g3log/test_unit/test_cpp_future_concepts.cpp

/** ==========================================================================
* 2012 by KjellKod.cc. This is PUBLIC DOMAIN to use at your own risk and comes
* with no warranties. This code is yours to share, use and modify with no
* strings attached and no restrictions or obligations.
 *
 * For more information see g3log/LICENSE or refer refer to http://unlicense.org
* ============================================================================*/

#include <gtest/gtest.h>

#include <chrono>
#include <exception>
#include <functional>
#include <future>
#include <memory>
#include <string>
#include <thread>
#include "g3log/future.hpp"
#include "g3log/time.hpp"

std::future<std::string> sillyFutureReturn() {
   std::packaged_task<std::string()> task([]() { return std::string("Hello Future"); });  // wrap the function
   std::future<std::string> result = task.get_future();                                   // get a future
   std::thread(std::move(task)).detach();                                                 // launch on a thread
   std::cout << "Waiting...";
   result.wait();
   return result;  // already wasted
}

TEST(Configuration, FutureSilly) {
   std::string hello = sillyFutureReturn().get();
   ASSERT_STREQ(hello.c_str(), "Hello Future");
}

struct MsgType {
   std::string msg_;
   MsgType(std::string m) :
       msg_(m){};
   std::string msg() { return msg_; }
};

TEST(TestOf_CopyableCall, Expecting_SmoothSailing) {
   using namespace kjellkod;
   const std::string str("Hello from struct");
   MsgType type(str);
   std::unique_ptr<Active> bgWorker(Active::createActive());
   std::future<std::string> fstring =
      g3::spawn_task(std::bind(&MsgType::msg, type), bgWorker.get());
   ASSERT_STREQ(str.c_str(), fstring.get().c_str());
}

TEST(TestOf_CopyableLambdaCall, Expecting_AllFine) {
   using namespace kjellkod;
   std::unique_ptr<Active> bgWorker(Active::createActive());

   // lambda task
   const std::string str_standalone("Hello from standalone");
   auto msg_lambda = [=]() {
      return (str_standalone + str_standalone);
   };
   std::string expected(str_standalone + str_standalone);

   auto fstring_standalone = g3::spawn_task(msg_lambda, bgWorker.get());
   ASSERT_STREQ(expected.c_str(), fstring_standalone.get().c_str());
}

template <typename F>
std::future<std::invoke_result_t<F>> ObsoleteSpawnTask(F f) {
   typedef std::invoke_result_t<F> result_type;
   typedef std::packaged_task<result_type()> task_type;

   task_type task(std::move(f));
   std::future<result_type> result = task.get_future();

   std::vector<std::function<void()>> vec;
   vec.push_back(g3::MoveOnCopy<task_type>(std::move(task)));
   std::thread(std::move(vec.back())).detach();
   result.wait();
   return std::move(result);
}

TEST(TestOf_ObsoleteSpawnTaskWithStringReturn, Expecting_FutureString) {
   std::string str("Hello");
   std::string expected(str + str);
   auto msg_lambda = [=]() {
      return (str + str);
   };
   auto future_string = ObsoleteSpawnTask(msg_lambda);

   ASSERT_STREQ(expected.c_str(), future_string.get().c_str());
}
// gcc thread example below
// tests code below copied from mail-list conversion between
// Lars Gullik Bjønnes and Jonathan Wakely
// http://gcc.gnu.org/ml/gcc-help/2011-11/msg00052.html

// --------------------------------------------------------------
namespace WORKING {
   using namespace g3;

#include <gtest/gtest.h>

#include <future>
#include <iostream>
#include <thread>
#include <vector>

   std::vector<std::function<void()>> vec;

   template <typename F>
   std::future<std::invoke_result_t<F>> spawn_task(F f) {
      typedef std::invoke_result_t<F> result_type;
      typedef std::packaged_task<result_type()> task_type;

      task_type task(std::move(f));
      std::future<result_type> res = task.get_future();

      vec.push_back(
         MoveOnCopy<task_type>(
            std::move(task)));

      std::thread([]() {
         auto task = std::move(vec.back());
         vec.pop_back();
         task();
      }).detach();

      return std::move(res);
   }

   double get_res() {
      return 42.2;
   }

   std::string msg3() {
      return "msg3";
   }
}  // namespace WORKING

TEST(Yalla, Testar) {
   using namespace WORKING;
   auto f = spawn_task(get_res);
   ASSERT_EQ(42.2, f.get());

   auto f2 = spawn_task(msg3);
   ASSERT_EQ("msg3", f2.get());

   ASSERT_TRUE(true);
}