feat grpc: add 'error_msg' tag to client span in case gRPC call was interrupted

commit_hash:24738f06f74becf63beebbf60deb3445a2ac394b

Author: pananton

grpc/include/userver/ugrpc/client/completion_status.hpp

@@ -53,6 +53,9 @@ enum class SpecialCaseCompletionType : std::uint8_t {
 /// @brief Convert SpecialCaseCompletionType to string representation.
 std::string_view ToString(SpecialCaseCompletionType type);
 
+/// @brief Convert SpecialCaseCompletionType to human-readable description.
+std::string_view GetSpecialCaseCompletionTypeDescription(SpecialCaseCompletionType type);
+
 /// @ingroup userver_ugrpc
 ///
 /// @brief Result type for gRPC client call completion.

grpc/src/ugrpc/client/completion_status.cpp

@@ -18,6 +18,22 @@ std::string_view ToString(SpecialCaseCompletionType type) {
     return "unknown";
 }
 
+std::string_view GetSpecialCaseCompletionTypeDescription(SpecialCaseCompletionType type) {
+    switch (type) {
+        case SpecialCaseCompletionType::kNetworkError:
+            return "underlying network operation failed (e.g., connection lost, socket error)";
+        case SpecialCaseCompletionType::kTimeoutDeadlinePropagated:
+            return "timed out because of the propagated deadline from the upstream request";
+        case SpecialCaseCompletionType::kCancelled:
+            return "task was cancelled (e.g. calling code dropped TaskWithResult object, or upstream client cancelled "
+                   "the request)";
+        case SpecialCaseCompletionType::kAbandoned:
+            return "object representing the call was destroyed before the call could complete normally";
+    }
+
+    return "unknown completion type";
+}
+
 }  // namespace ugrpc::client
 
 USERVER_NAMESPACE_END

grpc/src/ugrpc/client/middlewares/log/middleware.cpp

@@ -1,5 +1,7 @@
 #include <ugrpc/client/middlewares/log/middleware.hpp>
 
+#include <fmt/format.h>
+
 #include <userver/logging/level.hpp>
 #include <userver/logging/log_extra.hpp>
 #include <userver/tracing/tags.hpp>
@@ -116,8 +118,15 @@ void Middleware::PostFinish(MiddlewareCallContext& context, const CompletionStat
     } else {
         // Special case completion
         const auto completion_type = result.error();
-        logging::LogExtra
-            extra{{ugrpc::impl::kTypeTag, "special_case_completion"}, {"completion_type", ToString(completion_type)}};
+        logging::LogExtra extra{
+            {ugrpc::impl::kTypeTag, "special_case_completion"},
+            {"completion_type", ToString(completion_type)},
+            {tracing::kErrorMessage,
+             fmt::format(
+                 "Call is interrupted before it was finished and response with status code was received, reason='{}'",
+                 GetSpecialCaseCompletionTypeDescription(completion_type)
+             )}
+        };
         logger.Log(logging::Level::kWarning, "gRPC error", std::move(extra));
     }
 }