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/*******************************************************************************
* ============LICENSE_START====================================================
* * org.onap.aaf
* * ===========================================================================
* * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
* * ===========================================================================
* * 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.
* * ============LICENSE_END====================================================
* *
* * ECOMP is a trademark and service mark of AT&T Intellectual Property.
* *
******************************************************************************/
package org.onap.aaf.cache;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import org.onap.aaf.inno.env.Env;
import org.onap.aaf.inno.env.Trans;
/**
* Create and maintain a Map of Maps used for Caching
*
*
* @param <TRANS>
* @param <DATA>
*/
public class Cache<TRANS extends Trans, DATA> {
private static Clean clean;
private static Timer cleanseTimer;
public static final String CACHE_HIGH_COUNT = "CACHE_HIGH_COUNT";
public static final String CACHE_CLEAN_INTERVAL = "CACHE_CLEAN_INTERVAL";
// public static final String CACHE_MIN_REFRESH_INTERVAL = "CACHE_MIN_REFRESH_INTERVAL";
private static final Map<String,Map<String,Dated>> cacheMap;
static {
cacheMap = new HashMap<String,Map<String,Dated>>();
}
/**
* Dated Class - store any Data with timestamp
*
*
*/
public final static class Dated {
public Date timestamp;
public List<?> data;
public Dated(List<?> data) {
timestamp = new Date();
this.data = data;
}
public <T> Dated(T t) {
timestamp = new Date();
ArrayList<T> al = new ArrayList<T>(1);
al.add(t);
data = al;
}
public void touch() {
timestamp = new Date();
}
}
public static Map<String,Dated> obtain(String key) {
Map<String, Dated> m = cacheMap.get(key);
if(m==null) {
m = new ConcurrentHashMap<String, Dated>();
synchronized(cacheMap) {
cacheMap.put(key, m);
}
}
return m;
}
/**
* Clean will examine resources, and remove those that have expired.
*
* If "highs" have been exceeded, then we'll expire 10% more the next time. This will adjust after each run
* without checking contents more than once, making a good average "high" in the minimum speed.
*
*
*/
private final static class Clean extends TimerTask {
private final Env env;
private Set<String> set;
// The idea here is to not be too restrictive on a high, but to Expire more items by
// shortening the time to expire. This is done by judiciously incrementing "advance"
// when the "highs" are exceeded. This effectively reduces numbers of cached items quickly.
private final int high;
private long advance;
private final long timeInterval;
public Clean(Env env, long cleanInterval, int highCount) {
this.env = env;
high = highCount;
timeInterval = cleanInterval;
advance = 0;
set = new HashSet<String>();
}
public synchronized void add(String key) {
set.add(key);
}
public void run() {
int count = 0;
int total = 0;
// look at now. If we need to expire more by increasing "now" by "advance"
Date now = new Date(System.currentTimeMillis() + advance);
for(String name : set) {
Map<String,Dated> map = cacheMap.get(name);
if(map!=null) for(Map.Entry<String,Dated> me : map.entrySet()) {
++total;
if(me.getValue().timestamp.before(now)) {
map.remove(me.getKey());
++count;
}
}
// if(count>0) {
// env.info().log(Level.INFO, "Cache removed",count,"expired",name,"Elements");
// }
}
if(count>0) {
env.info().log(Level.INFO, "Cache removed",count,"expired Cached Elements out of", total);
}
// If High (total) is reached during this period, increase the number of expired services removed for next time.
// There's no point doing it again here, as there should have been cleaned items.
if(total>high) {
// advance cleanup by 10%, without getting greater than timeInterval.
advance = Math.min(timeInterval, advance+(timeInterval/10));
} else {
// reduce advance by 10%, without getting lower than 0.
advance = Math.max(0, advance-(timeInterval/10));
}
}
}
public static synchronized void startCleansing(Env env, String ... keys) {
if(cleanseTimer==null) {
cleanseTimer = new Timer("Cache Cleanup Timer");
int cleanInterval = Integer.parseInt(env.getProperty(CACHE_CLEAN_INTERVAL,"60000")); // 1 minute clean cycles
int highCount = Integer.parseInt(env.getProperty(CACHE_HIGH_COUNT,"5000"));
cleanseTimer.schedule(clean = new Clean(env, cleanInterval, highCount), cleanInterval, cleanInterval);
}
for(String key : keys) {
clean.add(key);
}
}
public static void stopTimer() {
if(cleanseTimer!=null) {
cleanseTimer.cancel();
cleanseTimer = null;
}
}
public static void addShutdownHook() {
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
Cache.stopTimer();
}
});
}
}
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