[tracker/wip/carlosg/insert-perf: 12/13] libtracker-data: Cache SQL string in char* form

[Carlos Garnacho <carlosg src gnome org>]

commit 4c95590eb9fc1ea2690203043f18cb90847b9c3b
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Nov 30 13:14:02 2020 +0100

    libtracker-data: Cache SQL string in char* form
    
    The string builder is a weird intermediate state that still takes some
    CPU to transform to string. We can do all of that just once.

 src/libtracker-data/tracker-sparql.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 45caa02df..6dd0307bf 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -68,7 +68,6 @@ static gboolean helper_translate_time (TrackerSparql  *sparql,
                                        GError        **error);
 static TrackerDBStatement * prepare_query (TrackerSparql         *sparql,
                                            TrackerDBInterface    *iface,
-                                           TrackerStringBuilder  *str,
                                            GPtrArray             *literals,
                                            GHashTable            *parameters,
                                            gboolean               cached,
@@ -164,6 +163,7 @@ struct _TrackerSparql
 
        TrackerContext *context;
        TrackerStringBuilder *sql;
+       gchar *sql_string;
 
        GHashTable *prefix_map;
        GList *filter_clauses;
@@ -225,6 +225,7 @@ tracker_sparql_finalize (GObject *object)
        g_hash_table_destroy (sparql->parameters);
        g_hash_table_destroy (sparql->cached_bindings);
 
+       g_clear_pointer (&sparql->sql_string, g_free);
 
        if (sparql->sql)
                tracker_string_builder_free (sparql->sql);
@@ -2027,6 +2028,7 @@ tracker_sparql_init_string_builder (TrackerSparql *sparql)
        TrackerStringBuilder *str;
 
        g_clear_pointer (&sparql->sql, tracker_string_builder_free);
+       g_clear_pointer (&sparql->sql_string, g_free);
        sparql->sql = sparql->current_state->sql = tracker_string_builder_new ();
        sparql->current_state->with_clauses = _prepend_placeholder (sparql);
 
@@ -4362,7 +4364,7 @@ get_solution_for_pattern (TrackerSparql      *sparql,
        }
 
        iface = tracker_data_manager_get_writable_db_interface (sparql->data_manager);
-       stmt = prepare_query (sparql, iface, sparql->sql,
+       stmt = prepare_query (sparql, iface,
                              TRACKER_SELECT_CONTEXT (sparql->context)->literal_bindings,
                              NULL, TRUE,
                              error);
@@ -9330,23 +9332,24 @@ tracker_sparql_new (TrackerDataManager *manager,
 static TrackerDBStatement *
 prepare_query (TrackerSparql         *sparql,
                TrackerDBInterface    *iface,
-               TrackerStringBuilder  *str,
                GPtrArray             *literals,
-              GHashTable            *parameters,
+               GHashTable            *parameters,
                gboolean               cached,
                GError               **error)
 {
        TrackerDBStatement *stmt;
-       gchar *query;
        guint i;
 
-       query = tracker_string_builder_to_string (str);
+       if (!sparql->sql_string) {
+               sparql->sql_string = tracker_string_builder_to_string (sparql->sql);
+               g_clear_pointer (&sparql->sql, tracker_string_builder_free);
+       }
+
        stmt = tracker_db_interface_create_statement (iface,
                                                      cached ?
                                                      TRACKER_DB_STATEMENT_CACHE_TYPE_SELECT :
                                                      TRACKER_DB_STATEMENT_CACHE_TYPE_NONE,
-                                                     error, "%s", query);
-       g_free (query);
+                                                     error, "%s", sparql->sql_string);
 
        if (!stmt || !literals)
                return stmt;
@@ -9496,12 +9499,13 @@ tracker_sparql_execute_cursor (TrackerSparql  *sparql,
                sparql->current_state = NULL;
                tracker_sparql_state_clear (&state);
 
+
                if (!retval)
                        goto error;
        }
 
        iface = tracker_data_manager_get_db_interface (sparql->data_manager);
-       stmt = prepare_query (sparql, iface, sparql->sql,
+       stmt = prepare_query (sparql, iface,
                              TRACKER_SELECT_CONTEXT (sparql->context)->literal_bindings,
                              parameters,
                              sparql->cacheable,