gstinfo: Optimize color escape code creation

When coloring is in use, those escape codes are going to be created many times
for almost all debug lines.

Don't create plenty of temporary allocations, and instead build the escape code
ourselves statically

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3498>

1 files changed, 36 insertions, 22 deletions

diff --git a/subprojects/gstreamer/gst/gstinfo.c b/subprojects/gstreamer/gst/gstinfo.c
index 3d81015465..b46bc15d04 100644
--- a/subprojects/gstreamer/gst/gstinfo.c
+++ b/subprojects/gstreamer/gst/gstinfo.c
@@ -1044,6 +1044,37 @@ gst_info_printf_pointer_extension_func (const char *format, void *ptr)
   return s;
 }
 
+/* Allocation-less generator of color escape code. Provide a 20 byte write
+ * area */
+static void
+_construct_term_color (guint colorinfo, gchar write_area[20])
+{
+  guint offset;
+
+  memcpy (write_area, "\033[00", 4);
+  offset = 4;
+
+  if (colorinfo & GST_DEBUG_BOLD) {
+    memcpy (write_area + offset, ";01", 3);
+    offset += 3;
+  }
+  if (colorinfo & GST_DEBUG_UNDERLINE) {
+    memcpy (write_area + offset, ";04", 3);
+    offset += 3;
+  }
+  if (colorinfo & GST_DEBUG_FG_MASK) {
+    memcpy (write_area + offset, ";3", 2);
+    write_area[offset + 2] = '0' + (colorinfo & GST_DEBUG_FG_MASK);
+    offset += 3;
+  }
+  if (colorinfo & GST_DEBUG_BG_MASK) {
+    memcpy (write_area + offset, ";4", 2);
+    write_area[offset + 2] = '0' + ((colorinfo & GST_DEBUG_BG_MASK) >> 4);
+    offset += 3;
+  }
+  strncpy (write_area + offset, "m", 2);
+}
+
 /**
  * gst_debug_construct_term_color:
  * @colorinfo: the color info
@@ -1058,26 +1089,11 @@ gst_info_printf_pointer_extension_func (const char *format, void *ptr)
 gchar *
 gst_debug_construct_term_color (guint colorinfo)
 {
-  GString *color;
-
-  color = g_string_new ("\033[00");
+  gchar tmp_color[20];
 
-  if (colorinfo & GST_DEBUG_BOLD) {
-    g_string_append_len (color, ";01", 3);
-  }
-  if (colorinfo & GST_DEBUG_UNDERLINE) {
-    g_string_append_len (color, ";04", 3);
-  }
-  if (colorinfo & GST_DEBUG_FG_MASK) {
-    g_string_append_printf (color, ";3%1d", colorinfo & GST_DEBUG_FG_MASK);
-  }
-  if (colorinfo & GST_DEBUG_BG_MASK) {
-    g_string_append_printf (color, ";4%1d",
-        (colorinfo & GST_DEBUG_BG_MASK) >> 4);
-  }
-  g_string_append_c (color, 'm');
+  _construct_term_color (colorinfo, tmp_color);
 
-  return g_string_free (color, FALSE);
+  return g_strdup (tmp_color);
 }
 
 /**
@@ -1374,13 +1390,12 @@ gst_debug_log_default (GstDebugCategory * category, GstDebugLevel level,
     if (color_mode == GST_DEBUG_COLOR_MODE_UNIX) {
 #endif
       /* colors, non-windows */
-      gchar *color = NULL;
+      gchar color[20];
       const gchar *clear;
       gchar pidcolor[10];
       const gchar *levelcolor;
 
-      color = gst_debug_construct_term_color (gst_debug_category_get_color
-          (category));
+      _construct_term_color (gst_debug_category_get_color (category), color);
       clear = "\033[00m";
       g_sprintf (pidcolor, "\033[%02dm", pid % 6 + 31);
       levelcolor = levelcolormap[level];
@@ -1393,7 +1408,6 @@ gst_debug_log_default (GstDebugCategory * category, GstDebugLevel level,
           clear, message_str);
       FFLUSH_DEBUG (log_file);
 #undef PRINT_FMT
-      g_free (color);
 #ifdef G_OS_WIN32
     } else {
       /* colors, windows. */