Orders Simulation

How to use this simulator

Compile

javac -cp ./src/gson-2.8.6.jar -d ./out ./src/sim/**/*.java ./src/sim/*.java

Run application

java -cp ./out:./src/gson-2.8.6.jar sim.SimulationRunner 2

• The last value in the above command configure the ingestion rate of orders per second.

Run tests

• Add Junit5 to the project in IntelliJ IDEA
• Run tests in each *Test.java class

Design

• SimulationRunner orchestrates the entire simulation. It starts order, kitchen and courier processor threads.
• Orders are generated at the configured rate by a background thread
• Orders are sent to the kitchen using a BlockingQueue
• AtomicBoolean is used to communicate to the kitchen that all order were generated
• Cooked orders are then placed in shelves (BlockingQueues) based on their temperature
• If there's no room on a shelf, the overflow shelf is used
• The system checks if overflow orders can be moved back to their temperature-based shelf
• If no orders could be moved and the overflow shelf is full, the first item (likely close to being stale) on the shelf is removed
• After an item is shelved, a new thread is created to deliver the order
• Just before the courier arrives, stale orders are removed from the temperature-based and overflow shelf since couriers do not deliver stale orders
• Courier removes order from shelf if it is available