feature: Automatically clear cache when -T changed

Author: dzz007

lib/cache.js

@@ -9,6 +9,12 @@ cache.init = function() {
   file.mkdir(file.cacheDir());
 };
 
+cache.deleteAll = function () {
+  cache.list().forEach(value => {
+    cache.del(value.name);
+  })
+};
+
 cache.get = function(k) {
   const fullpath = file.cacheFile(k);
   if (!file.exist(fullpath)) return null;

lib/helper.js

@@ -52,11 +52,12 @@ const LANGS = [
 const h = {};
 
 h.KEYS = {
-  user:     '../user',
-  stat:     '../stat',
-  plugins:  '../../plugins',
-  problems: 'problems',
-  problem:  p => p.fid + '.' + p.slug + '.' + p.category
+  user:        '../user',
+  stat:        '../stat',
+  plugins:     '../../plugins',
+  problems:    'problems',
+  translation: 'translationConfig',
+  problem:     p => p.fid + '.' + p.slug + '.' + p.category
 };
 
 h.prettyState = function(state) {

lib/plugins/cache.js

@@ -9,7 +9,21 @@ var session = require('../session');
 
 const plugin = new Plugin(50, 'cache', '', 'Plugin to provide local cache.');
 
-plugin.getProblems = function(needTranslation, cb) {
+// this function will clear all caches if needTranslation is different than stored
+// it will also store the new needTranslation into cache automatically
+function clearCacheIfTchanged(needTranslation) {
+  const translationConfig = cache.get(h.KEYS.translation);
+  if (!translationConfig || translationConfig['useEndpointTranslation'] != needTranslation) {
+    // cache doesn't have the key => old cache version, need to update
+    // or cache does have the key but it contains a different value
+    cache.deleteAll();
+    cache.set(h.KEYS.translation, { useEndpointTranslation: needTranslation });
+    log.debug('cache cleared: -T option changed');
+  }
+}
+
+plugin.getProblems = function (needTranslation, cb) {
+  clearCacheIfTchanged(needTranslation);
   const problems = cache.get(h.KEYS.problems);
   if (problems) {
     log.debug('cache hit: problems.json');
@@ -24,7 +38,8 @@ plugin.getProblems = function(needTranslation, cb) {
   });
 };
 
-plugin.getProblem = function(problem, needTranslation, cb) {
+plugin.getProblem = function (problem, needTranslation, cb) {
+  clearCacheIfTchanged(needTranslation);
   const k = h.KEYS.problem(problem);
   const _problem = cache.get(k);
   if (_problem) {