src/main/java/org/apache/sysml/hops/globalopt/gdfresolve/GDFMismatchHeuristicBlocksizeOrFirst.java

/*
 * 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.sysml.hops.globalopt.gdfresolve;

import org.apache.sysml.hops.globalopt.RewriteConfig;

public class GDFMismatchHeuristicBlocksizeOrFirst extends GDFMismatchHeuristic
{
	
	@Override
	public String getName(){
		return "BLOCKSIZE_OR_FIRST";
	}
	
	@Override
	public boolean resolveMismatch( RewriteConfig currRc, RewriteConfig newRc ) 
	{
		//check for blocksize mismatch
		if( currRc.getBlockSize() != newRc.getBlockSize() ) 
		{
			//choose the new rewrite config if its blocksize is larger than 
			//the current (intuition: we generally prefer larger blocksizes 
			//because this often enables better physical operators with constraints
			//like ncol(X) <= blocksize)
			return (currRc.getBlockSize() < newRc.getBlockSize());
		}
		
		//return the current rewrite configuration (first come first served)
		//if the previous check for blocksize mismatch failed
		return false;
	}
}