nanoresource-pool

Manage a pool of nanoresource instances.

Installation

$ npm install nanoresource-pool

Status

Stable

Usage

const { Pool } = require('nanoresource-pool')

const pool = new Pool()

// add a resource
pool.add(resource)

// query all 'active' resources with a
// property called 'filename' with a value that matches '*.js'
pool.query({ filename: '*.js' })

// close pool and all resources when all resources are inactive
pool.close(callbackA)

Example

Below is an example pool implementation of opened JavaScript and JSON files.

const Resource = require('nanoresource')
const Pool = require('nanoresource-pool')
const fs = require('fs')

class File extends Resource {
  constructor(filename) {
    super()
    this.fd = 0
    this.filename = filename
  }

  _open(callback) {
    fs.open(this.filename, (err, fd) => {
      this.fd = fd
      callback(err)
    })
  }

  _close(callback) {
    fs.close(this.fd, callback)
  }
}

// `js`and `json` resources are based on the `File` class
const js = new Pool(File)
const json = new Pool(File)
const files = new Pool()

files.add(js)
files.add(json)

json.resource('package-lock.json')
json.resource('package.json')

js.resource('test.js')
js.resource('index.js')
js.resource('example.js')

files.ready(() => {
  // `query()` will search for resources in pool and
  // in child pools (recursively) using
  // static values, regular expression, and function
  // predcates to find something
  let results = null
  results = files.query({ filename: '*.js' }))
  results = files.query({ filename: (filename) => /.*.json/.test(filename) }))

  // will close all resources waiting after waiting for
  // all resources to be inactive
  files.close((err) => {
  })
})

API

pool = new Pool([Factory[, opts]])

Creates a new Pool instance from Factory and opts where Factory is an optional nanoresource constructor function and opts can be an object like:

{
  guard: NanoGuard(),
  allowActive: false,
  autoOpen: true, // if `false` you must call `pool.open()`
}

pool.opened

A boolean to indicated if the Pool is opened.

pool.opening

A boolean to indicated if the Pool is opening.

pool.closed

A boolean to indicated if the Pool is closed.

pool.closing

A boolean to indicated if the Pool is closing.

pool.allowActive

A default boolean value passed to each resource.close() method call for resources when the pool closes.

pool.size

The number of open and active resources. Accumlates the size of any children pools added.

pool.actives

The number of active resource handles.

pool.list([opts])

Get a list of resources, optionally filtering out resources marked as "closed" or "closing" where opts can be:

{
  closed: true
}

pool.ready(callback)

Waits for pool to be ready and calls callback() when it is.

pool.open([callback])

Opens the pool. You only need to call this if opts.autoOpen was set to false in the Pool constructor.

pool.close([allowActive[, callback])

Close pool and all added resources and child pools. Passes allowActive directly to the all of the resource's close() methods. If you do not provide the allowActive value, pool.allowActive will be used by default.

pool.query([where[, opts[, callback]])

Query for resources added to the pool. This function will also query any added child pools on the instance.

pool.add(resource[, opts])

Add a resource to the pool. Will remove from pool when the resource successfully closes. Set opts.autoOpen = false to prevent the added resource from automatically opening.

pool.resource(...args)

Acquire a new resource based on the pool factory constructor. (calls new pool.Factory(...args)).

License

MIT