Tasks in C++

[jreneew2]

You resurrected an old thread from 2013. Anyway, take a look at our code here. It works fine for us using WPILib's built in task setup (which I think is really just a wrapper for a pthread).

https://github.com/team2053tigertron.../src/Robot.cpp

[AustinSchuh]

Originally Posted by jreneew2

(which I think is really just a wrapper for a pthread).

Task is a VXWorks API wrapper around pthreads. Any reason not to use pthreads directly?

Take a look at ::std::thread. It works well, and is much more cross platform. We use it exclusively.

[taichichuan]

Originally Posted by AustinSchuh

Task is a VXWorks API wrapper around pthreads. Any reason not to use pthreads directly?

Take a look at ::std::thread. It works well, and is much more cross platform. We use it exclusively.

Can you provide a simple example of using ::std::thread that's compatible with the roborio?

TIA,

Mike

[AustinSchuh]

Originally Posted by taichichuan

Can you provide a simple example of using ::std::thread that's compatible with the roborio?

TIA,

Mike

From our code:

-- snip --
    ::frc971::wpilib::GyroSender gyro_sender;
    ::std::thread gyro_thread(::std::ref(gyro_sender));

    //  Main loop here

    // Now cleanup
    gyro_sender.Quit();
    gyro_thread.join();

-- snip --

// Handles reading the gyro over SPI and sending out angles on a queue.
//
// This is designed to be passed into ::std::thread's constructor so it will run
// as a separate thread.
class GyroSender {
 public:
  GyroSender();

  // For ::std::thread to call.
  //
  // Initializes the gyro and then loops until Quit() is called taking readings.
  void operator()();

  void Quit() { run_ = false; }

 private:

  // Readings per second.
  static const int kReadingRate = 200;

  GyroInterface gyro_;

  ::std::atomic<bool> run_{true};
};

There are a bunch of different variants for how to create the ::std::function that ::std::thread takes for a constructor. A simpler version would be to define a void foo(){} and pass that in. You can also use ::std::bind to call arbitrary functions with arbitrary arguments.

[taichichuan]

Originally Posted by AustinSchuh

From our code:

-- snip --
    ::frc971::wpilib::GyroSender gyro_sender;
    ::std::thread gyro_thread(::std::ref(gyro_sender));

    //  Main loop here

    // Now cleanup
    gyro_sender.Quit();
    gyro_thread.join();

-- snip --

// Handles reading the gyro over SPI and sending out angles on a queue.
//
// This is designed to be passed into ::std::thread's constructor so it will run
// as a separate thread.
class GyroSender {
 public:
  GyroSender();

  // For ::std::thread to call.
  //
  // Initializes the gyro and then loops until Quit() is called taking readings.
  void operator()();

  void Quit() { run_ = false; }

 private:

  // Readings per second.
  static const int kReadingRate = 200;

  GyroInterface gyro_;

  ::std::atomic<bool> run_{true};
};

There are a bunch of different variants for how to create the ::std::function that ::std::thread takes for a constructor. A simpler version would be to define a void foo(){} and pass that in. You can also use ::std::bind to call arbitrary functions with arbitrary arguments.

Thanks!

Mike