| /** |
| * Copyright (C) 2015 DataTorrent, Inc. |
| * |
| * 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.datatorrent.api; |
| |
| import java.io.IOException; |
| |
| /** |
| * Interface to define writing/reading checkpoint state of any operator. |
| * |
| * @since 0.9.4 |
| */ |
| public interface StorageAgent |
| { |
| /** |
| * Save the object so that the same object can be loaded later using the given combination of |
| * operatorId and windowId. |
| * |
| * Typically the storage agent would serialize the state of the object during the save state. |
| * The serialized state can be accessed from anywhere on the cluster to recreate the object |
| * through the load callback. |
| * |
| * @param object - The operator whose state needs to be saved. |
| * @param operatorId - Identifier of the operator. |
| * @param windowId - Identifier for the specific state of the operator. |
| * @throws IOException |
| */ |
| public void save(Object object, int operatorId, long windowId) throws IOException; |
| |
| /** |
| * Get the input stream from which can be used to retrieve the stored objects back. |
| * |
| * @param operatorId Id for which the object was previously saved |
| * @param windowId WindowId for which the object was previously saved |
| * @return object (or a copy of it) which was saved earlier using the save call. |
| * @throws IOException |
| */ |
| public Object load(int operatorId, long windowId) throws IOException; |
| |
| /** |
| * Delete the artifacts related to store call of the operatorId and the windowId. |
| * |
| * Through this call, the agent is informed that the object saved against the operatorId |
| * and the windowId together will not be needed again. |
| * |
| * @param operatorId |
| * @param windowId |
| * @throws IOException |
| */ |
| public void delete(int operatorId, long windowId) throws IOException; |
| |
| /** |
| * Return an array windowId for which the object was saved but not deleted. |
| * |
| * The set is essentially difference between two sets. The first set contains |
| * all the windowIds passed using the successful save calls. The second set contains all |
| * the windowIds passed using the successful delete calls. |
| * |
| * @param operatorId - The operator for which the state was saved. |
| * @return Collection of windowIds for available states that can be retrieved through load. |
| * @throws IOException |
| */ |
| public long[] getWindowIds(int operatorId) throws IOException; |
| |
| } |