com.lithium.flow.util.RetryingFunction Maven / Gradle / Ivy

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/*
 * Copyright 2015 Lithium Technologies, Inc.
 *
 * 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.lithium.flow.util;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.ArrayList;
import java.util.List;
import java.util.function.IntFunction;

import javax.annotation.Nonnull;

/**
 * @author Matt Ayres
 */
public class RetryingFunction implements CheckedFunction {
	private final IntFunction delay;
	private final CheckedFunction function;
	private final int tries;

	public RetryingFunction(int tries, @Nonnull CheckedFunction function) {
		this(tries, 0, function);
	}

	public RetryingFunction(int tries, long delay, @Nonnull CheckedFunction function) {
		this(tries, i -> delay, function);
	}

	public RetryingFunction(int tries, @Nonnull IntFunction delay, @Nonnull CheckedFunction function) {
		this.delay = checkNotNull(delay);
		this.function = checkNotNull(function);
		this.tries = tries;
	}

	public R apply(@Nonnull T input) throws E {
		checkNotNull(input);

		if (tries == 1) {
			return function.apply(input);
		}

		List exceptions = null;

		int i = 0;
		do {
			try {
				return function.apply(input);
			} catch (Exception e) {
				if (exceptions == null) {
					exceptions = new ArrayList<>();
				}
				exceptions.add(e);

				if (!Sleep.softly(delay.apply(i).longValue())) {
					break;
				}
			}
		} while (++i < tries);

		throw new RetryingException(exceptions);
	}

	public R get(@Nonnull T input) throws E {
		return apply(input);
	}
}