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84 lines
1.8 KiB
84 lines
1.8 KiB
6 years ago
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/*
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* MinIO Cloud Storage, (C) 2019 MinIO, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package pubsub
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import (
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"sync"
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)
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// PubSub holds publishers and subscribers
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type PubSub struct {
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subs []chan interface{}
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pub chan interface{}
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mutex sync.Mutex
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}
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// process item to subscribers.
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func (ps *PubSub) process() {
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for item := range ps.pub {
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ps.mutex.Lock()
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for _, sub := range ps.subs {
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go func(s chan interface{}) {
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s <- item
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}(sub)
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}
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ps.mutex.Unlock()
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}
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}
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// Publish message to pubsub system
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func (ps *PubSub) Publish(item interface{}) {
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ps.pub <- item
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}
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// Subscribe - Adds a subscriber to pubsub system
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func (ps *PubSub) Subscribe() chan interface{} {
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ps.mutex.Lock()
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defer ps.mutex.Unlock()
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ch := make(chan interface{})
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ps.subs = append(ps.subs, ch)
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return ch
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}
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// Unsubscribe removes current subscriber
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func (ps *PubSub) Unsubscribe(ch chan interface{}) {
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ps.mutex.Lock()
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defer ps.mutex.Unlock()
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for i, sub := range ps.subs {
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if sub == ch {
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close(ch)
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ps.subs = append(ps.subs[:i], ps.subs[i+1:]...)
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}
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}
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}
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// HasSubscribers returns true if pubsub system has subscribers
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func (ps *PubSub) HasSubscribers() bool {
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ps.mutex.Lock()
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defer ps.mutex.Unlock()
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return len(ps.subs) > 0
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}
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// New inits a PubSub system
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func New() *PubSub {
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ps := &PubSub{}
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ps.pub = make(chan interface{})
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go ps.process()
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return ps
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}
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