dx-packages team mailing list archive

[Gunnar Hjalmarsson <1443178@xxxxxxxxxxxxxxxxxx>]

Thanks for your comment, Sebastien!

Let me say a few words about the reason for involving the
user_get_property() function in the first place.

In addition to generating lists of available options, the GUIs for
setting language and regional formats asks accountsservice about the
current value. Packages which rely on accountsservice in this respect
are:

- language-selector
- unity-control-center (for User Accounts)
- gnome-control-center (for both Region & Language and User Accounts)
- lightdm (for lightdm-gtk-greeter)
- ubuntu-system-settings

So far, as long as the user has not set some other value but the system
default, and since accountsservice does not store system defaults,
accountsservice has generated the value on the fly. The code for doing
so is somewhat expensive, and - as mentioned in the bug description -
user_get_property() is called frequently.

In the light of this, changing it so the user config is saved (based on
system default) is a way to improve the efficiency. If we would take the
other route, and let accountsservice respond with the empty string, we
would mess it up in several places.

Please note that I'm not asking for a detailed code review. I merely ask
if you are strongly against the approach (saving user settings based on
system defaults). After this explanation, I hope you are not. :)

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https://bugs.launchpad.net/bugs/1443178

Title:
  Accounts Service always relies on language fallback if never set by
  the user

Status in the base for Ubuntu mobile products:
  New
Status in accountsservice package in Ubuntu:
  In Progress
Status in ubuntu-system-settings package in Ubuntu:
  New
Status in unity8 package in Ubuntu:
  New

Bug description:
  current build number: 169
  device name: mako
  channel: ubuntu-touch/devel-proposed
  alias: ubuntu-touch/vivid-proposed
  last update: 2015-04-12 20:38:14
  version version: 169
  version ubuntu: 20150412
  version device: 20150210
  version custom: 20150412

  This causes a bad side effect when changing volume via indicator-
  sound, as that will cause a sync to accountsservice in order to sync
  the volume. Once that sync happens, it will request the user
  properties, and in case the user doesn't have a valid language at
  /var/lib/AccountsService/users/<user>, it will always rely on the
  fallback, which would be fine if calculating the fallback wasn't 't so
  cpu or i/o intensive (and that happens multiple times).

  As a test, just flash latest vivid image on mako, don't set any
  language when the wizard shows up, run top and then change the volume
  by pressing volume up/down. This is what I see with mako:

   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
  2609 phablet   20   0  499660 121220  52688 S   7.6  6.5   0:41.69 unity8
  5600 phablet   20   0    3676   1760   1288 R   6.0  0.1   0:00.19 language-option
  1312 root      20   0  211532  15572  11344 S   1.9  0.8   0:07.25 unity-system-co
  1316 phablet   20   0   36532   3792   2928 S   1.3  0.2   0:01.66 accounts-daemon

  And the reason why:
  src/user.c
  ...
  static void
  user_get_property (GObject    *object,
                     guint       param_id,
                     GValue     *value,
                     GParamSpec *pspec)
  {
          User *user = USER (object);
  ...
          case PROP_LANGUAGE:
                  if (user->language)
                          g_value_set_string (value, user->language);
                  else 
                          g_value_set_string (value, user_get_fallback_value (user, "Language"));
                  break;
          case PROP_FORMATS_LOCALE:
                  if (user->formats_locale)
                          g_value_set_string (value, user->formats_locale);
                  else 
                          g_value_set_string (value, user_get_fallback_value (user, "FormatsLocale"));
                  break;

  user_set_property never gets called unless the user changes the system
  language from system-settings or wizard.

  Once you change the language, it will set a valid language at
  /var/lib/AccountsService/users/<user>, causing this behavior to stop.

  Another bad side effect of this issue is that it takes quite a while
  for accountsservice to reply back to indicator-sound when the sync
  happens, possibly causing sync aborts (as indicator-sound only waits 1
  second before triggering another sync).

  Some possible ways to fix this issue:
  1) Make wizard to set language even when the selected language is already the default one;
  2) Change accountsservice to save the fallback value at the first time it gets that from the system;

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