github.com/sixexorg/magnetic-ring@v0.0.0-20191119090307-31705a21e419/events/event.go (about)

     1  /*
     2   * Copyright (C) 2018 The ontology Authors
     3   * This file is part of The ontology library.
     4   *
     5   * The ontology is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU Lesser General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * The ontology is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU Lesser General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU Lesser General Public License
    16   * along with The ontology.  If not, see <http://www.gnu.org/licenses/>.
    17   */
    18  
    19  package events
    20  
    21  import (
    22  	"errors"
    23  	"sync"
    24  )
    25  
    26  type Event struct {
    27  	m           sync.RWMutex
    28  	subscribers map[EventType]map[Subscriber]EventFunc
    29  }
    30  
    31  func NewEvent() *Event {
    32  	return &Event{
    33  		subscribers: make(map[EventType]map[Subscriber]EventFunc),
    34  	}
    35  }
    36  
    37  //  adds a new subscriber to Event.
    38  func (e *Event) Subscribe(eventtype EventType, eventfunc EventFunc) Subscriber {
    39  	e.m.Lock()
    40  	defer e.m.Unlock()
    41  
    42  	sub := make(chan interface{})
    43  	_, ok := e.subscribers[eventtype]
    44  	if !ok {
    45  		e.subscribers[eventtype] = make(map[Subscriber]EventFunc)
    46  	}
    47  	e.subscribers[eventtype][sub] = eventfunc
    48  
    49  	return sub
    50  }
    51  
    52  // UnSubscribe removes the specified subscriber
    53  func (e *Event) UnSubscribe(eventtype EventType, subscriber Subscriber) (err error) {
    54  	e.m.Lock()
    55  	defer e.m.Unlock()
    56  
    57  	subEvent, ok := e.subscribers[eventtype]
    58  	if !ok {
    59  		err = errors.New("No event type.")
    60  		return
    61  	}
    62  
    63  	delete(subEvent, subscriber)
    64  	close(subscriber)
    65  
    66  	return
    67  }
    68  
    69  //Notify subscribers that Subscribe specified event
    70  func (e *Event) Notify(eventtype EventType, value interface{}) (err error) {
    71  	e.m.RLock()
    72  	defer e.m.RUnlock()
    73  
    74  	subs, ok := e.subscribers[eventtype]
    75  	if !ok {
    76  		err = errors.New("No event type.")
    77  		return
    78  	}
    79  
    80  	for _, event := range subs {
    81  		go e.NotifySubscriber(event, value)
    82  	}
    83  	return
    84  }
    85  
    86  func (e *Event) NotifySubscriber(eventfunc EventFunc, value interface{}) {
    87  	if eventfunc == nil {
    88  		return
    89  	}
    90  
    91  	//invode subscriber event func
    92  	eventfunc(value)
    93  
    94  }
    95  
    96  //Notify all event subscribers
    97  func (e *Event) NotifyAll() (errs []error) {
    98  	e.m.RLock()
    99  	defer e.m.RUnlock()
   100  
   101  	for eventtype, _ := range e.subscribers {
   102  		if err := e.Notify(eventtype, nil); err != nil {
   103  			errs = append(errs, err)
   104  		}
   105  	}
   106  
   107  	return errs
   108  }