C++ future::get方法代码示例

void GoApp::check_for_computed_move()
{
	//return;

	if (game_status != COMPUTER_THINKING) {
		return;
	}

	auto status = computed_move.wait_for(std::chrono::seconds(0));
	if (status == std::future_status::ready) {
		try {
			auto move = computed_move.get();
			state.do_move(move);

			// Are there any more moves possible?
			if (state.get_moves().empty()) {
				game_status = GAME_OVER;
			}
			else {
				next_player();
			}

		} catch (std::exception& error) {
			game_status = GAME_ERROR;
			error_string = error.what();
		}
	}
}

int factorial1(std::future<int>& f)
{
    int n = f.get();
    int result = 1;
    for (int i = 1; i <= n; ++i)
        result *= i;

    return result;
}

    /**
     * Close the task. This will raise in this thread any exception the
     * task generated in the other thread. Calling this function is
     * optional, because the destructor will also call this function.
     * But because it can throw an exception, it is better to call it
     * explicitly.
     */
    void close() {
        // If an exception happened in the task, re-throw
        // it in this thread. This will block if the task
        // isn't finished.
        if (m_future.valid()) {
            m_future.get();
        }

        // Make sure task is done.
        if (m_thread.joinable()) {
            m_thread.join();
        }
    }

void handleFuture( std::future< _2Real::BlockResult > &obj, std::string const& info = "" )
{
	obj.wait();
	_2Real::BlockResult val = obj.get();
	switch ( val )
	{
	case _2Real::BlockResult::CARRIED_OUT:
		std::cout << "---- " << info << " was carried out" << std::endl;
		break;
	case _2Real::BlockResult::IGNORED:
		std::cout << "---- " << info << " was ignored" << std::endl;
		break;
	}
}

 std::pair<long double, int> getResult(
     std::chrono::system_clock::time_point deadline, int maxPrecision)
 {
     long double result = 1;
     int precision = 1;
     if (std::chrono::system_clock::now() < deadline) {        
         while (precision < maxPrecision) {
             const int nextPrecision = std::min(maxPrecision, precision * 2);
             future = std::async(std::launch::async, compute, nextPrecision);
             if (future.wait_until(deadline) == std::future_status::timeout)
                 break;
             result = future.get();
             precision = nextPrecision;
         }
     }
     return { result, precision };
 }

            /**
             * Get the header data from the file.
             *
             * @returns Header.
             * @throws Some form of osmium::io_error if there is an error.
             */
            osmium::io::Header header() {
                if (m_status == status::error) {
                    throw io_error("Can not get header from reader when in status 'error'");
                }

                try {
                    if (m_header_future.valid()) {
                        m_header = m_header_future.get();
                        if (m_read_which_entities == osmium::osm_entity_bits::nothing) {
                            m_status = status::eof;
                        }
                    }
                } catch (...) {
                    close();
                    m_status = status::error;
                    throw;
                }
                return m_header;
            }

//========================================================================
void CSirServer::NotifyResult(CLIENT* client, std::future<SCRESULT>& result)
{
	SCRESULT rc = result.get();
	stringstream ss;

	switch (rc)
	{
		case SCR_SUCCESS:
			ss << "OK";
		break;

		case SCR_TIMEOUT:
			ss << "TIMEOUT";
		break;

		default:
			ss << "ERROR";
		break;
	}
	ss << std::endl;

	Notify(client, ss.str());
}

    void on_update(const UpdateEvent & e) override
    {
        // Around 60 fps
        if (fixedTimer.milliseconds().count() >= 16 && turret.fired)
        {
            float timestep_ms = fixedTimer.milliseconds().count() / 1000.f;
            turret.projectile.fixed_update(timestep_ms);
            std::cout << timestep_ms << std::endl;
            //std::cout << turret.projectile.p.position << std::endl;
            fixedTimer.reset();
        }

        cameraController.update(e.timestep_ms);
        time += e.timestep_ms;
        shaderMonitor.handle_recompile();

        // If a new mesh is ready, retrieve it
        if (pointerFuture.valid())
        {
            auto status = pointerFuture.wait_for(std::chrono::seconds(0));
            if (status != std::future_status::timeout)
            {
                auto m = pointerFuture.get();
                supershape = m;
                supershape.pose.position = {0, 2, -2};
                pointerFuture = {};
            }
        }

        // If we don't currently have a background task, begin working on the next mesh
        if (!pointerFuture.valid() && regeneratePointer)
        {
            pointerFuture = std::async([]() {
                return make_supershape_3d(16, ssM, ssN1, ssN2, ssN3);
            });
        }
    }

TEST_F(DBusConnectionTest, LibdbusConnectionsMayCommitSuicide) {
    const ::DBusBusType libdbusType = ::DBusBusType::DBUS_BUS_SESSION;
    ::DBusError libdbusError;
    dbus_error_init(&libdbusError);
    ::DBusConnection* libdbusConnection = dbus_bus_get_private(libdbusType, &libdbusError);

    assert(libdbusConnection);
    dbus_connection_set_exit_on_disconnect(libdbusConnection, false);

    auto dispatchThread = std::thread(&dispatch, libdbusConnection);

    ::DBusMessage* libdbusMessageCall = dbus_message_new_method_call(
                    "org.freedesktop.DBus",
                    "/org/freedesktop/DBus",
                    "org.freedesktop.DBus",
                    "ListNames");

    dbus_message_set_signature(libdbusMessageCall, "");

    DBusPendingCall* libdbusPendingCall;

    dbus_connection_send_with_reply(
                    libdbusConnection,
                    libdbusMessageCall,
                    &libdbusPendingCall,
                    500);

    dbus_pending_call_set_notify(
                    libdbusPendingCall,
                    notifyThunk,
                    libdbusConnection,
                    NULL);

    ASSERT_EQ(true, future.get());
    dispatchThread.join();
}

BOOST_AUTO_TEST_CASE(future, *boost::unit_test::timeout(15))
{
    using boost::unit_test::framework::master_test_suite;

    boost::asio::io_context ios;

    std::future<int> fut = bp::async_system(
                              ios, boost::asio::use_future,
                              master_test_suite().argv[1],
                              "test", "--exit-code", "42");

    ios.run();

    int exit_code = 0;
    BOOST_CHECK_NO_THROW(exit_code = fut.get());

    BOOST_CHECK_EQUAL(exit_code, 42);
}

BOOST_AUTO_TEST_CASE(future_error, *boost::unit_test::timeout(15))
{
    using boost::unit_test::framework::master_test_suite;

    boost::asio::io_context ios;

    std::future<int> fut = bp::async_system(
                              ios, boost::asio::use_future,
                              "invalid-command");

    ios.run();

// return from thread
int getNum2(std::future<int> &f) {
  print("In getNum1");
  return f.get() + 10;
}

 /**
  * Check task for exceptions.
  *
  * If an exception happened in the task, re-throw it in this
  * thread. This will not do anything if there was no exception.
  */
 void check_for_exception() {
     if (m_future.valid() && m_future.wait_for(std::chrono::seconds(0)) == std::future_status::ready) {
         m_future.get();
     }
 }

void test(std::future<int>& input) {
  std::cout << input.get() << std::endl;
}

 inline void wait_until_done(std::future<T>& future) {
     if (future.valid()) {
         future.get();
     }
 }

 inline void check_for_exception(std::future<T>& future) {
     if (future.valid() && future.wait_for(std::chrono::seconds(0)) == std::future_status::ready) {
         future.get();
     }
 }