com.pivotal.gemfirexd.execute.QueryObserverHolder Maven / Gradle / Ivy
/*
* Copyright (c) 2010-2015 Pivotal Software, 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. See accompanying
* LICENSE file.
*/
package com.pivotal.gemfirexd.execute;
import java.util.Collection;
import com.pivotal.gemfirexd.internal.engine.GemFireXDQueryObserverHolder;
/**
* A holder for {@link QueryObserver}s to allow for adding removing observers.
*
* @author swale
*/
public class QueryObserverHolder {
/**
* Add a new {@link QueryObserver} to the list of observers for the VM. Note
* that any number of observers of a given Class can be present at a time.
* Restriction of only one observer of a give Class is removed.
*/
public static void putInstance(QueryObserver observer) {
GemFireXDQueryObserverHolder.putInstance(observer);
}
/**
* Add a new {@link QueryObserver} to the list of observers for the VM if no
* existing observer of the same Class is found.
*/
public static QueryObserver putInstanceIfAbsent(QueryObserver observer) {
return GemFireXDQueryObserverHolder.putInstanceIfAbsent(observer);
}
/** Return the current QueryObserver instance */
public static QueryObserver getInstance() {
return GemFireXDQueryObserverHolder.getInstance();
}
/**
* Returns the first observer of the given class (registered using
* {@link #putInstance(QueryObserver)} or
* {@link #putInstanceIfAbsent(QueryObserver)}, or null if none found.
*/
public static T getObserver(Class c) {
return GemFireXDQueryObserverHolder.getObserver(c);
}
/**
* Returns all the observers of the given class (registered using
* {@link #putInstance(QueryObserver)} or
* {@link #putInstanceIfAbsent(QueryObserver)}, or null if none found.
*/
public static Collection getObservers(
final Class c) {
return GemFireXDQueryObserverHolder.getObservers(c);
}
/**
* Returns all the registered observers.
*/
public static Collection getAllObservers() {
return GemFireXDQueryObserverHolder.getAllObservers();
}
/**
* Removes all observers of the given class (registered using
* {@link #putInstance(QueryObserver)} or
* {@link #putInstanceIfAbsent(QueryObserver)} and returns true if any
* observer was removed else false.
*/
public static boolean removeObserver(final Class c) {
return GemFireXDQueryObserverHolder.removeObserver(c);
}
/** remove the observer of given observer instance */
public static boolean removeObserver(QueryObserver observer) {
return GemFireXDQueryObserverHolder.removeObserver(observer);
}
}