Class: WriteSerializer

A job-scoped write serializer for driver transport access.

A printer driver issues transport I/O from several methods — print() (a long burst of transport.write() calls), getStatus() (a write + read round-trip), and driver-specific helpers. Nothing in the transport layer orders those against each other: a status poll firing mid-print() would interleave its write() between two raster write()s and corrupt the device's command stream.

WriteSerializer fixes that at the driver layer — the only layer that knows job boundaries. Each driver holds one instance and routes every transport-touching method through run(); calls then execute strictly in submission order, each waiting for the prior one to finish before touching the transport.

It is exactly the hand-rolled runLocked pattern proven in the brother-ql driver, lifted into one shared primitive so every driver serialises identically rather than carrying its own copy.

Like polling-on-status.ts, this module stays free of @types/node and DOM globals — it only needs Promise — so the contracts type surface stays platform-clean.

Usage on a driver printer class:

private readonly serializer = new WriteSerializer();

print(image: RawImageData): Promise<void> {
  return this.serializer.run(() => this.doPrint(image));
}

getStatus(): Promise<PrinterStatus> {
  return this.serializer.run(() => this.doGetStatus());
}

Constructors

Constructor

new WriteSerializer(): WriteSerializer;

Returns

WriteSerializer

Methods

run()

run<T>(fn: () => Promise<T>): Promise<T>;

Run fn once every previously-submitted operation has finished.

Concurrent callers queue and execute in submission order. The caller receives fn's resolved value, or its rejection — a thrown/rejecting fn rejects only its own caller and does not poison the lock: the next run() still proceeds.

Type Parameters

Type Parameter
T

Parameters

Parameter	Type
fn	() => Promise<T>

Returns

Promise<T>