senior-be-developer-task

Introduction

Hello! If you are viewing this repository you are probably a candidate for HyperGuest senior backend developer, congrats!

Before we begin, a few important notes please!

• Any AI tool is forbidden during this task. We already know Github copilot is a great tool, we don't need to test it :)
• This task is designated to test your problem-solving skills, still, code quality do matters! submit a code you would like to read as well
• At your sumption please include the next things :
  • your implementation of Queues.ts. Any other files are not allowed to be changed during this test.
  • write a clear explanation of your implementation.
  • suggest improvements! the code in this repository is not perfect, what would you do differently?
• Do not PR to this repo! if you would, all of your opponents would copy your answers ;)

Good luck!

Task description

The code in this repo is not working properly.

The script main.ts is trying to write "a lot" of data into a simulation of a key-value database ( implemented in Datable.ts). As Databases usually do - our database has small latency - between 0 to 100 ms per operation. In order to allow faster process of the messages our main.ts script puts all the operations in a queue (see the Queue.ts file). Than it launches a random number (between 3 to 6) of "workers" (see Worker.ts), that works asynchronously in parallel, reading messages from the queue and commit the operation to the "Database". Each worker should "confirm" to the queue that the message was proceeded, so the message would be deleted. The script wait for 10 seconds (enough time for all the workers to complete the work), prints the state of hte queue and the DB state, and exits.

However!
the results are wrong :(
We set all the initial values to 50, and than we add all numbers between 1 to 9 for each item. therefore the correct results so the correct output should be:

# > ts-node main.ts
Number of items:3
Number of workers:5
Queue size:  0
DB state:
 {
    "item2": 95,
    "item0": 95,
    "item1": 95
}

While running the script would look like this (different values would be shown on each run):

# > ts-node main.ts
Number of items:3
Number of workers:5
Queue size:  0
DB state:
 {
    "item2": 74,
    "item0": 74,
    "item1": 15
}

Please assist our dev team to implement a valid version of Queue.ts!

note: Any implementation that would effectively not allow any parallel work between the workers would be rejected.

How to submit

To submit your solution, please follow these guidelines:

1. Clone this repository to your own GitHub account and implement your solution
2. Make changes either as a PR on a separate branch or directly on main
3. Document your solution and thinking process in the README.md or create a new MD file
4. Don't change the output format as it makes review more difficult
5. Don't overengineer the solution - there's no need to change the structure of the whole codebase - Queue.ts is enough. But drop your suggestions in comments if you'd change anything else.
6. Send the link to your repository to the provided contact.

We'll evaluate your submission based on correctness, code quality, and your understanding of the concurrency problem.

NOTE: Please do not submit PRs to this repo or fork it directly, as then your submissions will be easily visible to other candidates.