[gnome-online-accounts/gnome-3-10] goaidentity: fall back to polling when monitoring is unavailable

[Debarshi Ray <debarshir src gnome org>]

commit 5dcc08e03828863898cfe3bb90758dd04638f283
Author: Ray Strode <rstrode redhat com>
Date:   Fri Sep 6 11:40:21 2013 -0400

    goaidentity: fall back to polling when monitoring is unavailable
    
    We don't support getting change notification for all kerberos credential
    cache types.  Rather than fail, in these cases, fall back to polling.
    
    This futureproofs the code and gives more robustness in the case of
    problems.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707402

 src/goaidentity/goakerberosidentitymanager.c |  114 ++++++++++++++++----------
 1 files changed, 71 insertions(+), 43 deletions(-)
---
diff --git a/src/goaidentity/goakerberosidentitymanager.c b/src/goaidentity/goakerberosidentitymanager.c
index 0b347ab..879ad25 100644
--- a/src/goaidentity/goakerberosidentitymanager.c
+++ b/src/goaidentity/goakerberosidentitymanager.c
@@ -57,6 +57,8 @@ struct _GoaKerberosIdentityManagerPrivate
   gboolean is_blocking_scheduler_job;
 
   volatile int pending_refresh_count;
+
+  guint polling_timeout_id;
 };
 
 typedef enum
@@ -117,6 +119,7 @@ G_DEFINE_TYPE_WITH_CODE (GoaKerberosIdentityManager,
                                                 identity_manager_interface_init)
                          G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                 initable_interface_init));
+#define FALLBACK_POLLING_INTERVAL 5
 
 static Operation *
 operation_new (GoaKerberosIdentityManager *self,
@@ -1326,16 +1329,24 @@ on_credentials_cache_changed (GFileMonitor               *monitor,
 }
 
 static gboolean
+on_polling_timeout (GoaKerberosIdentityManager *self)
+{
+  schedule_refresh (self);
+
+  return G_SOURCE_CONTINUE;
+}
+
+static gboolean
 monitor_credentials_cache (GoaKerberosIdentityManager  *self,
                            GError                     **error)
 {
   krb5_ccache default_cache;
   const char *cache_type;
   const char *cache_path;
-  GFile *file;
-  GFileMonitor *monitor;
+  GFileMonitor *monitor = NULL;
   krb5_error_code error_code;
-  GError *monitoring_error;
+  GError *monitoring_error = NULL;
+  gboolean can_monitor = TRUE;
 
   error_code = krb5_cc_default (self->priv->kerberos_context, &default_cache);
 
@@ -1359,12 +1370,9 @@ monitor_credentials_cache (GoaKerberosIdentityManager  *self,
 
   if (strcmp (cache_type, "FILE") != 0 && strcmp (cache_type, "DIR") != 0)
     {
-      g_set_error (error,
-                   GOA_IDENTITY_MANAGER_ERROR,
-                   GOA_IDENTITY_MANAGER_ERROR_UNSUPPORTED_CREDENTIALS,
-                   "Only 'FILE' and 'DIR' credential cache types are really supported, not '%s'",
+      goa_warning ("GoaKerberosIdentityManager: Using polling for change notification for credential cache 
type '%s'",
                    cache_type);
-      return FALSE;
+      can_monitor = FALSE;
     }
 
   g_free (self->priv->credentials_cache_type);
@@ -1388,44 +1396,57 @@ monitor_credentials_cache (GoaKerberosIdentityManager  *self,
   if (cache_path[0] == ':')
     cache_path++;
 
-  file = g_file_new_for_path (cache_path);
-
-  monitoring_error = NULL;
-  if (strcmp (cache_type, "FILE") == 0)
+  if (can_monitor)
     {
-      monitor = g_file_monitor_file (file,
-                                     G_FILE_MONITOR_NONE,
-                                     NULL,
-                                     &monitoring_error);
-    }
-  else if (strcmp (cache_type, "DIR") == 0)
-    {
-      GFile *directory;
+      GFile *file;
 
-      directory = g_file_get_parent (file);
-      monitor = g_file_monitor_directory (directory,
-                                          G_FILE_MONITOR_NONE,
-                                          NULL,
-                                          &monitoring_error);
-      g_object_unref (directory);
+      file = g_file_new_for_path (cache_path);
 
+      monitoring_error = NULL;
+      if (strcmp (cache_type, "FILE") == 0)
+        {
+          monitor = g_file_monitor_file (file,
+                                         G_FILE_MONITOR_NONE,
+                                         NULL,
+                                         &monitoring_error);
+        }
+      else if (strcmp (cache_type, "DIR") == 0)
+        {
+          GFile *directory;
+
+          directory = g_file_get_parent (file);
+          monitor = g_file_monitor_directory (directory,
+                                              G_FILE_MONITOR_NONE,
+                                              NULL,
+                                              &monitoring_error);
+          g_object_unref (directory);
+
+        }
+      g_object_unref (file);
     }
-  else
-    {
-      g_assert_not_reached ();
-    }
-  g_object_unref (file);
 
   if (monitor == NULL)
     {
-      g_propagate_error (error, monitoring_error);
-      return FALSE;
+      if (monitoring_error != NULL)
+        {
+          goa_warning ("GoaKerberosIdentityManager: Could not monitor credentials for %s (type %s), 
reverting to polling: %s",
+                       cache_path,
+                       cache_type,
+                       monitoring_error != NULL? monitoring_error->message : "");
+          g_clear_error (&monitoring_error);
+        }
+      can_monitor = FALSE;
+    }
+  else
+    {
+      self->priv->credentials_cache_changed_signal_id =
+        g_signal_connect (G_OBJECT (monitor), "changed",
+                          G_CALLBACK (on_credentials_cache_changed), self);
+      self->priv->credentials_cache_monitor = monitor;
     }
 
-  self->priv->credentials_cache_changed_signal_id =
-    g_signal_connect (G_OBJECT (monitor), "changed",
-                      G_CALLBACK (on_credentials_cache_changed), self);
-  self->priv->credentials_cache_monitor = monitor;
+  if (!can_monitor)
+    self->priv->polling_timeout_id = g_timeout_add_seconds (FALLBACK_POLLING_INTERVAL, (GSourceFunc) 
on_polling_timeout, self);
 
   return TRUE;
 }
@@ -1433,11 +1454,19 @@ monitor_credentials_cache (GoaKerberosIdentityManager  *self,
 static void
 stop_watching_credentials_cache (GoaKerberosIdentityManager *self)
 {
-  if (!g_file_monitor_is_cancelled (self->priv->credentials_cache_monitor))
-    g_file_monitor_cancel (self->priv->credentials_cache_monitor);
+  if (self->priv->credentials_cache_monitor != NULL)
+    {
+      if (!g_file_monitor_is_cancelled (self->priv->credentials_cache_monitor))
+        g_file_monitor_cancel (self->priv->credentials_cache_monitor);
+
+      g_clear_object (&self->priv->credentials_cache_monitor);
+    }
 
-  g_object_unref (self->priv->credentials_cache_monitor);
-  self->priv->credentials_cache_monitor = NULL;
+  if (self->priv->polling_timeout_id != 0)
+    {
+      g_source_remove (self->priv->polling_timeout_id);
+      self->priv->polling_timeout_id = 0;
+    }
 }
 
 static gboolean
@@ -1559,8 +1588,7 @@ goa_kerberos_identity_manager_dispose (GObject *object)
       self->priv->identities = NULL;
     }
 
-  if (self->priv->credentials_cache_monitor != NULL)
-    stop_watching_credentials_cache (self);
+  stop_watching_credentials_cache (self);
 
   if (self->priv->pending_operations != NULL)
     cancel_pending_operations (self);