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/*
* Copyright 2018 LinkedIn Corp.
*
* 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 azkaban.executor;
import com.google.common.collect.ImmutableSet;
import java.util.Collection;
import javax.inject.Inject;
import javax.inject.Singleton;
import org.apache.log4j.Logger;
/**
* Loads & provides executors.
*/
@Singleton
public class ActiveExecutors {
private static final Logger logger = Logger.getLogger(ExecutorManager.class);
private volatile ImmutableSet<Executor> activeExecutors;
private final ExecutorLoader executorLoader;
@Inject
public ActiveExecutors(final ExecutorLoader executorLoader) {
this.executorLoader = executorLoader;
}
/**
* Loads executors. Can be also used to reload executors if there have been changes in the DB.
*
* @throws ExecutorManagerException if no active executors are found or if loading executors
* fails.
*/
public void setupExecutors() throws ExecutorManagerException {
final ImmutableSet<Executor> newExecutors = loadExecutors();
if (newExecutors.isEmpty()) {
final String error = "No active executors found";
logger.error(error);
throw new ExecutorManagerException(error);
} else {
this.activeExecutors = newExecutors;
}
}
/**
* Returns all executors. The result is cached. To reload, call {@link #setupExecutors()}.
*
* @return all executors
*/
public Collection<Executor> getAll() {
return this.activeExecutors;
}
private ImmutableSet<Executor> loadExecutors() throws ExecutorManagerException {
logger.info("Initializing executors from database.");
return ImmutableSet.copyOf(this.executorLoader.fetchActiveExecutors());
}
}