From: William Harold Newman <william.newman@airmail.net>
Date: Tue, 2 Nov 2004 16:53:10 +0000 (+0000)
Subject: 0.8.16.27:
X-Git-Url: http://repo.macrolet.net/gitweb/?a=commitdiff_plain;h=dc9d03a1c43398d3a860520c6ea03e8d5838d142;p=sbcl.git

0.8.16.27:
	made SXHASH values for CLOS instances be well-distributed
---

diff --git a/src/pcl/low.lisp b/src/pcl/low.lisp
index ea468f4..021c50e 100644
--- a/src/pcl/low.lisp
+++ b/src/pcl/low.lisp
@@ -306,12 +306,19 @@
 	 nil)))
 
 ;;;; support for useful hashing of PCL instances
-(let ((hash-code 0))
-  (declare (fixnum hash-code))
-  (defun get-instance-hash-code ()
-    (if (< hash-code most-positive-fixnum)
-	(incf hash-code)
-	(setq hash-code 0))))
+
+(defvar *instance-hash-code-random-state* (make-random-state))
+(defun get-instance-hash-code ()
+  ;; ANSI SXHASH wants us to make a good-faith effort to produce
+  ;; hash-codes that are well distributed within the range of
+  ;; non-negative fixnums, and this RANDOM operation does that, unlike
+  ;; the sbcl<=0.8.16 implementation of this operation as
+  ;; (INCF COUNTER).
+  ;;
+  ;; Hopefully there was no virtue to the old counter implementation
+  ;; that I am insufficiently insightful to insee. -- WHN 2004-10-28
+  (random most-positive-fixnum
+	  *instance-hash-code-random-state*))
 
 (defun sb-impl::sxhash-instance (x)
   (cond
diff --git a/version.lisp-expr b/version.lisp-expr
index c9cbb67..bb81a17 100644
--- a/version.lisp-expr
+++ b/version.lisp-expr
@@ -17,4 +17,4 @@
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
-"0.8.16.26"
+"0.8.16.27"