/
listenable.go
142 lines (129 loc) · 4.22 KB
/
listenable.go
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 observer
import (
"reflect"
"sort"
"sync"
)
// Listenable could add and remove the event listener
type Listenable interface {
AddEventListener(listener EventListener)
AddEventListeners(listenersSlice []EventListener)
RemoveEventListener(listener EventListener)
RemoveEventListeners(listenersSlice []EventListener)
GetAllEventListeners() []EventListener
RemoveAllEventListeners()
}
// BaseListener base listenable
type BaseListener struct {
Listenable
ListenersCache map[reflect.Type][]EventListener
Mutex sync.RWMutex
}
// NewBaseListener a constructor of base listenable
func NewBaseListener() BaseListener {
return BaseListener{
ListenersCache: make(map[reflect.Type][]EventListener, 8),
}
}
// AddEventListener add event listener
func (bl *BaseListener) AddEventListener(listener EventListener) {
eventType := listener.GetEventType()
if eventType.Kind() == reflect.Ptr {
eventType = eventType.Elem()
}
bl.Mutex.Lock()
defer bl.Mutex.Unlock()
listenersSlice, loaded := bl.ListenersCache[eventType]
if !loaded {
listenersSlice = make([]EventListener, 0, 8)
}
// return if listenersSlice already has this listener
if loaded && containListener(listenersSlice, listener) {
return
}
listenersSlice = append(listenersSlice, listener)
sort.Slice(listenersSlice, func(i, j int) bool {
return listenersSlice[i].GetPriority() < listenersSlice[j].GetPriority()
})
bl.ListenersCache[eventType] = listenersSlice
}
// AddEventListeners add the slice of event listener
func (bl *BaseListener) AddEventListeners(listenersSlice []EventListener) {
for _, listener := range listenersSlice {
bl.AddEventListener(listener)
}
}
// RemoveEventListener remove the event listener
func (bl *BaseListener) RemoveEventListener(listener EventListener) {
eventType := listener.GetEventType()
if eventType.Kind() == reflect.Ptr {
eventType = eventType.Elem()
}
bl.Mutex.Lock()
defer bl.Mutex.Unlock()
listenersSlice, loaded := bl.ListenersCache[eventType]
if !loaded {
return
}
for i, l := range listenersSlice {
if l == listener {
listenersSlice = append(listenersSlice[:i], listenersSlice[i+1:]...)
}
}
bl.ListenersCache[eventType] = listenersSlice
}
// RemoveEventListeners remove the slice of event listener
// it will iterate all listener and remove it one by one
func (bl *BaseListener) RemoveEventListeners(listenersSlice []EventListener) {
for _, listener := range listenersSlice {
bl.RemoveEventListener(listener)
}
}
// RemoveAllEventListeners remove all
// using Lock
func (bl *BaseListener) RemoveAllEventListeners() {
bl.Mutex.Lock()
defer bl.Mutex.Unlock()
bl.ListenersCache = make(map[reflect.Type][]EventListener, 8)
}
// GetAllEventListeners get all listener
// using RLock
func (bl *BaseListener) GetAllEventListeners() []EventListener {
allListenersSlice := make([]EventListener, 0, 16)
bl.Mutex.RLock()
defer bl.Mutex.RUnlock()
for _, listenersSlice := range bl.ListenersCache {
allListenersSlice = append(allListenersSlice, listenersSlice...)
}
sort.Slice(allListenersSlice, func(i, j int) bool {
return allListenersSlice[i].GetPriority() < allListenersSlice[j].GetPriority()
})
return allListenersSlice
}
// containListener true if contain listener
// it's not thread safe
// usually it should be use in lock scope
func containListener(listenersSlice []EventListener, listener EventListener) bool {
for _, loadListener := range listenersSlice {
if loadListener == listener {
return true
}
}
return false
}