com.heroiclabs.sdk.android.util.http.RetryInterceptor.java Source code

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Here is the source code for com.heroiclabs.sdk.android.util.http.RetryInterceptor.java

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/*
 * Copyright 2016 Heroic Labs
 *
 * 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.heroiclabs.sdk.android.util.http;

import com.squareup.okhttp.Interceptor;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.util.Random;

import lombok.RequiredArgsConstructor;

/**
 * An OkHttp interceptor that retries calls in case of network failures.
 */
@RequiredArgsConstructor(suppressConstructorProperties = true)
public class RetryInterceptor implements Interceptor {

    /** Generator used to randomise delay between request attempts. */
    private final Random random = new Random();

    /** A maximum number of attempts. */
    private final int maxAttempts;

    /** {@inheritDoc} */
    @Override
    public Response intercept(final Chain chain) throws IOException {
        return attemptRequest(chain, 1);
    }

    /**
     * Recursive helper method that catches IOExceptions and calls itself again if the maximum number of allowed
     * retries has not yet been exceeded.
     *
     * @param chain The request chain.
     * @param count The number of the current attempt.
     * @return The response forwarded by the chain.
     * @throws IOException if even after all retries the request fails.
     */
    private Response attemptRequest(final Chain chain, final int count) throws IOException {
        try {
            final Request request = chain.request();
            final Response response = chain.proceed(request);

            // Treat blank 504 responses as network issues.
            if (response.code() == HttpURLConnection.HTTP_GATEWAY_TIMEOUT
                    && response.body().contentLength() == 0l) {
                throw new IOException("Unexpected 504 responses status");
            }

            return response;
        } catch (final IOException e) {
            if (count < maxAttempts) {
                try {
                    // Wait between 100 and 200 milliseconds, inclusive.
                    Thread.sleep(random.nextInt(101) + 100);
                } catch (final InterruptedException ex) {
                    // Don't care.
                }

                return attemptRequest(chain, count + 1);
            } else {
                throw e;
            }
        }
    }

}