Queue

Extends: EventEmitter

Source: queue.js:61

An ordered, event-driven task runner.

Queue extends Node's EventEmitter, so the inheritance chain and the emitted events both show up in the generated page.

Tasks pushed after Queue#clear runs are rejected — clearing aborts the in-flight signal.

Fires

• Queue#event:drain
• Queue#event:error

Listens

• module:forge/cache.Cache#event:evict

Example

Draining a queue

const q = new Queue({ concurrency: 2 });
q.on('drain', () => console.log('done'));
q.push({ id: 't1', run: async () => doWork() });
await q.drain();

• Since: 1.1.0
• Version: 1.3.0
• Copyright: 2024 The clean-jsdoc-theme team
• Author: The clean-jsdoc-theme team
• Requires: module:forge/cache
• TODO:
  • Add backpressure when the pending list exceeds a high-water mark.

Constructor

new Queue([options])

Parameters

• options (Object, optional, default: "{}") — Queue configuration.
  • options.concurrency (number, optional, default: 1) — How many tasks run at once (clamped to MAX_CONCURRENCY).
  • options.autoStart (boolean, optional, default: true) — Start draining as soon as a task is pushed.

Instance Methods

push(task) -> this

Add a task to the queue, inserted by Priority.

Parameters

• task (Task) — The task to enqueue.

Returns

• this — The queue, for chaining.

drain() -> Promise.<number>

Run every pending task and resolve once the queue is empty.

Returns

• Promise.<number> — The number of tasks that ran.

Fires

• Queue#event:drain

Example

const ran = await queue.drain();

tasks()

Iterate pending tasks in scheduling order, highest priority first.

Yields

• Task — The next pending task.

Example

The @lang directive forces this block's language

for (const task of queue.tasks()) {
  console.log(task.id satisfies string);
}

onError(error) -> void

Handle a task failure. Subclasses must implement this.

Parameters

• error (Error) — The error a task threw.

Returns

• void

_next() -> Task | undefined

Pull and start the next task. Internal scheduling step.

Returns

• Task | undefined — The task that was started, if any.

clear() -> void

Stop and clear the queue, aborting any in-flight task.

Returns

• void

Instance Fields

concurrency

Effective concurrency, clamped to MAX_CONCURRENCY.

Type

number