Ownership rules

Rust ownership — three rules:

1. Each value has one owner
2. When owner goes out of scope, value is dropped
3. You can borrow (&T) or move — not both mutably at once

playstepchallengeinstructor

OwnMoveBorrow (&)

Owner: ingestion_handler

owneringestion_handler owns String::from("webhook payload")

stackvalue valid while owner in scope

Move in ingestion

When the handler builds a payload and sends it to Kafka, ownership often transfers to the producer buffer — the handler must not use the string afterward unless it cloned.

vs JavaScript

JS objects are shared by reference — garbage collector reclaims when unreachable. Rust catches use-after-move at compile time.

Teach-back prompt

What happens if ingestion moved a buffer to Kafka and then logged it?