fix exec_count_db data race issue (OpenAtomFoundation#2671)

Co-authored-by: cjh <[email protected]>

include/pika_server.h

@@ -501,6 +501,17 @@ class PikaServer : public pstd::noncopyable {
    */
   int64_t GetLastSave() const {return lastsave_;}
   void UpdateLastSave(int64_t lastsave) {lastsave_ = lastsave;}
+  void InitStatistic(CmdTable *inited_cmd_table) {
+    // we insert all cmd name to statistic_.server_stat.exec_count_db,
+    // then when we can call PikaServer::UpdateQueryNumAndExecCountDB(const std::string&, const std::string&, bool) in parallel without lock
+    // although exec_count_db(unordered_map) is not thread-safe, but we won't trigger any insert or erase operation toward exec_count_db(unordered_map) during the running of pika
+    auto &exec_stat_map = statistic_.server_stat.exec_count_db;
+    for (auto& it : *inited_cmd_table) {
+      std::string cmd_name = it.first; //value copy is needed
+      pstd::StringToUpper(cmd_name); //cmd_name now is all uppercase
+      exec_stat_map.insert(std::make_pair(cmd_name, 0));
+    }
+  }
  private:
   /*
    * TimingTask use

src/pika.cc

@@ -211,7 +211,8 @@ int main(int argc, char* argv[]) {
   g_pika_rm = std::make_unique<PikaReplicaManager>();
   g_network_statistic = std::make_unique<net::NetworkStatistic>();
   g_pika_server->InitDBStruct();
-
+  //the cmd table of g_pika_cmd_table_manager must be inited before calling PikaServer::InitStatistic(CmdTable* )
+  g_pika_server->InitStatistic(g_pika_cmd_table_manager->GetCmdTable());
   auto status = g_pika_server->InitAcl();
   if (!status.ok()) {
     LOG(FATAL) << status.ToString();