On 07/24/2011 01:31 AM, Paolo Carlini wrote:
On 07/23/2011 10:31 PM, François Dumont wrote:
Hi
While working on DR 41975 I realized a small issue in current
rehash implementation that sometimes lead to load_factor being
greater than max_load_factor. Here is a patch to fix that:
Ok, good.
I think we could as well have everywhere:
const unsigned long __p = *std::lower_bound...
and then change the following *__p to __p. Isn't a tad cleaner?
Thanks,
Paolo.
Attached patch applied, I have integrated your remark Paolo.
2011-07-24 François Dumont <francois.cppd...@free.fr>
* include/bits/hashtable_policy.h (_Prime_rehash_policy): Use
__builtin_floor rather than __builtin_ceil to compute next resize
value.
* testsuite/23_containers/unordered_set/hash_policy/load_factor.cc:
New.
For info, I will submit a proposal for DR 41975 tomorrow or the day after.
Regards
Index: include/bits/hashtable_policy.h
===================================================================
--- include/bits/hashtable_policy.h (revision 176581)
+++ include/bits/hashtable_policy.h (working copy)
@@ -427,10 +427,10 @@
_Prime_rehash_policy::
_M_next_bkt(std::size_t __n) const
{
- const unsigned long* __p = std::lower_bound(__prime_list, __prime_list
+ const unsigned long __p = *std::lower_bound(__prime_list, __prime_list
+ _S_n_primes, __n);
_M_next_resize =
- static_cast<std::size_t>(__builtin_ceil(*__p * _M_max_load_factor));
+ static_cast<std::size_t>(__builtin_floor(__p * _M_max_load_factor));
return *__p;
}
@@ -441,10 +441,10 @@
_M_bkt_for_elements(std::size_t __n) const
{
const float __min_bkts = __n / _M_max_load_factor;
- const unsigned long* __p = std::lower_bound(__prime_list, __prime_list
+ const unsigned long __p = *std::lower_bound(__prime_list, __prime_list
+ _S_n_primes, __min_bkts);
_M_next_resize =
- static_cast<std::size_t>(__builtin_ceil(*__p * _M_max_load_factor));
+ static_cast<std::size_t>(__builtin_floor(__p * _M_max_load_factor));
return *__p;
}
@@ -469,17 +469,17 @@
if (__min_bkts > __n_bkt)
{
__min_bkts = std::max(__min_bkts, _M_growth_factor * __n_bkt);
- const unsigned long* __p =
- std::lower_bound(__prime_list, __prime_list + _S_n_primes,
- __min_bkts);
+ const unsigned long __p =
+ *std::lower_bound(__prime_list, __prime_list + _S_n_primes,
+ __min_bkts);
_M_next_resize = static_cast<std::size_t>
- (__builtin_ceil(*__p * _M_max_load_factor));
+ (__builtin_floor(__p * _M_max_load_factor));
return std::make_pair(true, *__p);
}
else
{
_M_next_resize = static_cast<std::size_t>
- (__builtin_ceil(__n_bkt * _M_max_load_factor));
+ (__builtin_floor(__n_bkt * _M_max_load_factor));
return std::make_pair(false, 0);
}
}
Index: testsuite/23_containers/unordered_set/hash_policy/load_factor.cc
===================================================================
--- testsuite/23_containers/unordered_set/hash_policy/load_factor.cc (revision 0)
+++ testsuite/23_containers/unordered_set/hash_policy/load_factor.cc (revision 0)
@@ -0,0 +1,58 @@
+// Copyright (C) 2011 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+//
+// { dg-options "-std=gnu++0x" }
+
+#include <unordered_set>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ bool test __attribute__((unused)) = true;
+ {
+ std::unordered_set<int> us;
+ for (int i = 0; i != 100000; ++i)
+ {
+ us.insert(i);
+ VERIFY( us.load_factor() <= us.max_load_factor() );
+ }
+ }
+ {
+ std::unordered_set<int> us;
+ us.max_load_factor(3.f);
+ for (int i = 0; i != 100000; ++i)
+ {
+ us.insert(i);
+ VERIFY( us.load_factor() <= us.max_load_factor() );
+ }
+ }
+ {
+ std::unordered_set<int> us;
+ us.max_load_factor(.3f);
+ for (int i = 0; i != 100000; ++i)
+ {
+ us.insert(i);
+ VERIFY( us.load_factor() <= us.max_load_factor() );
+ }
+ }
+}
+
+int main()
+{
+ test01();
+ return 0;
+}