| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.hadoop.io.retry; |
| |
| import java.io.Closeable; |
| |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * An implementer of this interface is capable of providing proxy objects for |
| * use in IPC communication, and potentially modifying these objects or creating |
| * entirely new ones in the event of certain types of failures. The |
| * determination of whether or not to fail over is handled by |
| * {@link RetryPolicy}. |
| */ |
| @InterfaceStability.Evolving |
| public interface FailoverProxyProvider extends Closeable { |
| |
| /** |
| * Get the proxy object which should be used until the next failover event |
| * occurs. |
| * |
| * @return the proxy object to invoke methods upon |
| */ |
| public Object getProxy(); |
| |
| /** |
| * Called whenever the associated {@link RetryPolicy} determines that an error |
| * warrants failing over. |
| * |
| * @param currentProxy the proxy object which was being used before this |
| * failover event |
| */ |
| public void performFailover(Object currentProxy); |
| |
| /** |
| * Return a reference to the interface this provider's proxy objects actually |
| * implement. If any of the methods on this interface are annotated as being |
| * {@link Idempotent}, then this fact will be passed to the |
| * {@link RetryPolicy#shouldRetry(Exception, int, int, boolean)} method on |
| * error, for use in determining whether or not failover should be attempted. |
| * |
| * @return the interface implemented by the proxy objects returned by |
| * {@link FailoverProxyProvider#getProxy()} |
| */ |
| public Class<?> getInterface(); |
| } |