be-technical-interview-rust/CHANGES.md

# Backend internal interview (rust)

## CHANGES: fixed branch

- Moving from **HashMap** to **BTreeMap** to preseve loading lines order, nevertheless still looks very cumbersome.
- Fix **lines parser** in Maps **metrics** and in **aggregated_metrics** to be handled properly.
- Fix **unwrap / expect** for obvious reasons, add simple error message via **map_err**, **unwrap_or_else** and **closure function**.
- Fix some source code lines order, output format and conversions.
- Change some **iterators** to <u>functional mode</u>.
- Separate tasks to independent funtions for better isolation, less responsibilities and help on **tests** handling.
- Adding **output_path** to help on result output options.
- Adding **elapsed time** to show how many millisecods took each metric file and total processing.
- Create type alias to make so long **Map types** more readable.
- Create a **MetricLine** struct to make parser easier (a lot of work should be done but requires full refactoring).
- Adding **input_2.txt** to process multiple metrics in parallel (done via **std::threads**), collect result properly via channels (**std:mpsc**) and show then properly.
- Create a **generate_metrics** to process each metric file and to be used in **test_expected_metrics**
- Following **unit tests** are implemented:
  - <u>test_load_input</u> test load input file **input.txt**.
  - <u>test_invalid_line_value</u> test use invalid value in line parsing.
  - <u>test_invalid_line</u> test use invlid value in line parsing.
  - <u>test_expected_metrics</u> test load input data from **input.txt** compare with **output_expected.txt**.
  
> [!Note]
> Code simply **works as expected** trying to be preserve initial approach and not too much disruptive changes.<br>
> It is able to **process multiple metrics in parallel** (input.txt and input_2.txt). <br>
> A full refactoring has to be done for <u>better quality, maintenance and be more readable</u>. (Structs, implementaitions, settings for multiple inputs, etc). <br>

Next round in: [Improve branch](/NewRelic/be-technical-interview-rust/src/branch/improved)