downloaders — added es-6-promise-pool as a wourkaround React Native concurrent fetches bug (react-native-netinfo/react-native-netinfo#10)

Author: kriskate

package.json

@@ -18,6 +18,7 @@
     ]
   },
   "dependencies": {
+    "es6-promise-pool": "^2.5.0",
     "expo": "^32.0.0",
     "react": "16.5.0",
     "react-native": "https://github.com/expo/react-native/archive/sdk-32.0.0.tar.gz",

src/utils/downloaders.js

@@ -4,8 +4,9 @@ import { url, folder_data } from '../constants/Data';
 import { loadCurrentWikiInfo, loadWiki, } from './loaders';
 import { model_wiki_info } from '../constants/Models';
 import { CacheManager } from 'react-native-expo-image-cache';
+import PromisePool from 'es6-promise-pool';
+
 
-// to-do cleanup image downloading
 export const downloadImages = async (wiki, progress_callback, cancel) => {
   // Logger.debug('downloading images');
 
@@ -22,27 +23,29 @@ export const downloadImages = async (wiki, progress_callback, cancel) => {
   });
   images.items.push(url.images.items('recipe'));
 
-  
-  let cProgress = 0;
   const keys = Object.keys(images);
-  const imagesTotal = keys.reduce((res, arr) => res += images[arr].length, 0);
-  const step = 1 / imagesTotal;
-
-  let _images = [];
+  
+  let flatImages = [];
   keys.forEach(key => {
-    _images = _images.concat(images[key])
+    flatImages = flatImages.concat(images[key])
   });
-  // console.log(_images)
 
-  return Promise.all(
-    _images.map(async image => {
-      // if(cancel()) return;
+  let _processedImages = 0;
+  const imagesTotal = flatImages.length;
+  let cProgress = 0;
+  const step = 1 / imagesTotal;
 
-      await CacheManager.get(image).getPath();
-      progress_callback(cProgress += step);
-      // Logger.silly(`downloaded -${image}-`)
+  const promiseProducer = () => {
+    if (_processedImages < imagesTotal) {
+      _processedImages++;
+      return CacheManager.get(flatImages[_processedImages-1]).getPath()
+        .then(progress_callback(cProgress += step));
+    } else {
+      return null;
     }
-  ));
+  }
+
+  return new PromisePool(promiseProducer, 5).start();
 }
 
 

yarn.lock

@@ -2624,6 +2624,11 @@ es-to-primitive@^1.1.1:
     is-date-object "^1.0.1"
     is-symbol "^1.0.1"
 
+es6-promise-pool@^2.5.0:
+  version "2.5.0"
+  resolved "https://registry.yarnpkg.com/es6-promise-pool/-/es6-promise-pool-2.5.0.tgz#147c612b36b47f105027f9d2bf54a598a99d9ccb"
+  integrity sha1-FHxhKza0fxBQJ/nSv1SlmKmdnMs=
+
 escape-html@~1.0.3:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/escape-html/-/escape-html-1.0.3.tgz#0258eae4d3d0c0974de1c169188ef0051d1d1988"