lidavidm commented on code in PR #12672: URL: https://github.com/apache/arrow/pull/12672#discussion_r867946898
########## cpp/src/arrow/engine/substrait/util.cc: ########## @@ -0,0 +1,139 @@ +// 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. + +#include "arrow/engine/substrait/util.h" +#include "arrow/util/async_generator.h" +#include "arrow/util/async_util.h" + +namespace arrow { + +namespace engine { + +namespace { +/// \brief A SinkNodeConsumer specialized to output ExecBatches via PushGenerator +class SubstraitSinkConsumer : public compute::SinkNodeConsumer { + public: + explicit SubstraitSinkConsumer( + AsyncGenerator<util::optional<compute::ExecBatch>>* generator) + : producer_(MakeProducer(generator)) {} + + Status Consume(compute::ExecBatch batch) override { + // Consume a batch of data + bool did_push = producer_.Push(batch); + if (!did_push) return Status::ExecutionError("Producer closed already"); + return Status::OK(); + } + + Status Init(const std::shared_ptr<Schema>& schema, + compute::BackpressureControl* backpressure_control) override { + return Status::OK(); + } + + static arrow::PushGenerator<util::optional<compute::ExecBatch>>::Producer MakeProducer( + AsyncGenerator<util::optional<compute::ExecBatch>>* out_gen); + + Future<> Finish() override { + producer_.Push(IterationEnd<util::optional<compute::ExecBatch>>()); + ARROW_UNUSED(producer_.Close()); + return Future<>::MakeFinished(); + } + + private: + PushGenerator<util::optional<compute::ExecBatch>>::Producer producer_; +}; + +/// \brief An executor to run a Substrait Query +/// This interface is provided as a utility when creating language +/// bindings for consuming a Substrait plan. +class SubstraitExecutor { + public: + explicit SubstraitExecutor( + std::shared_ptr<Buffer> substrait_buffer, + AsyncGenerator<util::optional<compute::ExecBatch>>* generator, + std::shared_ptr<compute::ExecPlan> plan, compute::ExecContext exec_context) + : substrait_buffer_(std::move(substrait_buffer)), + generator_(generator), + plan_(std::move(plan)), + exec_context_(exec_context) {} + + Result<std::shared_ptr<RecordBatchReader>> Execute() { + for (const compute::Declaration& decl : declarations_) { + RETURN_NOT_OK(decl.AddToPlan(plan_.get()).status()); + } + RETURN_NOT_OK(plan_->Validate()); + RETURN_NOT_OK(plan_->StartProducing()); + // schema of the output can be obtained by the output_schema + // of the input to the sink node. + auto schema = plan_->sinks()[0]->inputs()[0]->output_schema(); + std::shared_ptr<RecordBatchReader> sink_reader = compute::MakeGeneratorReader( + schema, std::move(*generator_), exec_context_.memory_pool()); + return sink_reader; + } + + Status Close() { return plan_->finished().status(); } + + Status Init() { + if (substrait_buffer_ == NULLPTR) { + return Status::Invalid("Buffer containing Substrait plan is null."); + } + std::function<std::shared_ptr<compute::SinkNodeConsumer>()> consumer_factory = [&] { + return std::make_shared<SubstraitSinkConsumer>(generator_); + }; + ARROW_ASSIGN_OR_RAISE(declarations_, + engine::DeserializePlan(*substrait_buffer_, consumer_factory)); + return Status::OK(); + } + + private: + std::shared_ptr<Buffer> substrait_buffer_; + AsyncGenerator<util::optional<compute::ExecBatch>>* generator_; + std::vector<compute::Declaration> declarations_; + std::shared_ptr<compute::ExecPlan> plan_; + compute::ExecContext exec_context_; +}; + +arrow::PushGenerator<util::optional<compute::ExecBatch>>::Producer +SubstraitSinkConsumer::MakeProducer( + AsyncGenerator<util::optional<compute::ExecBatch>>* out_gen) { + arrow::PushGenerator<util::optional<compute::ExecBatch>> push_gen; + auto out = push_gen.producer(); + *out_gen = std::move(push_gen); + return out; +} +} // namespace + +Result<std::shared_ptr<RecordBatchReader>> ExecuteSerializedPlan( + std::shared_ptr<Buffer> substrait_buffer) { + arrow::AsyncGenerator<util::optional<compute::ExecBatch>> sink_gen; + ARROW_ASSIGN_OR_RAISE(auto plan, compute::ExecPlan::Make()); + compute::ExecContext exec_context(arrow::default_memory_pool(), + ::arrow::internal::GetCpuThreadPool()); + arrow::engine::SubstraitExecutor executor(std::move(substrait_buffer), &sink_gen, + std::move(plan), exec_context); + RETURN_NOT_OK(executor.Init()); + ARROW_ASSIGN_OR_RAISE(auto sink_reader, executor.Execute()); + RETURN_NOT_OK(executor.Close()); Review Comment: I suppose we can have 'new' implementations of RecordBatchReader that do depend on Close() being called also add a destructor-time check. -- This is an automated message from the Apache Git Service. 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