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// -*- mode:C++; tab-width:4; c-basic-offset:4; indent-tabs-mode:nil -*-
/*
* This file is open source software, licensed to you under the terms
* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. You may not use this file except in compliance with the License.
*
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
*/
/*
* Copyright (C) 2018 Red Hat
*/
#include <future>
#include <numeric>
#include <iostream>
#include <seastar/core/alien.hh>
#include <seastar/core/smp.hh>
#include <seastar/core/app-template.hh>
#include <seastar/core/posix.hh>
#include <seastar/core/reactor.hh>
#include <seastar/util/later.hh>
#include <stdexcept>
#include <ranges>
#include <tuple>
using namespace seastar;
enum {
ENGINE_READY = 24,
ALIEN_DONE = 42,
};
int main(int argc, char** argv)
{
// we need a protocol that both seastar and alien understand.
// and on which, a seastar future can wait.
int engine_ready_fd = eventfd(0, 0);
auto alien_done = file_desc::eventfd(0, 0);
seastar::app_template app;
// use the raw fd, because seastar engine want to take over the fds, if it
// polls on them.
auto zim = std::async([&app, engine_ready_fd,
alien_done=alien_done.get()] {
eventfd_t result = 0;
// wait until the seastar engine is ready
int r = ::eventfd_read(engine_ready_fd, &result);
if (r < 0) {
throw std::runtime_error("failed to wait for seastar engine");
}
if (result != ENGINE_READY) {
throw std::runtime_error("seastar failed to sent us the ready message");
}
// test for alien::run_on()
std::promise<char> question;
auto answer = question.get_future();
alien::run_on(app.alien(), 0, [&question]() noexcept {
question.set_value('*');
});
// test for alien::submit_to(), which returns a std::future<int>
std::vector<std::future<int>> counts;
for (auto i : std::views::iota(0u, smp::count)) {
// send messages from alien.
counts.push_back(alien::submit_to(app.alien(), i, [i] {
return seastar::make_ready_future<int>(i);
}));
}
// test for alien::submit_to(), which returns a std::future<void>
alien::submit_to(app.alien(), 0, [] {
return seastar::make_ready_future<>();
}).wait();
int total = 0;
for (auto& count : counts) {
total += count.get();
}
// i am done. dismiss the engine
::eventfd_write(alien_done, ALIEN_DONE);
return std::make_tuple(answer.get(), total);
});
eventfd_t result = 0;
app.run(argc, argv, [&] {
return seastar::now().then([engine_ready_fd] {
// engine ready!
::eventfd_write(engine_ready_fd, ENGINE_READY);
return seastar::now();
}).then([alien_done = std::move(alien_done), &result]() mutable {
return do_with(seastar::pollable_fd(std::move(alien_done)), [&result] (pollable_fd& alien_done_fds) {
// check if alien has dismissed me.
return alien_done_fds.readable().then([&result, &alien_done_fds] {
auto ret = alien_done_fds.get_file_desc().read(&result, sizeof(result));
return make_ready_future<size_t>(*ret);
});
});
}).then([&result](size_t n) {
if (n != sizeof(result)) {
throw std::runtime_error("read from eventfd failed");
}
if (result != ALIEN_DONE) {
throw std::logic_error("alien failed to dismiss me");
}
return seastar::now();
}).handle_exception([](auto ep) {
std::cerr << "Error: " << ep << std::endl;
}).finally([] {
seastar::engine().exit(0);
});
});
auto [everything, total] = zim.get();
if (char expected = '*'; everything != '*') {
std::cerr << "Bad everything: " << everything << " != " << expected << std::endl;
return 1;
}
const auto shards = std::views::iota(0u, smp::count);
auto expected = std::accumulate(std::begin(shards), std::end(shards), 0);
if (total != expected) {
std::cerr << "Bad total: " << total << " != " << expected << std::endl;
return 1;
}
}
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