[tracker/wip/carlosg/portal: 30/34] libtracker-data: Cache connections in SERVICES{} virtual table

[Carlos Garnacho <carlosg src gnome org>]

commit c1a38151d66e1f05dd88a65aa148470296dd29f0
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Jan 24 17:31:29 2020 +0100

    libtracker-data: Cache connections in SERVICES{} virtual table
    
    These live as long as the virtual table module exists in memory (i.e.
    as long as the DB connection lives), this way portal sessions are more
    long lived than per-query.

 src/libtracker-data/tracker-vtab-service.c | 77 ++++++++++++++++++------------
 1 file changed, 47 insertions(+), 30 deletions(-)
---
diff --git a/src/libtracker-data/tracker-vtab-service.c b/src/libtracker-data/tracker-vtab-service.c
index b48efacdc..92496cf88 100644
--- a/src/libtracker-data/tracker-vtab-service.c
+++ b/src/libtracker-data/tracker-vtab-service.c
@@ -36,6 +36,7 @@ typedef struct {
 typedef struct {
        struct sqlite3_vtab parent;
        TrackerServiceModule *module;
+       GHashTable *cached_connections;
        GList *cursors;
 } TrackerServiceVTab;
 
@@ -69,6 +70,7 @@ tracker_service_vtab_free (gpointer data)
 {
        TrackerServiceVTab *vtab = data;
 
+       g_hash_table_unref (vtab->cached_connections);
        g_list_free (vtab->cursors);
        g_free (vtab);
 }
@@ -101,6 +103,10 @@ service_create (sqlite3            *db,
 
        vtab = g_new0 (TrackerServiceVTab, 1);
        vtab->module = module;
+       vtab->cached_connections = g_hash_table_new_full (g_str_hash,
+                                                         g_str_equal,
+                                                         g_free,
+                                                         g_object_unref);
 
        str = g_string_new ("CREATE TABLE x(\n");
 
@@ -208,6 +214,7 @@ service_filter (sqlite3_vtab_cursor  *vtab_cursor,
 {
        TrackerServiceCursor *cursor = (TrackerServiceCursor *) vtab_cursor;
        const ConstraintData *constraints = (const ConstraintData *) idx_str;
+       TrackerSparqlConnection *connection;
        gchar *uri_scheme = NULL;
        GError *error = NULL;
        gint i;
@@ -227,41 +234,51 @@ service_filter (sqlite3_vtab_cursor  *vtab_cursor,
        if (!cursor->service || !cursor->query)
                return SQLITE_ERROR;
 
-       uri_scheme = g_uri_parse_scheme (cursor->service);
-       if (g_strcmp0 (uri_scheme, "dbus") == 0) {
-               gchar *bus_name, *object_path;
-               GDBusConnection *dbus_connection;
-               GBusType bus_type;
-
-               if (!tracker_util_parse_dbus_uri (cursor->service,
-                                                 &bus_type,
-                                                 &bus_name, &object_path))
-                       goto fail;
-
-               dbus_connection = g_bus_get_sync (bus_type, NULL, &error);
-               if (!dbus_connection)
-                       goto fail;
-
-               cursor->conn = tracker_sparql_connection_bus_new (bus_name, object_path,
-                                                                 dbus_connection, &error);
-               g_free (bus_name);
-               g_free (object_path);
+       connection = g_hash_table_lookup (cursor->vtab->cached_connections,
+                                         cursor->service);
+
+       if (!connection) {
+               uri_scheme = g_uri_parse_scheme (cursor->service);
+               if (g_strcmp0 (uri_scheme, "dbus") == 0) {
+                       gchar *bus_name, *object_path;
+                       GDBusConnection *dbus_connection;
+                       GBusType bus_type;
+
+                       if (!tracker_util_parse_dbus_uri (cursor->service,
+                                                         &bus_type,
+                                                         &bus_name, &object_path))
+                               goto fail;
+
+                       dbus_connection = g_bus_get_sync (bus_type, NULL, &error);
+                       if (!dbus_connection)
+                               goto fail;
+
+                       connection = tracker_sparql_connection_bus_new (bus_name, object_path,
+                                                                       dbus_connection, &error);
+                       g_free (bus_name);
+                       g_free (object_path);
+
+                       if (!connection)
+                               goto fail;
+               } else if (g_strcmp0 (uri_scheme, "http") == 0) {
+                       connection = tracker_sparql_connection_remote_new (cursor->service);
+               }
 
-               if (!cursor->conn)
+               if (!connection) {
+                       g_set_error (&error,
+                                    TRACKER_SPARQL_ERROR,
+                                    TRACKER_SPARQL_ERROR_UNSUPPORTED,
+                                    "Unsupported uri '%s'",
+                                    cursor->service);
                        goto fail;
-       } else if (g_strcmp0 (uri_scheme, "http") == 0) {
-               cursor->conn = tracker_sparql_connection_remote_new (cursor->service);
-       }
+               }
 
-       if (!cursor->conn) {
-               g_set_error (&error,
-                            TRACKER_SPARQL_ERROR,
-                            TRACKER_SPARQL_ERROR_UNSUPPORTED,
-                            "Unsupported uri '%s'",
-                            cursor->service);
-               goto fail;
+               g_hash_table_insert (cursor->vtab->cached_connections,
+                                    g_strdup (cursor->service),
+                                    connection);
        }
 
+       cursor->conn = g_object_ref (connection);
        cursor->sparql_cursor = tracker_sparql_connection_query (cursor->conn,
                                                                 cursor->query,
                                                                 NULL, &error);