[evolution-data-server] Add e_data_factory_ref_initable_backend().

[Matthew Barnes <mbarnes src gnome org>]

commit 0fbad0dadd83624c61c304271794b64b661958e1
Author: Matthew Barnes <mbarnes redhat com>
Date:   Tue Jan 22 16:28:05 2013 -0500

    Add e_data_factory_ref_initable_backend().
    
    Similar to e_data_factory_ref_backend(), but allows for backends that
    implement the GInitable interface so they can fail gracefully if they
    are unable to initialize critical resources, such as a cache database.

 addressbook/libedata-book/e-data-book-factory.c    |   10 +---
 calendar/libedata-cal/e-data-cal-factory.c         |    9 +--
 .../reference/libebackend/libebackend-sections.txt |    1 +
 libebackend/e-data-factory.c                       |   60 +++++++++++++++++++-
 libebackend/e-data-factory.h                       |    6 ++
 5 files changed, 70 insertions(+), 16 deletions(-)
---
diff --git a/addressbook/libedata-book/e-data-book-factory.c b/addressbook/libedata-book/e-data-book-factory.c
index bd91104..9a7f8f4 100644
--- a/addressbook/libedata-book/e-data-book-factory.c
+++ b/addressbook/libedata-book/e-data-book-factory.c
@@ -97,14 +97,8 @@ data_book_factory_ref_backend (EDataFactory *factory,
 		return NULL;
 	}
 
-	backend = e_data_factory_ref_backend (factory, backend_name, source);
-
-	if (backend == NULL)
-		g_set_error (
-			error, E_DATA_BOOK_ERROR,
-			E_DATA_BOOK_STATUS_NO_SUCH_BOOK,
-			_("Invalid backend name '%s' in source '%s'"),
-			backend_name, e_source_get_display_name (source));
+	backend = e_data_factory_ref_initable_backend (
+		factory, backend_name, source, NULL, error);
 
 	g_free (backend_name);
 
diff --git a/calendar/libedata-cal/e-data-cal-factory.c b/calendar/libedata-cal/e-data-cal-factory.c
index 474bdd6..405249e 100644
--- a/calendar/libedata-cal/e-data-cal-factory.c
+++ b/calendar/libedata-cal/e-data-cal-factory.c
@@ -101,15 +101,10 @@ data_cal_factory_ref_backend (EDataFactory *factory,
 	}
 
 	hash_key = g_strdup_printf ("%s:%s", backend_name, type_string);
-	backend = e_data_factory_ref_backend (factory, hash_key, source);
+	backend = e_data_factory_ref_initable_backend (
+		factory, hash_key, source, NULL, error);
 	g_free (hash_key);
 
-	if (backend == NULL)
-		g_set_error (
-			error, E_DATA_CAL_ERROR, NoSuchCal,
-			_("Invalid backend name '%s' in source '%s'"),
-			backend_name, e_source_get_display_name (source));
-
 	g_free (backend_name);
 
 	return backend;
diff --git a/docs/reference/libebackend/libebackend-sections.txt b/docs/reference/libebackend/libebackend-sections.txt
index 9d2be5f..9854be2 100644
--- a/docs/reference/libebackend/libebackend-sections.txt
+++ b/docs/reference/libebackend/libebackend-sections.txt
@@ -170,6 +170,7 @@ ECollectionBackendFactoryPrivate
 <TITLE>EDataFactory</TITLE>
 EDataFactory
 e_data_factory_ref_backend
+e_data_factory_ref_initable_backend
 e_data_factory_ref_backend_factory
 <SUBSECTION Standard>
 E_DATA_FACTORY
diff --git a/libebackend/e-data-factory.c b/libebackend/e-data-factory.c
index efaac1f..d98df68 100644
--- a/libebackend/e-data-factory.c
+++ b/libebackend/e-data-factory.c
@@ -25,6 +25,7 @@
 #include "e-data-factory.h"
 
 #include <config.h>
+#include <glib/gi18n-lib.h>
 
 #include <libebackend/e-extensible.h>
 #include <libebackend/e-backend-factory.h>
@@ -243,6 +244,49 @@ e_data_factory_ref_backend (EDataFactory *data_factory,
                             const gchar *hash_key,
                             ESource *source)
 {
+	return e_data_factory_ref_initable_backend (
+		data_factory, hash_key, source, NULL, NULL);
+}
+
+/**
+ * e_data_factory_ref_initable_backend:
+ * @data_factory: an #EDataFactory
+ * @hash_key: hash key for an #EBackendFactory
+ * @source: an #ESource
+ * @cancellable: optional #GCancellable object, or %NULL
+ * @error: return location for a #GError, or %NULL
+ *
+ * Similar to e_data_factory_ref_backend(), but allows for backends that
+ * implement the #GInitable interface so they can fail gracefully if they
+ * are unable to initialize critical resources, such as a cache database.
+ *
+ * Returns either a newly-created or existing #EBackend for #ESource.
+ * The returned #EBackend is referenced for thread-safety and must be
+ * unreferenced with g_object_unref() when finished with it.
+ *
+ * If the newly-created backend implements the #GInitable interface, then
+ * g_initable_init() is also called on it using @cancellable and @error.
+ *
+ * The @data_factory retains a weak reference to @backend so it can return
+ * the same instance while @backend is in use.  When the last strong reference
+ * to @backend is dropped, @data_factory will lose its weak reference and will
+ * have to create a new #EBackend instance the next time the same @hash_key
+ * and @source are requested.
+ *
+ * If no suitable #EBackendFactory exists, or if the #EBackend fails to
+ * initialize, the function sets @error and returns %NULL.
+ *
+ * Returns: an #EBackend for @source, or %NULL
+ *
+ * Since: 3.8
+ **/
+EBackend *
+e_data_factory_ref_initable_backend (EDataFactory *data_factory,
+                                     const gchar *hash_key,
+                                     ESource *source,
+                                     GCancellable *cancellable,
+                                     GError **error)
+{
 	EBackendFactory *backend_factory;
 	GWeakRef *weak_ref;
 	EBackend *backend;
@@ -270,12 +314,26 @@ e_data_factory_ref_backend (EDataFactory *data_factory,
 	backend_factory =
 		e_data_factory_ref_backend_factory (data_factory, hash_key);
 
-	if (backend_factory == NULL)
+	if (backend_factory == NULL) {
+		g_set_error (
+			error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
+			_("No backend factory for hash key '%s'"),
+			hash_key);
 		goto exit;
+	}
 
 	/* Create a new backend for the given source and store it. */
 	backend = e_backend_factory_new_backend (backend_factory, source);
 
+	if (G_IS_INITABLE (backend)) {
+		GInitable *initable = G_INITABLE (backend);
+
+		if (!g_initable_init (initable, cancellable, error)) {
+			g_object_unref (backend);
+			backend = NULL;
+		}
+	}
+
 	/* This still does the right thing if backend is NULL. */
 	g_weak_ref_set (weak_ref, backend);
 
diff --git a/libebackend/e-data-factory.h b/libebackend/e-data-factory.h
index 2c8ee2a..e370a1b 100644
--- a/libebackend/e-data-factory.h
+++ b/libebackend/e-data-factory.h
@@ -80,6 +80,12 @@ GType		e_data_factory_get_type		(void) G_GNUC_CONST;
 EBackend *	e_data_factory_ref_backend	(EDataFactory *data_factory,
 						 const gchar *hash_key,
 						 ESource *source);
+EBackend *	e_data_factory_ref_initable_backend
+						(EDataFactory *data_factory,
+						 const gchar *hash_key,
+						 ESource *source,
+						 GCancellable *cancellable,
+						 GError **error);
 EBackendFactory *
 		e_data_factory_ref_backend_factory
 						(EDataFactory *data_factory,