Make account deletion async (sort of), and imply a selective commit

This means we don't need to commit separately after each deletion,
and means account plugins don't have to have the concept of flagging
an account for "delete this later" - much rejoicing.

It also has the incidental benefit that we no longer use the C++
reserved word 'delete' in a header file.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=27727

2 files changed, 70 insertions, 46 deletions

diff --git a/mission-control-plugins/account-storage.c b/mission-control-plugins/account-storage.c
index 53b00be0..b87909c3 100644
--- a/mission-control-plugins/account-storage.c
+++ b/mission-control-plugins/account-storage.c
@@ -119,13 +119,24 @@ default_get (const McpAccountStorage *storage,
   return FALSE;
 }
 
-static gboolean
-default_delete (const McpAccountStorage *storage,
-    const McpAccountManager *am,
+static void
+default_delete_async (McpAccountStorage *storage,
+    McpAccountManager *am,
     const gchar *account,
-    const gchar *key)
+    GAsyncReadyCallback callback,
+    gpointer user_data)
 {
-  return FALSE;
+  g_task_report_new_error (storage, callback, user_data,
+      default_delete_async, TP_ERROR, TP_ERROR_NOT_IMPLEMENTED,
+      "This storage plugin cannot delete accounts");
+}
+
+static gboolean
+default_delete_finish (McpAccountStorage *storage,
+    GAsyncResult *res,
+    GError **error)
+{
+  return g_task_propagate_boolean (G_TASK (res), error);
 }
 
 static gboolean
@@ -230,7 +241,8 @@ class_init (gpointer klass,
 
   iface->get = default_get;
   iface->create = default_create;
-  iface->delete = default_delete;
+  iface->delete_async = default_delete_async;
+  iface->delete_finish = default_delete_finish;
   iface->commit = default_commit;
   iface->list = default_list;
   iface->ready = default_ready;
@@ -646,61 +658,62 @@ mcp_account_storage_create (const McpAccountStorage *storage,
 }
 
 /**
- * McpAccountStorageDeleteFunc:
+ * mcp_account_storage_delete_async:
  * @storage: an #McpAccountStorage instance
  * @am: an #McpAccountManager instance
  * @account: the unique name of the account
- * @key: (allow-none): the setting whose value we wish to store - either an
- *  attribute like "DisplayName", or "param-" plus a parameter like
- *  "account" - or %NULL to delete the entire account
+ * @callback: called on success or failure
+ * @user_data: data for @callback
  *
- * An implementation of mcp_account_storage_delete().
+ * Delete the account @account, and commit the change,
+ * emitting #McpAccountStorage::deleted afterwards.
  *
- * Returns: %TRUE if the setting or settings are not
- * the plugin's cache after this operation, %FALSE otherwise.
+ * Unlike the 'delete' virtual method in earlier MC versions, this
+ * function is expected to commit the change to long-term storage,
+ * is expected to emit #McpAccountStorage::deleted, and is
+ * not called for the deletion of individual attributes or parameters.
+ *
+ * The default implementation just returns failure (asynchronously),
+ * and is appropriate for read-only storage.
  */
+void
+mcp_account_storage_delete_async (McpAccountStorage *storage,
+    McpAccountManager *am,
+    const gchar *account,
+    GAsyncReadyCallback callback,
+    gpointer user_data)
+{
+  McpAccountStorageIface *iface = MCP_ACCOUNT_STORAGE_GET_IFACE (storage);
+
+  SDEBUG (storage, "");
+  g_return_if_fail (iface != NULL);
+  g_return_if_fail (iface->delete_async != NULL);
+
+  iface->delete_async (storage, am, account, callback, user_data);
+}
 
 /**
- * mcp_account_storage_delete:
+ * mcp_account_storage_delete_finish:
  * @storage: an #McpAccountStorage instance
- * @am: an #McpAccountManager instance
- * @account: the unique name of the account
- * @key: (allow-none): the setting whose value we wish to store - either an
- *  attribute like "DisplayName", or "param-" plus a parameter like
- *  "account" - or %NULL to delete the entire account
- *
- * The plugin is expected to remove the setting for @key from its
- * internal cache and to remember that its state has changed, so
- * that it can delete said setting from its long term storage if
- * its long term storage method makes this necessary.
+ * @res: the result of mcp_account_storage_delete_async()
+ * @error: used to raise an error if %FALSE is returned
  *
- * If @key is %NULL, the plugin should forget all its settings for
- * @account,and remember to delete the entire account from its storage later.
+ * Process the result of mcp_account_storage_delete_async().
  *
- * The plugin is not expected to update its long term storage at
- * this point.
- *
- * The default implementation just returns %FALSE, and is appropriate for
- * read-only storage.
- *
- * Returns: %TRUE if the setting or settings are not
- * the plugin's cache after this operation, %FALSE otherwise.
- * This is very unlikely to ever be %FALSE, as a plugin is always
- * expected to be able to manipulate its own cache.
+ * Returns: %TRUE on success, %FALSE if the account could not be deleted
  */
 gboolean
-mcp_account_storage_delete (const McpAccountStorage *storage,
-    const McpAccountManager *am,
-    const gchar *account,
-    const gchar *key)
+mcp_account_storage_delete_finish (McpAccountStorage *storage,
+    GAsyncResult *result,
+    GError **error)
 {
   McpAccountStorageIface *iface = MCP_ACCOUNT_STORAGE_GET_IFACE (storage);
 
   SDEBUG (storage, "");
   g_return_val_if_fail (iface != NULL, FALSE);
-  g_return_val_if_fail (iface->delete != NULL, FALSE);
+  g_return_val_if_fail (iface->delete_finish != NULL, FALSE);
 
-  return iface->delete (storage, am, account, key);
+  return iface->delete_finish (storage, result, error);
 }
 
 /**
diff --git a/mission-control-plugins/account-storage.h b/mission-control-plugins/account-storage.h
index 198e8353..ff3633e2 100644
--- a/mission-control-plugins/account-storage.h
+++ b/mission-control-plugins/account-storage.h
@@ -107,7 +107,14 @@ struct _McpAccountStorageIface
   const gchar *provider;
 
   McpAccountStorageGetFunc get;
-  McpAccountStorageDeleteFunc delete;
+  void (*delete_async) (McpAccountStorage *storage,
+      McpAccountManager *am,
+      const gchar *account,
+      GAsyncReadyCallback callback,
+      gpointer user_data);
+  gboolean (*delete_finish) (McpAccountStorage *storage,
+      GAsyncResult *res,
+      GError **error);
   McpAccountStorageCommitFunc commit;
   McpAccountStorageListFunc list;
   McpAccountStorageReadyFunc ready;
@@ -149,10 +156,14 @@ gchar * mcp_account_storage_create (const McpAccountStorage *storage,
     const gchar *identification,
     GError **error);
 
-gboolean mcp_account_storage_delete (const McpAccountStorage *storage,
-    const McpAccountManager *am,
+void mcp_account_storage_delete_async (McpAccountStorage *storage,
+    McpAccountManager *am,
     const gchar *account,
-    const gchar *key);
+    GAsyncReadyCallback callback,
+    gpointer user_data);
+gboolean mcp_account_storage_delete_finish (McpAccountStorage *storage,
+    GAsyncResult *result,
+    GError **error);
 
 void mcp_account_storage_ready (const McpAccountStorage *storage,
     const McpAccountManager *am);