Use faster implementation for merging

lib/Onyx.js

@@ -6,7 +6,8 @@ import Storage from './storage';
 import * as Logger from './Logger';
 import cache from './OnyxCache';
 import createDeferredTask from './createDeferredTask';
-import mergeWithCustomized from './mergeWithCustomized';
+// eslint-disable-next-line rulesdir/prefer-import-module-contents
+import {fastMerge} from './fastMerge';
 
 // Keeps track of the last connectionID that was used so we can keep incrementing it
 let lastConnectionID = 0;
@@ -761,7 +762,8 @@ function applyMerge(key, data) {
  if (_.isObject(data) || _.every(mergeValues, _.isObject)) {
  // Object values are merged one after the other
  return _.reduce(mergeValues, (modifiedData, mergeValue) => {
- const newData = mergeWithCustomized({}, modifiedData, mergeValue);
+ // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
+ const newData = Object.assign({}, fastMerge(modifiedData, mergeValue));
 
  // We will also delete any object keys that are undefined or null.
  // Deleting keys is not supported by AsyncStorage so we do it this way.
@@ -832,7 +834,7 @@ function initializeWithDefaultKeyStates() {
  .then((pairs) => {
  const asObject = _.object(pairs);
 
- const merged = mergeWithCustomized(asObject, defaultKeyStates);
+ const merged = fastMerge(asObject, defaultKeyStates);
  cache.merge(merged);
  _.each(merged, (val, key) => keyChanged(key, val));
  });

lib/OnyxCache.js

@@ -1,5 +1,6 @@
 import _ from 'underscore';
-import mergeWithCustomized from './mergeWithCustomized';
+// eslint-disable-next-line rulesdir/prefer-import-module-contents
+import {fastMerge} from './fastMerge';
 
 const isDefined = _.negate(_.isUndefined);
 
@@ -110,7 +111,8 @@ class OnyxCache {
  * @param {Record<string, *>} data - a map of (cache) key - values
  */
  merge(data) {
- this.storageMap = mergeWithCustomized({}, this.storageMap, data);
+ // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
+ this.storageMap = Object.assign({}, fastMerge(this.storageMap, data));
 
  const storageKeys = this.getAllKeys();
  const mergedKeys = _.keys(data);

lib/fastMerge.js

@@ -0,0 +1,43 @@
+// Mostly copied from https://medium.com/@lubaka.a/how-to-remove-lodash-performance-improvement-b306669ad0e1
+
+function isMergeableObject(val) {
+ const nonNullObject = val && typeof val === 'object';
+ return nonNullObject
+ && Object.prototype.toString.call(val) !== '[object RegExp]'
+ && Object.prototype.toString.call(val) !== '[object Date]';
+}
+
+function mergeObject(target, source) {
+ const destination = {};
+ if (isMergeableObject(target)) {
+ // eslint-disable-next-line rulesdir/prefer-underscore-method
+ const targetKeys = Object.keys(target);
+ for (let i = 0; i < targetKeys.length; ++i) {
+ const key = targetKeys[i];
+ destination[key] = target[key];
+ }
+ }
+ // eslint-disable-next-line rulesdir/prefer-underscore-method
+ const sourceKeys = Object.keys(source);
+ for (let i = 0; i < sourceKeys.length; ++i) {
+ const key = sourceKeys[i];
+ if (!isMergeableObject(source[key]) || !target[key]) {
+ destination[key] = source[key];
+ } else {
+ // eslint-disable-next-line no-use-before-define
+ destination[key] = fastMerge(target[key], source[key]);
+ }
+ }
+
+ return destination;
+}
+
+// eslint-disable-next-line import/prefer-default-export, rulesdir/no-inline-named-export
+export function fastMerge(target, source) {
+ // eslint-disable-next-line rulesdir/prefer-underscore-method
+ const array = Array.isArray(source);
+ if (array) {
+ return source;
+ }
+ return mergeObject(target, source);
+}

lib/storage/providers/LocalForage.js

@@ -7,7 +7,8 @@
 import localforage from 'localforage';
 import _ from 'underscore';
 import SyncQueue from '../../SyncQueue';
-import mergeWithCustomized from '../../mergeWithCustomized';
+// eslint-disable-next-line rulesdir/prefer-import-module-contents
+import {fastMerge} from '../../fastMerge';
 
 localforage.config({
  name: 'OnyxDB',
@@ -24,7 +25,8 @@ const provider = {
  return localforage.getItem(key)
  .then((existingValue) => {
  const newValue = _.isObject(existingValue)
- ? mergeWithCustomized({}, existingValue, value)
+ // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
+ ? Object.assign({}, fastMerge(existingValue, value))
  : value;
  return localforage.setItem(key, newValue);
  });