pitrou commented on a change in pull request #9842:
URL: https://github.com/apache/arrow/pull/9842#discussion_r607706980
##########
File path: cpp/src/arrow/filesystem/s3fs.cc
##########
@@ -1142,82 +1145,67 @@ struct TreeWalker : public
std::enable_shared_from_this<TreeWalker> {
recursion_handler_(std::move(recursion_handler)) {}
private:
- std::mutex mutex_;
- Future<> future_;
- std::atomic<int32_t> num_in_flight_;
+ std::shared_ptr<TaskGroup> task_group_;
+ util::Mutex mutex_;
Review comment:
Is there a reason not to use `std::mutex` here?
##########
File path: cpp/src/arrow/filesystem/s3fs.cc
##########
@@ -1142,82 +1145,67 @@ struct TreeWalker : public
std::enable_shared_from_this<TreeWalker> {
recursion_handler_(std::move(recursion_handler)) {}
private:
- std::mutex mutex_;
- Future<> future_;
- std::atomic<int32_t> num_in_flight_;
+ std::shared_ptr<TaskGroup> task_group_;
+ util::Mutex mutex_;
Status DoWalk() {
- future_ = decltype(future_)::Make();
- num_in_flight_ = 0;
+ task_group_ =
+ TaskGroup::MakeThreaded(io_context_.executor(),
io_context_.stop_token());
WalkChild(base_dir_, /*nesting_depth=*/0);
// When this returns, ListObjectsV2 tasks either have finished or will
exit early
- return future_.status();
+ return task_group_->Finish();
}
- bool is_finished() const { return future_.is_finished(); }
-
- void ListObjectsFinished(Status st) {
- const auto in_flight = --num_in_flight_;
- if (!st.ok() || !in_flight) {
- future_.MarkFinished(std::move(st));
- }
- }
+ bool ok() const { return task_group_->ok(); }
struct ListObjectsV2Handler {
std::shared_ptr<TreeWalker> walker;
std::string prefix;
int32_t nesting_depth;
S3Model::ListObjectsV2Request req;
- void operator()(const Result<S3Model::ListObjectsV2Outcome>& result) {
+ Status operator()(const Result<S3Model::ListObjectsV2Outcome>& result) {
// Serialize calls to operation-specific handlers
- std::unique_lock<std::mutex> guard(walker->mutex_);
- if (walker->is_finished()) {
+ if (!walker->ok()) {
// Early exit: avoid executing handlers if DoWalk() returned
- return;
+ return Status::OK();
}
if (!result.ok()) {
- HandleError(result.status());
- return;
+ return result.status();
}
const auto& outcome = *result;
if (!outcome.IsSuccess()) {
- Status st = walker->error_handler_(outcome.GetError());
- HandleError(std::move(st));
- return;
+ {
+ auto guard = walker->mutex_.Lock();
+ return walker->error_handler_(outcome.GetError());
+ }
}
- HandleResult(outcome.GetResult());
+ return HandleResult(outcome.GetResult());
}
void SpawnListObjectsV2() {
auto walker = this->walker;
auto req = this->req;
- auto maybe_fut = walker->io_context_.executor()->Submit(
- walker->io_context_.stop_token(),
- [walker, req]() { return walker->client_->ListObjectsV2(req); });
- if (!maybe_fut.ok()) {
- HandleError(maybe_fut.status());
- return;
- }
- maybe_fut->AddCallback(*this);
+ auto cb = *this;
Review comment:
If you're capturing `*this` by value then you don't need to capture
`req` and `walker` as well.
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