| /* |
| * Copyright 2015-present Open Networking Foundation |
| * |
| * 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; |
| } |
| |
| @SuppressWarnings("squid:S1181") |
| // Yes we really do want to catch Throwable |
| @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++; |
| } |
| } |
| } |
| } |