nsolid-manager/nsolid/console/src/collect/storage.js

A manager that sets up and runs N|Solid for you

var fs = require('fs')
var rimraf = require('rimraf')
var path = require('path')
var level = require('levelup')
var mkdirp = require('mkdirp')
var leveldown = require('leveldown')

module.exports = getStorage

/**
 * Caching wrapper around createStorage
 */

function getStorage (storagePath, name, options = {}, done) {
  if (!storagePath) return done()

  // options is optional
  if (typeof options === 'function') {
    done = options
    options = {}
  }

  getStorage.dbs = getStorage.dbs || {}
  const dbPath = path.join(storagePath, name + '.db')

  function handleOpenError (e) {
    if (e.type === 'OpenError') {
      leveldown.repair(dbPath, function repairComplete (repairError) {
        if (repairError) return done(repairError)

        getStorage(storagePath, name, options, done)
      })
    } else {
      done(e)
    }
  }

  if (!getStorage.dbs[dbPath] || getStorage.dbs[dbPath].isClosed()) {
    const db = createStorage(dbPath, options)

    db.once('error', handleOpenError)
    db.once('ready', function dbReady () {
      db.removeListener('error', handleOpenError)
      if (getStorage.dbs[dbPath]) {
        delete getStorage.dbs[dbPath]
      }

      getStorage.dbs[dbPath] = db
      done(null, db)
    })
  } else {
    // db is available and open
    done(null, getStorage.dbs[dbPath])
  }
}

/**
 * Initialise a new leveldb instance
 */

function createStorage (dbPath, options) {
  if (!dbPath) return
  if (dbPath && typeof dbPath !== 'string') throw new TypeError('dbPath string required')

  const flush = !!options.flush

  try {
    if (flush) flushDir(dbPath)
    mkdirp.sync(dbPath)
  } catch (err) {
    // dir already exists is not an error for us
    if (err.code !== 'EEXISTS') throw err
  }

  return level(dbPath, {
    valueEncoding: 'json'
  })
}

/**
 * Wipe a directory.
 * Does nothing if dir is not a string or accessible.
 */

function flushDir (dir) {
  if (!dir || typeof dir !== 'string') return

  try {
    fs.accessSync(dir)
  } catch (err) {
    // ignore err, just return if can't access
    return
  }

  console.info('flushing', dir)
  rimraf.sync(dir)
}