[sysprof] writer: allow callers to define a counter range

[Christian Hergert <chergert src gnome org>]

commit d7ed2ddf301908ebf7c87f609da3b0a29f853c7e
Author: Christian Hergert <christian hergert me>
Date:   Thu Apr 14 21:36:07 2016 -0700

    writer: allow callers to define a counter range
    
    This allows dynamic counter ids that can be allocated in blocks.

 lib/sp-capture-writer.c |   18 ++++++++++++++++++
 lib/sp-capture-writer.h |    2 ++
 2 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/lib/sp-capture-writer.c b/lib/sp-capture-writer.c
index b416c57..55c4503 100644
--- a/lib/sp-capture-writer.c
+++ b/lib/sp-capture-writer.c
@@ -90,6 +90,9 @@ struct _SpCaptureWriter
   gsize pos;
   gsize len;
 
+  /* counter id sequence */
+  gint next_counter_id;
+
   /* Statistics while recording */
   SpCaptureStat stat;
 };
@@ -378,6 +381,7 @@ sp_capture_writer_new_from_fd (int   fd,
   self->fd = fd;
   self->buf = (guint8 *)g_malloc (buffer_size);
   self->len = buffer_size;
+  self->next_counter_id = 1;
 
   g_get_current_time (&tv);
   nowstr = g_time_val_to_iso8601 (&tv);
@@ -1086,3 +1090,17 @@ sp_capture_writer_set_counters (SpCaptureWriter *self,
 
   return TRUE;
 }
+
+gint
+sp_capture_writer_request_counter (SpCaptureWriter *self,
+                                   guint            n_counters)
+{
+  gint ret;
+
+  g_assert (self != NULL);
+
+  ret = self->next_counter_id;
+  ret += n_counters;
+
+  return ret;
+}
diff --git a/lib/sp-capture-writer.h b/lib/sp-capture-writer.h
index 81de7de..bdc35bf 100644
--- a/lib/sp-capture-writer.h
+++ b/lib/sp-capture-writer.h
@@ -98,6 +98,8 @@ gboolean            sp_capture_writer_flush           (SpCaptureWriter         *
 gboolean            sp_capture_writer_save_as         (SpCaptureWriter         *self,
                                                        const gchar             *filename,
                                                        GError                 **error);
+gint                sp_capture_writer_request_counter (SpCaptureWriter         *self,
+                                                       guint                    n_counters);
 SpCaptureReader    *sp_capture_writer_create_reader   (SpCaptureWriter         *self,
                                                        GError                 **error);
 gboolean            sp_capture_writer_splice          (SpCaptureWriter         *self,