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

[Matthew Barnes <mbarnes src gnome org>]

commit 936eed3e0baaa0c262ebb0b968d0bb70475a9ff4
Author: Matthew Barnes <mbarnes redhat com>
Date:   Tue Apr 17 12:43:43 2012 -0400

    Add e_data_factory_ref_backend_factory().
    
    Just a way to get access to the EBackendFactory itself.
    
    Needed on the account-mgmt branch to check whether a suitable E-D-S
    backend factory is available to handle a given GNOME Online Account
    provider type such as "exchange".

 .../reference/libebackend/libebackend-sections.txt |    1 +
 libebackend/e-data-factory.c                       |   48 +++++++++++++++++++-
 libebackend/e-data-factory.h                       |    6 ++-
 3 files changed, 52 insertions(+), 3 deletions(-)
---
diff --git a/docs/reference/libebackend/libebackend-sections.txt b/docs/reference/libebackend/libebackend-sections.txt
index e9fae05..f1872c3 100644
--- a/docs/reference/libebackend/libebackend-sections.txt
+++ b/docs/reference/libebackend/libebackend-sections.txt
@@ -42,6 +42,7 @@ e_backend_factory_get_type
 <TITLE>EDataFactory</TITLE>
 EDataFactory
 e_data_factory_ref_backend
+e_data_factory_ref_backend_factory
 <SUBSECTION Standard>
 E_DATA_FACTORY
 E_IS_DATA_FACTORY
diff --git a/libebackend/e-data-factory.c b/libebackend/e-data-factory.c
index 206b98f..d415695 100644
--- a/libebackend/e-data-factory.c
+++ b/libebackend/e-data-factory.c
@@ -239,8 +239,8 @@ e_data_factory_ref_backend (EDataFactory *factory,
 		goto exit;
 
 	/* Find a suitable backend factory using the hash key. */
-	backend_factory = g_hash_table_lookup (
-		factory->priv->backend_factories, hash_key);
+	backend_factory =
+		e_data_factory_ref_backend_factory (factory, hash_key);
 
 	if (backend_factory == NULL)
 		goto exit;
@@ -251,9 +251,53 @@ e_data_factory_ref_backend (EDataFactory *factory,
 	/* This still does the right thing if backend is NULL. */
 	g_weak_ref_set (weak_ref, backend);
 
+	g_object_unref (backend_factory);
+
 exit:
 	g_mutex_unlock (factory->priv->mutex);
 
 	return backend;
 }
 
+/**
+ * e_data_factory_ref_backend_factory:
+ * @factory: an #EDataFactory
+ * @hash_key: hash key for an #EBackendFactory
+ *
+ * Returns the #EBackendFactory for @hash_key, or %NULL if no such factory
+ * is registered.
+ *
+ * The returned #EBackendFactory is referenced for thread-safety.
+ * Unreference the #EBackendFactory with g_object_unref() when finished
+ * with it.
+ *
+ * Returns: the #EBackendFactory for @hash_key, or %NULL
+ *
+ * Since: 3.6
+ **/
+EBackendFactory *
+e_data_factory_ref_backend_factory (EDataFactory *factory,
+                                    const gchar *hash_key)
+{
+	GHashTable *backend_factories;
+	EBackendFactory *backend_factory;
+
+	g_return_val_if_fail (E_IS_DATA_FACTORY (factory), NULL);
+	g_return_val_if_fail (hash_key != NULL, NULL);
+
+	/* It should be safe to lookup backend factories without a mutex
+	 * because once initially populated the hash table remains fixed.
+	 *
+	 * XXX Which might imply the returned factory doesn't *really* need
+	 *     to be referenced for thread-safety, but better to do it when
+	 *     not really needed than wish we had in the future. */
+
+	backend_factories = factory->priv->backend_factories;
+	backend_factory = g_hash_table_lookup (backend_factories, hash_key);
+
+	if (backend_factory != NULL)
+		g_object_ref (backend_factory);
+
+	return backend_factory;
+}
+
diff --git a/libebackend/e-data-factory.h b/libebackend/e-data-factory.h
index be6705f..9abf1ef 100644
--- a/libebackend/e-data-factory.h
+++ b/libebackend/e-data-factory.h
@@ -19,8 +19,8 @@
 #ifndef E_DATA_FACTORY_H
 #define E_DATA_FACTORY_H
 
-#include <libebackend/e-backend.h>
 #include <libebackend/e-dbus-server.h>
+#include <libebackend/e-backend-factory.h>
 
 /* Standard GObject macros */
 #define E_TYPE_DATA_FACTORY \
@@ -72,6 +72,10 @@ GType		e_data_factory_get_type		(void) G_GNUC_CONST;
 EBackend *	e_data_factory_ref_backend	(EDataFactory *factory,
 						 const gchar *hash_key,
 						 ESource *source);
+EBackendFactory *
+		e_data_factory_ref_backend_factory
+						(EDataFactory *factory,
+						 const gchar *hash_key);
 
 G_END_DECLS