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Lease

@rotorsoft/act-root

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

Type Alias: Lease

Lease = object

Defined in: libs/act/src/types/reaction.ts:228

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:231

Watermark: last successfully processed event ID

by​

readonly by: string

Defined in: libs/act/src/types/reaction.ts:232

Unique identifier of the lease holder (UUID)

lagging​

readonly lagging: boolean

Defined in: libs/act/src/types/reaction.ts:234

Whether this stream is behind (lagging frontier)

retry​

readonly retry: number

Defined in: libs/act/src/types/reaction.ts:233

Number of retry attempts (0 = first attempt)

source?​

readonly optional source: string

Defined in: libs/act/src/types/reaction.ts:230

Optional source stream for filtering

stream​

readonly stream: string

Defined in: libs/act/src/types/reaction.ts:229

The target stream name being processed