Extra Homework 3

Due by 11:59pm on Wednesday, 05/02

Instructions

Download extra03.zip. Inside the archive, you will find a file called extra03.py, along with a copy of the Ok autograder.

Submission: When you are done, submit with python3 ok --submit. You may submit more than once before the deadline; only the final submission will be scored.

Using Ok

The ok program helps you test your code and track your progress. The first time you run the autograder, you will be asked to log in with your @berkeley.edu account using your web browser. Please do so. Each time you run ok, it will back up your work and progress on our servers. You can run all the doctests with the following command:

python3 ok

To test a specific question, use the -q option with the name of the function:

python3 ok -q <function>

By default, only tests that fail will appear. If you want to see how you did on all tests, you can use the -v option:

python3 ok -v

If you do not want to send your progress to our server or you have any problems logging in, add the --local flag to block all communication:

python3 ok --local

When you are ready to submit, run ok with the --submit option:

python3 ok --submit

Readings: You might find the following references useful:

• Section 4.8

Q1: Interleave

We know that the behavior of multiple threads can be unpredictable.

However, in many cases there are only a finite set of possible outcomes that can result from executing a set of threads in parallel. In this problem, you will compute all possible final states of an environment, given an initial set of bindings from names to values and a list of threads.

Your job is to implement all_final_frames, a function that takes an initial state and a list of threads and returns a list of final states the threads could leave the environment in. This list can have duplicates and is unordered.

def all_final_frames(initial_frame, threads):
    """
    >>> s = all_final_frames({'x' : 10}, [increment, double])
    >>> sorted(set(u['x'] for u in s))
    [11, 20, 21, 22]
    >>> sorted(set((u['x'], u['y'], u['z']) for u in s))  # x, y, z triples
    [(11, 10, 10), (20, 10, 10), (21, 20, 10), (22, 10, 11)]

    >>> increment.lock = True
    >>> double.lock = True
    >>> s = all_final_frames({'x' : 10}, [increment, double])
    >>> sorted(set(u['x'] for u in s))
    [21, 22]

    >>> increment.lock = False
    >>> double.lock = False
    >>> s = all_final_frames({'x' : 2}, [increment, double, square])
    >>> sorted(set(u['x'] for u in s))
    [3, 4, 5, 6, 8, 9, 10, 16, 17, 18, 25, 36]

    >>> increment.lock = True
    >>> double.lock = True
    >>> s = all_final_frames({'x' : 2}, [increment, double, square])
    >>> sorted(set(u['x'] for u in s))
    [4, 5, 8, 9, 10, 16, 17, 18, 25, 36]

    >>> square.lock = True
    >>> s = all_final_frames({'x' : 2}, [increment, double, square])
    >>> sorted(set(u['x'] for u in s))
    [9, 10, 17, 18, 25, 36]
    """
    final_frames = []

    def execute_all(frame, threads):
        "*** YOUR CODE HERE ***"

    execute_all(initial_frame, threads)
    return final_frames

Use Ok to test your code:

python3 ok -q all_final_frames