Include candidate files under options.db_log_dir in FindObsoleteFiles()

Summary: In FindObsoleteFiles(), we don't scan db_log_dir. Add it.

Test Plan: make all check

Reviewers: ljin, igor, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb, yhchiang

Differential Revision: https://reviews.facebook.net/D21429

db/db_impl.cc

@@ -588,6 +588,14 @@ void DBImpl::FindObsoleteFiles(DeletionState& deletion_state,
         deletion_state.candidate_files.emplace_back(log_file, 0);
       }
     }
+    // Add info log files in db_log_dir
+    if (options_.db_log_dir.empty() && options_.db_log_dir != dbname_) {
+      std::vector<std::string> info_log_files;
+      env_->GetChildren(options_.db_log_dir, &info_log_files);  // Ignore errors
+      for (std::string log_file : info_log_files) {
+        deletion_state.candidate_files.emplace_back(log_file, 0);
+      }
+    }
   }
 }