From: Igor Putovny <igor.putovny@nic.cz>
Date: Wed, 11 Jun 2025 15:44:38 +0000 (+0200)
Subject: Hash: Assert that table is not resized during HASH_WALK
X-Git-Tag: v3.1.4~5
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e26860a2507112c85cfd811c507a8e6afa4a8fff;p=thirdparty%2Fbird.git

Hash: Assert that table is not resized during HASH_WALK

According to measurements of hash_test, hash table with this assertion added
was not found to be significantly slower than without it on average. Therefore
we conclude that this addition would not hamper the performance of HASH_WALK.
---

diff --git a/lib/hash.h b/lib/hash.h
index 470293859..c08458109 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -177,10 +177,12 @@
 #define HASH_WALK(v,next,n)						\
   do {									\
     HASH_TYPE(v) *n;							\
+    const uint _count = (v).count;					\
     uint _i;								\
     uint _s = HASH_SIZE(v);						\
     for (_i = 0; _i < _s; _i++)						\
-      for (n = (v).data[_i]; n; n = n->next)
+      for (n = (v).data[_i]; n;						\
+	  ({ASSERT_DIE(v.count == _count);}), n = n->next)
 
 #define HASH_WALK_END } while (0)
 
@@ -188,10 +190,12 @@
 #define HASH_WALK_DELSAFE(v,next,n)					\
   do {									\
     HASH_TYPE(v) *n, *_next;						\
+    const uint _order = (v).order;					\
     uint _i;								\
     uint _s = HASH_SIZE(v);						\
     for (_i = 0; _i < _s; _i++)						\
-      for (n = (v).data[_i]; n && (_next = n->next, 1); n = _next)
+      for (n = (v).data[_i]; n && (_next = n->next, 1);			\
+	 ({ASSERT_DIE((v).order == _order);}), n = _next)
 
 #define HASH_WALK_DELSAFE_END } while (0)
 
@@ -199,10 +203,13 @@
 #define HASH_WALK_FILTER(v,next,n,nn)					\
   do {									\
     HASH_TYPE(v) *n, **nn;						\
+    const uint _order = (v).order;					\
     uint _i;								\
     uint _s = HASH_SIZE(v);						\
     for (_i = 0; _i < _s; _i++)						\
-      for (nn = (v).data + _i; n = *nn; (*nn == n) ? (nn = &n->next) : NULL)
+      for (nn = (v).data + _i; n = *nn;					\
+	  ({ASSERT_DIE((v).order == _order);}),				\
+	  (*nn == n) ? (nn = &n->next) : NULL)
 
 #define HASH_WALK_FILTER_END } while (0)