RetryInterceptor.java

/*
 * Copyright 2014-2015 GameUp
 *
 * 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 io.gameup.android.http;

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

import java.io.IOException;

/**
 * An OkHttp interceptor that retries calls in case of network failures.
 */
public class RetryInterceptor implements Interceptor {

    /** A fixed maximum number of connection attempts. */
    public static final int MAX_ATTEMPTS = 3;

    /** {@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 {
            return chain.proceed(chain.request());
        }
        catch (final IOException e) {
            if (count < MAX_ATTEMPTS) {
                return attemptRequest(chain, count + 1);
            }
            else {
                throw e;
            }
        }
    }

}