lidavidm commented on code in PR #44495:
URL: https://github.com/apache/arrow/pull/44495#discussion_r1809767566
##########
cpp/src/arrow/c/bridge.cc:
##########
@@ -2511,4 +2516,333 @@ Result<std::shared_ptr<ChunkedArray>>
ImportDeviceChunkedArray(
return ImportChunked</*IsDevice=*/true>(stream, mapper);
}
+namespace {
+
+class AsyncRecordBatchIterator {
+ public:
+ struct State {
+ State(uint64_t queue_size, const DeviceMemoryMapper mapper)
+ : queue_size_{queue_size}, mapper_{std::move(mapper)} {}
+
+ const uint64_t queue_size_;
+ const DeviceMemoryMapper mapper_;
+ ArrowAsyncProducer* producer_;
+ DeviceAllocationType device_type_;
+
+ std::mutex mutex_;
+ std::shared_ptr<Schema> schema_;
+ std::condition_variable cv_;
+ std::queue<std::pair<ArrowAsyncTask, std::shared_ptr<KeyValueMetadata>>>
batches_;
+ bool end_of_stream_ = false;
+ Status error_{Status::OK()};
+ };
+
+ AsyncRecordBatchIterator(uint64_t queue_size, const DeviceMemoryMapper
mapper)
+ : state_{std::make_shared<State>(queue_size, std::move(mapper))} {}
+
+ explicit AsyncRecordBatchIterator(std::shared_ptr<State> state)
+ : state_{std::move(state)} {}
+
+ const std::shared_ptr<Schema>& schema() const { return state_->schema_; }
+
+ DeviceAllocationType device_type() const { return state_->device_type_; }
+
+ Result<RecordBatchWithMetadata> Next() {
Review Comment:
I guess blocking calls are OK due to MakeBackgroundGenerator here?
##########
cpp/src/arrow/c/bridge.cc:
##########
@@ -2511,4 +2516,333 @@ Result<std::shared_ptr<ChunkedArray>>
ImportDeviceChunkedArray(
return ImportChunked</*IsDevice=*/true>(stream, mapper);
}
+namespace {
+
+class AsyncRecordBatchIterator {
+ public:
+ struct State {
+ State(uint64_t queue_size, const DeviceMemoryMapper mapper)
+ : queue_size_{queue_size}, mapper_{std::move(mapper)} {}
+
+ const uint64_t queue_size_;
+ const DeviceMemoryMapper mapper_;
+ ArrowAsyncProducer* producer_;
+ DeviceAllocationType device_type_;
+
+ std::mutex mutex_;
+ std::shared_ptr<Schema> schema_;
+ std::condition_variable cv_;
+ std::queue<std::pair<ArrowAsyncTask, std::shared_ptr<KeyValueMetadata>>>
batches_;
+ bool end_of_stream_ = false;
+ Status error_{Status::OK()};
+ };
+
+ AsyncRecordBatchIterator(uint64_t queue_size, const DeviceMemoryMapper
mapper)
+ : state_{std::make_shared<State>(queue_size, std::move(mapper))} {}
+
+ explicit AsyncRecordBatchIterator(std::shared_ptr<State> state)
+ : state_{std::move(state)} {}
+
+ const std::shared_ptr<Schema>& schema() const { return state_->schema_; }
+
+ DeviceAllocationType device_type() const { return state_->device_type_; }
+
+ Result<RecordBatchWithMetadata> Next() {
+ std::pair<ArrowAsyncTask, std::shared_ptr<KeyValueMetadata>> task;
+ {
+ std::unique_lock<std::mutex> lock(state_->mutex_);
+ state_->cv_.wait(lock, [&] {
+ return !state_->error_.ok() || !state_->batches_.empty() ||
+ state_->end_of_stream_;
+ });
+ if (!state_->error_.ok()) {
+ return state_->error_;
+ }
+
+ if (state_->batches_.empty() && state_->end_of_stream_) {
+ return RecordBatchWithMetadata{nullptr, nullptr};
+ }
+
+ task = state_->batches_.front();
+ state_->batches_.pop();
+ }
+
+ state_->producer_->request(state_->producer_, 1);
+ ArrowDeviceArray out;
+ if (task.first.extract_data(&task.first, &out) != 0) {
+ std::unique_lock<std::mutex> lock(state_->mutex_);
+ if (state_->error_.ok()) {
Review Comment:
nit: I don't think you need this check? You can always wait on the CV with
the condition
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