Start by clarifying requirements and constraints (e.g., command types, expected latency, failure handling). Then propose a serial command queue with a single worker that processes commands one at a time, using async/await or a dedicated serial dispatch queue. Finally, detail timeout handling, response matching, and testing strategy.
Pro tip: Emphasize idempotency and cancellation: when a timeout occurs, ensure the command is not retried blindly, and provide a way to cancel pending commands to avoid stale responses. Also, mention using Combine or async sequences for clean concurrency.
Ask about command types, expected response times, maximum queue size, and whether commands can be cancelled. Confirm the failure policy: should timeouts trigger retries, fallbacks, or just error reporting?
Propose a thread-safe queue (e.g., using a serial DispatchQueue or an actor) that enqueues commands from any component. A single worker dequeues and executes commands sequentially, ensuring strict serialization.
For each command, start a timer (e.g., DispatchSourceTimer or Task with timeout). Match responses using a unique command ID or sequence number. On timeout, cancel the command and invoke the failure policy.
Specify behavior on timeout: e.g., mark command as failed, notify the caller, and optionally retry with backoff. Ensure the queue continues processing subsequent commands and that resources are cleaned up.
Describe unit tests with a mock BLE layer to simulate responses, timeouts, and concurrent enqueues. Include integration tests on real devices and stress tests for high load.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.