Merge pull request #67 from strongloop/feature/memory-persistence

Add an option for the memory connector to persist model instances

.gitignore

@@ -11,3 +11,4 @@ docs/html
 docs/man
 npm-debug.log
 .project
+test/memory.json

lib/connector.js

@@ -98,6 +98,7 @@ Connector.prototype.defineProperty = function (model, propertyName, propertyDefi
  */
 Connector.prototype.disconnect = function disconnect(cb) {
   // NO-OP
+  cb && process.nextTick(cb);
 };
 
 /**

lib/connectors/memory.js

@@ -2,6 +2,8 @@ var util = require('util');
 var Connector = require('../connector');
 var geo = require('../geo');
 var utils = require('../utils');
+var fs = require('fs');
+var async = require('async');
 
 /**
  * Initialize the Oracle connector against the given data source
@@ -10,24 +12,24 @@ var utils = require('../utils');
  * @param {Function} [callback] The callback function
  */
 exports.initialize = function initializeDataSource(dataSource, callback) {
-  dataSource.connector = new Memory();
+  dataSource.connector = new Memory(null, dataSource.settings);
   dataSource.connector.connect(callback);
 };
 
 exports.Memory = Memory;
 
-function Memory(m) {
-  if (m) {
+function Memory(m, settings) {
+  if (m instanceof Memory) {
     this.isTransaction = true;
     this.cache = m.cache;
     this.ids = m.ids;
-    this.constructor.super_.call(this, 'memory');
+    this.constructor.super_.call(this, 'memory', settings);
     this._models = m._models;
   } else {
     this.isTransaction = false;
     this.cache = {};
     this.ids = {};
-    this.constructor.super_.call(this, 'memory');
+    this.constructor.super_.call(this, 'memory', settings);
   }
 }
 
@@ -36,16 +38,77 @@ util.inherits(Memory, Connector);
 Memory.prototype.connect = function (callback) {
   if (this.isTransaction) {
     this.onTransactionExec = callback;
+  } else {
+    this.loadFromFile(callback);
+  }
+};
+
+Memory.prototype.loadFromFile = function(callback) {
+  var self = this;
+  if (self.settings.file) {
+    fs.readFile(self.settings.file, {encoding: 'utf8', flag: 'r'}, function (err, data) {
+      if (err && err.code !== 'ENOENT') {
+        callback && callback(err);
+      } else {
+        if (data) {
+          data = JSON.parse(data.toString());
+          self.ids = data.ids || {};
+          self.cache = data.models || {};
+        } else {
+          if(!self.cache) {
+            self.ids = {};
+            self.cache = {};
+          }
+        }
+        callback && callback();
+      }
+    });
   } else {
     process.nextTick(callback);
   }
 };
 
+/*!
+ * Flush the cache into the json file if necessary
+ * @param {Function} callback
+ */
+Memory.prototype.saveToFile = function (result, callback) {
+  var self = this;
+  if (this.settings.file) {
+    if(!self.writeQueue) {
+      // Create a queue for writes
+      self.writeQueue = async.queue(function (task, cb) {
+        // Flush out the models/ids
+        var data = JSON.stringify({
+          ids: self.ids,
+          models: self.cache
+        }, null, '  ');
+
+        fs.writeFile(self.settings.file, data, function (err) {
+          cb(err);
+          task.callback && task.callback(err, task.data);
+        });
+      }, 1);
+    }
+    // Enqueue the write
+    self.writeQueue.push({
+      data: result,
+      callback: callback
+    });
+  } else {
+    process.nextTick(function () {
+      callback && callback(null, result);
+    });
+  }
+};
+
 Memory.prototype.define = function defineModel(definition) {
   this.constructor.super_.prototype.define.apply(this, [].slice.call(arguments));
   var m = definition.model.modelName;
-  this.cache[m] = {};
-  this.ids[m] = 1;
+  if(!this.cache[m]) {
+    this.cache[m] = {};
+    this.ids[m] = 1;
+  }
 };
 
 Memory.prototype.create = function create(model, data, callback) {
@@ -68,10 +131,11 @@ Memory.prototype.create = function create(model, data, callback) {
   var idName = this.idName(model);
   id = (props[idName] && props[idName].type && props[idName].type(id)) || id;
   this.setIdValue(model, data, id);
+  if(!this.cache[model]) {
+    this.cache[model] = {};
+  }
   this.cache[model][id] = JSON.stringify(data);
-  process.nextTick(function () {
-    callback(null, id);
-  });
+  this.saveToFile(id, callback);
 };
 
 Memory.prototype.updateOrCreate = function (model, data, callback) {
@@ -90,9 +154,7 @@ Memory.prototype.updateOrCreate = function (model, data, callback) {
 
 Memory.prototype.save = function save(model, data, callback) {
   this.cache[model][this.getIdValue(model, data)] = JSON.stringify(data);
-  process.nextTick(function () {
-    callback(null, data);
-  });
+  this.saveToFile(data, callback);
 };
 
 Memory.prototype.exists = function exists(model, id, callback) {
@@ -110,7 +172,7 @@ Memory.prototype.find = function find(model, id, callback) {
 
 Memory.prototype.destroy = function destroy(model, id, callback) {
   delete this.cache[model][id];
-  process.nextTick(callback);
+  this.saveToFile(null, callback);
 };
 
 Memory.prototype.fromDb = function (model, data) {
@@ -273,7 +335,7 @@ Memory.prototype.destroyAll = function destroyAll(model, where, callback) {
   if (!where) {
     this.cache[model] = {};
   }
-  process.nextTick(callback);
+  this.saveToFile(null, callback);
 };
 
 Memory.prototype.count = function count(model, callback, where) {

test/memory.test.js

@@ -0,0 +1,95 @@
+var jdb = require('../');
+var DataSource = jdb.DataSource;
+var path = require('path');
+var fs = require('fs');
+var assert = require('assert');
+var async = require('async');
+
+describe('Memory connector', function () {
+  var file = path.join(__dirname, 'memory.json');
+
+  function readModels(done) {
+    fs.readFile(file, function (err, data) {
+      var json = JSON.parse(data.toString());
+      assert(json.models);
+      assert(json.ids.User);
+      done(err, json);
+    });
+  }
+
+  before(function (done) {
+    fs.unlink(file, function (err) {
+      if (!err || err.code === 'ENOENT') {
+        done();
+      }
+    });
+  });
+
+  it('should save to a json file', function (done) {
+    var ds = new DataSource({
+      connector: 'memory',
+      file: file
+    });
+
+    var User = ds.createModel('User', {
+      name: String,
+      bio: String,
+      approved: Boolean,
+      joinedAt: Date,
+      age: Number
+    });
+
+    var count = 0;
+    var ids = [];
+    async.eachSeries(['John1', 'John2', 'John3'], function (item, cb) {
+      User.create({name: item}, function (err, result) {
+        ids.push(result.id);
+        count++;
+        readModels(function (err, json) {
+          assert.equal(Object.keys(json.models.User).length, count);
+          cb(err);
+        });
+      });
+    }, function (err, results) {
+      // Now try to delete one
+      User.deleteById(ids[0], function (err) {
+        readModels(function (err, json) {
+          assert.equal(Object.keys(json.models.User).length, 2);
+          User.upsert({id: ids[1], name: 'John'}, function(err, result) {
+            readModels(function (err, json) {
+              assert.equal(Object.keys(json.models.User).length, 2);
+              var user = JSON.parse(json.models.User[ids[1]]);
+              assert.equal(user.name, 'John');
+              done();
+            });
+          });
+        });
+      });
+    });
+
+  });
+
+  // The saved memory.json from previous test should be loaded
+  it('should load from the json file', function (done) {
+    var ds = new DataSource({
+      connector: 'memory',
+      file: file
+    });
+
+    var User = ds.createModel('User', {
+      name: String,
+      bio: String,
+      approved: Boolean,
+      joinedAt: Date,
+      age: Number
+    });
+
+    User.find(function (err, users) {
+      // There should be 2 records
+      assert.equal(users.length, 2);
+      done(err);
+    });
+
+  });
+});
+