C++ std::future类代码示例

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();
		}
	}
}

void StopHTTPServer()
{
    LogPrint(BCLog::HTTP, "Stopping HTTP server\n");
    if (workQueue) {
        LogPrint(BCLog::HTTP, "Waiting for HTTP worker threads to exit\n");
        workQueue->WaitExit();
        delete workQueue;
        workQueue = nullptr;
    }
    if (eventBase) {
        LogPrint(BCLog::HTTP, "Waiting for HTTP event thread to exit\n");
        // Give event loop a few seconds to exit (to send back last RPC responses), then break it
        // Before this was solved with event_base_loopexit, but that didn't work as expected in
        // at least libevent 2.0.21 and always introduced a delay. In libevent
        // master that appears to be solved, so in the future that solution
        // could be used again (if desirable).
        // (see discussion in https://github.com/bitcoin/bitcoin/pull/6990)
        if (threadResult.valid() && threadResult.wait_for(std::chrono::milliseconds(2000)) == std::future_status::timeout) {
            LogPrintf("HTTP event loop did not exit within allotted time, sending loopbreak\n");
            event_base_loopbreak(eventBase);
        }
        threadHTTP.join();
    }
    if (eventHTTP) {
        evhttp_free(eventHTTP);
        eventHTTP = 0;
    }
    if (eventBase) {
        event_base_free(eventBase);
        eventBase = 0;
    }
    LogPrint(BCLog::HTTP, "Stopped HTTP server\n");
}

  static bool IsReady(std::future<void>& future)
  {
#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 6))
    return future.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
#else
    return future.wait_for(std::chrono::seconds(0));
#endif
  }

    /**
     * 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 };
 }

void interruptible_wait(std::future<T>& uf)
{
	while (!this_thread_interrupt_flag.is_set())
	{
		if (uf.wait_for(lk, std::future_status::ready == std::chrono::milliseconds(1)))
			break;
	}
}

void AI::WaitForFuture(const std::future<void>& fut, bool bPondering)
{
	std::uint64_t timePerMove = GetTimePerMove();
	if(bPondering)
	{
		timePerMove /= 2;
	}

	// Wait until the thread finishes or it gets timed out
	if(fut.wait_for(std::chrono::nanoseconds(timePerMove)) == std::future_status::timeout)
	{
		// If the thread did not finish execution, signal the thread to exit, and wait till the thread exits.
	
		m_bStopMinimax = true;
		fut.wait();
		m_bStopMinimax = false;
	}
}

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

    return result;
}

void test(std::future<void> fut)
{    
    switch (fut.wait_for(std::chrono::milliseconds(500)))
    {
        case std::future_status::ready: std::cout << "ready\n"; break;
        case std::future_status::deferred: std::cout << "deferred\n"; break;
        case std::future_status::timeout: std::cout << "timeout\n"; break;
    };
}

//----------------------------------------------------------------------//
void SoftServo::threadFunc(std::future<bool> shutdown,
			   SoftServo *const servo) // change this in the future to use a thread safe shared pipe reader/writer
{
  while (shutdown.wait_for(std::chrono::nanoseconds(0)) != 
	 std::future_status::ready)
    {
      servo->updateMove();
    }
}

            /**
             * 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;
            }

static bool checkIfFinished(std::future<void>& match) {
    auto status = match.wait_for(std::chrono::seconds(0));
    if(status == std::future_status::timeout) {
        return false;
    }
    else if(status == std::future_status::ready) {
        return true;
    }
    else {
        return false;
    }
}

//----------------------------------------------------------------------//
void JoyStick::threadFunc(std::future<bool> shutdown,
			  const JoyStick *const js)
{
  while (shutdown.wait_for(std::chrono::nanoseconds(0)) != 
	 std::future_status::ready)
    {
      if (!js->readEvent())
	{
	  js->d_owner->handleReadError();
	}
    }
}

    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);
            });
        }
    }