1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 package org.apache.giraph.block_app.framework.block; 19 20 import java.util.Iterator; 21 22 import org.apache.giraph.block_app.framework.piece.AbstractPiece; 23 import org.apache.giraph.function.Consumer; 24 25 /** 26 * Composable unit of execution. Used to combine other Blocks into 27 * bigger units. Each Piece represents a Block itself. 28 * 29 * Execution is represented as an iterator across Pieces. 30 * 31 * The whole application run is represented by a single block at the end. 32 */ 33 @SuppressWarnings("rawtypes") 34 public interface Block extends Iterable<AbstractPiece> { 35 /** 36 * Create iterator representing all pieces needed to be executed 37 * in this block. 38 * 39 * After Iterator.next call returns, master compute of returned Piece is 40 * guaranteed to be called before calling hasNext/next on the iterator. 41 * (allows for iterators logic to depend on the execution dynamically, 42 * and not be only static) 43 */ 44 @Override 45 Iterator<AbstractPiece> iterator(); 46 47 /** 48 * Calls consumer for each Piece: 49 * - in no particular order 50 * - potentially calling multiple times on same Piece 51 * - even if Piece might never be returned in the iterator 52 * - it will be called at least once for every piece that is 53 * going to be returned by iterator 54 * 55 * Can be used for static analysis/introspection of the block, 56 * without actually executing them. 57 */ 58 void forAllPossiblePieces(Consumer<AbstractPiece> consumer); 59 60 /** 61 * How many pieces are in this block. 62 * Sometimes we don't know (eg RepeatBlock). 63 * 64 * @return How many pieces are in this block. 65 */ 66 PieceCount getPieceCount(); 67 }