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event_mgr.go
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event_mgr.go
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// Copyright (c) 2014 Couchbase, Inc.
// 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 manager
import (
"fmt"
"github.com/couchbase/indexing/secondary/logging"
"sync"
)
///////////////////////////////////////////////////////
// Type Definition
///////////////////////////////////////////////////////
type EventType byte
const (
EVENT_NONE EventType = iota
EVENT_CREATE_INDEX
EVENT_DROP_INDEX
EVENT_UPDATE_TOPOLOGY
)
type eventManager struct {
mutex sync.Mutex
isClosed bool
notifiers map[EventType]([]*notifier)
}
type notifier struct {
id string
notifications chan interface{}
}
///////////////////////////////////////////////////////
// Package Local Function
///////////////////////////////////////////////////////
//
// Create a new event manager
//
func newEventManager() (*eventManager, error) {
r := &eventManager{isClosed: false,
notifiers: make(map[EventType]([]*notifier))}
return r, nil
}
//
// Terminate the eventManager
//
func (e *eventManager) close() {
defer func() {
if r := recover(); r != nil {
logging.Warnf("panic in eventManager.Close() : %s. Ignored.\n", r)
}
}()
e.mutex.Lock()
defer e.mutex.Unlock()
if e.isClosed {
return
}
e.isClosed = true
for _, notifiers := range e.notifiers {
for _, notifier := range notifiers {
close(notifier.notifications)
}
}
}
//
// Register a new event listener
//
func (e *eventManager) register(id string, evtType EventType) (<-chan interface{}, error) {
e.mutex.Lock()
defer e.mutex.Unlock()
notifiers, ok := e.notifiers[evtType]
if !ok {
notifiers = make([]*notifier, 0, DEFAULT_NOTIFIER_QUEUE_SIZE)
e.notifiers[evtType] = notifiers
}
for _, notifier := range notifiers {
if notifier.id == id {
return nil, NewError(ERROR_EVT_DUPLICATE_NOTIFIER, NORMAL, EVENT_MANAGER, nil,
fmt.Sprintf("Notifier %d already registered", id))
}
}
notifier := ¬ifier{id: id,
notifications: make(chan interface{}, DEFAULT_EVT_QUEUE_SIZE)}
e.notifiers[evtType] = append(e.notifiers[evtType], notifier)
return notifier.notifications, nil
}
//
// De-register a event listener
//
func (e *eventManager) unregister(id string, evtType EventType) {
e.mutex.Lock()
defer e.mutex.Unlock()
notifiers, ok := e.notifiers[evtType]
if !ok {
return
}
for i, notifier := range notifiers {
if notifier.id == id {
if i < len(notifiers)-1 {
e.notifiers[evtType] = append(notifiers[:i], notifiers[i+1:]...)
} else {
e.notifiers[evtType] = notifiers[:i]
}
}
}
}
//
// Notify
//
func (e *eventManager) notify(evtType EventType, obj interface{}) {
e.mutex.Lock()
defer e.mutex.Unlock()
notifiers, ok := e.notifiers[evtType]
if !ok {
return
}
// TODO : There is a possibility that the channel is blocked and
// this function holding onto the mutex
for _, notifier := range notifiers {
notifier.notifications <- obj
}
}