org.apache.giraph.block_app.framework.block.RepeatBlock.java Source code

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Here is the source code for org.apache.giraph.block_app.framework.block.RepeatBlock.java

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/*
 * 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.block;

import java.util.Collections;
import java.util.Iterator;

import org.apache.giraph.block_app.framework.piece.AbstractPiece;
import org.apache.giraph.function.Consumer;
import org.apache.giraph.function.primitive.IntSupplier;

import com.google.common.collect.Iterables;

/**
 * Block that repeats another block given number of times.
 */
@SuppressWarnings("rawtypes")
public final class RepeatBlock implements Block {
    private final Block block;
    private final IntSupplier repeatTimes;

    public RepeatBlock(final int repeatTimes, Block block) {
        this.block = block;
        this.repeatTimes = new IntSupplier() {
            @Override
            public int get() {
                return repeatTimes;
            }
        };
    }

    /**
     * Creates a repeat block, that before starting execution takes number of
     * iterations from the given supplier.
     *
     * This allows number of iterations to be dynamic, and depend on
     * execution that happens before.
     * Note - it doesn't allow for number of repetitions to change during the
     * loop itself - as it is supplier is called only when this block gets
     * its turn.
     */
    public RepeatBlock(IntSupplier repeatTimes, Block block) {
        this.block = block;
        this.repeatTimes = repeatTimes;
    }

    /**
     * Create a repeat block that executes unlimited number of times.
     *
     * Should rarely be used, as it will cause application never to finish,
     * unless other unconventional ways of termination are used.
     */
    public static Block unlimited(Block block) {
        return new RepeatBlock(Integer.MAX_VALUE, block);
    }

    @Override
    public Iterator<AbstractPiece> iterator() {
        return Iterables.concat(Collections.nCopies(repeatTimes.get(), block)).iterator();
    }

    @Override
    public void forAllPossiblePieces(Consumer<AbstractPiece> consumer) {
        block.forAllPossiblePieces(consumer);
    }

    @Override
    public String toString() {
        return "RepeatBlock(" + repeatTimes + " * " + block + ")";
    }
}