reduce.cpp

/*
 * Copyright (c) 2022 NVIDIA Corporation
 *
 * Licensed under the Apache License Version 2.0 with LLVM Exceptions
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *   https://llvm.org/LICENSE.txt
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <nvexec/stream_context.cuh>
#include <stdexec/execution.hpp>

#include <thrust/device_vector.h>

#include <cstdio>
#include <span>

namespace ex = stdexec;
using stdexec::__tag_invoke::tag_invoke;
struct sink_receiver {
  using is_receiver = void;
  friend void tag_invoke(stdexec::set_value_t, sink_receiver, auto&&...) noexcept {}
  friend void tag_invoke(stdexec::set_error_t, sink_receiver, auto&&) noexcept {}
  friend void tag_invoke(stdexec::set_stopped_t, sink_receiver) noexcept {}
  friend stdexec::empty_env tag_invoke(stdexec::get_env_t, sink_receiver) noexcept { return {}; }
};

struct empty_environment {
};

template <class...>
[[deprecated]] void print() {}

// unqualified call to tag_invoke:
int main() {
  const int n = 2 * 1024;
  thrust::device_vector<float> input(n, 1.0f);
  float* first = thrust::raw_pointer_cast(input.data());
  float* last = thrust::raw_pointer_cast(input.data()) + input.size();
  nvexec::stream_context stream_ctx{};
  auto sched = stream_ctx.get_scheduler();

 // auto domain = ex::get_domain(sched);
 // print<decltype(domain)>();
  
  auto snd = ex::just(std::span{first, last})
           | nvexec::reduce(42.0f);

 // ::print<stdexec::__detail::__name_of<decltype(snd)>>();
  // nvexec::stream_scheduler gpu = stream_ctx.get_scheduler();         
  // using stdexec::__tag_invoke::tag_invoke;  
  // tag_invoke(stdexec::get_completion_signatures, snd, empty_environment{});

  auto [result] =
    stdexec::sync_wait(ex::on(sched, std::move(snd))).value();

 }