Implement concurrent order-accept/pickup simulator

Concurrent restaurant order + pickup simulator

Design and implement a thread-safe simulation for a restaurant that:

• Receives incoming orders concurrently (multiple producer threads).
• Prepares orders concurrently (one or more worker/chef threads).
• Allows customers to pick up orders concurrently (multiple consumer threads).

Requirements

1. Each order has:

• order_id (unique integer)
• item_name (string)
• cook_time_ms (positive integer)

1. API / operations to support (names can vary):

• placeOrder(order_id, item_name, cook_time_ms)
• startKitchen(num_chefs) (starts background processing)
• pickupOrder(order_id) blocks until the specified order is ready, then returns it
• shutdown() stops background threads gracefully

1. Correctness constraints:

• No order can be picked up before it is cooked.
• Each order is cooked exactly once and picked up at most once.
• No deadlocks; avoid busy-waiting.
• The system should handle N orders with concurrent placement and pickup.

What to discuss/implement

• Your choice of synchronization primitives (mutex/lock, condition variable, semaphore, blocking queue, etc.).
• Data structures used to track order state.
• How you ensure fairness and avoid race conditions.

(You may assume a single process and shared memory; no networking required.)