libtracker-sparql: Avoid frequent malloc/free in Trig serializer

The TrackerTriple struct we preserve to compare current/previous value
and abbreviate the resulting turtle is created for each row. Store
this in the serializer, so we avoid a malloc/free for each row.

1 files changed, 24 insertions, 30 deletions

diff --git a/src/libtracker-sparql/tracker-serializer-trig.c b/src/libtracker-sparql/tracker-serializer-trig.c
index 0ed05a98a..2af6d557f 100644
--- a/src/libtracker-sparql/tracker-serializer-trig.c
+++ b/src/libtracker-sparql/tracker-serializer-trig.c
@@ -42,7 +42,7 @@ struct _TrackerQuad
 struct _TrackerSerializerTrig
 {
 	TrackerSerializer parent_instance;
-	TrackerQuad *last_quad;
+	TrackerQuad last_quad;
 	GString *data;
 	guint stream_closed : 1;
 	guint cursor_started : 1;
@@ -63,15 +63,10 @@ typedef enum
 	TRACKER_QUAD_BREAK_OBJECT,
 } TrackerQuadBreak;
 
-static TrackerQuad *
-tracker_quad_new_from_cursor (TrackerSparqlCursor *cursor)
+static void
+tracker_quad_init_from_cursor (TrackerQuad         *quad,
+                               TrackerSparqlCursor *cursor)
 {
-	TrackerQuad *quad;
-
-	if (tracker_sparql_cursor_get_n_columns (cursor) < 3)
-		return NULL;
-
-	quad = g_new0 (TrackerQuad, 1);
 	quad->subject_type = tracker_sparql_cursor_get_value_type (cursor, 0);
 	quad->object_type = tracker_sparql_cursor_get_value_type (cursor, 2);
 	quad->subject = g_strdup (tracker_sparql_cursor_get_string (cursor, 0, NULL));
@@ -80,6 +75,8 @@ tracker_quad_new_from_cursor (TrackerSparqlCursor *cursor)
 
 	if (tracker_sparql_cursor_get_n_columns (cursor) >= 4)
 		quad->graph = g_strdup (tracker_sparql_cursor_get_string (cursor, 3, NULL));
+	else
+		quad->graph = NULL;
 
 	if (quad->subject_type == TRACKER_SPARQL_VALUE_TYPE_STRING) {
 		if (g_str_has_prefix (quad->subject, "urn:bnode:")) {
@@ -94,25 +91,22 @@ tracker_quad_new_from_cursor (TrackerSparqlCursor *cursor)
 			quad->object_type = TRACKER_SPARQL_VALUE_TYPE_BLANK_NODE;
 		}
 	}
-
-	return quad;
 }
 
 static void
-tracker_quad_free (TrackerQuad *quad)
+tracker_quad_clear (TrackerQuad *quad)
 {
-	g_free (quad->subject);
-	g_free (quad->predicate);
-	g_free (quad->object);
-	g_free (quad->graph);
-	g_free (quad);
+	g_clear_pointer (&quad->subject, g_free);
+	g_clear_pointer (&quad->predicate, g_free);
+	g_clear_pointer (&quad->object, g_free);
+	g_clear_pointer (&quad->graph, g_free);
 }
 
 static TrackerQuadBreak
 tracker_quad_get_break (TrackerQuad *last,
                         TrackerQuad *cur)
 {
-	if (!last)
+	if (!last->subject)
 		return TRACKER_QUAD_BREAK_NONE;
 
 	if (g_strcmp0 (last->graph, cur->graph) != 0)
@@ -201,7 +195,7 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 	TrackerSparqlCursor *cursor;
 	TrackerNamespaceManager *namespaces;
 	GError *inner_error = NULL;
-	TrackerQuad *cur;
+	TrackerQuad cur;
 
 	if (!serializer_trig->data)
 		serializer_trig->data = g_string_new (NULL);
@@ -236,9 +230,9 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 			serializer_trig->cursor_started = TRUE;
 		}
 
-		cur = tracker_quad_new_from_cursor (cursor);
+		tracker_quad_init_from_cursor (&cur, cursor);
 
-		if (!cur) {
+		if (!cur.subject && cur.predicate && cur.object) {
 			g_set_error (error,
 			             TRACKER_SPARQL_ERROR,
 			             TRACKER_SPARQL_ERROR_INTERNAL,
@@ -246,15 +240,15 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 			return FALSE;
 		}
 
-		br = tracker_quad_get_break (serializer_trig->last_quad, cur);
+		br = tracker_quad_get_break (&serializer_trig->last_quad, &cur);
 
 		if (br <= TRACKER_QUAD_BREAK_GRAPH) {
 			if (br == TRACKER_QUAD_BREAK_GRAPH)
 				g_string_append (serializer_trig->data, " .\n}\n\n");
 
-			if (cur->graph) {
+			if (cur.graph) {
 				g_string_append (serializer_trig->data, "GRAPH ");
-				print_value (serializer_trig->data, cur->graph,
+				print_value (serializer_trig->data, cur.graph,
 				             TRACKER_SPARQL_VALUE_TYPE_URI, namespaces);
 				g_string_append_c (serializer_trig->data, ' ');
 			}
@@ -265,7 +259,7 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 		if (br <= TRACKER_QUAD_BREAK_SUBJECT) {
 			if (br == TRACKER_QUAD_BREAK_SUBJECT)
 				g_string_append (serializer_trig->data, " .\n\n  ");
-			print_value (serializer_trig->data, cur->subject, cur->subject_type, namespaces);
+			print_value (serializer_trig->data, cur.subject, cur.subject_type, namespaces);
 		}
 
 		if (br <= TRACKER_QUAD_BREAK_PREDICATE) {
@@ -274,7 +268,7 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 			else
 				g_string_append_c (serializer_trig->data, ' ');
 
-			print_value (serializer_trig->data, cur->predicate,
+			print_value (serializer_trig->data, cur.predicate,
 			             TRACKER_SPARQL_VALUE_TYPE_URI, namespaces);
 		}
 
@@ -283,12 +277,12 @@ serialize_up_to_size (TrackerSerializerTrig  *serializer_trig,
 				g_string_append (serializer_trig->data, ",");
 
 			g_string_append_c (serializer_trig->data, ' ');
-			print_value (serializer_trig->data, cur->object, cur->object_type, namespaces);
+			print_value (serializer_trig->data, cur.object, cur.object_type, namespaces);
 		}
 
 		serializer_trig->has_quads = TRUE;
-		g_clear_pointer (&serializer_trig->last_quad, tracker_quad_free);
-		serializer_trig->last_quad = cur;
+		tracker_quad_clear (&serializer_trig->last_quad);
+		memcpy (&serializer_trig->last_quad, &cur, sizeof (TrackerQuad));
 	}
 
 	/* Close the last quad */
@@ -337,7 +331,7 @@ tracker_serializer_trig_close (GInputStream  *istream,
 {
 	TrackerSerializerTrig *serializer_trig = TRACKER_SERIALIZER_TRIG (istream);
 
-	g_clear_pointer (&serializer_trig->last_quad, tracker_quad_free);
+	tracker_quad_clear (&serializer_trig->last_quad);
 
 	if (serializer_trig->data) {
 		g_string_free (serializer_trig->data, TRUE);