| /* |
| * 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.giraph.block_app.framework.api; |
| |
| import org.apache.giraph.block_app.framework.piece.global_comm.ReducerHandle; |
| import org.apache.giraph.reducers.ReduceOperation; |
| import org.apache.hadoop.io.Writable; |
| |
| /** |
| * Api for creating reducer handles. |
| */ |
| public interface CreateReducersApi extends BlockConfApi { |
| |
| /** |
| * Create local reducer, returning a handle to it. |
| * |
| * Local reducer means that each worker thread has it's own local partially |
| * reduced value, which are at the end reduced all together. |
| * Preferable, unless it cannot be used, because all copies of the object |
| * do not fit the memory. |
| */ |
| <S, R extends Writable> ReducerHandle<S, R> createLocalReducer( |
| ReduceOperation<S, R> reduceOp); |
| |
| /** |
| * Create local reducer, returning a handle to it. |
| * |
| * Local reducer means that each worker thread has it's own local partially |
| * reduced value, which are at the end reduced all together. |
| * Preferable, unless it cannot be used, because all copies of the object |
| * do not fit the memory. |
| */ |
| <S, R extends Writable> ReducerHandle<S, R> createLocalReducer( |
| ReduceOperation<S, R> reduceOp, R globalInitialValue); |
| |
| /** |
| * Create global reducer, returning a handle to it. |
| * |
| * Global reducer means that there is only one value for each worker, |
| * and each call to reduce will have to obtain a global lock, and incur |
| * synchronization costs. |
| * Use only when objects are so large, that having many copies cannot |
| * fit into memory. |
| */ |
| <S, R extends Writable> ReducerHandle<S, R> createGlobalReducer( |
| ReduceOperation<S, R> reduceOp); |
| |
| /** |
| * Create global reducer, returning a handle to it. |
| * |
| * Global reducer means that there is only one value for each worker, |
| * and each call to reduce will have to obtain a global lock, and incur |
| * synchronization costs. |
| * Use only when objects are so large, that having many copies cannot |
| * fit into memory. |
| */ |
| <S, R extends Writable> ReducerHandle<S, R> createGlobalReducer( |
| ReduceOperation<S, R> reduceOp, R globalInitialValue); |
| |
| /** |
| * Function that creates a reducer - abstracting away whether it is |
| * local or global reducer |
| */ |
| public interface CreateReducerFunctionApi { |
| <S, R extends Writable> ReducerHandle<S, R> createReducer( |
| ReduceOperation<S, R> reduceOp); |
| } |
| } |