/**
* 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.whirr;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.Map;
import java.util.ServiceLoader;
import org.apache.whirr.service.ClusterActionHandler;
import org.apache.whirr.service.ClusterActionHandlerFactory;
import com.google.common.base.Function;
import com.google.common.collect.MapMaker;
import com.google.common.collect.Maps;
/**
* HandlerMapFactory used in ScriptBasedClusterAction classes to create a map of action handlers.
* This implementation allow reuse of the same handler map by multiple ScriptBasedClusterAction
* instances.
*
* Note: Another motivation of extracting this code outside of ScriptBasedClusterAction is that the
* same code inside action implementation is not possible to mock by Mockito for JUnit testing
* purposes. Without this code the action classes can be plugged with another factory and remain
* JUnit testable.
*/
public class HandlerMapFactory {
protected static final class ReturnHandlerByRoleOrPrefix implements Function<String, ClusterActionHandler> {
private final Map<String, ClusterActionHandlerFactory> factoryMap;
private final Map<String, ClusterActionHandler> handlerMap;
protected ReturnHandlerByRoleOrPrefix(Map<String, ClusterActionHandlerFactory> factoryMap,
Map<String, ClusterActionHandler> handlerMap) {
this.factoryMap = checkNotNull(factoryMap, "factoryMap");
this.handlerMap = checkNotNull(handlerMap, "handlerMap");
}
@Override
public ClusterActionHandler apply(String arg0) {
checkNotNull(arg0, "role");
for (String prefix : factoryMap.keySet()) {
if (arg0.startsWith(prefix)) {
return checkNotNull(
factoryMap.get(prefix).create(arg0.substring(prefix.length())),
"Unable to create the action handler"
);
}
}
return checkNotNull(handlerMap.get(arg0), "Action handler not found");
}
}
public static Map<String, ClusterActionHandler> create() {
return create(ServiceLoader.load(ClusterActionHandlerFactory.class),
ServiceLoader.load(ClusterActionHandler.class));
}
public static Map<String, ClusterActionHandler> create(
Iterable<ClusterActionHandlerFactory> factories,
Iterable<ClusterActionHandler> handlers
) {
Map<String, ClusterActionHandlerFactory> factoryMap =
indexFactoriesByRolePrefix(checkNotNull(factories, "factories"));
Map<String, ClusterActionHandler> handlerMap =
indexHandlersByRole(checkNotNull(handlers, "handlers"));
return new MapMaker().makeComputingMap(
new ReturnHandlerByRoleOrPrefix(factoryMap, handlerMap));
}
static Map<String, ClusterActionHandlerFactory> indexFactoriesByRolePrefix(
Iterable<ClusterActionHandlerFactory> handlers) {
return Maps.uniqueIndex(handlers, new Function<ClusterActionHandlerFactory, String>() {
@Override
public String apply(ClusterActionHandlerFactory arg0) {
return arg0.getRolePrefix();
}
});
}
static Map<String, ClusterActionHandler> indexHandlersByRole(Iterable<ClusterActionHandler> handlers) {
return Maps.uniqueIndex(handlers, new Function<ClusterActionHandler, String>() {
@Override
public String apply(ClusterActionHandler arg0) {
return arg0.getRole();
}
});
}
}