Lease

@rotorsoft/act-root

---

@rotorsoft/act-root / act/src / Lease

Type Alias: Lease

Lease = object

Defined in: libs/act/src/types/reaction.ts:326

Lease information for distributed stream processing.

Leases prevent concurrent processing of the same stream by multiple workers. When a worker acquires a lease, it has exclusive rights to process events for that stream until the lease expires or is acknowledged.

The drain process uses leases to:

• Prevent race conditions in distributed setups
• Track processing progress (watermark)
• Manage retries on failures
• Balance load between lagging and leading streams

Example

app.on("acked", (leases) => {
  leases.forEach(lease => {
    console.log(`Processed ${lease.stream} up to event ${lease.at}`);
  });
});

app.on("blocked", (blocked) => {
  blocked.forEach(({ stream, retry, error }) => {
    console.error(`Stream ${stream} blocked after ${retry} retries: ${error}`);
  });
});

See

Drain for drain cycle results

Properties

at

readonly at: number

Defined in: libs/act/src/types/reaction.ts:329

Watermark: last successfully processed event ID

---

by

readonly by: string

Defined in: libs/act/src/types/reaction.ts:330

Unique identifier of the lease holder (UUID)

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due?

readonly optional due?: number

Defined in: libs/act/src/types/reaction.ts:346

Defer marker on the finalize path. When set on a lease passed to Store.ack, the entry is deferred alongside its watermark advance: the adapter advances the watermark to at (the last event handled this cycle) and persists due (ms since epoch) as the stream's deferred_at, setting retry to the entry's own value — atomically with the other entries' acks. Advance and defer are independent legs, so a partial-progress defer keeps the handled prefix (it never re-runs on redelivery) while the remainder waits for due. Deferred entries are not part of ack's return value. Never set on leases returned by claim or carried by lifecycle events.

---

lagging

readonly lagging: boolean

Defined in: libs/act/src/types/reaction.ts:332

Whether this stream is behind (lagging frontier)

---

lane?

readonly optional lane?: string

Defined in: libs/act/src/types/reaction.ts:333

Drain lane the stream is bound to

---

retry

readonly retry: number

Defined in: libs/act/src/types/reaction.ts:331

Number of retry attempts (0 = first attempt)

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source?

readonly optional source?: string

Defined in: libs/act/src/types/reaction.ts:328

Optional source the subscription consumes from (literal name or regex pattern)

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stream

readonly stream: string

Defined in: libs/act/src/types/reaction.ts:327

The target stream name being processed