diff options
Diffstat (limited to 'src/mongo/util/future.h')
| -rw-r--r-- | src/mongo/util/future.h | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/src/mongo/util/future.h b/src/mongo/util/future.h index f9e3324b090..59e1a98bc2c 100644 --- a/src/mongo/util/future.h +++ b/src/mongo/util/future.h @@ -343,10 +343,17 @@ public: } /** - * This ends the Future continuation chain by calling a callback on completion. Use this to - * escape back into a callback-based API. + * Attaches a `func` callback that will consume the result of this `Future` when it completes. A + * `getAsync` call can be the tail end of a continuation chain, and that is only position at + * which it can appear. + * + * The result argument passed to `func` is `Status` if `T` is `void`, otherwise `StatusWith<T>`. + * The `func(result)` return type must be `void`, and not a discarded return value. + * + * `func` must not throw an exception. It is invoked as if by a `noexcept` function, and it will + * `std::terminate` the process. This is because there is no appropriate context in which to + * handle such an asynchronous exception. * - * For now, the callback must not fail, since there is nowhere to propagate the error to. * TODO decide how to handle func throwing. */ TEMPLATE(typename Func) @@ -607,6 +614,10 @@ public: // it should be doable, but will be fairly complicated. // + /** + * Attach a completion callback to asynchronously consume this `ExecutorFuture`'s result. + * \see `Future<T>::getAsync()`. + */ TEMPLATE(typename Func) REQUIRES(future_details::isCallableExactR<void, Func, StatusOrStatusWith<T>>) void getAsync(Func&& func) && noexcept { |