CS 3005: Programming in C++

Faster Calculations

Introduction

We want to be able to calculate our grid numbers more quickly. One way to accomplish this is to use more cores of the CPU. We’ll use threads of execution to accomplish this task.

Assignment

In this assignment you will create a class ThreadedGrid, that inherits from the NumberGrid class and becomes the parent of the ComplexFractal class. The main purpose of the ThreadedGrid class is to override the calculateAllNumbers method so that it will use threads to calculate numbers simultaneously.

The ppm_menu program needs to adjust its commands.

The menu will now provide two options for calculation:

• fractal-calculate: Calculate the escape values for the fractal.
• fractal-calculate-single-thread: Calculate the escape values for the fractal, single-thread.

fractal-calculate-single-thread will call a new function to do the non-threaded version of calculation.

Programming Requirements

The following files must be updated or created and stored in the src directory of your repository.

Create ThreadedGrid.{h,cpp}

This class inherits from the NumberGrid class, and becomes the parent of ComplexFractal.

Data Members:

• A std::vector of task objects. You can decide what those task objects should be. You may even make a simple class to store the information for a single task. If so, that support class should be declared and implemented in the ThreadedGrid.{h,cpp} files.
• A std::mutex object to control critical access to the vector of task objects.

Methods:

• ThreadedGrid(); The default constructor. Leaves the task queue empty, and lets the parent class default constructor set values for its data members.
• ThreadedGrid(const int& height, const int& width); Leaves the task queue empty, and passes the parameters on to the parent class constructor.
• virtual ~ThreadedGrid(); Empty, but required destructor.
• virtual void calculateAllNumbers(); Overrides the method of the parent class. Uses the worker method in several threads to do the work. Be sure to manage the task queue, and clean up the threads when they have finished. Use the thread library to decide how many threads to launch, based on the capacity of the computer. It may be useful to use try/catch when creating threads to protect against limited resources.
• virtual void worker(); As long as tasks are available in the task queue, get one, and complete it. Should use calculateNumber() and setNumber().

Update ComplexFractal.{h,cpp}

ComplexFractal should now inherit from ThreadedGrid. This will require minor changes to the class declaration in the header file and in the constructor chaining in the implementation file.

Update image_menu.h and image_drawing.cpp

Add this function:

• void calculateFractalSingleThread(ActionData& action_data); This function calls the NumberGrid version of calculateAllNumbers instead of the ThreadedGrid version, which would be the default. This is accomplished with this syntax: grid.NumberGrid::calculateAllNumbers(), assuming grid is a reference to a polymorphic NumberGrid object.

Note that calculateFractal() will not change. However, because of ThreadedGrid’s override of calculateAllNumbers(), calculateFractal() will automatically use the threaded version.

Update Functions in controllers.cpp

• void configureMenu( MenuData& menu_data ) add the new/updated actions with the names and descriptions listed below.

Table of New Commands

Update Makefile

The following commands should work correctly.

• make hello - builds the hello program
• make questions_3 - builds the questions_3 program
• make ascii_image - builds the ascii_image program
• make image_file - builds the image_file program
• make ppm_menu - builds the image_file program
• make all - builds all programs
• make - builds all programs (same as make all)
• make clean - removes all .o files, and all executable programs

Additional Documentation

• C++ Reference
• Examples from class

Show Off Your Work

To receive credit for this assignment, you must

• use git to add, commit and push your solution to your repository for this class.
• successfully pass all unit tests and acceptance tests

Additionally, the program must build, run and give correct output.

Extra Challenges (Not Required)

• Create additional command(s) that let the user select how many threads to use.
• Override the setPPM method to be threaded.
• Are there other compute-resource bound parts of the code that take long enough to be worth the effort of converting to threaded?

Last Updated 09/11/2023