[tracker/wip/carlosg/portal: 294/298] libtracker-data: Cache connections in SERVICES{} virtual table

[Carlos Garnacho <carlosg src gnome org>]

commit a9f9d9505a40f706bae323b64d7b08571d5dd4fd
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 | 82 +++++++++++++++++-------------
 1 file changed, 48 insertions(+), 34 deletions(-)
---
diff --git a/src/libtracker-data/tracker-vtab-service.c b/src/libtracker-data/tracker-vtab-service.c
index b3b1861ed..985b3f91a 100644
--- a/src/libtracker-data/tracker-vtab-service.c
+++ b/src/libtracker-data/tracker-vtab-service.c
@@ -40,13 +40,13 @@ typedef struct {
 typedef struct {
        struct sqlite3_vtab parent;
        TrackerServiceModule *module;
+       GHashTable *cached_connections;
        GList *cursors;
 } TrackerServiceVTab;
 
 typedef struct {
        struct sqlite3_vtab_cursor parent;
        TrackerServiceVTab *vtab;
-       TrackerSparqlConnection *conn;
        TrackerSparqlCursor *sparql_cursor;
        GHashTable *parameter_columns;
        gchar *service;
@@ -74,6 +74,7 @@ tracker_service_vtab_free (gpointer data)
 {
        TrackerServiceVTab *vtab = data;
 
+       g_hash_table_unref (vtab->cached_connections);
        g_list_free (vtab->cursors);
        g_free (vtab);
 }
@@ -86,7 +87,6 @@ tracker_service_cursor_free (gpointer data)
        g_clear_pointer (&cursor->parameter_columns, g_hash_table_unref);
        g_free (cursor->service);
        g_free (cursor->query);
-       g_clear_object (&cursor->conn);
        g_clear_object (&cursor->sparql_cursor);
 
        g_free (cursor);
@@ -107,6 +107,10 @@ 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");
 
@@ -272,6 +276,7 @@ service_filter (sqlite3_vtab_cursor  *vtab_cursor,
 {
        TrackerServiceCursor *cursor = (TrackerServiceCursor *) vtab_cursor;
        const ConstraintData *constraints = (const ConstraintData *) idx_str;
+       TrackerSparqlConnection *connection;
        TrackerSparqlStatement *statement;
        GHashTable *names = NULL, *values = NULL;
        gchar *uri_scheme = NULL;
@@ -323,48 +328,57 @@ service_filter (sqlite3_vtab_cursor  *vtab_cursor,
        if (!cursor->service || !cursor->query)
                goto fail;
 
-       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;
+       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)) {
+                               g_set_error (&error,
+                                            TRACKER_SPARQL_ERROR,
+                                            TRACKER_SPARQL_ERROR_UNSUPPORTED,
+                                            "Failed to parse uri '%s'",
+                                            cursor->service);
+                               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 (!tracker_util_parse_dbus_uri (cursor->service,
-                                                 &bus_type,
-                                                 &bus_name, &object_path)) {
+                       if (!connection)
+                               goto fail;
+               } else if (g_strcmp0 (uri_scheme, "http") == 0) {
+                       connection = tracker_sparql_connection_remote_new (cursor->service);
+               }
+
+               if (!connection) {
                        g_set_error (&error,
                                     TRACKER_SPARQL_ERROR,
                                     TRACKER_SPARQL_ERROR_UNSUPPORTED,
-                                    "Failed to parse uri '%s'",
+                                    "Unsupported uri '%s'",
                                     cursor->service);
                        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);
-
-               if (!cursor->conn)
-                       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);
        }
 
-       statement = tracker_sparql_connection_query_statement (cursor->conn,
+       statement = tracker_sparql_connection_query_statement (connection,
                                                               cursor->query,
                                                               NULL, &error);
        if (error)