@digidem/atomic-fs-blob-store/index.js

blob store that stores blobs on the local file system (like fs-blob-store but atomic)

var mkdirp = require('mkdirp')
var LRU = require('lru-cache')
var eos = require('end-of-stream')
var duplexify = require('duplexify')
var path = require('path')
var fs = require('fs')
var createAtomicWriteStream = require('@digidem/fs-write-stream-atomic')

var noop = function() {}

var join = function(root, dir) {
  return path.join(root, path.resolve('/', dir).replace(/^[a-zA-Z]:/, ''))
}

var listen = function(stream, opts, cb) {
  if (!cb) return stream
  eos(stream, function(err) {
    if (err) return cb(err)
    cb(null, opts)
  })
  return stream
}

var BlobStore = function(opts) {
  if (!(this instanceof BlobStore)) return new BlobStore(opts)
  if (typeof opts === 'string') opts = {path:opts}

  this.path = opts.path
  this.cache = LRU(opts.cache || 100)
  // this.fsCreateWriteStream = opts.atomic ?
    // createAtomicWriteStream : fs.createWriteStream
  this.fsCreateWriteStream = createAtomicWriteStream
}

BlobStore.prototype.createWriteStream = function(opts, cb) {
  if (typeof opts === 'string') opts = {key:opts}
  if (opts.name && !opts.key) opts.key = opts.name
  cb = cb || function () {}

  var key = join(this.path, opts.key)
  var dir = path.dirname(key)
  var cache = this.cache
  var createWriteStream = this.fsCreateWriteStream

  var proxy = duplexify()
  proxy.setReadable(false)

  function setup () {
    var w = createWriteStream(key, opts)
    w.once('finish', function () {
      cb(null, opts)
    })
    w.once('error', cb)
    proxy.setWritable(w)
  }

  if (cache.get(dir)) {
    setup()
  } else {
    mkdirp(dir, function(err) {
      if (proxy.destroyed) return
      if (err) return proxy.destroy(err)
      cache.set(dir, true)
      setup()
    })
  }

  return proxy
}

BlobStore.prototype.createReadStream = function(key, opts) {
  if (key && typeof key === 'object') return this.createReadStream(key.key, key)
  return fs.createReadStream(join(this.path, key), opts)
}

BlobStore.prototype.exists = function(opts, cb) {
  if (typeof opts === 'string') opts = {key:opts}
  var key = join(this.path, opts.key)
  fs.stat(key, function(err, stat) {
    if (err && err.code !== 'ENOENT') return cb(err)
    cb(null, !!stat)
  })
}

BlobStore.prototype.remove = function(opts, cb) {
  if (typeof opts === 'string') opts = {key:opts}
  if (!opts) opts = noop
  var key = join(this.path, opts.key)
  fs.unlink(key, function(err) {
    if (err && err.code !== 'ENOENT') return cb(err)
    cb()
  })
}

module.exports = BlobStore