open-consul/consul/state/notify.go

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2015-09-20 08:36:39 +00:00
package state
import (
"sync"
)
// NotifyGroup is used to allow a simple notification mechanism.
// Channels can be marked as waiting, and when notify is invoked,
// all the waiting channels get a message and are cleared from the
// notify list.
type NotifyGroup struct {
l sync.Mutex
notify map[chan struct{}]struct{}
}
// Notify will do a non-blocking send to all waiting channels, and
// clear the notify list
func (n *NotifyGroup) Notify() {
n.l.Lock()
defer n.l.Unlock()
for ch, _ := range n.notify {
select {
case ch <- struct{}{}:
default:
}
}
n.notify = nil
}
// Wait adds a channel to the notify group
func (n *NotifyGroup) Wait(ch chan struct{}) {
n.l.Lock()
defer n.l.Unlock()
if n.notify == nil {
n.notify = make(map[chan struct{}]struct{})
}
n.notify[ch] = struct{}{}
}
// Clear removes a channel from the notify group
func (n *NotifyGroup) Clear(ch chan struct{}) {
n.l.Lock()
defer n.l.Unlock()
if n.notify == nil {
return
}
delete(n.notify, ch)
}
// WaitCh allocates a channel that is subscribed to notifications
func (n *NotifyGroup) WaitCh() chan struct{} {
ch := make(chan struct{}, 1)
n.Wait(ch)
return ch
}