code: private void processJournal() throws IOException {
          FileUtils.deleteIfExists(mJournalFileTmp);
          for (Iterator<CacheEntry> i = mLruEntries.values().iterator(); i.hasNext(); ) {
              CacheEntry cacheEntry = i.next();
              if (!cacheEntry.isUnderEdit()) {
                  mSize += cacheEntry.getSize();
              } else {
                  cacheEntry.delete();
                  i.remove();
              }
          }
      }
docs: Computes the initial size and collects garbage as a part of opening the
  cache. Dirty entries are assumed to be inconsistent and will be deleted.