Daniel,
> Suppose we have a vector of futures of type T and we want to reduce the
> values contained in the futures using T op(T, T), with initial value of
> init. What is the HPX recommended way of doing this? What should the
> implementation of "future<T> myreduce(vector<future<T> > fs, T init, Op
> op)" be?
>
> hpx::parallel::reduce can't be used with a vector of futures.
> hpx::lcos::reduce isn't what we're looking for as this isn't a distributed
> operation. One option is to use hpx::when_any and accumulate the values as
> they are ready. But this serializes the accumulation of the futures, which
> may not be desirable.
How about:
vector<future<T>> v = ...;
future<T> f =
dataflow(unwrapped(
[](vector<T> && data) -> T
{
return parallel::reduce(
par, data.begin(), data.end(), op);
}),
std::move(v)
);
Now you can do other things until you actually need the result of the reduce
operation, at which point you call
T reduce_result = f.get();
Alternatively you can attach a continuation to f to add more asynchrony.
HTH
Regards Hartmut
---------------
http://boost-spirit.com
http://stellar.cct.lsu.edu
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