/*-
 * ============LICENSE_START=======================================================
 * org.openecomp.aai
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. 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.
 * ============LICENSE_END=========================================================
 */

package org.openecomp.aai.util;

/*
 * logging to hbase encountered hotspotting issues, so per
 * http://archive.cloudera.com/cdh5/cdh/5/hbase-0.98.6-cdh5.3.8/book/rowkey.design.html
 * we decided to salt the rowkeys
 * as these keys are generated in a couple places, I made a class to contain that logic
 */
public class HbaseSaltPrefixer {
	private int NUM_REGION_BUCKETS = 3; //the number of hbase region servers per cluster

	private static class SingletonHolder{
		private static final HbaseSaltPrefixer INSTANCE = new HbaseSaltPrefixer();
	}
	
	/**
	 * Instantiates a new hbase salt prefixer.
	 */
	private HbaseSaltPrefixer(){}
	
	/**
	 * Gets the single instance of HbaseSaltPrefixer.
	 *
	 * @return single instance of HbaseSaltPrefixer
	 */
	public static HbaseSaltPrefixer getInstance() {
		return SingletonHolder.INSTANCE;
	}
	
	/**
	 * Prepend salt.
	 *
	 * @param key the key
	 * @return the string
	 */
	public String prependSalt(String key) {
		int salt = Math.abs(key.hashCode()) % NUM_REGION_BUCKETS;
		return salt + "-" + key;
	}
}