name_cache.cpp

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#ifndef NAME_CACHE_IMPLEMENTATION_FILE
#define NAME_CACHE_IMPLEMENTATION_FILE

/*****************************************************************************\
*                                                                             *
*  Name   : name_cache                                                        *
*  Author : Chris Koeritz                                                     *
*                                                                             *
*******************************************************************************
* Copyright (c) 1992-$now By Author.  This program 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 2 of   *
* the License or (at your option) any later version.  This is online at:      *
*     http://www.fsf.org/copyleft/gpl.html                                    *
* Please send any updates to: fred@gruntose.com                               *
\*****************************************************************************/

#include "dns_entry.h"
#include "name_cache.h"

#include <basis/function.h>
#include <basis/log_base.h>
#include <basis/mutex.h>
#include <data_struct/symbol_table.cpp>
#include <mechanisms/ithread.h>

const int RESOLUTION_INTERVAL = 500;
  // the number of milliseconds between attempts to resolve the names.

class name_cache_resolver : public ithread
{
public:
  name_cache_resolver(name_cache &parent)
  : ithread(RESOLUTION_INTERVAL), _parent(parent) {}

  void perform_activity(void *formal(data)) {
//hmmm: resolve names that are not yet.
  }

private:
  name_cache &_parent;
};


class dns_entry_table : public symbol_table<dns_entry> {};


name_cache::name_cache(int max_entries)
: _max_cache(max_entries),
  _lock(new mutex),
  _name_list(new dns_entry_table)
{}

name_cache::~name_cache()
{
  WHACK(_name_list);
  WHACK(_lock);
}

void name_cache::add(const istring &name, const dns_entry &to_add)
{
  auto_synchronizer l(*_lock);
  dns_entry *found = _name_list->find(name);
  if (!found) {
    // add a new entry.
    if (_name_list->symbols() >= _max_cache) {
      _name_list->whack(_name_list->name(0));
//this is bad; make it zap least recently used.
    }
    _name_list->add(name, to_add);
    return;
  }
  // replace the existing info if the new info claims to be resolved.
  if (to_add._resolved) *found = to_add;
}

bool name_cache::remove(const istring &to_whack)
{
  auto_synchronizer l(*_lock);
  return _name_list->whack(to_whack) == common::OKAY;
}

dns_entry name_cache::lookup(const istring &name) const
{
  auto_synchronizer l(*_lock);
  dns_entry *found = _name_list->find(name);
  if (!found) return dns_entry();  // doesn't exist.
  return *found;
}

void name_cache::show_names(istring &to_fill)
{
  auto_synchronizer l(*_lock);
  for (int i = 0; i < _name_list->symbols(); i++) {
    dns_entry &found = (*_name_list)[i];
    to_fill += found.text_form() + log_base::platform_ending();
  }
}


#endif //NAME_CACHE_IMPLEMENTATION_FILE

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