Step 3: Loop threads with condition_var

To duplicate

In /Step_3/ directory run make. Executable will build as Lock.out. To run executable, run ./Lock.out.

Files

• LockGuard.h
• main.cpp (with DEBUG code)
• main_no_debug.cpp (identical, except without DEBUG code)

Documentation

Doxygen documentation is available for this step of the project.

Step 3 main page
LockGuard.h	Documentation	Code
main.cpp	Documentation	Code
main_no_debug.cpp	Documentation	Code

Results

It produced this output, which matched expectations:

armaan@ubuntuVM:Step_3$ ./Lock.out 
main: starting all threads
thread3: starting, waiting.
thread2: starting, waiting.
thread1: starting, waiting.
thread1: signal received, doing work ....
thread1: done with work, signal next thread
thread2: signal received, doing work ....
thread2: done with work, signal next thread
thread3: signal received, doing work ....
thread3: done with work, signal next thread
thread1: signal received, doing work ....
thread1: done with work, signal next thread
thread2: signal received, doing work ....
^C
armaan@ubuntuVM:Step_3$ 

Test conditions

• Pass:
  • Produce output consistent with example output in prompt
  • Avoid anomalous thread behavior, including but not limted to, deadlock and data races.
• Fail: Any other result.

Method

Research

Details about my research into threading and other topics are available here: Reference in Appendix

Coding

I wrote three functions to do work, and one overloaded function to facilitate debug. See Reference in Appendix for details. In brief, they are:

• A general-purpose print function that the threads call from a thread-safe state
• A thread worker function that listens for a signal, verifies whether it is its turn or not, and updates the other threads on whose turn it is.
• A main function that initializes everything up and sets it in motion.
• A debug print function called from many places in the code only if a bool controlling it is set to true.

Doxygen

Considerations for creating documentation are discussed here: Reference in Appendix

Requirements

3) Use c++11 std::condition_var in solution from #3 to synchronize threads

-- Psuedo Code --

     main:

       1) start: thread 1, thread 2, thread 3
       2) all threads block on condition_signal
       3) main signals condition_signal
       4) join all threads to prevent exit main // gimmee

       thread 1:
          break from condition_signal due to step 3
          sleep (random(1,5))
          signal thread 2
          wait on condition_signal

      example output:
          main: starting all threads
          thread1: starting, waiting.
          thread2: starting, waiting.
          thread3: starting, waiting.
          main: starting thread 1.
          thread1: signal received, doing work ....
          thread1: done with work, signal next thread
          thread2: signal received, doing work ....
          thread2: done with work, signal next thread

          on and on and on until you CTRL-C the program

Prelims

Parsing Requirements

Initially had trouble parsing requirements. Reference in Appendix

Environment

Environment remains the same as the previous steps.

Refamiliarization with C++

Continue needing to refamiliarize myself with C++ after spending large amount of time with C and Python. See Reference in Appendix for details.