com.hazelcast.instance.NodeExtensionFactory Maven / Gradle / Ivy
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/*
* Copyright (c) 2008-2019, 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 com.hazelcast.instance;
import com.hazelcast.core.HazelcastException;
import com.hazelcast.logging.Logger;
import com.hazelcast.spi.annotation.PrivateApi;
import com.hazelcast.util.ExceptionUtil;
import com.hazelcast.util.ServiceLoader;
import java.util.Iterator;
import java.util.List;
@PrivateApi
public final class NodeExtensionFactory {
private static final String NODE_EXTENSION_FACTORY_ID = "com.hazelcast.instance.NodeExtension";
private NodeExtensionFactory() {
}
/**
* Uses the Hazelcast ServiceLoader to discover all registered {@link
* NodeExtension} classes and identify the one to instantiate and use as
* the provided {@code node}'s extension. It chooses the class based on
* the provided priority list of class names, these are the rules:
* -
* A class's priority is its zero-based index in the list.
*
-
* Lower number means higher priority.
*
-
* A class that doesn't appear in the list doesn't qualify for selection.
*
*
* The dynamic selection of the node extension allows Hazelcast
* Enterprise's JAR to be swapped in for the core Hazelcast JAR with no
* changes to user's code or configuration. Hazelcast core code can call
* this method with a priority list naming both the default and the
* enterprise node extension and it will automatically prefer the
* Enterprise one when present.
*
* The explicit priority list is necessary because a Hazelcast Jet JAR
* contains both the default node extension and the Jet node extension,
* but the one to choose depends on whether the user is requesting to
* start an IMDG or a Jet instance.
*
* @param node Hazelcast node whose extension this method must provide
* @param extensionPriorityList priority list of fully qualified extension class names
* @return the selected node extension
*/
public static NodeExtension create(Node node, List extensionPriorityList) {
try {
ClassLoader classLoader = node.getConfigClassLoader();
Class chosenExtension = null;
int chosenPriority = Integer.MAX_VALUE;
for (Iterator> iter =
ServiceLoader.classIterator(NodeExtension.class, NODE_EXTENSION_FACTORY_ID, classLoader);
iter.hasNext();
) {
Class currExt = iter.next();
warnIfDuplicate(currExt);
int currPriority = extensionPriorityList.indexOf(currExt.getName());
if (currPriority == -1) {
continue;
}
if (currPriority < chosenPriority) {
chosenPriority = currPriority;
chosenExtension = currExt;
}
}
if (chosenExtension == null) {
throw new HazelcastException("ServiceLoader didn't find any services registered under "
+ NODE_EXTENSION_FACTORY_ID);
}
return chosenExtension.getConstructor(Node.class).newInstance(node);
} catch (Exception e) {
throw ExceptionUtil.rethrow(e);
}
}
private static void warnIfDuplicate(Class klass) {
if (!klass.equals(DefaultNodeExtension.class) && klass.getName().equals(DefaultNodeExtension.class.getName())) {
Logger.getLogger(NodeExtensionFactory.class).warning(
"DefaultNodeExtension class has been loaded by two different class-loaders.\n"
+ "Classloader 1: " + NodeExtensionFactory.class.getClassLoader() + '\n'
+ "Classloader 2: " + klass.getClassLoader() + '\n'
+ "Are you running Hazelcast Jet in an OSGi environment?"
+ " If so, set the bundle class-loader in the Config using the setClassloader() method");
}
}
}