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print notifications: Don't send repeated printer-added notifications.
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Some printer and/or CUPS behavior can end up triggering frequent
"added" notifications for the same printer.

Suppress added notifications for removed printers for two hours
after removal. This should prevent useless notifications while
not permanently suppressing them.
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@mtwebster
mtwebster committed May 13, 2024
1 parent 3f9372f commit 80974b7
Showing 1 changed file with 107 additions and 2 deletions.
109 changes: 107 additions & 2 deletions plugins/print-notifications/csd-print-notifications-manager.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,9 @@
#define CUPS_CONNECTION_TEST_INTERVAL 300
#define CHECK_INTERVAL 60 /* secs */

#define PRINTER_REMOVED_LIFETIME 7200 * 1000 * 1000 /* 1 hour (micro) */
#define PRINTER_REMOVED_UPDATE_INTERVAL 1260 /* 21 min (sec) */

#if (CUPS_VERSION_MAJOR > 1) || (CUPS_VERSION_MINOR > 5)
#define HAVE_CUPS_1_6 1
#endif
Expand Down Expand Up @@ -84,6 +87,8 @@ struct CsdPrintNotificationsManagerPrivate
GPid scp_handler_pid;
GList *timeouts;
GHashTable *printing_printers;
GHashTable *removed_printers;
guint removed_printer_timeout_id;
GList *active_notifications;
guint cups_connection_timeout_id;
guint check_source_id;
Expand Down Expand Up @@ -332,6 +337,96 @@ on_cups_notification (GDBusConnection *connection,
process_new_notifications (user_data);
}

typedef struct
{
CsdPrintNotificationsManager *manager;
gint64 removed_time;
} RemovePrinterData;

static gboolean
drop_expired_removal (const gchar *printer_name,
RemovePrinterData *foreach_data,
gpointer user_data)
{
RemovePrinterData *current_data = (RemovePrinterData *) user_data;

if (current_data->removed_time > foreach_data->removed_time + PRINTER_REMOVED_LIFETIME) {
g_debug ("Removing printer from removed-printers queue: %s (removed over %ds ago)",
printer_name, PRINTER_REMOVED_LIFETIME / 1000 / 1000);

return TRUE;
}

return FALSE;
}

static gboolean
removed_cache_update (CsdPrintNotificationsManager *manager)
{
gint64 current_time = g_get_monotonic_time ();
RemovePrinterData *current_data = g_new0 (RemovePrinterData, 1);

g_debug ("Periodic update of removed-printers");

current_data->manager = manager;
current_data->removed_time = current_time;

g_hash_table_foreach_remove (manager->priv->removed_printers,
(GHRFunc) drop_expired_removal,
current_data);

if (g_hash_table_size (manager->priv->removed_printers) == 0) {
g_debug ("No more printers in removed-printers queue, stopping update timer.");
manager->priv->removed_printer_timeout_id = 0;
return G_SOURCE_REMOVE;
}

return G_SOURCE_CONTINUE;
}

static gboolean
should_notify_new_printer (CsdPrintNotificationsManager *manager,
const gchar *printer_name)
{
g_debug ("Checking if user should be notified about a new printer: %s", printer_name);
RemovePrinterData *data = g_hash_table_lookup (manager->priv->removed_printers, printer_name);

if (data) {
g_hash_table_remove (manager->priv->removed_printers, printer_name);
return FALSE;
}

return TRUE;
}

static void
add_or_update_removed_cache (CsdPrintNotificationsManager *manager,
const gchar *printer_name)
{
RemovePrinterData *data = g_new0 (RemovePrinterData, 1);
data->removed_time = g_get_monotonic_time ();
gboolean new;

new = g_hash_table_replace (manager->priv->removed_printers,
g_strdup (printer_name),
data);

if (new) {
g_debug ("Printer %s has been removed, adding to removed-printers queue.", printer_name);
} else {
g_debug ("Printer %s has been re-removed, updating its removed timestamp.", printer_name);
}

if (g_hash_table_size (manager->priv->removed_printers) > 0 &&
manager->priv->removed_printer_timeout_id == 0) {
g_debug ("Starting removed-printer timer");
manager->priv->removed_printer_timeout_id =
g_timeout_add_seconds (PRINTER_REMOVED_UPDATE_INTERVAL,
(GSourceFunc) removed_cache_update,
manager);
}
}

static gchar *
get_statuses_second (guint i,
const gchar *printer_name)
Expand Down Expand Up @@ -504,12 +599,17 @@ process_cups_notification (CsdPrintNotificationsManager *manager,
manager->priv->dests,
manager->priv->num_dests)) {
/* Translators: New printer has been added */
primary_text = g_strdup (_("Printer added"));
secondary_text = g_strdup (printer_name);
if (should_notify_new_printer (manager, printer_name)) {
primary_text = g_strdup (_("Printer added"));
secondary_text = g_strdup (printer_name);
} else {
g_debug ("A recently-removed printer %s has been re-added, skipping notification.", printer_name);
}
}
} else if (g_strcmp0 (notify_subscribed_event, "printer-deleted") == 0) {
cupsFreeDests (manager->priv->num_dests, manager->priv->dests);
manager->priv->num_dests = cupsGetDests (&manager->priv->dests);
add_or_update_removed_cache (manager, printer_name);
} else if (g_strcmp0 (notify_subscribed_event, "job-completed") == 0 && my_job) {
g_hash_table_remove (manager->priv->printing_printers,
printer_name);
Expand Down Expand Up @@ -1345,6 +1445,7 @@ csd_print_notifications_manager_start_idle (gpointer data)
cinnamon_settings_profile_start (NULL);

manager->priv->printing_printers = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
manager->priv->removed_printers = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_free);

/*
* Set a password callback which cancels authentication
Expand Down Expand Up @@ -1387,6 +1488,8 @@ csd_print_notifications_manager_start (CsdPrintNotificationsManager *manager,
manager->priv->scp_handler_spawned = FALSE;
manager->priv->timeouts = NULL;
manager->priv->printing_printers = NULL;
manager->priv->removed_printers = NULL;
manager->priv->removed_printer_timeout_id = 0;
manager->priv->active_notifications = NULL;
manager->priv->cups_bus_connection = NULL;
manager->priv->cups_connection_timeout_id = 0;
Expand Down Expand Up @@ -1431,6 +1534,8 @@ csd_print_notifications_manager_stop (CsdPrintNotificationsManager *manager)
cancel_subscription (manager->priv->subscription_id);

g_clear_pointer (&manager->priv->printing_printers, g_hash_table_destroy);
g_clear_pointer (&manager->priv->removed_printers, g_hash_table_destroy);
g_clear_handle_id (&manager->priv->removed_printer_timeout_id, g_source_remove);

g_clear_object (&manager->priv->cups_bus_connection);

Expand Down

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