From 8ac4c35bf7e2edfbc889b4f2af2f90378f3fa23e Mon Sep 17 00:00:00 2001
From: Matias Romeo <matias.romeo@gmail.com>
Date: Mon, 12 Aug 2024 16:54:53 -0300
Subject: [PATCH] Return constant reference in value_promoter

---
 include/evm_runtime/config_wrapper.hpp |  4 ++--
 include/evm_runtime/value_promoter.hpp | 20 +++++++++-----------
 src/config_wrapper.cpp                 |  4 ++--
 3 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/include/evm_runtime/config_wrapper.hpp b/include/evm_runtime/config_wrapper.hpp
index 931cc019..b893dd70 100644
--- a/include/evm_runtime/config_wrapper.hpp
+++ b/include/evm_runtime/config_wrapper.hpp
@@ -58,8 +58,8 @@ struct config_wrapper {
     void update_consensus_parameters(eosio::asset ram_price_mb, uint64_t gas_price);
     void update_consensus_parameters2(std::optional<uint64_t> gas_txnewaccount, std::optional<uint64_t> gas_newaccount, std::optional<uint64_t> gas_txcreate, std::optional<uint64_t> gas_codedeposit, std::optional<uint64_t> gas_sset);
 
-    consensus_parameter_data_type get_consensus_param();
-    std::pair<consensus_parameter_data_type, bool> get_consensus_param_and_maybe_promote();
+    const consensus_parameter_data_type& get_consensus_param();
+    std::pair<const consensus_parameter_data_type&, bool> get_consensus_param_and_maybe_promote();
 
     void set_token_contract(eosio::name token_contract); // only set during init
     eosio::name get_token_contract() const;
diff --git a/include/evm_runtime/value_promoter.hpp b/include/evm_runtime/value_promoter.hpp
index e7d58f13..635a1479 100644
--- a/include/evm_runtime/value_promoter.hpp
+++ b/include/evm_runtime/value_promoter.hpp
@@ -16,29 +16,27 @@
     };
 
 #define VALUE_PROMOTER_IMPL(T)\
-    T get_value(time_point_sec genesis_time, time_point current_time)const {\
-        T current_value = cached_value;\
+    const T& get_value(time_point_sec genesis_time, time_point current_time)const {\
         if(pending_value.has_value() && pending_value->is_active(genesis_time, current_time)) {\
-            current_value = pending_value->value;\
+            return pending_value->value;\
         }\
-        return current_value;\
+        return cached_value;\
     }\
-    std::pair<T, bool> get_value_and_maybe_promote(time_point_sec genesis_time, time_point current_time) {\
-        T current_value = cached_value;\
+    std::pair<const T&, bool> get_value_and_maybe_promote(time_point_sec genesis_time, time_point current_time) {\
         bool promoted = false;\
         if(pending_value.has_value() && pending_value->is_active(genesis_time, current_time)) {\
-            current_value = pending_value->value;\
             promote_pending();\
             promoted = true;\
         }\
-        return std::pair<T, bool>(current_value, promoted);\
+        return std::pair<const T&, bool>(cached_value, promoted);\
     }\
     template <typename Visitor>\
     void update(Visitor&& visitor_fn, time_point_sec genesis_time, time_point current_time) {\
-        auto value = get_value_and_maybe_promote(genesis_time, current_time);\
-        visitor_fn(value.first);\
+        auto tmp = get_value_and_maybe_promote(genesis_time, current_time);\
+        T value = tmp.first;\
+        visitor_fn(value);\
         pending_value.emplace(T##_pending{\
-            .value = value.first,\
+            .value = value,\
             .time = current_time\
         });\
     }\
diff --git a/src/config_wrapper.cpp b/src/config_wrapper.cpp
index bb308bab..4724df8a 100644
--- a/src/config_wrapper.cpp
+++ b/src/config_wrapper.cpp
@@ -324,13 +324,13 @@ void config_wrapper::update_consensus_parameters2(std::optional<uint64_t> gas_tx
     set_dirty();
 }
 
-consensus_parameter_data_type config_wrapper::get_consensus_param() {
+const consensus_parameter_data_type& config_wrapper::get_consensus_param() {
     // should not happen
     eosio::check(_cached_config.consensus_parameter.has_value(), "consensus_parameter not exist");
     return _cached_config.consensus_parameter->get_value(_cached_config.genesis_time, get_current_time());
 }
 
-std::pair<consensus_parameter_data_type, bool> config_wrapper::get_consensus_param_and_maybe_promote() {
+std::pair<const consensus_parameter_data_type&, bool> config_wrapper::get_consensus_param_and_maybe_promote() {
 
     // should not happen
     eosio::check(_cached_config.consensus_parameter.has_value(), "consensus_parameter not exist");