text: // namespace_index.h
  
  /**
   *    Copyright (C) 2013 10gen Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program 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 Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #pragma once
  
  #include <list>
  #include <string>
  
  #include "mongo/base/disallow_copying.h"
  #include "mongo/db/storage/mmap_v1/catalog/namespace.h"
  #include "mongo/db/storage/mmap_v1/diskloc.h"
  #include "mongo/db/storage/mmap_v1/durable_mapped_file.h"
  
  namespace mongo {
  
      class NamespaceDetails;
      class NamespaceHashTable;
      class OperationContext;
  
      /* NamespaceIndex is the ".ns" file you see in the data directory.  It is the "system catalog"
         if you will: at least the core parts.  (Additional info in system.* collections.)
      */
      class NamespaceIndex {
          MONGO_DISALLOW_COPYING(NamespaceIndex);
      public:
          NamespaceIndex(const std::string& dir, const std::string& database);
          ~NamespaceIndex();
  
          /* returns true if the file represented by this file exists on disk */
          bool pathExists() const;
  
          void init(OperationContext* txn);
  
          void add_ns( OperationContext* txn,
                       StringData ns, const DiskLoc& loc, bool capped);
          void add_ns( OperationContext* txn,
                       StringData ns, const NamespaceDetails* details );
          void add_ns( OperationContext* txn,
                       const Namespace& ns, const NamespaceDetails* details );
  
          NamespaceDetails* details(StringData ns) const;
          NamespaceDetails* details(const Namespace& ns) const;
  
          void kill_ns( OperationContext* txn,
                        StringData ns);
  
          bool allocated() const { return _ht.get() != 0; }
  
          void getCollectionNamespaces( std::list<std::string>* tofill ) const;
  
          boost::filesystem::path path() const;
  
          unsigned long long fileLength() const { return _f.length(); }
  
      private:
          void maybeMkdir() const;
  
          const std::string _dir;
          const std::string _database;
  
          DurableMappedFile _f;
          std::unique_ptr<NamespaceHashTable> _ht;
      };
  
  }
  