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/*
* Copyright 2015 Open Networking Laboratory
*
* 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 org.onlab.util;
import java.util.function.Function;
import com.google.common.base.Throwables;
/**
* Function that retries execution on failure.
*
* @param <U> input type
* @param <V> output type
*/
public class RetryingFunction<U, V> implements Function<U, V> {
private final Function<U, V> baseFunction;
private final Class<? extends Throwable> exceptionClass;
private final int maxRetries;
private final int maxDelayBetweenRetries;
public RetryingFunction(Function<U, V> baseFunction,
Class<? extends Throwable> exceptionClass,
int maxRetries,
int maxDelayBetweenRetries) {
this.baseFunction = baseFunction;
this.exceptionClass = exceptionClass;
this.maxRetries = maxRetries;
this.maxDelayBetweenRetries = maxDelayBetweenRetries;
}
@Override
public V apply(U input) {
int retryAttempts = 0;
while (true) {
try {
return baseFunction.apply(input);
} catch (Throwable t) {
if (!exceptionClass.isAssignableFrom(t.getClass()) || retryAttempts == maxRetries) {
Throwables.propagate(t);
}
Tools.randomDelay(maxDelayBetweenRetries);
retryAttempts++;
}
}
}
}
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