hazelcast-master/hazelcast/src/main/java/com/hazelcast/jet/impl/pipeline/transform/MergeTransform.java
/*
 * Copyright (c) 2008-2023, Hazelcast, Inc. All Rights Reserved.
 *
 * Licensed 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 com.hazelcast.jet.impl.pipeline.transform;

import com.hazelcast.jet.core.Edge;
import com.hazelcast.jet.impl.pipeline.PipelineImpl.Context;
import com.hazelcast.jet.impl.pipeline.Planner;
import com.hazelcast.jet.impl.pipeline.Planner.PlannerVertex;

import javax.annotation.Nonnull;

import static com.hazelcast.function.FunctionEx.identity;
import static com.hazelcast.jet.core.Vertex.LOCAL_PARALLELISM_USE_DEFAULT;
import static com.hazelcast.jet.core.processor.Processors.mapP;
import static java.util.Arrays.asList;

public class MergeTransform<T> extends AbstractTransform {

    private static final long serialVersionUID = 1L;

    public MergeTransform(@Nonnull Transform upstream1, @Nonnull Transform upstream2) {
        super("merge", asList(upstream1, upstream2));
    }

    @Override
    public void addToDag(Planner p, Context context) {
        determineLocalParallelism(LOCAL_PARALLELISM_USE_DEFAULT, context, p.isPreserveOrder());
        PlannerVertex pv = p.addVertex(this, name(), determinedLocalParallelism(), mapP(identity()));
        if (p.isPreserveOrder()) {
            p.addEdges(this, pv.v, Edge::isolated);
        } else {
            p.addEdges(this, pv.v);
        }
    }
}
