perf(sinsp): sinsp_thread_manager::get_field_accessor

userspace/libsinsp/thread_manager.h

@@ -202,8 +202,9 @@ class SINSP_PUBLIC sinsp_thread_manager : public libsinsp::state::built_in_table
 
 	const libsinsp::state::dynamic_struct::field_accessor<std::string>* get_field_accessor(
 	        const std::string& field) const {
-		if(m_foreign_fields_accessors.count(field) > 0) {
-			return &m_foreign_fields_accessors.at(field);
+		if(auto it = m_foreign_fields_accessors.find(field);
+		   it != m_foreign_fields_accessors.end()) {
+			return &it->second;
 		}
 		return nullptr;
 	}

userspace/libsinsp/threadinfo.cpp

@@ -44,7 +44,9 @@ sinsp_threadinfo::sinsp_threadinfo(const std::shared_ptr<ctor_params>& params):
         m_main_fdtable(m_fdtable.table_ptr()),
         m_args_table_adapter("args", m_args),
         m_env_table_adapter("env", m_env),
-        m_cgroups_table_adapter("cgroups", m_cgroups) {
+        m_cgroups_table_adapter("cgroups", m_cgroups),
+        m_container_id_accessor(params->thread_manager->get_field_accessor(
+                sinsp_thread_manager::s_container_id_field_name)) {
 	init();
 }
 
@@ -408,13 +410,11 @@ std::string sinsp_threadinfo::get_exepath() const {
 }
 
 std::string sinsp_threadinfo::get_container_id() {
-	std::string container_id;
-
-	const auto accessor = m_params->thread_manager->get_field_accessor(
-	        sinsp_thread_manager::s_container_id_field_name);
-	if(accessor) {
-		get_dynamic_field(*accessor, container_id);
+	if(!m_container_id_accessor) {
+		return {};
 	}
+	std::string container_id;
+	get_dynamic_field(*m_container_id_accessor, container_id);
 	return container_id;
 }
 

userspace/libsinsp/threadinfo.h

@@ -671,6 +671,8 @@ class SINSP_PUBLIC sinsp_threadinfo : public libsinsp::state::table_entry {
 	        decltype(m_cgroups),
 	        libsinsp::state::pair_table_entry_adapter<std::string, std::string>>
 	        m_cgroups_table_adapter;
+
+	const libsinsp::state::dynamic_struct::field_accessor<std::string>* m_container_id_accessor;
 };
 
 /*@}*/