[tracker/wip/carlosg/data-update-error-propagation: 3/11] libtracker-data: Improve error handling with modseq management

[Carlos Garnacho <carlosg src gnome org>]

commit b9df73960b68b91445e3741abb93ea0dd843ab94
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sun Feb 21 18:06:52 2021 +0100

    libtracker-data: Improve error handling with modseq management
    
    Instead of initializing the modseq from the database at a random point
    without possibility of error propagation, ensure this is initialized when
    beginning the first non-ontology transaction, and propagate the possible
    error.
    
    This allows the rest of the modseq code be oblivious about GErrors
    without shame.

 src/libtracker-data/tracker-data-update.c | 37 ++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 16 deletions(-)
---
diff --git a/src/libtracker-data/tracker-data-update.c b/src/libtracker-data/tracker-data-update.c
index 9ad19b009..f78ccaf39 100644
--- a/src/libtracker-data/tracker-data-update.c
+++ b/src/libtracker-data/tracker-data-update.c
@@ -409,39 +409,45 @@ tracker_data_dispatch_delete_statement_callbacks (TrackerData *data,
        }
 }
 
-static gint
-tracker_data_update_get_next_modseq (TrackerData *data)
+static gboolean
+tracker_data_update_initialize_modseq (TrackerData  *data,
+                                       GError      **error)
 {
        TrackerDBCursor    *cursor = NULL;
        TrackerDBInterface *temp_iface;
        TrackerDBStatement *stmt;
-       GError             *error = NULL;
+       GError             *inner_error = NULL;
        gint                max_modseq = 0;
 
+       /* Is it already initialized? */
+       if (data->transaction_modseq != 0)
+               return TRUE;
+
        temp_iface = tracker_data_manager_get_writable_db_interface (data->manager);
 
-       stmt = tracker_db_interface_create_statement (temp_iface, TRACKER_DB_STATEMENT_CACHE_TYPE_SELECT, 
&error,
+       stmt = tracker_db_interface_create_statement (temp_iface, TRACKER_DB_STATEMENT_CACHE_TYPE_SELECT, 
&inner_error,
                                                      "SELECT MAX(\"nrl:modified\") AS A FROM 
\"rdfs:Resource\"");
 
        if (stmt) {
-               cursor = tracker_db_statement_start_cursor (stmt, &error);
+               cursor = tracker_db_statement_start_cursor (stmt, &inner_error);
                g_object_unref (stmt);
        }
 
        if (cursor) {
-               if (tracker_db_cursor_iter_next (cursor, NULL, &error)) {
-                       max_modseq = MAX (tracker_db_cursor_get_int (cursor, 0), max_modseq);
+               if (tracker_db_cursor_iter_next (cursor, NULL, &inner_error)) {
+                       max_modseq = tracker_db_cursor_get_int (cursor, 0);
+                       data->transaction_modseq = max_modseq + 1;
                }
 
                g_object_unref (cursor);
        }
 
-       if (G_UNLIKELY (error)) {
-               g_warning ("Could not get new resource ID: %s\n", error->message);
-               g_error_free (error);
+       if (G_UNLIKELY (inner_error)) {
+               g_propagate_error (error, inner_error);
+               return FALSE;
        }
 
-       return ++max_modseq;
+       return TRUE;
 }
 
 static void
@@ -514,10 +520,6 @@ tracker_data_new (TrackerDataManager *manager)
 static gint
 get_transaction_modseq (TrackerData *data)
 {
-       if (G_UNLIKELY (data->transaction_modseq == 0)) {
-               data->transaction_modseq = tracker_data_update_get_next_modseq (data);
-       }
-
        /* Always use 1 for ontology transactions */
        if (data->in_ontology_transaction) {
                return 1;
@@ -2801,6 +2803,10 @@ tracker_data_begin_transaction (TrackerData  *data,
                return;
        }
 
+       if (!data->in_ontology_transaction &&
+           !tracker_data_update_initialize_modseq (data, error))
+               return;
+
        data->resource_time = time (NULL);
 
        data->has_persistent = FALSE;
@@ -2858,7 +2864,6 @@ tracker_data_commit_transaction (TrackerData  *data,
                return;
        }
 
-       get_transaction_modseq (data);
        if (data->has_persistent && !data->in_ontology_transaction) {
                data->transaction_modseq++;
        }