In Sydney, all train carraiges have an identifiable four digit number.

For example, in the above image, the train carriage number is 3592.

A popular game amongst Sydney train passengers is to find some arrangement of the numbers, and four mathematical operators (+, -, x, /), that will give a result of 10.

For example, in the above image, the numbers 3 5 9 2 can be arranged as

3 x 2 - 5 + 9 = 10

In this exercise, you are given starter code that currently takes in a FIVE digit number, and prints out all possible arrangements of the numbers, and four mathematical operators (+, -, x, /), that will give a result of 10.

It does this by generating all possible combinations into a vec of tuples. Each tuple is a combination of the numbers and operators: (<Vec<i32>, Vec<char>>), where the first element is a vector of the digits, and the second element is a vector of the operators.

It then iterates through the vec of tuples, evaluates the expression left to right, without order of operations, and prints out the expression if it evaluates to 10. Your task is to modify the code to take advantage of rust's fearless concurrency to speed up the program.

To do this, you will need to roughly follow the following steps:

1. Chunk the vec of tuples into a vec of vecs of tuples
2. Create a new thread scope
3. For each chunk (a singular vec of tuples) spawn a new thread (inside the scope)
4. Have each thread iterate through its chunk, and evaluate the expression
5. Have each thread print out the expression if it evaluates to 10

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The due date for this exercise is Week 9 Wednesday 21:00:00.

Note that this is an individual exercise; the work you submit with give must be entirely your own.

In order to get started, you will need to create a Cargo project

You can do this by running the cargo new command in your terminal

6991 cargo new channels
Created binary (application) `channels` package

In this exercise you will be making use of Rust's channels to communicate between workers.

To do this, it is assumed that you have completed the previous exercise, and have a working solution that:

• chunks the work into a set of smaller vectors
• creates a thread scope
• spawns a thread for each sub task/vector
• does the calculation (and prints) in each thread

• Before the new thread scope is created, you create a channel
• Each thread sends the number of calculations it found to the channel
• After all the calculations are done, you receive the number of calculations from each thread, and print out the total number of calculations

Your output should look something like this:

6991 cargo run -- 12345
cr -- 12345
   Compiling either v1.8.0
   Compiling itertools v0.10.5
   Compiling channels v0.1.0
    Finished dev [unoptimized + debuginfo] target(s) in 1.74s
     Running `target/debug/channels 12345`
There are 2880 potential combinations
2 / 4 + 3 - 1 * 5 = 10
// -- CUT FOR BREVITY, YOUR PROGRAM WILL OUTPUT MORE -- 
2 * 4 - 3 + 5 / 1 = 10
Thread 0 found 5 combinations
Thread 3 found 11 combinations
Thread 4 found 19 combinations
Thread 2 found 4 combinations
Thread 5 found 9 combinations
Thread 1 found 11 combinations
Total: 59

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The due date for this exercise is Week 9 Wednesday 21:00:00.

Note that this is an individual exercise; the work you submit with give must be entirely your own.

• Some text that looks exactly like: {{{ counter }}}
• A button that will send a POST request to /counter

6991 cargo run -- 12345
Server running on port 12345

http://localhost:12345

http://localhost:12345


    
Hello World!!
{{{ counter }}}

• Spawn a thread per connection
• Make State shared across threads, by using a locking primitive
• Increment the counter in state when a POST request is received
• Replace the {{{ counter }}} placeholder with the actual value of the counter

To test your code, you can run the server, and then visit the page in your browser. Marks will be determined based off 6991 cargo test correctly running. The given 6991 autotest will simply call 6991 cargo test.

When you think your program is working, you can use autotest to run some simple automated tests:

6991 autotest

When you are finished working on this exercise, you must submit your work by running give:

6991 give-crate

The due date for this exercise is Week 9 Wednesday 21:00:00.

Note that this is an individual exercise; the work you submit with give must be entirely your own.

They know some basic rust (equiv to up to week 7 of the course), but are not familiar with the details of the Send and Sync traits (etc).

Your task is to write answers to their questions, which can be found in the starter code questions.md.

You will find this useful as revision for the final exam.

When you are finished working on this exercise, you must submit your work by running give:

give cs6991 lab08_send_sync questions.md

The due date for this exercise is Week 9 Wednesday 21:00:00.

Note that this is an individual exercise; the work you submit with give must be entirely your own.

The starter code has two simple endpoints, designed to show off some of the advantages of building web servers in Rust, specifically around type safety and compile-time error checking.

The first endpoint is GET /ping, which returns a simple string "pong".

The second endpoint is POST /users, which expects a JSON body with a single field, username, and returns a JSON response with the username and some id.

These are represented by the CreateUser and User structs in the starter code! The axum framework allows the function for that route to use these structs as parameters and return types, and returns a 400 status code for bad arguments, if the input cannot be transformed into those structs.

Your task is to add a third endpoint, GET /hello/{name}, which returns a string "Hello, {name}!".

You can test your code by running RUST_LOG=info 6991 cargo run and then running the following commands in a separate terminal:

curl https://localhost:3000/hello/shrey

The book Zero2Prod is a great book that highlights the benefits of building web servers in Rust, and goes through the large process of building a production-ready web server in Rust, including testing, logging, deployment and more.