add more logs

Summary:

as subject

Test Plan:db_test

Reviewers: dhruba

db/db_impl.cc

@@ -285,7 +285,12 @@ void DBImpl::DeleteObsoleteFiles() {
         Log(options_.info_log, "Delete type=%d #%lld\n",
             int(type),
             static_cast<unsigned long long>(number));
-        env_->DeleteFile(dbname_ + "/" + filenames[i]);
+        Status st = env_->DeleteFile(dbname_ + "/" + filenames[i]);
+        if(!st.ok()) {
+          Log(options_.info_log, "Delete type=%d #%lld FAILED\n",
+              int(type),
+              static_cast<unsigned long long>(number));
+        }
       }
     }
   }

db/version_set.cc

@@ -844,6 +844,9 @@ Status VersionSet::Recover() {
   }
   current.resize(current.size() - 1);
 
+  Log(options_->info_log, "Recovering from manifest file:%s\n",
+      current.c_str());
+
   std::string dscname = dbname_ + "/" + current;
   SequentialFile* file;
   s = env_->NewSequentialFile(dscname, &file);
@@ -935,6 +938,13 @@ Status VersionSet::Recover() {
     last_sequence_ = last_sequence;
     log_number_ = log_number;
     prev_log_number_ = prev_log_number;
+
+    Log(options_->info_log, "Recovering from manifest file:%s succeeded,"
+        "manifest_file_number is %lld, next_file_number is %lld, "
+        "last_sequence is %lld, log_number is %lld,"
+        "prev_log_number is %lld\n",
+        current.c_str(), manifest_file_number_, next_file_number_,
+        last_sequence_, log_number_, prev_log_number_);
   }
 
   return s;