Plan C for foiling the algorithmic complexity attack

(based on Chip's plan A (binary compatibility with 5.8.0 and 5.8.1),
 Chip's plan B (do something new inside the hv functions)
 and introspective sort)
Provides infrastructure for hashes to change their hash function
if necessary, and code in hsplit to detect pathalogical data and
instigate a random rehashing.
Needs refinement. Let's see how much smoke it creates.

p4raw-id: //depot/perl@21471

1 files changed, 1 insertions, 0 deletions

diff --git a/sv.h b/sv.h
index 5d2fab27bc..a9a57dfdda 100644
--- a/sv.h
+++ b/sv.h
@@ -213,6 +213,7 @@ perform the upgrade if necessary.  See C<svtype>.
 
 #define SVrepl_EVAL	0x40000000	/* Replacement part of s///e */
 
+#define SVphv_REHASH	0x10000000	/* HV is recalculating hash values */
 #define SVphv_SHAREKEYS 0x20000000	/* keys live on shared string table */
 #define SVphv_LAZYDEL	0x40000000	/* entry in xhv_eiter must be deleted */
 #define SVphv_HASKFLAGS	0x80000000	/* keys have flag byte after hash */