Refactor: Clean up local caching code

src/components/app.jsx

@@ -5,7 +5,7 @@ import ChangesetsViewerContainer from '../containers/summaryViewer';
 import DiffViewerContainer from '../containers/diffViewer';
 import FileViewerContainer from '../containers/fileViewer';
 import settings from '../settings';
-import clearLocalCache from '../utils/localCache';
+import { clearCache } from '../utils/localCache';
 import '../style.css';
 import AppDisclaimer from './disclaimer';
 import GitHubRibbon from './githubRibbon';
@@ -42,7 +42,7 @@ export default () => (
     <Route
       path="/clear-cache"
       render={() => {
-        if (clearLocalCache()) {
+        if (clearCache()) {
           return (<p>The local database has been cleared.</p>);
         }
         return (<p>Failed to clear the local DB.</p>);

src/settings.js

@@ -1,4 +1,4 @@
-export default {
+const settings = {
   BZ_URL: 'http://bugzilla.mozilla.org',
   CACHE_CONFIG: {
     SECONDS_TO_EXPIRE: 1 * 60 * 60, // 1 hour
@@ -29,3 +29,11 @@ export default {
   HG_DAYS_AGO: new Date((new Date()).getTime() - (2 * 24 * 60 * 60 * 1000))
     .toISOString().substring(0, 10),
 };
+
+if (settings.CACHE_CONFIG.ENABLED) {
+  console.debug('Local caching enabled');
+} else {
+  console.debug('Local caching disabled');
+}
+
+export default settings;

src/utils/hg.js

@@ -1,6 +1,6 @@
-import * as localForage from 'localforage';
 import settings from '../settings';
 import { JSON_HEADERS, PLAIN_HEADERS } from './fetch_data';
+import { getFromCache, saveInCache } from './localCache';
 
 export const HG_HOST = 'https://hg.mozilla.org';
 
@@ -75,64 +75,34 @@ const pushesToCsets = async (pushes, hidden) => {
   return filteredCsets;
 };
 
-
-const isExpiredCache = (lastCaching) => {
-  const MSTOS = 1000;
-  const currentTime = (new Date()).getTime();
-  const secondsDifference = (currentTime - lastCaching) / MSTOS;
-  console.debug((currentTime - lastCaching) / MSTOS);
-  return (
-    (typeof lastCaching === 'number') &&
-    (secondsDifference > settings.CACHE_CONFIG.SECONDS_TO_EXPIRE))
-    || false;
-};
-
-const getCsetsFromCache = async (repoName, hidden) => {
+const getChangesets = async (repoName, hidden) => {
   let csets = [];
+  if (settings.CACHE_CONFIG.ENABLED) {
     try {
-    const lastCaching = await localForage.getItem('cachedTime');
-    const cachedCsets = await localForage.getItem('changesets');
-    if (!isExpiredCache(lastCaching) && cachedCsets) {
-      console.debug(`Retrieved cached changesets. We have ${cachedCsets.length} changesets.`);
-      csets = cachedCsets;
-    } else {
-      console.debug('The cache has expired');
-    }
+      csets = await getFromCache('changesets');
     } catch (e) {
       // We only log since we want to fetch the changesets from Hg
       console.error(e);
     }
 
-  if (csets.length === 0) {
+    if (!csets || csets.length === 0) {
       console.debug('The local cache was not available.');
-    const pushes = await getJsonPushes(repoName);
-    const text = await (pushes).json();
+      const text = await (await getJsonPushes(repoName)).json();
       csets = await pushesToCsets(text.pushes, hidden);
+    }
 
     try {
-      const currentTime = (new Date()).getTime();
-      console.debug('Storing on local cache.');
-      await localForage.setItem('changesets', csets);
-      await localForage.setItem('cachedTime', currentTime);
+      saveInCache('changesets', csets);
     } catch (e) {
       console.info('We have failed to store to the local cache');
       // We don't want to throw an error and abort code execution
       console.error(e);
     }
-  }
-
-  return csets;
-};
-
-export default async (repoName, hidden) => {
-  let csets = [];
-  if (settings.CACHE_CONFIG.ENABLED) {
-    console.debug('Local caching enabled');
-    csets = await getCsetsFromCache(repoName, hidden);
   } else {
-    console.debug('Local caching disabled');
     const text = await (await getJsonPushes(repoName)).json();
     csets = await pushesToCsets(text.pushes, hidden);
   }
   return csets;
 };
+
+export default getChangesets;

src/utils/localCache.js

@@ -1,8 +1,47 @@
-import { clear } from 'localforage';
+import * as localForage from 'localforage';
+import settings from '../settings';
 
-export default () => {
+const CACHING_KEY = 'cachedTime';
+
+export const isExpiredCache = (lastCaching) => {
+  const MSTOS = 1000;
+  const currentTime = (new Date()).getTime();
+  const secondsDifference = (currentTime - lastCaching) / MSTOS;
+  console.debug((currentTime - lastCaching) / MSTOS);
+  return (
+    (typeof lastCaching === 'number') &&
+    (secondsDifference > settings.CACHE_CONFIG.SECONDS_TO_EXPIRE))
+    || false;
+};
+
+export const getFromCache = async (key) => {
+  let data;
   try {
-    clear();
+    const lastCaching = await localForage.getItem(CACHING_KEY);
+    data = await localForage.getItem(key);
+    if (!isExpiredCache(lastCaching) && data) {
+      console.debug('Retrieved data from the local cache.');
+    } else {
+      console.debug('The cache has expired');
+      data = undefined;
+    }
+  } catch (e) {
+    // We only log since we want to fetch the changesets from Hg
+    console.error(e);
+  }
+  return data;
+};
+
+export const saveInCache = async (key, data) => {
+  const currentTime = (new Date()).getTime();
+  console.debug('Storing on local cache.');
+  await localForage.setItem(key, data);
+  await localForage.setItem(CACHING_KEY, currentTime);
+};
+
+export const clearCache = () => {
+  try {
+    localForage.clear();
     return true;
   } catch (e) {
     console.log(e);