ClientRetryFilter.java

/*
   Copyright (c) 2016 LinkedIn Corp.

   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.
*/

/* $Id$ */
package com.linkedin.r2.filter.transport;

import com.linkedin.r2.RetriableRequestException;
import com.linkedin.r2.filter.NextFilter;
import com.linkedin.r2.filter.R2Constants;
import com.linkedin.r2.filter.message.rest.RestFilter;
import com.linkedin.r2.filter.message.stream.StreamFilter;
import com.linkedin.r2.message.Request;
import com.linkedin.r2.message.RequestContext;
import com.linkedin.r2.message.Response;
import com.linkedin.r2.message.rest.RestRequest;
import com.linkedin.r2.message.rest.RestResponse;
import com.linkedin.r2.message.stream.StreamRequest;
import com.linkedin.r2.message.stream.StreamResponse;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Filter implementation that checks if we need to retry. The server will put a wire attribute
 * when a retry is requested. This filter checks for that attribute and convert it to a
 * {@link RetriableRequestException}.
 *
 * @author Xialin Zhu
 * @see ServerRetryFilter
 */
public class ClientRetryFilter implements RestFilter, StreamFilter
{
  private static final Logger LOG = LoggerFactory.getLogger(ServerRetryFilter.class);

  @Override
  public void onRestError(Throwable ex,
      RequestContext requestContext,
      Map<String, String> wireAttrs,
      NextFilter<RestRequest, RestResponse> nextFilter)
  {
    processError(ex, requestContext, wireAttrs, nextFilter);
  }

  @Override
  public void onStreamError(Throwable ex,
      RequestContext requestContext,
      Map<String, String> wireAttrs,
      NextFilter<StreamRequest, StreamResponse> nextFilter)
  {
    processError(ex, requestContext, wireAttrs, nextFilter);
  }

  private <REQ extends Request, RES extends Response> void processError(Throwable ex,
      RequestContext requestContext,
      Map<String, String> wireAttrs,
      NextFilter<REQ, RES> nextFilter)
  {
    String retryAttr = wireAttrs.get(R2Constants.RETRY_MESSAGE_ATTRIBUTE_KEY);
    if (retryAttr != null)
    {
      nextFilter.onError(new RetriableRequestException(retryAttr), requestContext, wireAttrs);
    }
    else
    {
      nextFilter.onError(ex, requestContext, wireAttrs);
    }
  }
}