src/main/java/org/apache/giraph/graph/VertexReader.java

/*
 * 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.graph;

import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.TaskAttemptContext;

import java.io.IOException;

@SuppressWarnings("rawtypes")
public interface VertexReader<
        I extends WritableComparable,
        V extends Writable,
        E extends Writable,
        M extends Writable> {
    /**
     * Use the input split and context to setup reading the vertices.
     * Guaranteed to be called prior to any other function.
     *
     * @param inputSplit
     * @param context
     * @throws IOException
     * @throws InterruptedException
     */
    void initialize(InputSplit inputSplit, TaskAttemptContext context)
        throws IOException, InterruptedException;

    /**
     *
     * @return false iff there are no more vertices
     * @throws IOException
     * @throws InterruptedException
     */
    boolean nextVertex() throws IOException, InterruptedException;

    /**
     *
     * @return the current vertex which has been read.  nextVertex() should be called first.
     * @throws IOException
     * @throws InterruptedException
     */
    BasicVertex<I, V, E, M> getCurrentVertex() throws IOException, InterruptedException;

    /**
     * Close this {@link VertexReader} to future operations.
     *
     * @throws IOException
     */
    void close() throws IOException;

    /**
     * How much of the input has the {@link VertexReader} consumed i.e.
     * has been processed by?
     *
     * @return Progress from <code>0.0</code> to <code>1.0</code>.
     * @throws IOException
     * @throws InterruptedException
     */
    float getProgress() throws IOException, InterruptedException;
}