kszucs commented on code in PR #45360: URL: https://github.com/apache/arrow/pull/45360#discussion_r2083090655
########## cpp/src/parquet/chunker_internal_codegen.py: ########## @@ -0,0 +1,124 @@ +#!/usr/bin/env python + +# 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. + +""" +Produce the given number gearhash tables for rolling hash calculations. + +Each table consists of 256 64-bit integer values and by default 8 tables are +produced. The tables are written to a header file that can be included in the +C++ code. + +The generated numbers are deterministic "random" numbers created by MD5 hashing +a fixed seed and the table index. This ensures that the tables are the same +across different runs and platforms. The function of generating the numbers is +less important as long as they have sufficiently uniform distribution. + +Reference implementations: +- https://github.com/Borelset/destor/blob/master/src/chunking/fascdc_chunking.c +- https://github.com/nlfiedler/fastcdc-rs/blob/master/examples/table64.rs + +Usage: + python chunker_internal_codegen.py [ntables] + + ntables: Number of gearhash tables to generate (default 8), the + the C++ implementation expects 8 tables so this should not be + changed unless the C++ code is also updated. + + The generated header file is written to ./chunker_internal_generated.h +""" + +import hashlib +import pathlib +import sys +from io import StringIO + + +template = """\ +// 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. + +#pragma once +#include <cstdint> Review Comment: Updated and regenerated the hash table header file. -- 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: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
