lang/java/reef-common/src/main/java/org/apache/reef/util/ExceptionHandlingEventHandler.java

/*
 * 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.reef.util;

import org.apache.reef.annotations.audience.Private;
import org.apache.reef.wake.EventHandler;

/**
 * An ExceptionHandler that wraps another one, but catches all exceptions thrown by that one and forwards them
 * to an ExceptionHandler.
 *
 * @param <T> the event type handled
 */
@Private
public final class ExceptionHandlingEventHandler<T> implements EventHandler<T> {

  private final EventHandler<T> wrapped;
  private final EventHandler<Throwable> exceptionHandler;

  public ExceptionHandlingEventHandler(final EventHandler<T> wrapped,
                                       final EventHandler<Throwable> exceptionHandler) {
    this.wrapped = wrapped;
    this.exceptionHandler = exceptionHandler;
  }

  @Override
  @SuppressWarnings("checkstyle:illegalcatch")
  public void onNext(final T t) {
    try {
      this.wrapped.onNext(t);
    } catch (final Throwable throwable) {
      this.exceptionHandler.onNext(throwable);
    }
  }
}