xiarixiaoyao commented on a change in pull request #3952: URL: https://github.com/apache/hudi/pull/3952#discussion_r754826477
########## File path: hudi-client/hudi-client-common/src/main/java/org/apache/hudi/optimize/HilbertCurve.java ########## @@ -0,0 +1,321 @@ +/* + * 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.hudi.optimize; + +import java.math.BigInteger; +import java.util.Arrays; + +/** + * Converts between Hilbert index ({@code BigInteger}) and N-dimensional points. + * + * <p> + * Note: + * <a href="https://github.com/davidmoten/hilbert-curve/blob/master/src/main/java/org/davidmoten/hilbert/HilbertCurve.java";>GitHub</a>). + * the Licensed of above link is also http://www.apache.org/licenses/LICENSE-2.0 + */ +public final class HilbertCurve { + + private final int bits; + private final int dimensions; + // cached calculations + private final int length; + + private HilbertCurve(int bits, int dimensions) { + this.bits = bits; + this.dimensions = dimensions; + // cache a calculated values for small perf improvements + this.length = bits * dimensions; + } + + /** + * Returns a builder for and object that performs transformations for a Hilbert + * curve with the given number of bits. + * + * @param bits + * depth of the Hilbert curve. If bits is one, this is the top-level + * Hilbert curve + * @return builder for object to do transformations with the Hilbert Curve + */ + public static Builder bits(int bits) { + return new Builder(bits); + } + + /** + * Builds a {@link HilbertCurve} instance. + */ + public static final class Builder { + final int bits; + + private Builder(int bits) { + if (bits <= 0 || bits >= 64) { + throw new IllegalArgumentException(String.format("bits must be greater than zero and less than 64, now found bits value: %s", bits)); + } + this.bits = bits; + } + + public HilbertCurve dimensions(int dimensions) { + if (dimensions < 2) { + throw new IllegalArgumentException(String.format("dimensions must be at least 2, now found dimensions value: %s", dimensions)); + } + return new HilbertCurve(bits, dimensions); + } + } + + /** + * Converts a point to its Hilbert curve index. + * + * @param point + * an array of {@code long}. Each ordinate can be between 0 and + * 2<sup>bits</sup>-1. + * @return index (nonnegative {@link BigInteger}) + * @throws IllegalArgumentException + * if length of point array is not equal to the number of + * dimensions. + */ + public BigInteger index(long... point) { Review comment: agree -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@hudi.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
