https://github.com/sueszli/concurrent-elevators

elevators concurrency problem in java
https://github.com/sueszli/concurrent-elevators

concurrent-programming modern-java

Last synced: 20 days ago
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elevators concurrency problem in java

• Host: GitHub
• URL: https://github.com/sueszli/concurrent-elevators
• Owner: sueszli
• License: mit
• Created: 2023-01-18T16:34:57.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-04-25T00:45:42.000Z (7 months ago)
• Last Synced: 2024-10-05T23:21:30.047Z (about 1 month ago)
• Topics: concurrent-programming, modern-java
• Language: Java
• Homepage:
• Size: 490 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
A super minimal implementation of a thread-pool-executor service / scheduler in Java. The goal is to provide a simple,

easy to understand implementation. The implementation is not intended to be used in production, but rather to be used as

a learning tool.

## Problem

- There are 7 elevators in a building with 55 floors.

- Each floor has exactly one button to request an elevator.

- Elevators have the capacity of carrying an arbitrary, given number of people.

- Elevators don't change direction and don't stop mid-trip.

- People can only choose their destination freely, when they are on the ground-floor:

    - up: ground-floor [0] − can only travel to ⟶ non-ground-floor [1;54]

    - down: non-ground-floor [1;54] − can only travel to ⟶ ground-floor [0]

- The requests are handled globally.

- The elevator-scheduler assigns a chosen request to an elevator based on some arbitrary algorithm.

- If there are no elevators available, the request is queued up.

## Design decisions

- Decided to use vanilla Java without any non-default libraries for the sake of simplicity.

- Got rid of the suggested "up"/"down" directions since they can be inferred from the current floor.

- Chose a poison-pill approach to terminate the scheduler (also

  see: [this similar implementation](https://gitlab.com/niklaswimmer/dc-tower-elevator-challange/-/blob/main/app/src/main/java/me/nikx/dctower/TowerController.java))

- Chose JDK-19 to make use of type inferrence with `var` and other nifty features.