/*
 * 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.nemo.compiler.optimizer.policy;

import org.apache.nemo.common.ir.IRDAG;
import org.apache.nemo.common.ir.vertex.executionproperty.ParallelismProperty;
import org.apache.nemo.compiler.optimizer.pass.compiletime.composite.DefaultCompositePass;
import org.apache.nemo.compiler.optimizer.pass.compiletime.composite.LargeShuffleCompositePass;
import org.apache.nemo.compiler.optimizer.pass.compiletime.composite.LoopOptimizationCompositePass;
import org.apache.nemo.compiler.optimizer.pass.runtime.Message;

/**
 * A policy to demonstrate the large shuffle optimization, witch batches disk seek during data shuffle, conditionally.
 */
public final class ConditionalLargeShufflePolicy implements Policy {
  public static final PolicyBuilder BUILDER =
    new PolicyBuilder()
      .registerCompileTimePass(new LargeShuffleCompositePass(), dag -> getMaxParallelism(dag) > 300)
      .registerCompileTimePass(new LoopOptimizationCompositePass())
      .registerCompileTimePass(new DefaultCompositePass());
  private final Policy policy;

  /**
   * Default constructor.
   */
  public ConditionalLargeShufflePolicy() {
    this.policy = BUILDER.build();
  }

  /**
   * Returns the maximum parallelism of the vertices of a IR DAG.
   *
   * @param dag dag to observe.
   * @return the maximum parallelism, or 1 by default.
   */
  private static int getMaxParallelism(final IRDAG dag) {
    return dag.getVertices().stream()
      .mapToInt(vertex -> vertex.getPropertyValue(ParallelismProperty.class).orElse(1))
      .max().orElse(1);
  }

  @Override
  public IRDAG runCompileTimeOptimization(final IRDAG dag, final String dagDirectory) {
    return this.policy.runCompileTimeOptimization(dag, dagDirectory);
  }

  @Override
  public IRDAG runRunTimeOptimizations(final IRDAG dag, final Message<?> message) {
    return this.policy.runRunTimeOptimizations(dag, message);
  }
}