lidavidm commented on a change in pull request #9613:
URL: https://github.com/apache/arrow/pull/9613#discussion_r587733815
##########
File path: cpp/src/arrow/io/caching.cc
##########
@@ -193,6 +195,36 @@ Result<std::shared_ptr<Buffer>>
ReadRangeCache::Read(ReadRange range) {
return Status::Invalid("ReadRangeCache did not find matching cache entry");
}
+Future<> ReadRangeCache::Wait() {
+ struct State {
+ explicit State(std::vector<Future<std::shared_ptr<Buffer>>> f)
+ : futures(std::move(f)), remaining(futures.size()) {}
+ std::vector<Future<std::shared_ptr<Buffer>>> futures;
+ std::atomic<size_t> remaining;
+ };
+
+ std::vector<Future<std::shared_ptr<Buffer>>> futures;
+ for (const auto& entry : impl_->entries) {
+ futures.push_back(entry.future);
+ }
+ auto out = Future<>::Make();
+ auto state = std::make_shared<State>(std::move(futures));
+ for (const auto& future : state->futures) {
+ future.AddCallback([state, out](const Result<std::shared_ptr<Buffer>>&)
mutable {
+ if (state->remaining.fetch_sub(1) != 1) return;
Review comment:
Future<T> is already convertible to Future<>. So what you suggest would
work, but we'd need the fail-fast behavior, yes.
A flag like that, though, does change the semantics rather dramatically, I'd
rather keep them as separate functions.
----------------------------------------------------------------
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.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
