Distributed Lock with Fencing¶
A lease coordinates current ownership; a fencing token lets the resource reject stale owners.
flowchart LR
J[Junior: why locks expire] --> M[Middle: how fencing works] --> S[Senior: failures and mistakes] --> P[Professional: safe operation at scale]
flowchart LR
Worker --> Lock --> Token --> Resource
Resource -->|reject older token| Stale[Stale worker]
| Level | Guide | You are done when |
|---|---|---|
| Junior | Definition and why | You can explain stale-holder corruption. |
| Middle | How it works | You can trace token issuance and enforcement. |
| Senior | Failures and mistakes | You can test expiry, failover, and contention. |
| Professional | Best practices and scale | You can design an operable fenced resource. |
Practice rule: Never treat possession of a lease as proof that a delayed write is still valid.