dbus: more efficient implementation of properties

The way the various properties[] arrays are initialized is inefficient:
 - only the .data members change at runtime, yet the whole arrays of
   properties with all the fields are constructed on the stack one by
   one by the code.
 - there's duplication, eg. the properties of "org.freedesktop.systemd1.Unit"
   are repeated in several unit types.

Fix it by moving the information about properties into static const
sections. Instead of storing the .data directly in the property, store
a constant offset from a run-time base.
The small arrays of struct BusBoundProperties bind together the constant
information with the right runtime information (the base pointer).

On my system the code shrinks by 60 KB, data increases by 10 KB.

1 files changed, 51 insertions, 39 deletions

diff --git a/src/dbus-manager.c b/src/dbus-manager.c
index 710cbcb453..6d272cb321 100644
--- a/src/dbus-manager.c
+++ b/src/dbus-manager.c
@@ -491,46 +491,52 @@ static int bus_manager_send_unit_files_changed(Manager *m) {
         return r;
 }
 
-static DBusHandlerResult bus_manager_message_handler(DBusConnection *connection, DBusMessage *message, void *data) {
-        Manager *m = data;
+static const char systemd_property_string[] = PACKAGE_STRING "\0" DISTRIBUTION "\0" SYSTEMD_FEATURES;
 
-        const BusProperty properties[] = {
-                { "org.freedesktop.systemd1.Manager", "Version",       bus_property_append_string,    "s",  PACKAGE_STRING     },
-                { "org.freedesktop.systemd1.Manager", "Distribution",  bus_property_append_string,    "s",  DISTRIBUTION       },
-                { "org.freedesktop.systemd1.Manager", "Features",      bus_property_append_string,    "s",  SYSTEMD_FEATURES   },
-                { "org.freedesktop.systemd1.Manager", "RunningAs",     bus_manager_append_running_as, "s",  &m->running_as     },
-                { "org.freedesktop.systemd1.Manager", "Tainted",       bus_manager_append_tainted,    "s",  m                  },
-                { "org.freedesktop.systemd1.Manager", "InitRDTimestamp", bus_property_append_uint64,  "t",  &m->initrd_timestamp.realtime },
-                { "org.freedesktop.systemd1.Manager", "InitRDTimestampMonotonic", bus_property_append_uint64, "t", &m->initrd_timestamp.monotonic },
-                { "org.freedesktop.systemd1.Manager", "StartupTimestamp", bus_property_append_uint64, "t",  &m->startup_timestamp.realtime },
-                { "org.freedesktop.systemd1.Manager", "StartupTimestampMonotonic", bus_property_append_uint64, "t", &m->startup_timestamp.monotonic },
-                { "org.freedesktop.systemd1.Manager", "FinishTimestamp", bus_property_append_uint64,  "t",  &m->finish_timestamp.realtime },
-                { "org.freedesktop.systemd1.Manager", "FinishTimestampMonotonic", bus_property_append_uint64, "t",&m->finish_timestamp.monotonic },
-                { "org.freedesktop.systemd1.Manager", "LogLevel",      bus_manager_append_log_level,  "s",  m, bus_manager_set_log_level },
-                { "org.freedesktop.systemd1.Manager", "LogTarget",     bus_manager_append_log_target, "s",  m, bus_manager_set_log_target },
-                { "org.freedesktop.systemd1.Manager", "NNames",        bus_manager_append_n_names,    "u",  m                  },
-                { "org.freedesktop.systemd1.Manager", "NJobs",         bus_manager_append_n_jobs,     "u",  m                  },
-                { "org.freedesktop.systemd1.Manager", "NInstalledJobs",bus_property_append_uint32,    "u",  &m->n_installed_jobs },
-                { "org.freedesktop.systemd1.Manager", "NFailedJobs",   bus_property_append_uint32,    "u",  &m->n_failed_jobs  },
-                { "org.freedesktop.systemd1.Manager", "Progress",      bus_manager_append_progress,   "d",  m                  },
-                { "org.freedesktop.systemd1.Manager", "Environment",   bus_property_append_strv,      "as", m->environment     },
-                { "org.freedesktop.systemd1.Manager", "ConfirmSpawn",  bus_property_append_bool,      "b",  &m->confirm_spawn  },
-                { "org.freedesktop.systemd1.Manager", "ShowStatus",    bus_property_append_bool,      "b",  &m->show_status    },
-                { "org.freedesktop.systemd1.Manager", "UnitPath",      bus_property_append_strv,      "as", m->lookup_paths.unit_path },
-                { "org.freedesktop.systemd1.Manager", "NotifySocket",  bus_property_append_string,    "s",  m->notify_socket   },
-                { "org.freedesktop.systemd1.Manager", "ControlGroupHierarchy", bus_property_append_string, "s", m->cgroup_hierarchy },
-                { "org.freedesktop.systemd1.Manager", "MountAuto",     bus_property_append_bool,      "b",  &m->mount_auto     },
-                { "org.freedesktop.systemd1.Manager", "SwapAuto",      bus_property_append_bool,      "b",  &m->swap_auto      },
-                { "org.freedesktop.systemd1.Manager", "DefaultControllers", bus_property_append_strv, "as", m->default_controllers },
-                { "org.freedesktop.systemd1.Manager", "DefaultStandardOutput", bus_manager_append_exec_output, "s", &m->default_std_output },
-                { "org.freedesktop.systemd1.Manager", "DefaultStandardError",  bus_manager_append_exec_output, "s", &m->default_std_error  },
+static const BusProperty bus_systemd_properties[] = {
+        { "Version",       bus_property_append_string,    "s",  0                                             },
+        { "Distribution",  bus_property_append_string,    "s",  sizeof(PACKAGE_STRING)                        },
+        { "Features",      bus_property_append_string,    "s",  sizeof(PACKAGE_STRING) + sizeof(DISTRIBUTION) },
+        { NULL, }
+};
+
+static const BusProperty bus_manager_properties[] = {
+        { "RunningAs",     bus_manager_append_running_as,          "s", offsetof(Manager, running_as)                  },
+        { "Tainted",       bus_manager_append_tainted,             "s", 0 },
+        { "InitRDTimestamp", bus_property_append_uint64,           "t", offsetof(Manager, initrd_timestamp.realtime)   },
+        { "InitRDTimestampMonotonic", bus_property_append_uint64,  "t", offsetof(Manager, initrd_timestamp.monotonic)  },
+        { "StartupTimestamp", bus_property_append_uint64,          "t", offsetof(Manager, startup_timestamp.realtime)  },
+        { "StartupTimestampMonotonic", bus_property_append_uint64, "t", offsetof(Manager, startup_timestamp.monotonic) },
+        { "FinishTimestamp", bus_property_append_uint64,           "t", offsetof(Manager, finish_timestamp.realtime)   },
+        { "FinishTimestampMonotonic", bus_property_append_uint64,  "t", offsetof(Manager, finish_timestamp.monotonic)  },
+        { "LogLevel",      bus_manager_append_log_level,           "s", 0,                                             0, bus_manager_set_log_level },
+        { "LogTarget",     bus_manager_append_log_target,          "s", 0,                                             0, bus_manager_set_log_target },
+        { "NNames",        bus_manager_append_n_names,             "u", 0 },
+        { "NJobs",         bus_manager_append_n_jobs,              "u", 0 },
+        { "NInstalledJobs",bus_property_append_uint32,             "u", offsetof(Manager, n_installed_jobs)            },
+        { "NFailedJobs",   bus_property_append_uint32,             "u", offsetof(Manager, n_failed_jobs)               },
+        { "Progress",      bus_manager_append_progress,            "d", 0 },
+        { "Environment",   bus_property_append_strv,              "as", offsetof(Manager, environment),                true },
+        { "ConfirmSpawn",  bus_property_append_bool,               "b", offsetof(Manager, confirm_spawn)               },
+        { "ShowStatus",    bus_property_append_bool,               "b", offsetof(Manager, show_status)                 },
+        { "UnitPath",      bus_property_append_strv,              "as", offsetof(Manager, lookup_paths.unit_path),     true },
+        { "NotifySocket",  bus_property_append_string,             "s", offsetof(Manager, notify_socket),              true },
+        { "ControlGroupHierarchy", bus_property_append_string,     "s", offsetof(Manager, cgroup_hierarchy),           true },
+        { "MountAuto",     bus_property_append_bool,               "b", offsetof(Manager, mount_auto)                  },
+        { "SwapAuto",      bus_property_append_bool,               "b", offsetof(Manager, swap_auto)                   },
+        { "DefaultControllers", bus_property_append_strv,         "as", offsetof(Manager, default_controllers),        true },
+        { "DefaultStandardOutput", bus_manager_append_exec_output, "s", offsetof(Manager, default_std_output)          },
+        { "DefaultStandardError",  bus_manager_append_exec_output, "s", offsetof(Manager, default_std_error)           },
 #ifdef HAVE_SYSV_COMPAT
-                { "org.freedesktop.systemd1.Manager", "SysVConsole",   bus_property_append_bool,      "b",  &m->sysv_console   },
-                { "org.freedesktop.systemd1.Manager", "SysVInitPath",  bus_property_append_strv,      "as", m->lookup_paths.sysvinit_path },
-                { "org.freedesktop.systemd1.Manager", "SysVRcndPath",  bus_property_append_strv,      "as", m->lookup_paths.sysvrcnd_path },
+        { "SysVConsole",   bus_property_append_bool,               "b", offsetof(Manager, sysv_console)                },
+        { "SysVInitPath",  bus_property_append_strv,              "as", offsetof(Manager, lookup_paths.sysvinit_path), true },
+        { "SysVRcndPath",  bus_property_append_strv,              "as", offsetof(Manager, lookup_paths.sysvrcnd_path), true },
 #endif
-                { NULL, NULL, NULL, NULL, NULL }
-        };
+        { NULL, }
+};
+
+static DBusHandlerResult bus_manager_message_handler(DBusConnection *connection, DBusMessage *message, void *data) {
+        Manager *m = data;
 
         int r;
         DBusError error;
@@ -1416,8 +1422,14 @@ static DBusHandlerResult bus_manager_message_handler(DBusConnection *connection,
                 if (!reply)
                         goto oom;
 
-        } else
-                return bus_default_message_handler(connection, message, NULL, INTERFACES_LIST, properties);
+        } else {
+                const BusBoundProperties bps[] = {
+                        { "org.freedesktop.systemd1.Manager", bus_systemd_properties, systemd_property_string },
+                        { "org.freedesktop.systemd1.Manager", bus_manager_properties, m },
+                        { NULL, }
+                };
+                return bus_default_message_handler(connection, message, NULL, INTERFACES_LIST, bps);
+        }
 
         if (job_type != _JOB_TYPE_INVALID) {
                 const char *name, *smode, *old_name = NULL;