Add API function to calculate total memory in use by all GC blocks

(Apply part of commit db2b9f1 from 'racket_gc' branch.)

* include/gc.h (GC_get_memory_use): New API function declaration.
* misc.c (get_size, GC_get_memory_use): New function.

1 files changed, 19 insertions, 0 deletions

diff --git a/misc.c b/misc.c
index e67a76f1..55d078c8 100644
--- a/misc.c
+++ b/misc.c
@@ -2014,6 +2014,25 @@ GC_API void * GC_CALL GC_do_blocking(GC_fn_type fn, void * client_data)
   }
 #endif /* !NO_DEBUGGING */
 
+static void get_size(struct hblk *h, word lptr)
+{
+  hdr *hhdr = HDR(h);
+  long bytes = WORDS_TO_BYTES(hhdr->hb_sz);
+
+  bytes += HBLKSIZE-1;
+  bytes &= ~(HBLKSIZE-1);
+
+  *(long *)lptr += bytes;
+}
+long GC_get_memory_use()
+{
+  long c = 0;
+  LOCK();
+  GC_apply_to_all_blocks(get_size, (word)&c);
+  UNLOCK();
+  return c;
+}
+
 /* Getter functions for the public Read-only variables.                 */
 
 /* GC_get_gc_no() is unsynchronized and should be typically called      */