pkg/messaging/sub.go

//Copyright 2017 Huawei Technologies Co., Ltd
//
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
package messaging

import "sync"

var (
	subscriptions      = map[string][]chan []byte{}
	subscriptionsMutex sync.Mutex
)

func Subscribe(channel string) chan []byte {
	sub := make(chan []byte)
	subscriptionsMutex.Lock()
	subscriptions[channel] = append(subscriptions[channel], sub)
	subscriptionsMutex.Unlock()
	return sub
}

func Unsubscribe(channel string, sub chan []byte) {
	subscriptionsMutex.Lock()
	newSubs := []chan []byte{}
	subs := subscriptions[channel]
	for _, s := range subs {
		if s != sub {
			newSubs = append(newSubs, s)
		}
	}
	subscriptions[channel] = newSubs
	subscriptionsMutex.Unlock()
}