HW3
released: 10/05, 22:00
due: 10/12, 13:00

- Read Mike Dahlin's "Basic Threads Programming: Standards and Strategy"
  (https://naizhengtan.github.io/21fall/notes/programming-with-threads.pdf)
- Study 10/05's lecture handout 
  (https://naizhengtan.github.io/21fall/notes/handout_5a.pdf)
and answer the following questions.
Submit your answers to Canvas assignments. There is an entry for this homework.


Question 1: is the program still correct if we replace the "cond_signal" at
handout line 48 with "cond_broadcast"? (yes/no) Why? (explain in 1-2 sentences)


Question 2: here is the "database problem" we discussed on class:

    """
    - readers and writers interact with a database
    - readers never modify database
    - writers read and modify data
    - we allow multiple readers touching the database
    - we only allow one writer (no other readers) touching the database
    """

    Follow Mike Dahlin's problem solving strategy (S3 in his write-up)
    and write down your step 1-3 below.

Answer:

    1. 
      1.a [your words]
      1.b [your words]
      1.c [your words]
    2. 
      [your words]
    3. 
      [your words]


Question 3: read the "smoker problem" and write down the first 3 steps of our
problem solving strategy.

  """
  smoker problem
  - There are three smokers and one agent.
  - Each smoker continuously rolls a cigarette and then smokes it.
  - But to roll and smoke a cigarette, the smoker needs three ingredients: tobacco, paper, and matches.
  - One of the smoker has paper, another has tobacco, and the third has matches.
  - The agent has an infinite supply of all three materials.
  - The agent randomly places two of the ingredients on the table.
  - The smoker who has the remaining ingredient then makes and smokes a cigarette, telling the agent on completion.
  - The agent then puts out another two of the three ingredients, and the cycle repeats.
  """

Answer:

    1. 
      1.a [your words]
      1.b [your words]
      1.c [your words]
    2. 
      [your words]
    3. 
      [your words]

Question 4: Read the handout panel 2 and answer the question at line 178 in 1-2 sentences.


Question 5: Read the handout panel 3 and answer the question B at line 223 below.
(note: write pseudocode like the handout; use comments to explain if necessary)

Answer:

// assume you have the sharedlock in panel 3

/* init code you have */

Database::read() {
  // your pseudocode here
}

Database::write() {
  // your pseudocode here
}