fix bug

db/version_set.cc

@@ -328,7 +328,9 @@ Status Version::Get(const ReadOptions& options, const LookupKey& k,
   Slice ikey = k.internal_key();
   Slice user_key = k.user_key();
   const Comparator* ucmp = vset_->icmp_.user_comparator();
-  Status s;
+  
+  stats->seek_file = nullptr;
+  stats->seek_file_level = -1;
 
   struct State {
     GetStats* stats;
@@ -337,6 +339,8 @@ Status Version::Get(const ReadOptions& options, const LookupKey& k,
     Slice user_key;
     const Comparator* ucmp;
     std::string* value;
+    FileMetaData *last_file_read;
+    int last_file_level;
 
     VersionSet *vset;
     Status s;
@@ -344,11 +348,13 @@ Status Version::Get(const ReadOptions& options, const LookupKey& k,
     static bool Match(void* arg, int level, FileMetaData* f) {
       State* state = reinterpret_cast<State*>(arg);
 
-      if (state->stats->seek_file == nullptr) {
+      if (state->last_file_read != nullptr && state->stats->seek_file == nullptr) {
         // We have had more than one seek for this read.  Charge the 1st file.
-        state->stats->seek_file = f;
-        state->stats->seek_file_level = level;
+        state->stats->seek_file = state->last_file_read;
+        state->stats->seek_file_level = state->last_file_level;
       }
+      state->last_file_read = f;
+      state->last_file_level = level;
 
       Saver saver;
       saver.state = kNotFound;
@@ -378,18 +384,18 @@ Status Version::Get(const ReadOptions& options, const LookupKey& k,
     }
   };
 
-  stats->seek_file = nullptr;
-  stats->seek_file_level = -1;
-
   State state;
   state.s = Status::NotFound(Slice());
   state.stats = stats;
+  state.last_file_read = nullptr;
+  state.last_file_level = -1;
+
   state.ikey = ikey;
   state.user_key = user_key;
   state.ucmp = ucmp;
   state.value = value;
   state.vset = vset_;
-
+  
   ForEachOverlapping(user_key, ikey, &state, &State::Match);
 
   return state.s;