fix a bug of the ticker NO_FILE_OPENS (facebook#9677)

Summary:
In the original code, the value of `NO_FILE_OPENS` corresponding to the Ticker item will be increased regardless of whether the file is successfully opened or not. Even counts are repeated, which can lead to skewed counts.

Pull Request resolved: facebook#9677

Reviewed By: jay-zhuang

Differential Revision: D34725733

Pulled By: ajkr

fbshipit-source-id: 841234ed03802c0105fd2107d82a740265ead576

db/table_cache.cc

@@ -114,15 +114,18 @@ Status TableCache::GetTableReader(
   if (s.ok()) {
     s = ioptions_.fs->NewRandomAccessFile(fname, fopts, &file, nullptr);
   }
-  RecordTick(ioptions_.stats, NO_FILE_OPENS);
-  if (s.IsPathNotFound()) {
+  if (s.ok()) {
+    RecordTick(ioptions_.stats, NO_FILE_OPENS);
+  } else if (s.IsPathNotFound()) {
     fname = Rocks2LevelTableFileName(fname);
     s = PrepareIOFromReadOptions(ro, ioptions_.clock, fopts.io_options);
     if (s.ok()) {
       s = ioptions_.fs->NewRandomAccessFile(fname, file_options, &file,
                                             nullptr);
     }
-    RecordTick(ioptions_.stats, NO_FILE_OPENS);
+    if (s.ok()) {
+      RecordTick(ioptions_.stats, NO_FILE_OPENS);
+    }
   }
 
   if (s.ok()) {