url-handle-manager.cc

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2017-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave 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 of the License, or
// (at your option) any later version.
//
// Octave 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 Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
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////////////////////////////////////////////////////////////////////////
 
// Extracted from urlwrite.cc.
 
#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include <cmath>
 
#include "url-handle-manager.h"
 
namespace octave
{
  static double
  make_handle_fraction (void)
  {
    static double maxrand = RAND_MAX + 2.0;
 
    return (rand () + 1.0) / maxrand;
  }
 
  url_handle url_handle_manager::get_handle (void)
  {
    url_handle retval;
 
    // Curl handles are negative integers plus some random fractional
    // part.  To avoid running out of integers, we recycle the integer
    // part but tack on a new random part each time.
 
    auto p = handle_free_list.begin ();
 
    if (p != handle_free_list.end ())
      {
        retval = *p;
        handle_free_list.erase (p);
      }
    else
      {
        retval = url_handle (next_handle);
 
        next_handle = std::ceil (next_handle) - 1.0 - make_handle_fraction ();
      }
 
    return retval;
  }
 
  void url_handle_manager::free (const url_handle& h)
  {
    if (h.ok ())
      {
        auto p = handle_map.find (h);
 
        if (p == handle_map.end ())
          error ("url_handle_manager::free: invalid object %g", h.value ());
 
        // Curl handles are negative integers plus some random
        // fractional part.  To avoid running out of integers, we
        // recycle the integer part but tack on a new random part
        // each time.
 
        handle_map.erase (p);
 
        if (h.value () < 0)
          handle_free_list.insert
            (std::ceil (h.value ()) - make_handle_fraction ());
      }
  }
}