bkietz commented on a change in pull request #8680:
URL: https://github.com/apache/arrow/pull/8680#discussion_r534356842
##########
File path: cpp/src/arrow/util/future.cc
##########
@@ -243,6 +253,12 @@ class ConcreteFutureImpl : public FutureImpl {
}
}
cv_.notify_all();
+
+ // run callbacks
+ for (auto&& callback : callbacks_) {
Review comment:
I'm not sure why this isn't safe. During iteration the vector won't be
dropped (since we have at least the reference held by the thread calling
`MarkFinished`) or mutated (since attempting to add a callback to a finished
future will immediately evaluate that callback)
##########
File path: cpp/src/arrow/util/future.h
##########
@@ -264,11 +335,125 @@ class Future {
}
/// \brief Make a finished Future<> with the provided Status.
- template <typename E = ValueType, typename = detail::Empty::EnableIfSame<E>>
+ template <typename E = ValueType, typename = typename std::enable_if<
+ std::is_same<E,
detail::Empty>::value>::type>
static Future<> MakeFinished(Status s = Status::OK()) {
return MakeFinished(E::ToResult(std::move(s)));
}
+ /// \brief Consumer API: Register a callback to run when this future
completes
Review comment:
will do
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