hash_db.h

Go to the documentation of this file.

/*
 * hash_db.h
 *
 * Copyright (C) 2006  Thomas A. Vaughan
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THOMAS A. VAUGHAN ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THOMAS A. VAUGHAN BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Simple implementation of a transactionally safe hash database.
 */

#ifndef WAVEPACKET_HASH_DB__H__
#define WAVEPACKET_HASH_DB__H__

// includes --------------------------------------------------------------------
#include "datahash/datahash.h"          // these are what we store


namespace hash_db {

/// \ingroup datahash_top
/*@{*/

////////////////////////////////////////////////////////////////////////////////
///
/// \defgroup hash_db Simple Hash Database API
///
/// Quick API for atomically storing and retrieving collections of objects.
///
/// This is NOT scalable!  Do not use for storage of lots of objects, or high
/// performance, etc.  This is a quick-and-dirty implementation for atomic
/// storage of a small number of small objects.
///
/// Similar to BerkelyDB model: you can get and put objects based on a client-
/// defined ID.
///
////////////////////////////////////////////////////////////////////////////////
/*@{*/


////////////////////////////////////////////////////////////////////////////////
///
///     hash_db::Database
///
///     This is the object to use.  Uses advisory locking under the covers, so
///     only 1 process can access at a time.
///
////////////////////////////////////////////////////////////////////////////////

class Database {
public:
        // virtual destructor --------------------------------------------------
        virtual ~Database(void) throw();

        // hash_db::Database class interface methods ---------------------------

        /// get IDs for all objects in database
        virtual void getIds(OUT SetString& ids) = 0;

        /// add the given object (hash) to the database with the given ID
        virtual bool addObject(IN const char * id,
                                IN smart_ptr<Datahash> obj) = 0;

        /// retrieve the object with the specified ID
        virtual smart_ptr<Datahash> getObject(IN const char * id) = 0;

        /// delete the object with the specified ID
        virtual bool deleteObject(IN const char * id) = 0;

        /// commit all outstanding changes
        virtual bool commit(void) = 0;

        // public static methods (factories) -----------------------------------

        /// create Database object from specified file
        static smart_ptr<Database> create(IN const char * db_file);
};



};      // hash_db namespace

#endif  // WAVEPACKET_HASH_DB__H__