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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.pragmaticminds.crunch.api.trigger.strategy;

import org.pragmaticminds.crunch.api.records.MRecord;

import java.io.Serializable;
import java.util.Set;

/**
 * Describes rules to trigger processing of an incoming event.
 * On base of the implemented strategy the result is positive and triggers processing of the EventExtractor
 *
 * @author Erwin Wagasow
 * Created by Erwin Wagasow on 26.07.2018
 */
public interface TriggerStrategy extends Serializable {
    /**
     * Decides if the event is to be triggered by the decision base typed value
     * @param values contains the indicator if processing is to be triggered
     * @return true if triggering was positive
     */
    boolean isToBeTriggered(MRecord values);

    /**
     * Returns all channel identifiers which are necessary for the function to do its job.
     * It is not allowed to return null, an empty set can be returned (but why should??).
     *
     * @return a {@link Set} all channel identifiers that are needed by the Evaluation Function.
     */
    Set getChannelIdentifiers();
}