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moby--moby/utils/jsonmessagepublisher.go

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package utils
import (
"sync"
"time"
)
func NewJSONMessagePublisher() *JSONMessagePublisher {
return &JSONMessagePublisher{}
}
type JSONMessageListener chan<- JSONMessage
type JSONMessagePublisher struct {
m sync.RWMutex
subscribers []JSONMessageListener
}
func (p *JSONMessagePublisher) Subscribe(l JSONMessageListener) {
p.m.Lock()
p.subscribers = append(p.subscribers, l)
p.m.Unlock()
}
func (p *JSONMessagePublisher) SubscribersCount() int {
p.m.RLock()
count := len(p.subscribers)
p.m.RUnlock()
return count
}
// Unsubscribe closes and removes the specified listener from the list of
// previously registed ones.
// It returns a boolean value indicating if the listener was successfully
// found, closed and unregistered.
func (p *JSONMessagePublisher) Unsubscribe(l JSONMessageListener) bool {
p.m.Lock()
defer p.m.Unlock()
for i, subscriber := range p.subscribers {
if subscriber == l {
close(l)
p.subscribers = append(p.subscribers[:i], p.subscribers[i+1:]...)
return true
}
}
return false
}
func (p *JSONMessagePublisher) Publish(m JSONMessage) {
p.m.RLock()
for _, subscriber := range p.subscribers {
// We give each subscriber a 100ms time window to receive the event,
// after which we move to the next.
select {
case subscriber <- m:
case <-time.After(100 * time.Millisecond):
}
}
p.m.RUnlock()
}