PS-9181: Fix masking_functions flusher thread loading

https://perconadev.atlassian.net/browse/PS-9181

The component_masking_functions fails to start cache flusger thread
from within compoent init function.

Make query_cache loading lazy. This allows to postpone flusher
initialization till the moment when component and server are
complettely initialized.

components/masking_functions/CMakeLists.txt

@@ -52,7 +52,6 @@ set(DATAMASKING_SOURCES
   include/masking_functions/primitive_singleton.hpp
   include/masking_functions/query_builder_fwd.hpp
   include/masking_functions/query_builder.hpp
-  include/masking_functions/query_cache_fwd.hpp
   include/masking_functions/query_cache.hpp
   include/masking_functions/random_string_generators.hpp
   include/masking_functions/registration_routines.hpp

components/masking_functions/include/masking_functions/query_cache.hpp

@@ -16,8 +16,6 @@
 #ifndef MASKING_FUNCTIONS_QUERY_CACHE_HPP
 #define MASKING_FUNCTIONS_QUERY_CACHE_HPP
 
-#include "masking_functions/query_cache_fwd.hpp"
-
 #include <atomic>
 #include <condition_variable>
 #include <memory>
@@ -37,8 +35,7 @@ namespace masking_functions {
 class query_cache {
  public:
   // passing unique_ptr by value to transfer ownership
-  query_cache(query_builder_ptr query_builder,
-              std::uint64_t flusher_interval_seconds);
+  query_cache();
   query_cache(const query_cache &other) = delete;
   query_cache(query_cache &&other) = delete;
   query_cache &operator=(const query_cache &other) = delete;

components/masking_functions/src/component.cpp

@@ -37,8 +37,6 @@
 #include "masking_functions/command_service_tuple.hpp"
 #include "masking_functions/component_sys_variable_service_tuple.hpp"
 #include "masking_functions/primitive_singleton.hpp"
-#include "masking_functions/query_builder.hpp"
-#include "masking_functions/query_cache.hpp"
 #include "masking_functions/registration_routines.hpp"
 #include "masking_functions/string_service_tuple.hpp"
 #include "masking_functions/sys_vars.hpp"
@@ -164,13 +162,6 @@ static mysql_service_status_t component_init() {
     return 1;
   }
 
-  auto builder{std::make_unique<masking_functions::query_builder>(
-      masking_functions::get_dict_database_name())};
-  masking_functions::primitive_singleton<
-      masking_functions::query_cache_ptr>::instance() =
-      std::make_unique<masking_functions::query_cache>(
-          std::move(builder), masking_functions::get_flush_interval_seconds());
-
   LogComponentErr(INFORMATION_LEVEL, ER_LOG_PRINTF_MSG,
                   "Component successfully initialized");
   return 0;
@@ -179,10 +170,6 @@ static mysql_service_status_t component_init() {
 static mysql_service_status_t component_deinit() {
   int result = 0;
 
-  masking_functions::primitive_singleton<
-      masking_functions::query_cache_ptr>::instance()
-      .reset();
-
   if (!masking_functions::unregister_udfs()) {
     LogComponentErr(ERROR_LEVEL, ER_LOG_PRINTF_MSG, "Cannot unregister UDFs");
     result = 1;

components/masking_functions/src/masking_functions/query_cache.cpp

@@ -46,12 +46,13 @@ constexpr const char flusher_thd_psi_os_name[]{"mf_flusher"};
 
 namespace masking_functions {
 
-query_cache::query_cache(query_builder_ptr query_builder,
-                         std::uint64_t flusher_interval_seconds)
-    : dict_query_builder_{std::move(query_builder)},
+query_cache::query_cache()
+    : dict_query_builder_{std::make_unique<masking_functions::query_builder>(
+          masking_functions::get_dict_database_name())},
       dict_cache_{},
       dict_cache_mutex_{},
-      flusher_interval_seconds_{flusher_interval_seconds},
+      flusher_interval_seconds_{
+          masking_functions::get_flush_interval_seconds()},
       is_flusher_stopped_{true} {
   // we do not initialize m_dict_cache with create_dict_cache_internal() here
   // as this constructor is called from the component initialization method

components/masking_functions/src/masking_functions/registration_routines.cpp

@@ -56,7 +56,7 @@ namespace {
 using global_string_services = masking_functions::primitive_singleton<
     masking_functions::string_service_tuple>;
 using global_query_cache =
-    masking_functions::primitive_singleton<masking_functions::query_cache_ptr>;
+    masking_functions::primitive_singleton<masking_functions::query_cache>;
 
 constexpr std::string_view masking_dictionaries_privilege_name =
     "MASKING_DICTIONARIES_ADMIN";
@@ -965,16 +965,15 @@ class gen_blocklist_impl {
         escape_string(make_charset_string_from_arg(ctx, 2));
 
     {
-      auto sresult = global_query_cache::instance()->contains(cs_dict_a_escaped,
-                                                              cs_term_escaped);
+      auto sresult = global_query_cache::instance().contains(cs_dict_a_escaped,
+                                                             cs_term_escaped);
 
       if (!sresult) {
         return cs_term_escaped;
       }
     }
 
-    auto sresult =
-        global_query_cache::instance()->get_random(cs_dict_b_escaped);
+    auto sresult = global_query_cache::instance().get_random(cs_dict_b_escaped);
 
     if (!sresult.empty()) {
       masking_functions::charset_string utf8_result{
@@ -1020,7 +1019,7 @@ class gen_dictionary_impl {
     const auto cs_dictionary_escaped =
         escape_string(make_charset_string_from_arg(ctx, 0));
     auto sresult =
-        global_query_cache::instance()->get_random(cs_dictionary_escaped);
+        global_query_cache::instance().get_random(cs_dictionary_escaped);
 
     if (!sresult.empty()) {
       return sresult;
@@ -1061,7 +1060,7 @@ class masking_dictionaries_flush_impl {
 
   mysqlpp::udf_result_t<STRING_RESULT> calculate(const mysqlpp::udf_context &ctx
                                                  [[maybe_unused]]) {
-    global_query_cache::instance()->reload_cache();
+    global_query_cache::instance().reload_cache();
 
     return "1";
   }
@@ -1106,7 +1105,7 @@ class masking_dictionary_remove_impl {
     const auto cs_dictionary_escaped =
         escape_string(make_charset_string_from_arg(ctx, 0));
 
-    if (!global_query_cache::instance()->remove(cs_dictionary_escaped)) {
+    if (!global_query_cache::instance().remove(cs_dictionary_escaped)) {
       return std::nullopt;
     }
 
@@ -1160,8 +1159,8 @@ class masking_dictionary_term_add_impl {
     const auto cs_term_escaped =
         escape_string(make_charset_string_from_arg(ctx, 1));
 
-    if (!global_query_cache::instance()->insert(cs_dictionary_escaped,
-                                                cs_term_escaped)) {
+    if (!global_query_cache::instance().insert(cs_dictionary_escaped,
+                                               cs_term_escaped)) {
       return std::nullopt;
     }
 
@@ -1215,8 +1214,8 @@ class masking_dictionary_term_remove_impl {
     const auto cs_term_escaped =
         escape_string(make_charset_string_from_arg(ctx, 1));
 
-    if (!global_query_cache::instance()->remove(cs_dictionary_escaped,
-                                                cs_term_escaped)) {
+    if (!global_query_cache::instance().remove(cs_dictionary_escaped,
+                                               cs_term_escaped)) {
       return std::nullopt;
     }