WIP: remove async from storage module

lib/storage.js

@@ -7,16 +7,21 @@
  * It's essentially fs, mkdirp and crash safe write and read functions
  */
 const fs = require('fs')
+const fsPromises = require('fs/promises')
 const path = require('path')
-const async = require('async')
+const { callbackify, promisify } = require('util')
 const storage = {}
 const { Readable } = require('stream')
 
 // eslint-disable-next-line node/no-callback-literal
 storage.exists = (path, cb) => fs.access(path, fs.constants.F_OK, (err) => { cb(!err) })
+storage.existsAsync = path => fsPromises.access(path, fs.constants.F_OK).then(() => true, () => false)
 storage.rename = fs.rename
+storage.renameAsync = fsPromises.rename
 storage.writeFile = fs.writeFile
+storage.writeFileAsync = fsPromises.writeFile
 storage.unlink = fs.unlink
+storage.unlinkAsync = fsPromises.unlink
 storage.appendFile = fs.appendFile
 storage.readFile = fs.readFile
 storage.readFileStream = fs.createReadStream
@@ -25,21 +30,21 @@ storage.mkdir = fs.mkdir
 /**
  * Explicit name ...
  */
-storage.ensureFileDoesntExist = (file, callback) => {
-  storage.exists(file, exists => {
-    if (!exists) return callback(null)
-
-    storage.unlink(file, err => callback(err))
-  })
+storage.ensureFileDoesntExistAsync = async file => {
+  if (await storage.existsAsync(file)) await storage.unlinkAsync(file)
 }
 
+storage.ensureFileDoesntExist = (file, callback) => callbackify(storage.ensureFileDoesntExistAsync)(file, err => callback(err))
+
 /**
  * Flush data in OS buffer to storage if corresponding option is set
  * @param {String} options.filename
  * @param {Boolean} options.isDir Optional, defaults to false
  * If options is a string, it is assumed that the flush of the file (not dir) called options was requested
  */
-storage.flushToStorage = (options, callback) => {
+storage.flushToStorage = (options, callback) => callbackify(storage.flushToStorageAsync)(options, callback)
+
+storage.flushToStorageAsync = async (options) => {
   let filename
   let flags
   if (typeof options === 'string') {
@@ -62,23 +67,29 @@ storage.flushToStorage = (options, callback) => {
    * database is loaded and a crash happens.
    */
 
-  fs.open(filename, flags, (err, fd) => {
-    if (err) {
-      return callback((err.code === 'EISDIR' && options.isDir) ? null : err)
+  let fd, errorOnFsync, errorOnClose
+  try {
+    fd = await fsPromises.open(filename, flags)
+    try {
+      await fd.sync()
+    } catch (errFS) {
+      errorOnFsync = errFS
     }
-    fs.fsync(fd, errFS => {
-      fs.close(fd, errC => {
-        if ((errFS || errC) && !((errFS.code === 'EPERM' || errFS.code === 'EISDIR') && options.isDir)) {
-          const e = new Error('Failed to flush to storage')
-          e.errorOnFsync = errFS
-          e.errorOnClose = errC
-          return callback(e)
-        } else {
-          return callback(null)
-        }
-      })
-    })
-  })
+  } catch (error) {
+    if (error.code !== 'EISDIR' || !options.isDir) throw error
+  } finally {
+    try {
+      await fd.close()
+    } catch (errC) {
+      errorOnClose = errC
+    }
+  }
+  if ((errorOnFsync || errorOnClose) && !((errorOnFsync.code === 'EPERM' || errorOnClose.code === 'EISDIR') && options.isDir)) {
+    const e = new Error('Failed to flush to storage')
+    e.errorOnFsync = errorOnFsync
+    e.errorOnClose = errorOnClose
+    throw e
+  }
 }
 
 /**
@@ -109,6 +120,8 @@ storage.writeFileLines = (filename, lines, callback = () => {}) => {
   }
 }
 
+storage.writeFileLinesAsync = (filename, lines) => promisify(storage.writeFileLines)(filename, lines)
+
 /**
  * Fully write or rewrite the datafile, immune to crashes during the write operation (data will not be lost)
  * @param {String} filename
@@ -116,25 +129,24 @@ storage.writeFileLines = (filename, lines, callback = () => {}) => {
  * @param {Function} callback Optional callback, signature: err
  */
 storage.crashSafeWriteFileLines = (filename, lines, callback = () => {}) => {
+  callbackify(storage.crashSafeWriteFileLinesAsync)(filename, lines, callback)
+}
+
+storage.crashSafeWriteFileLinesAsync = async (filename, lines) => {
   const tempFilename = filename + '~'
 
-  async.waterfall([
-    async.apply(storage.flushToStorage, { filename: path.dirname(filename), isDir: true }),
-    cb => {
-      storage.exists(filename, exists => {
-        if (exists) storage.flushToStorage(filename, err => cb(err))
-        else return cb()
-      })
-    },
-    cb => {
-      storage.writeFileLines(tempFilename, lines, cb)
-    },
-    async.apply(storage.flushToStorage, tempFilename),
-    cb => {
-      storage.rename(tempFilename, filename, err => cb(err))
-    },
-    async.apply(storage.flushToStorage, { filename: path.dirname(filename), isDir: true })
-  ], err => callback(err))
+  await storage.flushToStorageAsync({ filename: path.dirname(filename), isDir: true })
+
+  const exists = await storage.existsAsync(filename)
+  if (exists) await storage.flushToStorageAsync({ filename })
+
+  await storage.writeFileLinesAsync(tempFilename, lines)
+
+  await storage.flushToStorageAsync(tempFilename)
+
+  await storage.renameAsync(tempFilename, filename)
+
+  await storage.flushToStorageAsync({ filename: path.dirname(filename), isDir: true })
 }
 
 /**
@@ -142,21 +154,20 @@ storage.crashSafeWriteFileLines = (filename, lines, callback = () => {}) => {
  * @param {String} filename
  * @param {Function} callback signature: err
  */
-storage.ensureDatafileIntegrity = (filename, callback) => {
-  const tempFilename = filename + '~'
+storage.ensureDatafileIntegrity = (filename, callback) => callbackify(storage.ensureDatafileIntegrityAsync)(filename, callback)
 
-  storage.exists(filename, filenameExists => {
-    // Write was successful
-    if (filenameExists) return callback(null)
+storage.ensureDatafileIntegrityAsync = async filename => {
+  const tempFilename = filename + '~'
 
-    storage.exists(tempFilename, oldFilenameExists => {
-      // New database
-      if (!oldFilenameExists) return storage.writeFile(filename, '', 'utf8', err => { callback(err) })
+  const filenameExists = await storage.existsAsync(filename)
+  // Write was successful
+  if (filenameExists) return
 
-      // Write failed, use old version
-      storage.rename(tempFilename, filename, err => callback(err))
-    })
-  })
+  const oldFilenameExists = await storage.existsAsync(tempFilename)
+  // New database
+  if (!oldFilenameExists) await storage.writeFileAsync(filename, '', 'utf8')
+  // Write failed, use old version
+  else await storage.renameAsync(tempFilename, filename)
 }
 
 // Interface