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GDBusProxy: Remove error in get_cached_property() and add set_cached_property()

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This makes it possible to use the cached properties mechanism even if
constructing the proxy with the DO_NOT_LOAD_PROPERTIES flag.

This is useful for cases where you obtain the and track object
properties out-of-band. For example, in udisks, the plan is to have
something like this

 Manager.GetObjects    (out ao paths, out aa{sa{sv}} all_properties);
 Manager.ObjectAdded   (o path, a{sa{sv}} all_properties);
 Manager.ObjectChanged (o path, a{sa{sv}} all_properties);
 Manager.ObjectRemoved (o path, a{sa{sv}} all_properties);

E.g. the first GetObjects() call will return *all* data about *all*
exported objects. Further, this way a client will only need to listen
these three signals (three AddMatch) on the Manager object and it will
never need to do GetAll() etc (e.g. can use DO_NOT_LOAD_PROPERTIES).

(Of course this only works if the client is interested in all
objects... while this is true for udisks it is generally not true for
other D-Bus services).

Also use expected_interface to check for programming errors.
This commit is contained in:
David Zeuthen
2010-05-12 20:43:40 -04:00
parent b690e637d4
commit f909cb5b27
8 changed files with 174 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files

162
gio/gdbusproxy.c
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@@ -490,66 +490,149 @@ g_dbus_proxy_get_cached_property_names (GDBusProxy *proxy,
return names;
}
static const GDBusPropertyInfo *
lookup_property_info_or_warn (GDBusProxy *proxy,
const gchar *property_name)
{
const GDBusPropertyInfo *info;
if (proxy->priv->expected_interface == NULL)
return NULL;
info = g_dbus_interface_info_lookup_property (proxy->priv->expected_interface, property_name);
if (info == NULL)
{
g_warning ("Trying to lookup property %s which isn't in expected interface %s",
property_name,
proxy->priv->expected_interface->name);
}
return info;
}
/**
* g_dbus_proxy_get_cached_property:
* @proxy: A #GDBusProxy.
* @property_name: Property name.
* @error: Return location for error or %NULL.
*
* Looks up the value for a property from the cache. This call does no blocking IO.
* Looks up the value for a property from the cache. This call does no
* blocking IO.
*
* Normally you will not need to modify the returned variant since it is updated automatically
* in response to <literal>org.freedesktop.DBus.Properties.PropertiesChanged</literal>
* D-Bus signals (which also causes #GDBusProxy::g-properties-changed to be emitted).
* If @proxy has an expected interface (see
* #GDBusProxy:g-interface-info), then @property_name (for existence)
* is checked against it.
*
* However, for properties for which said D-Bus signal is not emitted, you
* can catch other signals and modify the returned variant accordingly (remember to emit
* #GDBusProxy::g-properties-changed yourself).
*
* Returns: A reference to the #GVariant instance that holds the value for @property_name or
* %NULL if @error is set. Free the reference with g_variant_unref().
* Returns: A reference to the #GVariant instance that holds the value
* for @property_name or %NULL if the value is not in the cache. The
* returned reference must be freed with g_variant_unref().
*
* Since: 2.26
*/
GVariant *
g_dbus_proxy_get_cached_property (GDBusProxy *proxy,
const gchar *property_name,
GError **error)
const gchar *property_name)
{
GVariant *value;
g_return_val_if_fail (G_IS_DBUS_PROXY (proxy), NULL);
g_return_val_if_fail (property_name != NULL, NULL);
value = NULL;
if (proxy->priv->flags & G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES)
{
g_set_error (error,
G_IO_ERROR,
G_IO_ERROR_FAILED,
_("Properties are not available (proxy created with G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES)"));
goto out;
}
value = g_hash_table_lookup (proxy->priv->properties, property_name);
if (value == NULL)
{
g_set_error (error,
G_IO_ERROR,
G_IO_ERROR_FAILED,
_("No property with name %s"),
property_name);
const GDBusPropertyInfo *info;
info = lookup_property_info_or_warn (proxy, property_name);
/* no difference */
goto out;
}
g_variant_ref (value);
out:
return value;
}
/**
* g_dbus_proxy_set_cached_property:
* @proxy: A #GDBusProxy
* @property_name: Property name.
* @value: Value for the property or %NULL to remove it from the cache.
*
* If @value is not %NULL, sets the cached value for the property with
* name @property_name to the value in @value.
*
* If @value is %NULL, then the cached value is removed from the
* property cache.
*
* If @proxy has an expected interface (see
* #GDBusProxy:g-interface-info), then @property_name (for existence)
* and @value (for the type) is checked against it.
*
* If the @value #GVariant is floating, it is consumed. This allows
* convenient 'inline' use of g_variant_new(), e.g.
* |[
* g_dbus_proxy_set_cached_property (proxy,
* "SomeProperty",
* g_variant_new ("(si)",
* "A String",
* 42));
* ]|
*
* Normally you will not need to use this method since @proxy is
* tracking changes using the
* <literal>org.freedesktop.DBus.Properties.PropertiesChanged</literal>
* D-Bus signal. However, for performance reasons an object may decide
* to not use this signal for some properties and instead use a
* proprietary out-of-band mechanism to transmit changes.
*
* As a concrete example, consider an object with a property
* <literal>ChatroomParticipants</literal> which is an array of
* strings. Instead of transmitting the same (long) array every time
* the property changes, it is more efficient to only transmit the
* delta using e.g. signals <literal>ChatroomParticipantJoined(String
* name)</literal> and <literal>ChatroomParticipantParted(String
* name)</literal>.
*
* Since: 2.26
*/
void
g_dbus_proxy_set_cached_property (GDBusProxy *proxy,
const gchar *property_name,
GVariant *value)
{
const GDBusPropertyInfo *info;
g_return_if_fail (G_IS_DBUS_PROXY (proxy));
g_return_if_fail (property_name != NULL);
if (value != NULL)
{
info = lookup_property_info_or_warn (proxy, property_name);
if (info != NULL)
{
if (g_strcmp0 (info->signature, g_variant_get_type_string (value)) != 0)
{
g_warning (_("Trying to set property %s of type %s but according to the expected "
"interface the type is %s"),
property_name,
g_variant_get_type_string (value),
info->signature);
goto out;
}
}
g_hash_table_insert (proxy->priv->properties,
g_strdup (property_name),
g_variant_ref_sink (value));
}
else
{
g_hash_table_remove (proxy->priv->properties, property_name);
}
out:
;
}
/* ---------------------------------------------------------------------------------------------------- */
static void
@@ -1306,13 +1389,15 @@ lookup_method_info_or_warn (GDBusProxy *proxy,
{
const GDBusMethodInfo *info;
if (!proxy->priv->expected_interface)
if (proxy->priv->expected_interface == NULL)
return NULL;
info = g_dbus_interface_info_lookup_method (proxy->priv->expected_interface, method_name);
if (!info)
g_warning ("Trying to invoke method %s which isn't in expected interface %s",
method_name, proxy->priv->expected_interface->name);
if (info == NULL)
{
g_warning ("Trying to invoke method %s which isn't in expected interface %s",
method_name, proxy->priv->expected_interface->name);
}
return info;
}
@@ -1586,9 +1671,12 @@ g_dbus_proxy_call_sync (GDBusProxy *proxy,
if (proxy->priv->expected_interface)
{
expected_method_info = g_dbus_interface_info_lookup_method (proxy->priv->expected_interface, target_method_name);
if (!expected_method_info)
g_warning ("Trying to invoke method %s which isn't in expected interface %s",
target_method_name, target_interface_name);
if (expected_method_info == NULL)
{
g_warning ("Trying to invoke method `%s' which isn't in expected interface `%s'",
target_method_name,
target_interface_name);
}
}
else
{