/*
* Copyright (c) 2008-2013, Hazelcast, Inc. 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.
*/
package cz.cuni.mff.d3s.been.mapstore.mongodb;
import java.util.*;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.data.mongodb.core.MongoTemplate;
import com.hazelcast.core.*;
import com.mongodb.*;
import cz.cuni.mff.d3s.been.core.task.TaskEntry;
/**
* Implementation of {@link MapStore} for MongoDB.
*
* The implementation is based on hazelcast-spring with modification for the
* BEEN project. Licence honored.
*
*/
public class MongoMapStore implements MapStore, MapLoaderLifecycleSupport {
protected static final Logger log = LoggerFactory.getLogger(MongoMapStore.class);
private static final String FAILED_STORE_MIRROR_MAP_SUFFIX = "FAILOVER";
// name of the Hazelcast List where are stored all names of already loaded maps
private static final String LOADED_LIST = "LOADED_LIST";
// TODO - consider configurable delay and period
private static final long FLUSH_INITIAL_DELAY_SECONDS = 180;
private static final long FLUSH_PERIOD_SECONDS = 180;
private HazelcastInstance hazelcastInstance;
// name of the map which is covered by this mapstore
private String mapName;
// name of the failover map for map covered by this mapstore
private String failedStoreMapName;
private MongoDBConverter converter;
private DBCollection coll;
private MongoTemplate mongoTemplate;
// tells us if map covered by this mapstore has been already loaded into memory
private volatile boolean mapIsLoaded;
/**
* Create a new MongoDB MapStore
*
* @param mongoTemplate Spring template for MongoDB persistence
*/
public MongoMapStore(MongoTemplate mongoTemplate) {
this.mongoTemplate = mongoTemplate;
}
private IMap failedStoreMap;
/**
* Get failover map in case database is down
*
* @return The failover map
*/
public IMap getFailedStoreMap() {
return failedStoreMap;
}
private static final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
@Override
public void store(Object key, Object value) {
if (!storePersistent(key, value)) {
getFailedStoreMap().put(key, value);
} else {
resolveFailedObjects();
}
}
@Override
public void storeAll(Map map) {
for (Object key : map.keySet()) {
store(key, map.get(key));
}
resolveFailedObjects();
}
@Override
public void delete(Object key) {
if (!deletePersistent(key)) {
getFailedStoreMap().put(key, null);
}
}
@Override
public void deleteAll(Collection keys) {
BasicDBList dbo = new BasicDBList();
for (Object key : keys) {
dbo.add(new BasicDBObject("_id", key));
}
BasicDBObject dbb = new BasicDBObject("$or", dbo);
coll.remove(dbb);
}
@Override
public Object load(Object key) {
try {
DBObject dbo = new BasicDBObject();
dbo.put("_id", key);
DBObject obj = coll.findOne(dbo);
if (obj == null)
return null;
try {
Class clazz = Class.forName(obj.get("_class").toString());
Object object = converter.toObject(clazz, obj);
if (object instanceof TaskEntry) {
setLoadedFromMapStore((TaskEntry) object);
}
return object;
} catch (ClassNotFoundException e) {
log.error(e.getMessage(), e);
}
return null;
} catch (Throwable t) {
String msg = String.format("Cannot load key '%s' of map '%s'", key.toString(), mapName);
log.error(msg, t);
return null;
}
}
@Override
public Map loadAll(Collection keys) {
try {
Map map = new HashMap();
BasicDBList dbo = new BasicDBList();
for (Object key : keys) {
dbo.add(new BasicDBObject("_id", key));
}
BasicDBObject dbb = new BasicDBObject("$or", dbo);
DBCursor cursor = coll.find(dbb);
while (cursor.hasNext()) {
try {
DBObject obj = cursor.next();
Class clazz = Class.forName(obj.get("_class").toString());
Object object = converter.toObject(clazz, obj);
if (object instanceof TaskEntry) {
setLoadedFromMapStore((TaskEntry) object);
}
map.put(obj.get("_id"), object);
} catch (ClassNotFoundException e) {
log.error(e.getMessage(), e);
}
}
return map;
} catch (Throwable t) {
log.warn("Cannot load collection from MongoDB", t);
} finally {
mapIsLoaded = true;
}
return null;
}
@Override
public Set loadAllKeys() {
boolean loaded = false;
ILock l = hazelcastInstance.getLock("LOADING_" + mapName);
l.lock();
IList loadedList = hazelcastInstance.getList(LOADED_LIST);
if (loadedList.contains(mapName)) {
loaded = true;
}
Set keyset = Collections.emptySet();
if (!loaded) {
try {
keyset = new HashSet();
BasicDBList dbo = new BasicDBList();
dbo.add("_id");
DBCursor cursor = coll.find(null, dbo);
while (cursor.hasNext()) {
keyset.add(cursor.next().get("_id"));
}
loadedList.add(mapName);
} catch (Throwable t) {
keyset = Collections.emptySet();
log.warn("Cannot load keys from MongoDB", t);
}
}
l.unlock();
return keyset;
}
@Override
public void init(HazelcastInstance hazelcastInstance, Properties properties, String mapName) {
if (properties.get("collection") != null) {
this.mapName = (String) properties.get("collection");
} else {
this.mapName = mapName;
}
this.failedStoreMapName = String.format("%s_%s", this.mapName, FAILED_STORE_MIRROR_MAP_SUFFIX);
this.failedStoreMap = hazelcastInstance.getMap(failedStoreMapName);
this.hazelcastInstance = hazelcastInstance;
this.coll = mongoTemplate.getCollection(this.mapName);
this.converter = new SpringMongoDBConverter(mongoTemplate);
scheduleFailoverMapFlusher();
}
@Override
public void destroy() {
// the last attempt to save the cluster from this mapstore. If this is the last node in the cluster and
// failover map is not empty, cluster will be in inconsistent state after restart - maybe recoverable,
// maybe not.
resolveFailedObjects();
}
private boolean deletePersistent(Object key) {
try {
DBObject dbo = new BasicDBObject();
dbo.put("_id", key);
coll.remove(dbo);
} catch (Throwable e) {
String message = String.format(
"Item with key '%s' couldn't be deleted from hazelcast persistent mapstore, reason: %s",
key.toString(),
e.getMessage());
log.debug(message, e);
return false;
}
return true;
}
private synchronized void resolveFailedObjects() {
IMap failedStoreMap = getFailedStoreMap();
if (failedStoreMap.size() > 0 && failedStoreMap.lockMap(5, TimeUnit.SECONDS)) {
try {
for (Object failedKey : failedStoreMap.keySet()) {
Object failedValue = failedStoreMap.get(failedKey);
if (failedValue == null) {
if (deletePersistent(failedKey)) {
break;
}
failedStoreMap.remove(failedKey);
} else {
if (storePersistent(failedKey, failedValue)) {
break;
}
failedStoreMap.remove(failedKey);
}
}
} finally {
failedStoreMap.unlockMap();
}
}
}
private void scheduleFailoverMapFlusher() {
final Runnable flusher = new Runnable() {
public void run() {
if (mapIsLoaded) {
try {
resolveFailedObjects();
} catch (Exception e) {
log.error(String.format("Periodic flushing of map '%s' failed", mapName), e);
}
}
}
};
scheduler.scheduleAtFixedRate(flusher, FLUSH_INITIAL_DELAY_SECONDS, FLUSH_PERIOD_SECONDS, TimeUnit.SECONDS);
}
private boolean storePersistent(Object key, Object value) {
try {
DBObject dbo = converter.toDBObject(value);
dbo.put("_id", key);
coll.save(dbo);
} catch (Throwable e) {
String message = String.format(
"Item with key '%s' couldn't be stored in hazelcast persistent mapstore, reason: %s",
key.toString(),
e.getMessage());
log.debug(message, e);
return false;
}
return true;
}
private void setLoadedFromMapStore(final TaskEntry entry) {
entry.setLoadedFromPersistence(true);
}
}