allow configurable storage engine

lib/datastore.js

@@ -21,6 +21,7 @@ class Datastore extends EventEmitter {
    * @param {Function} [options.afterSerialization] Optional, serialization hooks
    * @param {Number} [options.corruptAlertThreshold] Optional, threshold after which an alert is thrown if too much data is corrupt
    * @param {Function} [options.compareStrings] Optional, string comparison function that overrides default for sorting
+   * @param {Object} [options.storage] Optional, custom storage engine
    *
    * Event Emitter - Events
    * * compaction.done - Fired whenever a compaction operation was finished
@@ -58,7 +59,8 @@ class Datastore extends EventEmitter {
       nodeWebkitAppName: options.nodeWebkitAppName,
       afterSerialization: options.afterSerialization,
       beforeDeserialization: options.beforeDeserialization,
-      corruptAlertThreshold: options.corruptAlertThreshold
+      corruptAlertThreshold: options.corruptAlertThreshold, 
+      storage: options.storage
     })
 
     // This new executor is ready if we don't use persistence

lib/persistence.js

@@ -21,6 +21,7 @@ class Persistence {
    */
   constructor (options) {
     this.db = options.db
+    this.storage = options.storage || storage
     this.inMemoryOnly = this.db.inMemoryOnly
     this.filename = this.db.filename
     this.corruptAlertThreshold = options.corruptAlertThreshold !== undefined ? options.corruptAlertThreshold : 0.1
@@ -92,7 +93,7 @@ class Persistence {
       }
     })
 
-    storage.crashSafeWriteFileLines(this.filename, lines, err => {
+    this.storage.crashSafeWriteFileLines(this.filename, lines, err => {
       if (err) return callback(err)
       this.db.emit('compaction.done')
       return callback(null)
@@ -146,7 +147,7 @@ class Persistence {
 
     if (toPersist.length === 0) return callback(null)
 
-    storage.appendFile(this.filename, toPersist, 'utf8', err => callback(err))
+    this.storage.appendFile(this.filename, toPersist, 'utf8', err => callback(err))
   }
 
   /**
@@ -254,7 +255,7 @@ class Persistence {
         Persistence.ensureDirectoryExists(path.dirname(this.filename), err => {
           // TODO: handle error
           // eslint-disable-next-line node/handle-callback-err
-          storage.ensureDatafileIntegrity(this.filename, err => {
+          this.storage.ensureDatafileIntegrity(this.filename, err => {
             // TODO: handle error
             const treatedDataCallback = (err, treatedData) => {
               if (err) return cb(err)
@@ -275,15 +276,15 @@ class Persistence {
               this.db.persistence.persistCachedDatabase(cb)
             }
 
-            if (storage.readFileStream) {
+            if (this.storage.readFileStream) {
               // Server side
-              const fileStream = storage.readFileStream(this.filename, { encoding: 'utf8' })
+              const fileStream = this.storage.readFileStream(this.filename, { encoding: 'utf8' })
               this.treatRawStream(fileStream, treatedDataCallback)
               return
             }
 
             // Browser
-            storage.readFile(this.filename, 'utf8', (err, rawData) => {
+            this.storage.readFile(this.filename, 'utf8', (err, rawData) => {
               if (err) return cb(err)
 
               try {
@@ -309,7 +310,7 @@ class Persistence {
    * cb is optional, signature: err
    */
   static ensureDirectoryExists (dir, callback = () => {}) {
-    storage.mkdir(dir, { recursive: true }, err => { callback(err) })
+    this.storage.mkdir(dir, { recursive: true }, err => { callback(err) })
   }
 
   /**