LeetLLM
MediumSchedulingPython 3

Worker Lease Registry

Coordinate worker ownership with TTL leases, heartbeat extension, stale-worker rejection, and fencing tokens.

40m2 sample tests4 hidden tests

Implement LeaseRegistry, an in-memory lease table for long-running worker jobs.

Requirements

  • acquire(run_id, worker_id, now) returns a lease dictionary or None.
  • Only one active lease may exist per run.
  • An expired lease can be acquired by another worker.
  • Every new lease gets a monotonically increasing fencing_token.
  • heartbeat(lease_id, fencing_token, now) extends the current lease and returns True or False.
  • validate(run_id, lease_id, fencing_token, now) returns whether a worker may still mutate the run.
  • release(lease_id, fencing_token) releases only the current lease.

Example

python
1registry = LeaseRegistry(ttl_seconds=10) 2lease = registry.acquire("run-1", "worker-a", now=0) 3assert lease["fencing_token"] == 1 4assert registry.acquire("run-1", "worker-b", now=5) is None 5assert registry.acquire("run-1", "worker-b", now=11)["fencing_token"] == 2

Constraints

  • Keep it single-process and in memory.
  • Use the provided now value. Don't call wall-clock time.
  • Treat expiry as expired when expires_at <= now.

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