[GitHub] [incubator-yunikorn-core] yangwwei commented on a change in pull request #141: [YUNIKORN-117] Create event cache for queue and application events

[GitBox <gi...@apache.org>]

yangwwei commented on a change in pull request #141:
URL: https://github.com/apache/incubator-yunikorn-core/pull/141#discussion_r439197866



##########
File path: pkg/events/event_cache.go
##########
@@ -0,0 +1,112 @@
+/*
+ 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 events
+
+import (
+	"sync"
+
+	"github.com/apache/incubator-yunikorn-core/pkg/log"
+)
+
+const defaultEventChannelSize = 100000
+
+var once sync.Once
+var cache *EventCache
+
+type EventCache struct {
+	channel EventChannel // channelling input eventChannel
+	store   EventStore   // storing eventChannel
+	started bool         // whether the service is started
+	stop    chan bool    // whether the service is stop
+
+	sync.Mutex
+}
+
+func GetEventCache() *EventCache {
+	once.Do(func(){
+		store := newEventStoreImpl()
+
+		cache = &EventCache{
+			channel: newEventChannelImpl(defaultEventChannelSize),
+			store:   store,
+			started: false,
+			stop:    make(chan bool),
+		}
+	})
+	return cache
+}
+
+// TODO consider thread pool
+func (ec *EventCache) StartService() {
+	ec.Lock()
+	defer ec.Unlock()
+
+	if !ec.started {
+		// start main event processing thread
+		go ec.processEvent()
+
+		ec.started = true
+	}
+}
+
+func (ec *EventCache) IsStarted() bool {
+	ec.Lock()
+	defer ec.Unlock()
+
+	return ec.started
+}
+
+func (ec *EventCache) Stop() {
+	ec.Lock()
+	defer ec.Unlock()
+
+	if ec.started {
+		ec.stop <- true
+		ec.channel.Stop()
+		ec.started = false
+	}
+}
+
+func (ec *EventCache) AddEvent(event Event) {
+	ec.channel.AddEvent(event)
+}
+
+func (ec *EventCache) GetEventStore() EventStore {
+	return ec.store
+}
+
+func (ec *EventCache) processEvent() {
+	for {
+		select {
+			case <- ec.stop:
+				return
+			case event, ok := <- ec.channel.GetChannel():
+				if event != nil {
+					ec.store.Store(event)
+				} else {
+					log.Logger().Debug("nil object in EventChannel")
+					if !ok {
+						log.Logger().Info("the EventChannel is closed - closing the EventCache")
+						ec.Stop()
+						return
+					}
+				}
+		}
+	}
+}

Review comment:
       remove this.




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