GMappedFile: add refcounting, switch to GSlice

- add g_mapped_file_ref() and g_mapped_file_unref().
  - deprecate g_mapped_file_free().
  - move to GSlice for allocating the GMappedFile struct.

docs/reference/glib/glib-sections.txt

@@ -1114,6 +1114,8 @@ g_dir_close
 <SUBSECTION>
 GMappedFile
 g_mapped_file_new
+g_mapped_file_ref
+g_mapped_file_unref
 g_mapped_file_free
 g_mapped_file_get_length
 g_mapped_file_get_contents

glib/glib.symbols

@@ -683,9 +683,13 @@ g_timeout_source_new_seconds
 g_mapped_file_new G_GNUC_MALLOC
 g_mapped_file_get_length
 g_mapped_file_get_contents
+g_mapped_file_ref
+g_mapped_file_unref
+#ifndef G_DISABLE_DEPRECATED
 g_mapped_file_free
 #endif
 #endif
+#endif
 
 #if IN_HEADER(__G_MARKUP_H__)
 #if IN_FILE(__G_MARKUP_C__)

glib/gmappedfile.c

@@ -52,6 +52,7 @@
 #include "gmessages.h"
 #include "gstdio.h"
 #include "gstrfuncs.h"
+#include "gatomic.h"
 
 #include "glibintl.h"
 
@@ -69,6 +70,7 @@ struct _GMappedFile
 {
   gsize  length;
   gchar *contents;
+  int    ref_count;
 #ifdef G_OS_WIN32
   HANDLE mapping;
 #endif
@@ -92,8 +94,8 @@ struct _GMappedFile
  * will not be modified, or if all modifications of the file are done
  * atomically (e.g. using g_file_set_contents()). 
  *
- * Return value: a newly allocated #GMappedFile which must be freed
- *    with g_mapped_file_free(), or %NULL if the mapping failed. 
+ * Return value: a newly allocated #GMappedFile which must be unref'd
+ *    with g_mapped_file_unref(), or %NULL if the mapping failed.
  *
  * Since: 2.8
  */
@@ -125,7 +127,8 @@ g_mapped_file_new (const gchar  *filename,
       return NULL;
     }
 
-  file = g_new0 (GMappedFile, 1);
+  file = g_slice_new0 (GMappedFile);
+  file->ref_count = 1;
 
   if (fstat (fd, &st) == -1)
     {
@@ -207,7 +210,7 @@ g_mapped_file_new (const gchar  *filename,
 
  out:
   close (fd);
-  g_free (file);
+  g_slice_free (GMappedFile, file);
 
   return NULL;
 }
@@ -255,29 +258,73 @@ g_mapped_file_get_contents (GMappedFile *file)
  * g_mapped_file_free:
  * @file: a #GMappedFile
  *
- * Unmaps the buffer of @file and frees it. 
+ * This call existed before #GMappedFile had refcounting and is currently
+ * exactly the same as g_mapped_file_unref().
  *
  * Since: 2.8
+ * Deprecated:2.22: Use g_mapped_file_unref() instead.
  */
 void
 g_mapped_file_free (GMappedFile *file)
 {
-  g_return_if_fail (file != NULL);
-
-  if (file->length)
-  {
-#ifdef HAVE_MMAP
-    munmap (file->contents, file->length);
-#endif
-#ifdef G_OS_WIN32
-    UnmapViewOfFile (file->contents);
-    CloseHandle (file->mapping);
-#endif
-  }
-
-  g_free (file);
+  g_mapped_file_unref (file);
 }
 
+/**
+ * g_mapped_file_ref:
+ * @file: a #GMappedFile
+ *
+ * Increments the reference count of @file by one.  It is safe to call
+ * this function from any thread.
+ *
+ * Return value: the passed in #GMappedFile.
+ *
+ * Since: 2.22
+ **/
+GMappedFile *
+g_mapped_file_ref (GMappedFile *file)
+{
+  g_return_val_if_fail (file != NULL, NULL);
+  g_return_val_if_fail (file->ref_count > 0, file);
+
+  g_atomic_int_inc (&file->ref_count);
+
+  return file;
+}
+
+/**
+ * g_mapped_file_unref:
+ * @file: a #GMappedFile
+ *
+ * Decrements the reference count of @file by one.  If the reference count
+ * drops to 0, unmaps the buffer of @file and frees it.
+ *
+ * It is safe to call this function from any thread.
+ *
+ * Since 2.22
+ **/
+void
+g_mapped_file_unref (GMappedFile *file)
+{
+  g_return_if_fail (file != NULL);
+  g_return_if_fail (file->ref_count > 0);
+
+  if (g_atomic_int_dec_and_test (&file->ref_count))
+    {
+      if (file->length)
+        {
+#ifdef HAVE_MMAP
+          munmap (file->contents, file->length);
+#endif
+#ifdef G_OS_WIN32
+          UnmapViewOfFile (file->contents);
+          CloseHandle (file->mapping);
+#endif
+        }
+
+      g_slice_free (GMappedFile, file);
+    }
+}
 
 #define __G_MAPPED_FILE_C__
 #include "galiasdef.c"

glib/gmappedfile.h

@@ -37,7 +37,12 @@ GMappedFile *g_mapped_file_new          (const gchar  *filename,
 				         GError      **error) G_GNUC_MALLOC;
 gsize        g_mapped_file_get_length   (GMappedFile  *file);
 gchar       *g_mapped_file_get_contents (GMappedFile  *file);
+GMappedFile *g_mapped_file_ref          (GMappedFile  *file);
+void         g_mapped_file_unref        (GMappedFile  *file);
+
+#ifndef G_DISABLE_DEPRECATED
 void         g_mapped_file_free         (GMappedFile  *file);
+#endif
 
 G_END_DECLS