paleolimbot commented on code in PR #4459: URL: https://github.com/apache/datafusion-comet/pull/4459#discussion_r3736300052
########## native/core/src/execution/rust_udf/imported_c.rs: ########## @@ -0,0 +1,311 @@ +// 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. + +//! Adapter wrapping a C-ABI [`CometCScalarKernel`] as a DataFusion +//! [`ScalarUDFImpl`]. +//! +//! Lifecycle inside `invoke_with_args`: +//! +//! 1. Build a fresh [`CometCScalarKernelImpl`] via the kernel's `new_impl`. +//! 2. Call `init` with the input field types (and any scalar args) to get +//! the return type. +//! 3. Call `execute` once with the batch. +//! 4. Drop the impl (its `release` callback runs). + +use std::ffi::CStr; +use std::sync::Mutex; + +use arrow::array::ArrayRef; +use arrow::datatypes::{DataType, Field}; +use arrow::ffi::{from_ffi_and_data_type, FFI_ArrowArray, FFI_ArrowSchema}; +use comet_udf_sdk::c_abi::{CometCScalarKernel, CometCScalarKernelImpl}; +use datafusion::common::DataFusionError; +use datafusion::logical_expr::{ + ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl, Signature, TypeSignature, Volatility, +}; + +/// Adapter wrapping a [`CometCScalarKernel`] as a DataFusion +/// [`ScalarUDFImpl`]. +pub struct ImportedCScalarUdf { + name: String, + /// Boxed so the kernel's address is stable; held inside a Mutex + /// because the FFI Drop is not Sync-safe under concurrent invocation. + /// The kernel itself is logically immutable post-load — the lock only + /// protects the FFI calls' aliasing rules. (DataFusion serializes + /// invocations of a given ScalarUDFImpl per-batch through + /// invoke_with_args anyway; the lock is defensive.) Review Comment: > but ABI v1 does not require a kernel's new_impl to be callable concurrently I think you can change this...I believe `new_impl` is callable concurrently in your exporter implementation. This can be made clear by making `self` a `const *` if it isn't already. We do this for our C UDFs in SedonaDB (if we routed everything through a Mutex we may as well be using a GIL-limited Python UDF). -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
