refactor: change the way adding src tvm id in access log

```
void Middleware::OnCallStart(MiddlewareCallContext& context) const {
    // Add common storage to extra log tags for other middlewares
    context.GetStorageContext().Emplace(kLogExtraTag, logging::LogExtra{});
}
```

This is a rather difficult operation involving dynamic allocation. It is cheaper not to create a kLogExtraTag key if it is not used.

On the other hand `SetAdditionalLogKeys` is a bit more convinient contract, cause it is not neccessary for a middleware check if LogExtra variable exists
commit_hash:5d13b5f73902e2b3fe4083cc47025728938bc0a9

Author: bykhovtsev

.mapping.json

@@ -2222,6 +2222,7 @@
   "grpc/include/userver/ugrpc/server/impl/stream_adapter.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/impl/stream_adapter.hpp",
   "grpc/include/userver/ugrpc/server/metadata_utils.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/metadata_utils.hpp",
   "grpc/include/userver/ugrpc/server/middlewares/access_log/component.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/middlewares/access_log/component.hpp",
+  "grpc/include/userver/ugrpc/server/middlewares/access_log/log_extra.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/middlewares/access_log/log_extra.hpp",
   "grpc/include/userver/ugrpc/server/middlewares/baggage/component.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/middlewares/baggage/component.hpp",
   "grpc/include/userver/ugrpc/server/middlewares/baggage/middleware.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/middlewares/baggage/middleware.hpp",
   "grpc/include/userver/ugrpc/server/middlewares/base.hpp":"taxi/uservices/userver/grpc/include/userver/ugrpc/server/middlewares/base.hpp",
@@ -2351,6 +2352,7 @@
   "grpc/src/ugrpc/server/impl/service_worker.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/impl/service_worker.cpp",
   "grpc/src/ugrpc/server/impl/service_worker_impl.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/impl/service_worker_impl.cpp",
   "grpc/src/ugrpc/server/middlewares/access_log/component.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/middlewares/access_log/component.cpp",
+  "grpc/src/ugrpc/server/middlewares/access_log/log_extra.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/middlewares/access_log/log_extra.cpp",
   "grpc/src/ugrpc/server/middlewares/access_log/middleware.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/middlewares/access_log/middleware.cpp",
   "grpc/src/ugrpc/server/middlewares/access_log/middleware.hpp":"taxi/uservices/userver/grpc/src/ugrpc/server/middlewares/access_log/middleware.hpp",
   "grpc/src/ugrpc/server/middlewares/baggage/middleware.cpp":"taxi/uservices/userver/grpc/src/ugrpc/server/middlewares/baggage/middleware.cpp",

grpc/benchmarks/format_log_message.cpp

@@ -17,18 +17,16 @@ void FormatLogMessage(benchmark::State& state) {
     std::string peer = "2a02:aaaa:aaaa:aaaa::1:1f";
     std::chrono::system_clock::time_point start_time(std::chrono::seconds{1024 * 1024 * 42});
     std::string_view call_name = "hello.HelloService/SayHello";
-    logging::LogExtra log_extra;
 
     // NOLINTNEXTLINE(clang-analyzer-deadcode.DeadStores)
     for (auto _ : state) {
-        auto result = ugrpc::server::impl::FormatLogMessage(
-            metadata, peer, start_time, call_name, grpc::StatusCode::OK, log_extra
-        );
+        auto result =
+            ugrpc::server::impl::FormatLogMessage(metadata, peer, start_time, call_name, grpc::StatusCode::OK, nullptr);
         benchmark::DoNotOptimize(result);
     }
 
     auto result =
-        ugrpc::server::impl::FormatLogMessage(metadata, peer, start_time, call_name, grpc::StatusCode::OK, log_extra);
+        ugrpc::server::impl::FormatLogMessage(metadata, peer, start_time, call_name, grpc::StatusCode::OK, nullptr);
 
     const std::string_view log_line_view{result.ExtractTextLogItem().log_line};  // Convert SmallString to string_view
 

grpc/include/userver/ugrpc/server/middlewares/access_log/component.hpp

@@ -15,7 +15,7 @@ USERVER_NAMESPACE_BEGIN
 namespace ugrpc::server::middlewares::access_log {
 
 /// @brief Storage to handle additional fields in access_log
-/// @snippet grpc/tests/logging_test.cpp
+/// @snippet grpc/tests/logging_test.cpp grpc log extra tag
 inline const utils::AnyStorageDataTag<ugrpc::server::StorageContext, logging::LogExtra> kLogExtraTag;
 
 /// @ingroup userver_components userver_base_classes

grpc/include/userver/ugrpc/server/middlewares/access_log/log_extra.hpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <userver/logging/log_extra.hpp>
+#include <userver/ugrpc/server/middlewares/base.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace ugrpc::server::middlewares::access_log {
+/// @brief Adds or extends log extra fields for gRPC access logging
+/// @param context Middleware call context containing the storage
+/// @param log_extra Additional log fields to add (will be moved from)
+/// @snippet grpc/tests/logging_test.cpp grpc log extra tag
+///
+/// If log extra fields already exist in the context, extends them with new fields.
+/// Otherwise, creates new log extra storage with the provided fields.
+void SetAdditionalLogKeys(MiddlewareCallContext& context, logging::LogExtra&& log_extra);
+}  // namespace ugrpc::server::middlewares::access_log
+
+USERVER_NAMESPACE_END

grpc/src/ugrpc/server/impl/format_log_message.cpp

@@ -74,7 +74,7 @@ logging::impl::LogExtraTskvFormatter FormatLogMessage(
     std::chrono::system_clock::time_point start_time,
     std::string_view call_name,
     grpc::StatusCode code,
-    const logging::LogExtra& log_extra
+    const logging::LogExtra* log_extra
 ) {
     static const auto timezone = utils::datetime::LocalTimezoneTimestring(start_time, "%z");
 
@@ -120,7 +120,9 @@ logging::impl::LogExtraTskvFormatter FormatLogMessage(
         ToString(code)
     );
 
-    formatter.Append(log_extra);
+    if (log_extra) {
+        formatter.Append(*log_extra);
+    }
 
     return formatter;
 }

grpc/src/ugrpc/server/impl/format_log_message.hpp

@@ -19,7 +19,7 @@ logging::impl::LogExtraTskvFormatter FormatLogMessage(
     std::chrono::system_clock::time_point start_time,
     std::string_view call_name,
     grpc::StatusCode code,
-    const logging::LogExtra& log_extra
+    const logging::LogExtra* log_extra
 );
 
 }  // namespace ugrpc::server::impl

grpc/src/ugrpc/server/middlewares/access_log/log_extra.cpp

@@ -0,0 +1,21 @@
+#include <userver/ugrpc/server/middlewares/access_log/log_extra.hpp>
+
+#include <userver/ugrpc/server/middlewares/access_log/component.hpp>
+
+USERVER_NAMESPACE_BEGIN
+
+namespace ugrpc::server::middlewares::access_log {
+
+void SetAdditionalLogKeys(MiddlewareCallContext& context, logging::LogExtra&& log_extra) {
+    auto* extra = context.GetStorageContext().GetOptional(kLogExtraTag);
+
+    if (extra) {
+        extra->Extend(std::move(log_extra));
+    } else {
+        context.GetStorageContext().Emplace(kLogExtraTag, std::move(log_extra));
+    }
+}
+
+}  // namespace ugrpc::server::middlewares::access_log
+
+USERVER_NAMESPACE_END

grpc/src/ugrpc/server/middlewares/access_log/middleware.cpp

@@ -21,7 +21,7 @@ void WriteAccessLog(
         constexpr auto kLevel = logging::Level::kInfo;
 
         if (access_tskv_logger.ShouldLog(kLevel)) {
-            const auto& log_extra = context.GetStorageContext().Get(kLogExtraTag);
+            const auto* log_extra = context.GetStorageContext().GetOptional(kLogExtraTag);
 
             access_tskv_logger.Log(
                 kLevel,
@@ -45,11 +45,6 @@ void WriteAccessLog(
 
 Middleware::Middleware(Settings&& settings) : logger_(std::move(settings.access_tskv_logger)) {}
 
-void Middleware::OnCallStart(MiddlewareCallContext& context) const {
-    // Add common storage to extra log tags for other middlewares
-    context.GetStorageContext().Emplace(kLogExtraTag, logging::LogExtra{});
-}
-
 void Middleware::OnCallFinish(MiddlewareCallContext& context, const grpc::Status& status) const {
     WriteAccessLog(context, status, *logger_);
 }

grpc/src/ugrpc/server/middlewares/access_log/middleware.hpp

@@ -17,8 +17,6 @@ class Middleware final : public MiddlewareBase {
 public:
     explicit Middleware(Settings&& settings);
 
-    void OnCallStart(MiddlewareCallContext& context) const override;
-
     void OnCallFinish(MiddlewareCallContext& context, const grpc::Status& status) const override;
 
 private:

grpc/tests/logging_test.cpp

@@ -2,11 +2,11 @@
 
 #include <gmock/gmock.h>
 
+#include <ugrpc/server/middlewares/access_log/middleware.hpp>
+#include <userver/ugrpc/server/middlewares/access_log/log_extra.hpp>
 #include <userver/utest/log_capture_fixture.hpp>
 #include <userver/utils/regex.hpp>
 
-#include <ugrpc/server/middlewares/access_log/middleware.hpp>
-
 #include <tests/unit_test_client.usrv.pb.hpp>
 #include <tests/unit_test_service.usrv.pb.hpp>
 #include <userver/ugrpc/tests/service_fixtures.hpp>
@@ -73,17 +73,20 @@ class ServiceWithAccessLogFixture : public ugrpc::tests::ServiceFixtureBase {
 // Test middleware that adds custom tags to LogExtra
 class TagsMiddleware final : public ugrpc::server::MiddlewareBase {
 public:
+    /// [grpc log extra tag]
     void OnCallStart(ugrpc::server::MiddlewareCallContext& context) const override {
-        auto* log_extra = context.GetStorageContext().GetOptional(ugrpc::server::middlewares::access_log::kLogExtraTag);
-
-        if (log_extra) {
-            log_extra->Extend("user_id", "12345");
-            log_extra->Extend("session_id", "abc-def-ghi");
-            log_extra->Extend("request_id", "req-98765");
-            log_extra->Extend("custom_tag", "test-value");
-            log_extra->Extend("numeric_tag", "42");
-        }
+        ugrpc::server::middlewares::access_log::SetAdditionalLogKeys(
+            context,
+            logging::LogExtra{
+                std::pair<std::string, std::string>("user_id", "12345"),
+                std::pair<std::string, std::string>("session_id", "abc-def-ghi"),
+                std::pair<std::string, std::string>("request_id", "req-98765"),
+                std::pair<std::string, std::string>("custom_tag", "test-value"),
+                std::pair<std::string, std::string>("numeric_tag", "42"),
+            }
+        );
     }
+    /// [grpc log extra tag]
 };
 
 template <typename GrpcService>