/**
* 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 org.apache.ambari.view.pig.persistence;
import com.google.gson.Gson;
import org.apache.ambari.view.ViewContext;
import org.apache.ambari.view.pig.persistence.utils.FilteringStrategy;
import org.apache.ambari.view.pig.persistence.utils.Indexed;
import org.apache.ambari.view.pig.persistence.utils.ItemNotFound;
import org.apache.ambari.view.pig.persistence.utils.OnlyOwnersFilteringStrategy;
import org.apache.commons.configuration.Configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.List;
/**
* Engine for storing objects to key-value storage
*/
public abstract class KeyValueStorage implements Storage {
private final static Logger LOG =
LoggerFactory.getLogger(KeyValueStorage.class);
protected final Gson gson = new Gson();
protected ViewContext context;
/**
* Constructor
* @param context View Context instance
*/
public KeyValueStorage(ViewContext context) {
this.context = context;
}
/**
* Returns config instance, adapter to Persistence API
* @return config instance
*/
protected abstract Configuration getConfig();
@Override
public synchronized void store(Indexed obj) {
String modelIndexingPropName = getIndexPropertyName(obj.getClass());
if (obj.getId() == null) {
int lastIndex = getConfig().getInt(modelIndexingPropName, 0);
lastIndex ++;
getConfig().setProperty(modelIndexingPropName, lastIndex);
obj.setId(Integer.toString(lastIndex));
}
String modelPropName = getItemPropertyName(obj.getClass(), Integer.parseInt(obj.getId()));
String json = serialize(obj);
write(modelPropName, json);
}
@Override
public <T extends Indexed> T load(Class<T> model, int id) throws ItemNotFound {
String modelPropName = getItemPropertyName(model, id);
LOG.debug(String.format("Loading %s", modelPropName));
if (getConfig().containsKey(modelPropName)) {
String json = read(modelPropName);
LOG.debug(String.format("json: %s", json));
return deserialize(model, json);
} else {
throw new ItemNotFound();
}
}
/**
* Write json to storage
* @param modelPropName key
* @param json value
*/
protected void write(String modelPropName, String json) {
getConfig().setProperty(modelPropName, json);
}
/**
* Read json from storage
* @param modelPropName key
* @return value
*/
protected String read(String modelPropName) {
return getConfig().getString(modelPropName);
}
/**
* Remove line from storage
* @param modelPropName key
*/
protected void clear(String modelPropName) {
getConfig().clearProperty(modelPropName);
}
protected String serialize(Indexed obj) {
return gson.toJson(obj);
}
protected <T extends Indexed> T deserialize(Class<T> model, String json) {
return gson.fromJson(json, model);
}
@Override
public synchronized <T extends Indexed> List<T> loadAll(Class<T> model, FilteringStrategy filter) {
ArrayList<T> list = new ArrayList<T>();
String modelIndexingPropName = getIndexPropertyName(model);
LOG.debug(String.format("Loading all %s-s", model.getName()));
int lastIndex = getConfig().getInt(modelIndexingPropName, 0);
for(int i=1; i<=lastIndex; i++) {
try {
T item = load(model, i);
if ((filter == null) || filter.isConform(item)) {
list.add(item);
}
} catch (ItemNotFound ignored) {
}
}
return list;
}
@Override
public synchronized <T extends Indexed> List<T> loadAll(Class<T> model) {
return loadAll(model, new OnlyOwnersFilteringStrategy(this.context.getUsername()));
}
@Override
public synchronized void delete(Class model, int id) {
LOG.debug(String.format("Deleting %s:%d", model.getName(), id));
String modelPropName = getItemPropertyName(model, id);
clear(modelPropName);
}
@Override
public boolean exists(Class model, int id) {
return getConfig().containsKey(getItemPropertyName(model, id));
}
private String getIndexPropertyName(Class model) {
return String.format("%s:index", model.getName());
}
private String getItemPropertyName(Class model, int id) {
return String.format("%s.%d", model.getName(), id);
}
}