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
19 package org.apache.giraph.graph;
20
21 import org.apache.hadoop.io.Writable;
22 import org.apache.hadoop.io.WritableComparable;
23
24 /**
25 * Handles all the situations that can arise upon creation/removal of
26 * vertices and edges.
27 *
28 * @param <I> Vertex id
29 * @param <V> Vertex data
30 * @param <E> Edge data
31 */
32 @SuppressWarnings("rawtypes")
33 public interface VertexResolver<I extends WritableComparable,
34 V extends Writable, E extends Writable> {
35 /**
36 * A vertex may have been removed, created zero or more times and had
37 * zero or more messages sent to it. This method will handle all situations
38 * excluding the normal case (a vertex already exists and has zero or more
39 * messages sent it to).
40 *
41 * @param vertexId Vertex id (can be used for {@link Vertex}'s initialize())
42 * @param vertex Original vertex or null if none
43 * @param vertexChanges Changes that happened to this vertex or null if none
44 * @param hasMessages True iff vertex received messages in the last superstep
45 * @return Vertex to be returned, if null, and a vertex currently exists
46 * it will be removed
47 */
48 Vertex<I, V, E> resolve(I vertexId,
49 Vertex<I, V, E> vertex,
50 VertexChanges<I, V, E> vertexChanges,
51 boolean hasMessages);
52 }