std::experimental::when_all combines a set of futures
into a single future that becomes ready when all of
the futures in the set become ready.
template<typename ... FutureTypes> std::experimental::future<std::tuple<FutureTypes...> > when_all(FutureTypes&&... futures);
Each type in FutureTypes
is an instantiation of either std::experimental::future or std::experimental::shared_future. For each
value in futures
a call to valid()
must return true. All
future which is an instantation of std::experimental::future must be passed as
an rvalue.
The supplied futures are transferred into internal storage. The asynchronous
result associated with each future is marked so that when all the
futures are ready the future returned from
when_all is ready.
If all the futures are already ready at the
point of the call, the returned future will also be ready.
A std::experimental::future<std::tuple<FutureTypes>
> which becomes ready
when all of the supplied futures becomes ready.
When the future is ready, the stored value is
a std::tuple holding the supplied futures.
The marking each of the individual futures as ready
synchronizes with any call to wait() or get() on the returned future that sees
the result as ready.
std::bad_alloc if the required internal
storage cannot be allocated.
#include <experimental/future>