SparkApplicationMaster commented on code in PR #17093: URL: https://github.com/apache/datafusion/pull/17093#discussion_r2265989211
########## datafusion/spark/src/function/hash/murmur3.rs: ########## @@ -0,0 +1,152 @@ +// 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. + +use arrow::array::{ArrayRef, ArrowNativeTypeOp, PrimitiveArray}; +use arrow::datatypes::{DataType, Int32Type}; +use datafusion_common::Result; +use datafusion_expr::{ + ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl, Signature, Volatility, +}; +use datafusion_functions::utils::make_scalar_function; + +use std::any::Any; +use std::sync::Arc; + +use crate::function::hash::utils::SparkHasher; + +/// <https://spark.apache.org/docs/latest/api/sql/index.html#hash> +#[derive(Debug)] +pub struct SparkMurmur3Hash { + signature: Signature, + seed: i64, +} + +impl Default for SparkMurmur3Hash { + fn default() -> Self { + Self::new() + } +} + +impl SparkMurmur3Hash { + pub fn new() -> Self { + Self { + signature: Signature::variadic_any(Volatility::Immutable), + seed: 42, + } + } +} + +impl ScalarUDFImpl for SparkMurmur3Hash { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "hash" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { + Ok(DataType::Int32) + } + + fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { + let func = |arr: &[ArrayRef]| { + let mut result = vec![self.seed as i32; arr[0].len()]; + Murmur3Hasher::hash_arrays(arr, &mut result)?; + Ok(Arc::new(PrimitiveArray::<Int32Type>::from(result)) as ArrayRef) + }; + make_scalar_function(func, vec![])(&args.args) + } +} + +#[inline] +pub fn murmur3_hash<T: AsRef<[u8]>>(data: T, seed: u32) -> u32 { + #[inline] + fn mix_k1(mut k1: i32) -> i32 { + k1 = k1.mul_wrapping(0xcc9e2d51u32 as i32); + k1 = k1.rotate_left(15); + k1 = k1.mul_wrapping(0x1b873593u32 as i32); + k1 + } + + #[inline] + fn mix_h1(mut h1: i32, k1: i32) -> i32 { + h1 ^= k1; + h1 = h1.rotate_left(13); + h1 = h1.mul_wrapping(5).add_wrapping(0xe6546b64u32 as i32); + h1 + } + + #[inline] + fn fmix(mut h1: i32, len: i32) -> i32 { + h1 ^= len; + h1 ^= (h1 as u32 >> 16) as i32; + h1 = h1.mul_wrapping(0x85ebca6bu32 as i32); + h1 ^= (h1 as u32 >> 13) as i32; + h1 = h1.mul_wrapping(0xc2b2ae35u32 as i32); + h1 ^= (h1 as u32 >> 16) as i32; + h1 + } + + #[inline] + unsafe fn hash_bytes_by_int(data: &[u8], seed: u32) -> i32 { + // safety: data length must be aligned to 4 bytes + let mut h1 = seed as i32; + for i in (0..data.len()).step_by(4) { + let ints = data.as_ptr().add(i) as *const i32; + let mut half_word = ints.read_unaligned(); + if cfg!(target_endian = "big") { + half_word = half_word.reverse_bits(); Review Comment: Please check whether .reverse_bits() needs to be replaced to .swap_bytes() here In scala version there is some code that ensures little-endian byte order for this variable: https://github.com/scala/scala/blob/3f6bdaeafde17d790023cc3f299b81eaaf876ca3/src/library/scala/util/hashing/MurmurHash3.scala#L210 But byte order isn't bit order, bit order is not changed here, so reverse_bits may produce different result -- 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...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
