safe_unordered_container.h

Go to the documentation of this file.

// Safe container implementation  -*- C++ -*-
 
// Copyright (C) 2011-2026 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.
 
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
 
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.
 
/** @file debug/safe_unordered_container.h
 *  This file is a GNU debug extension to the Standard C++ Library.
 */
 
#ifndef _GLIBCXX_DEBUG_SAFE_UNORDERED_CONTAINER_H
#define _GLIBCXX_DEBUG_SAFE_UNORDERED_CONTAINER_H 1
 
#include <debug/assertions.h>
#include <debug/macros.h>
#include <debug/functions.h>
#include <debug/safe_unordered_base.h>
 
namespace __gnu_debug
{
  template<typename _Container>
    class _Safe_unordered_container;
 
#ifdef __glibcxx_node_extract // >= C++17 && HOSTED
  template<typename _ExtractKey, typename _Source>
    struct _UContInvalidatePred
    {
      template<typename _Iterator>
        bool
        operator()(_Iterator __it) const
        { return _M_source._M_cont().count(_ExtractKey{}(*__it)) == 0; }
 
      const _Safe_unordered_container<_Source>& _M_source;
    };
 
  template<typename _ExtractKey, typename _Source>
    struct _UMContInvalidatePred
    {
      template<typename _Iterator>
        bool
        operator()(_Iterator __it) const
        {
          auto __rng =
            _M_source._M_cont()._M_base().equal_range(_ExtractKey{}(*__it));
          for (auto __rit = __rng.first;
               __rit != __rng.second; ++__rit)
            {
              if (__it == __rit)
                return false;
            }
 
          return true;
        }
 
      const _Safe_unordered_container<_Source>& _M_source;
    };
 
  template<typename _Source, typename _InvalidatePred>
    struct _UContMergeGuard
    {
      _UContMergeGuard(_Safe_unordered_container<_Source>& __src) noexcept
      : _M_source(__src), _M_size(__src._M_cont().size()), _M_pred { __src }
      { }
 
      _UContMergeGuard(const _UContMergeGuard&) = delete;
 
      ~_UContMergeGuard()
      {
        const std::size_t __size = _M_source._M_cont().size();
        if (__size == _M_size)
          return;
 
        __try
          {
            if (__size == 0)
              _M_source._M_invalidate_all();
            else
              _M_source._M_invalidate_all_if(_M_pred);
          }
        __catch(...)
        {
          _M_source._M_invalidate_all();
        }
      }
 
      _Safe_unordered_container<_Source>& _M_source;
      const std::size_t _M_size;
      _InvalidatePred _M_pred;
  };
#endif // >= C++17 && HOSTED
 
  /**
   * @brief Base class for constructing a @a safe unordered container type
   * that tracks iterators that reference it.
   *
   * The class template %_Safe_unordered_container simplifies the
   * construction of @a safe unordered containers that track the iterators
   * that reference the container, so that the iterators are notified of
   * changes in the container that may affect their operation, e.g., if
   * the container invalidates its iterators or is destructed. This class
   * template may only be used by deriving from it and passing the name
   * of the derived class as its template parameter via the curiously
   * recurring template pattern. The derived class must have @c
   * iterator and @c const_iterator types that are instantiations of
   * class template _Safe_iterator for this container and @c local_iterator
   * and @c const_local_iterator types that are instantiations of class
   * template _Safe_local_iterator for this container. Iterators will
   * then be tracked automatically.
   */
  template<typename _Container>
    class _Safe_unordered_container : public _Safe_unordered_container_base
    {
      const _Container&
      _M_cont() const noexcept
      { return *static_cast<const _Container*>(this); }
 
      const _Safe_unordered_container*
      _M_self() const
      { return this; }
 
    protected:
#ifdef __glibcxx_node_extract // >= C++17 && HOSTED
      template<typename _ExtractKey, typename _Source>
        friend struct ::__gnu_debug::_UContInvalidatePred;
 
      template<typename _ExtractKey, typename _Source>
        friend struct ::__gnu_debug::_UMContInvalidatePred;
 
      template<typename _Source, typename _InvalidatePred>
        friend struct ::__gnu_debug::_UContMergeGuard;
 
      template<typename _ExtractKey, typename _Source>
        static _UContMergeGuard<_Source,
                                _UContInvalidatePred<_ExtractKey, _Source>>
        _S_uc_guard(_ExtractKey, _Safe_unordered_container<_Source>& __src)
        {
          typedef _UContInvalidatePred<_ExtractKey, _Source> _InvalidatePred;
          return _UContMergeGuard<_Source, _InvalidatePred>(__src);
        }
 
      template<typename _ExtractKey, typename _Source>
        static _UContMergeGuard<_Source,
                                _UMContInvalidatePred<_ExtractKey, _Source>>
        _S_umc_guard(_ExtractKey, _Safe_unordered_container<_Source>& __src)
        {
          typedef _UMContInvalidatePred<_ExtractKey, _Source> _InvalidatePred;
          return _UContMergeGuard<_Source, _InvalidatePred>(__src);
        }
#endif // >= C++17 && HOSTED
 
      void
      _M_invalidate_all()
      {
        __gnu_cxx::__scoped_lock sentry(_M_self()->_M_get_mutex());
        auto __end = _M_cont()._M_base().cend();
        _M_invalidate_if(
          [__end](decltype(__end) __it)
          { return __it != __end; },
          sentry);
 
        auto __local_end = _M_cont()._M_base().cend(0);
        _M_invalidate_local_if(
          [__local_end](decltype(__local_end) __it)
          { return __it != __local_end; },
          sentry);
      }
 
      template<typename _Predicate>
        void
        _M_invalidate_all_if(_Predicate __pred)
        {
          __gnu_cxx::__scoped_lock sentry(_M_self()->_M_get_mutex());
          _M_invalidate_if(__pred, sentry);
          _M_invalidate_local_if(__pred, sentry);
        }
 
      template<typename _VictimIt>
        void
        _M_invalidate(_VictimIt __victim)
        {
          __gnu_cxx::__scoped_lock sentry(_M_self()->_M_get_mutex());
          _M_invalidate(__victim, sentry);
        }
 
      template<typename _VictimIt>
        void
        _M_invalidate(_VictimIt __victim, const __gnu_cxx::__scoped_lock& __lock)
        {
          auto __end = _M_cont()._M_base().cend();
          _M_invalidate_if(
            [__victim](decltype(__end) __it)
            { return __it == __victim; },
            __lock);
 
          auto __local_end = _M_cont()._M_base().cend(0);
          _M_invalidate_local_if(
            [__victim](decltype(__local_end) __it)
            { return __it == __victim; },
            __lock);
        }
 
    private:
      /** Invalidates all iterators @c x that reference this container,
          are not singular, and for which @c __pred(x) returns @c
          true. @c __pred will be invoked with the normal iterators nested
          in the safe ones. */
      template<typename _Predicate>
        void
        _M_invalidate_if(_Predicate __pred, const __gnu_cxx::__scoped_lock&);
 
      /** Invalidates all local iterators @c x that reference this container,
          are not singular, and for which @c __pred(x) returns @c
          true. @c __pred will be invoked with the normal local iterators
          nested in the safe ones. */
      template<typename _Predicate>
        void
        _M_invalidate_local_if(_Predicate __pred,
                               const __gnu_cxx::__scoped_lock&);
    };
} // namespace __gnu_debug
 
#include <debug/safe_unordered_container.tcc>
 
#endif