| /* |
| * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved. |
| * |
| * 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.lib.db; |
| |
| import java.util.*; |
| |
| /** |
| * This is the base implementation of an input operator which consumes data from a key value store. |
| * Subclasses should implement the method which converts key value pairs into tuples. |
| * <p> |
| * The default behavior is to get all the values using the keys from the store for each window. Subclasses are free to override this behavior. |
| * </p> |
| * @displayName Abstract Key Value Store Input |
| * @category Store |
| * @tags input operator, key value |
| * |
| * @param <T> The tuple type. |
| * @param <S> The store type. |
| * @since 0.9.3 |
| */ |
| public abstract class AbstractKeyValueStoreInputOperator<T, S extends KeyValueStore> extends AbstractStoreInputOperator<T, S> |
| { |
| protected List<Object> keys = new ArrayList<Object>(); |
| |
| /** |
| * Adds the key to the list of keys to be fetched for each window |
| * |
| * @param key a key. |
| */ |
| public void addKey(Object key) |
| { |
| keys.add(key); |
| } |
| |
| @Override |
| public void emitTuples() |
| { |
| List<Object> allValues = store.getAll(keys); |
| Map<Object, Object> m = new HashMap<Object, Object>(); |
| Iterator<Object> keyIterator = keys.iterator(); |
| Iterator<Object> valueIterator = allValues.iterator(); |
| while (keyIterator.hasNext() && valueIterator.hasNext()) { |
| m.put(keyIterator.next(), valueIterator.next()); |
| } |
| outputPort.emit(convertToTuple(m)); |
| } |
| |
| /** |
| * Implementations should provide the way of converting from a map of key value pairs from the store to a tuple. |
| * |
| * @param o map of keys and values. |
| * @return tuple. |
| */ |
| public abstract T convertToTuple(Map<Object, Object> o); |
| |
| } |