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// Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef HOST_DATA_SOURCE_FACTORY_H
#define HOST_DATA_SOURCE_FACTORY_H
#include <dhcpsrv/base_host_data_source.h>
#include <dhcpsrv/database_connection.h>
#include <exceptions/exceptions.h>
#include <boost/scoped_ptr.hpp>
#include <string>
namespace isc {
namespace dhcp {
/// @brief No host data source instance exception
///
/// Thrown if an attempt is made to get a reference to the current
/// host data source instance and none is currently available.
class NoHostDataSourceManager : public Exception {
public:
NoHostDataSourceManager(const char* file, size_t line, const char* what) :
isc::Exception(file, line, what) {}
};
/// @brief Host Data Source Factory
///
/// This class comprises nothing but static methods used to create a host data
/// source object. It analyzes the database information passed to the creation
/// function and instantiates an appropriate host data source object based on
/// the type requested.
///
/// Strictly speaking these functions could be stand-alone functions. However,
/// it is convenient to encapsulate them in a class for naming purposes.
class HostDataSourceFactory {
public:
/// @brief Create an instance of a host data source.
///
/// Each database backend has its own host data source type. This static
/// method sets the "current" host data source to be an object of the
/// appropriate type. The actual host data source is returned by the
/// "instance" method.
///
/// @note When called, the current host data source is <b>always</b> destroyed
/// and a new one created - even if the parameters are the same.
///
/// dbaccess is a generic way of passing parameters. Parameters are passed
/// in the "name=value" format, separated by spaces. The data MUST include
/// a keyword/value pair of the form "type=dbtype" giving the database
/// type, e.q. "mysql" or "sqlite3".
///
/// @param dbaccess Database access parameters. These are in the form of
/// "keyword=value" pairs, separated by spaces. They are backend-
/// -end specific, although must include the "type" keyword which
/// gives the backend in use.
///
/// @param db_lost_callback function to invoke if connectivity to host
/// data source is lost.
///
/// @throw isc::InvalidParameter dbaccess string does not contain the "type"
/// keyword.
/// @throw isc::dhcp::InvalidType The "type" keyword in dbaccess does not
/// identify a supported backend.
static void create(const std::string& dbaccess,
DatabaseConnection::Callback db_lost_callback = NULL);
/// @brief Destroy host data source
///
/// Destroys the current host data source object. This should have the effect
/// of closing the database connection. The method is a no-op if no
/// host data source is available.
static void destroy();
/// @brief Hold pointer to host data source instance
///
/// Holds a pointer to the singleton host data source. The singleton
/// is encapsulated in this method to avoid a "static initialization
/// fiasco" if defined in an external static variable.
static HostDataSourcePtr& getHostDataSourcePtr();
};
}; // end of isc::dhcp namespace
}; // end of isc namespace
#endif
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