forked from snapcore/snapd
/
hub.go
81 lines (67 loc) · 1.73 KB
/
hub.go
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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2016 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package notifications
import (
"sync"
)
// A Hub allows subscribers to receive notifications.
type Hub struct {
sync.Mutex
subscribers Subscribers
}
// NewHub returns an initialised hub
func NewHub() *Hub {
return &Hub{
subscribers: make(Subscribers),
}
}
// SubscriberCount returns the number of subscribers
func (h *Hub) SubscriberCount() int {
h.Lock()
defer h.Unlock()
return len(h.subscribers)
}
// Subscribe registers a subscriber to receive notifications.
func (h *Hub) Subscribe(s *Subscriber) {
h.Lock()
defer h.Unlock()
if _, ok := h.subscribers[s.uuid]; !ok {
h.subscribers[s.uuid] = s
}
}
// Unsubscribe unregisters a subscriber from notifications.
func (h *Hub) Unsubscribe(s *Subscriber) {
h.Lock()
defer h.Unlock()
h.doUnsubscribe(s)
}
func (h *Hub) doUnsubscribe(s *Subscriber) {
s.conn.Close()
delete(h.subscribers, s.uuid)
}
// Publish broadcasts a notification to subscribers.
func (h *Hub) Publish(n *Notification) {
h.Lock()
defer h.Unlock()
for _, s := range h.subscribers {
err := s.Notify(n)
if err != nil {
h.doUnsubscribe(s)
}
}
}