124 lines
4.0 KiB
C++
124 lines
4.0 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License Version 2.0 with LLVM Exceptions
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* https://llvm.org/LICENSE.txt
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <unifex/just.hpp>
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#include <unifex/let_value.hpp>
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#include <unifex/let_value_with.hpp>
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#include <unifex/scheduler_concepts.hpp>
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#include <unifex/sync_wait.hpp>
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#include <unifex/timed_single_thread_context.hpp>
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#include <unifex/then.hpp>
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#include <unifex/when_all.hpp>
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#include <chrono>
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#include <iostream>
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using namespace unifex;
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using namespace std::chrono;
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using namespace std::chrono_literals;
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int main() {
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timed_single_thread_context context;
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auto async = [&](auto&& func) {
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return then(
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schedule_after(context.get_scheduler(), 100ms),
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(decltype(func))func);
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};
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// Simple usage of 'let_value()'
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// - defines an async scope in which the result of one async
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// operation is in-scope for the duration of a second operation.
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std::optional<int> result =
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sync_wait(let_value(async([] { return 42; }), [&](int& x) {
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printf("addressof x = %p, val = %i\n", (void*)&x, x);
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return async([&]() -> int {
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printf("successor tranform\n");
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printf("addressof x = %p, val = %i\n", (void*)&x, x);
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return x;
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});
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}));
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auto asyncVector = [&]() {
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return async([] {
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std::cout << "producing vector" << std::endl;
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return std::vector<int>{1, 2, 3, 4};
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});
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};
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// More complicated 'let_value' example that shows recursive let_value-scopes,
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// additional
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sync_wait(then(
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when_all(
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let_value(asyncVector(),
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[&](std::vector<int>& v) {
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return async([&] {
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std::cout << "printing vector" << std::endl;
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for (int& x : v) {
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std::cout << x << ", ";
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}
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std::cout << std::endl;
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});
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}),
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let_value(just(42),
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[&](int& x) {
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return let_value(async([&] { return x / 2; }), [&](int& y) {
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return async([&] { return x + y; });
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});
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})),
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[](std::variant<std::tuple<>> a, std::variant<std::tuple<int>> b) {
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std::cout << "when_all finished - [" << a.index() << ", "
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<< std::get<0>(std::get<0>(b)) << "]\n";
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}));
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std::cout << "let_value done " << *result << "\n";
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// Simple usage of 'let_value_with()'
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// - defines an async scope in which the result of a passed invocable
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// is in-scope for the duration of an operation.
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std::optional<int> let_with_result =
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sync_wait(let_value_with([] { return 42; }, [&](int& x) {
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printf("addressof x = %p, val = %i\n", (void*)&x, x);
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return async([&]() -> int {
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printf("successor tranform\n");
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printf("addressof x = %p, val = %i\n", (void*)&x, x);
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return x;
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});
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}));
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std::cout << "let_value_with done " << *let_with_result << "\n";
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// let_value_with example showing use with a non-moveable type and
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// in-place construction.
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std::optional<int> let_with_atomic_result =
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sync_wait(let_value_with([] { return std::atomic<int>{42}; },
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[&](std::atomic<int>& x) {
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++x;
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printf("addressof x = %p, val = %i\n", (void*)&x, x.load());
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return async([&]() -> int {
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++x;
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printf("successor tranform\n");
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printf("addressof x = %p, val = %i\n", (void*)&x, x.load());
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return x.load();
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});
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}));
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std::cout <<
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"let_value_with on atomic type " << *let_with_atomic_result << "\n";
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return 0;
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}
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