/**
* 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.hadoop.io.file.tfile;
import java.io.IOException;
import java.util.Random;
import org.apache.hadoop.io.BytesWritable;
import org.apache.hadoop.io.file.tfile.RandomDistribution.DiscreteRNG;
class KeySampler {
Random random;
int min, max;
DiscreteRNG keyLenRNG;
private static final int MIN_KEY_LEN = 4;
public KeySampler(Random random, RawComparable first, RawComparable last,
DiscreteRNG keyLenRNG) throws IOException {
this.random = random;
min = keyPrefixToInt(first);
max = keyPrefixToInt(last);
this.keyLenRNG = keyLenRNG;
}
private int keyPrefixToInt(RawComparable key) throws IOException {
byte[] b = key.buffer();
int o = key.offset();
return (b[o] & 0xff) << 24 | (b[o + 1] & 0xff) << 16
| (b[o + 2] & 0xff) << 8 | (b[o + 3] & 0xff);
}
public void next(BytesWritable key) {
key.setSize(Math.max(MIN_KEY_LEN, keyLenRNG.nextInt()));
random.nextBytes(key.get());
int n = random.nextInt(max - min) + min;
byte[] b = key.get();
b[0] = (byte) (n >> 24);
b[1] = (byte) (n >> 16);
b[2] = (byte) (n >> 8);
b[3] = (byte) n;
}
}