org.apache.kylin.cube.cuboid.algorithm.generic.lib.FixedGenerationCount.java Source code

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Here is the source code for org.apache.kylin.cube.cuboid.algorithm.generic.lib.FixedGenerationCount.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.kylin.cube.cuboid.algorithm.generic.lib;

import org.apache.commons.math3.exception.NumberIsTooSmallException;

/**
 * Stops after a fixed number of generations. Each time {@link #isSatisfied(Population)} is invoked, a generation
 * counter is incremented. Once the counter reaches the configured <code>maxGenerations</code> value,
 * {@link #isSatisfied(Population)} returns true.
 *
 */
public class FixedGenerationCount implements StoppingCondition {
    /** Maximum number of generations (stopping criteria) */
    private final int maxGenerations;
    /** Number of generations that have passed */
    private int numGenerations = 0;

    /**
     * Create a new FixedGenerationCount instance.
     *
     * @param maxGenerations number of generations to evolve
     * @throws NumberIsTooSmallException if the number of generations is &lt; 1
     */
    public FixedGenerationCount(final int maxGenerations) throws NumberIsTooSmallException {
        if (maxGenerations <= 0) {
            throw new NumberIsTooSmallException(maxGenerations, 1, true);
        }
        this.maxGenerations = maxGenerations;
    }

    /**
     * Determine whether or not the given number of generations have passed. Increments the number of generations
     * counter if the maximum has not been reached.
     *
     * @param population ignored (no impact on result)
     * @return <code>true</code> IFF the maximum number of generations has been exceeded
     */
    public boolean isSatisfied(final Population population) {
        if (this.numGenerations < this.maxGenerations) {
            numGenerations++;
            return false;
        }
        return true;
    }

    /**
     * Returns the number of generations that have already passed.
     * @return the number of generations that have passed
     */
    public int getNumGenerations() {
        return numGenerations;
    }

}