p-batch

Batch async operations

Useful, when you have batch endpoint (that can accept multiple queries at once) and want to group requests to this endpoint in parallel user requests.

Install

$ npm install --save p-batch

Usage

const PBatch = require('p-batch');

batch = new PBatch(keys => {
	console.log('Batching', keys);
	return keys.map(k => k + 1);
}, {
	maxBatchSize: 3
});

const results = await Promise.all([1, 2, 3, 4, 5].map(key => batch.add(key));

// first logs "Batching [1, 2, 3]"
// then       "Batching [4, 5]"
// results will contain [2, 3, 4, 5, 6]

API

PBatch(loader, [options])

Returns a new batch instance.

loader

Type: Function

Loader function. Accepts array of batched keys and returns array of results or throws with array of errors (or plain error, that will propagate to all promises).

options

maxBatchSize

Type: number Default: Infinity

Maximum batch size.

dispatchSignal

Type: Function Default: fn => process.nextTick(fn)

Executed after first key put in batch. It should call it's first argument, when it is time for dispatching.

Useful, if you need to wait constant time after last key batching for ex.

batch

PBatch instance.

.add(key)

Adds key to current batch. If batch is empty – schedules dispatch on next tick.

.addAll(keys)

Shortcut for Promise.all(keys.map(key => batch.add(key))).

.dispatch()

Runs loader on batched keys. Useful, when batch should be dispatched right now.

By default current batch will be dispatched on next tick.

License

MIT © Vsevolod Strukchinsky