
import "sync/atomic"
// Interface funcs are safe to invoke concurrently.
type Interface interface {
// Done returns a chan that blocks until Close is called. It never returns data.
Done() <-chan struct{}
// Close closes the latch; all future calls to Closed return true. Safe to invoke multiple times.
Close()
// Closed returns false while the latch is "open" and true after it has been closed via Close.
Closed() bool
}
type L struct {
value int32
line chan struct{}
}
// New returns a new "open" latch such that Closed returns false until Close is invoked.
func New() Interface {
return new(L).Reset()
}
func (l *L) Done() <-chan struct{} { return l.line }
// Close may panic for an uninitialized L
func (l *L) Close() {
if atomic.AddInt32(&l.value, 1) == 1 {
close(l.line)
}
<-l.line // concurrent calls to Close block until the latch is actually closed
}
func (l *L) Closed() (result bool) {
select {
case <-l.line:
result = true
default:
}
return
}
// Reset clears the state of the latch, not safe to execute concurrently with other L methods.
func (l *L) Reset() *L {
l.line, l.value = make(chan struct{}), 0
return l
}
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