Do not hit problem cache without full props

Author: Vigilans

lib/plugins/cache.js

@@ -28,13 +28,20 @@ plugin.getProblem = function(problem, cb) {
   const k = h.KEYS.problem(problem);
   const _problem = cache.get(k);
   if (_problem) {
-    // Only hit description with html tags (<pre> always exists for presenting testcase)
-    if (_problem.desc.includes("<pre>")) {
+    // do not hit problem without html tags in desc (<pre> always exists for presenting testcase)
+    if (!_problem.desc.includes("<pre>")) {
+      log.debug('cache discarded for being no longer valid: ' + k + '.json');
+    }
+    // do not hit problem without likes & dislikes (logic will be improved in new lib)
+    else if (!['likes', 'dislikes'].every(p => p in _problem)) {
+      log.debug('cache discarded for being too old: ' + k + '.json');
+    }
+    // cache hit
+    else {
       log.debug('cache hit: ' + k + '.json');
       _.extendOwn(problem, _problem);
       return cb(null, problem);
     }
-    log.debug('cache discarded for being no longer valid: ' + k + '.json');
   }
 
   plugin.next.getProblem(problem, function(e, _problem) {