libstdc++-v3/testsuite/23_containers/unordered_set/max_load_factor/robustness.cc

// { dg-do run { target c++11 } }

// Copyright (C) 2011-2021 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/>.

#include <unordered_set>
#include <limits>
#include <ext/throw_allocator.h>
#include <testsuite_hooks.h>

template<template<typename _Value, typename _Hash,
		  typename _Pred, typename _Alloc>
	   typename _USet>
  void test()
  {
    typedef std::numeric_limits<std::size_t> nl_size_t;
    _USet<int, std::hash<int>, std::equal_to<int>,
	  __gnu_cxx::throw_allocator_limit<int> > us;
    int val = 0;
    for (; val != 100; ++val)
      {
	VERIFY( us.insert(val).second );
	VERIFY( us.load_factor() <= us.max_load_factor() );
      }

    float cur_max_load_factor = us.max_load_factor();
    int counter = 0;
    std::size_t thrown_exceptions = 0;

    // Reduce max load factor.
    us.max_load_factor(us.max_load_factor() / 4);

    // At this point load factor is higher than max_load_factor because we can't
    // rehash in max_load_factor call.
    VERIFY( us.load_factor() > us.max_load_factor() );

    while (true)
      {
	__gnu_cxx::limit_condition::limit_adjustor adjustor(counter++);
	bool do_break = false;
	try
	  {
	    size_t nbkts = us.bucket_count();
	    // Check that unordered_set will still be correctly resized when
	    // needed.
	    VERIFY( us.insert(val++).second );
	    VERIFY( us.bucket_count() != nbkts );
	    VERIFY( us.load_factor() <= us.max_load_factor() );
	    do_break = true;
	  }
	catch (const __gnu_cxx::forced_error&)
	  {
	    // max load factor doesn't change.
	    VERIFY( us.max_load_factor() == .25f );
	    ++thrown_exceptions;
	  }

	if (do_break)
	  break;
      }

    VERIFY( thrown_exceptions > 0 );
  }


template<typename _Value, typename _Hash,
	 typename _Pred, typename _Alloc>
  using unordered_set_power2_rehash =
  std::_Hashtable<_Value, _Value, _Alloc,
		  std::__detail::_Identity,
		  _Pred,
		  _Hash,
		  std::__detail::_Mask_range_hashing,
		  std::__detail::_Default_ranged_hash,
		  std::__detail::_Power2_rehash_policy,
		  std::__detail::_Hashtable_traits<false, true, true>>;

int main()
{
  test<std::unordered_set>();
  test<unordered_set_power2_rehash>();
  return 0;
}