/*
 * 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.flink.streaming.tests;

import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.runtime.state.CheckpointListener;

/**
 * This mapper simulates failure by throwing exceptions. The timing to throw an
 * exception by configuring the number of records to process, and number of
 * complete checkpoints to be acknowledged before throwing the exception.
 *
 * <p>The total times to simulate a failure across multiple execution attempts
 * of the operator can also be configured. Note that this also takes into account
 * failures that were not triggered by this mapper, e.g. TaskManager failures.
 */
public class FailureMapper<T> extends RichMapFunction<T, T> implements CheckpointListener {

	private static final long serialVersionUID = -5286927943454740016L;

	private final long numProcessedRecordsFailureThreshold;
	private final long numCompleteCheckpointsFailureThreshold;
	private final int maxNumFailures;

	private long numProcessedRecords;
	private long numCompleteCheckpoints;

	public FailureMapper(
			long numProcessedRecordsFailureThreshold,
			long numCompleteCheckpointsFailureThreshold,
			int maxNumFailures) {

		this.numProcessedRecordsFailureThreshold = numProcessedRecordsFailureThreshold;
		this.numCompleteCheckpointsFailureThreshold = numCompleteCheckpointsFailureThreshold;
		this.maxNumFailures = maxNumFailures;
	}

	@Override
	public T map(T value) throws Exception {
		numProcessedRecords++;

		if (isReachedFailureThreshold()) {
			throw new Exception("Artificial failure.");
		}

		return value;
	}

	@Override
	public void notifyCheckpointComplete(long checkpointId) throws Exception {
		numCompleteCheckpoints++;

		if (isReachedFailureThreshold()) {
			throw new Exception("Artificial failure.");
		}
	}

	private boolean isReachedFailureThreshold() {
		return numProcessedRecords >= numProcessedRecordsFailureThreshold
			&& numCompleteCheckpoints >= numCompleteCheckpointsFailureThreshold
			&& getRuntimeContext().getAttemptNumber() < maxNumFailures;
	}
}