[tracker/wip/carlosg/portal: 42/47] libtracker-data: Cache connections in SERVICES{} virtual table

[Carlos Garnacho <carlosg src gnome org>]

commit bbc6735f50cbc9022e8e36dba2eb00309806e43b
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 | 100 ++++++++++++++++-------------
 1 file changed, 57 insertions(+), 43 deletions(-)
---
diff --git a/src/libtracker-data/tracker-vtab-service.c b/src/libtracker-data/tracker-vtab-service.c
index 51a257384..5f0265a65 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;
@@ -86,6 +86,7 @@ tracker_service_vtab_free (gpointer data)
 {
        TrackerServiceVTab *vtab = data;
 
+       g_hash_table_unref (vtab->cached_connections);
        g_list_free (vtab->cursors);
        g_free (vtab);
 }
@@ -98,7 +99,6 @@ 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);
@@ -119,6 +119,10 @@ 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");
 
@@ -284,6 +288,7 @@ 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;
@@ -335,57 +340,66 @@ 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_PARSE,
+                                            "Failed to parse uri '%s'",
+                                            cursor->service);
+                               goto fail;
+                       }
 
-               if (!tracker_util_parse_dbus_uri (cursor->service,
-                                                 &bus_type,
-                                                 &bus_name, &object_path)) {
-                       g_set_error (&error,
-                                    TRACKER_SPARQL_ERROR,
-                                    TRACKER_SPARQL_ERROR_PARSE,
-                                    "Failed to parse uri '%s'",
-                                    cursor->service);
-                       goto fail;
+                       if (!g_dbus_is_name (bus_name)) {
+                               g_set_error (&error,
+                                            TRACKER_SPARQL_ERROR,
+                                            TRACKER_SPARQL_ERROR_PARSE,
+                                            "Invalid bus name '%s'",
+                                            bus_name);
+                               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 (!g_dbus_is_name (bus_name)) {
+               if (!connection) {
                        g_set_error (&error,
                                     TRACKER_SPARQL_ERROR,
-                                    TRACKER_SPARQL_ERROR_PARSE,
-                                    "Invalid bus name '%s'",
-                                    bus_name);
+                                    TRACKER_SPARQL_ERROR_UNSUPPORTED,
+                                    "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)