keyv-nedb-core/index.js

nedb-core adapter for keyv

const promisify = require('util').promisify
const Datastore = require('nedb-core')
const JSONB = require('json-buffer')

const prop = (p) => (x) => x == null ? undefined : x[p]
const always = (v) => () => v

function KeyvNedbCore (options, deserialize) {
  this.deserialize = deserialize || JSONB.parse
  this.nedb = new Datastore(options)
  this.opsCount = 0
  if (options && typeof options.automaticEviction === 'number' && options.automaticEviction > 0) {
    this.autoEvict = options.automaticEviction
  } else {
    this.autoEvict = false
  }
  this.dbaccess = {
    find: promisify(this.nedb.find.bind(this.nedb)),
    findOne: promisify(this.nedb.findOne.bind(this.nedb)),
    remove: promisify(this.nedb.remove.bind(this.nedb)),
    update: promisify(this.nedb.update.bind(this.nedb))
  }
}

function getOpsChain (obj) {
  ++obj.opsCount
  let chain = Promise.resolve(true)
  if (obj.autoEvict && obj.opsCount >= obj.autoEvict) {
    chain = chain.then(() => obj.evictExpired())
  }
  return chain
}

KeyvNedbCore.prototype = {
  clear () {
    this.opsCount = 0
    return this.dbaccess.remove({}, { multi: true }).then(always(undefined))
  },
  delete (key) {
    return getOpsChain(this)
      .then(() => this.dbaccess.findOne({ key }))
      .then((v) => {
        let ret = true
        if (!v) {
          ret = false
        }
        return this.dbaccess.remove({ key }).then(always(ret))
      })
  },
  get (key) {
    return getOpsChain(this).then(() => this.dbaccess.findOne({ key })).then(prop('value'))
  },
  set (key, value) {
    return getOpsChain(this).then(() => this.dbaccess.update({ key }, { key, value }, { upsert: true })).then(always(true))
  },
  evictExpired () {
    this.opsCount = 0
    return this.dbaccess.find({}).then(docs => {
      let acts = []
      for (let doc of docs) {
        let value = (typeof doc.value === 'string') ? this.deserialize(doc.value) : doc
        if (value == null) {
          continue
        }
        if (typeof value.expires === 'number' && Date.now() > value.expires) {
          acts.push(this.delete(doc.key))
        }
      }
      return Promise.all(acts).then(always(true))
    })
  }
}

module.exports = KeyvNedbCore