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// Copyright (C) 2012-2023 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 LEASE_MGR_FACTORY_H
#define LEASE_MGR_FACTORY_H
#include <database/database_connection.h>
#include <dhcpsrv/tracking_lease_mgr.h>
#include <exceptions/exceptions.h>
#include <boost/scoped_ptr.hpp>
#include <string>
namespace isc {
namespace dhcp {
/// @brief No lease manager exception
///
/// Thrown if an attempt is made to get a reference to the current lease
/// manager and none is currently available.
class NoLeaseManager : public Exception {
public:
NoLeaseManager(const char* file, size_t line, const char* what) :
isc::Exception(file, line, what) {}
};
/// @brief Lease Manager Factory
///
/// This class comprises nothing but static methods used to create a lease
/// manager. It analyzes the database information passed to the creation
/// function and instantiates an appropriate lease manager 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.
///
/// @todo: Will need to develop some form of registration mechanism for
/// user-supplied backends (so that there is no need to modify the code).
class LeaseMgrFactory {
public:
/// @brief Create an instance of a lease manager.
///
/// Each database backend has its own lease manager type. This static
/// method sets the "current" lease manager to be a manager of the
/// appropriate type. The actual lease manager is returned by the
/// "instance" method.
///
/// @note When called, the current lease manager 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.
///
/// @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);
/// @brief Destroy lease manager
///
/// Destroys the current lease manager object. This should have the effect
/// of closing the database connection. The method is a no-op if no
/// lease manager is available.
static void destroy();
/// @brief Recreate an instance of a lease manager with optionally
/// preserving registered callbacks.
///
/// @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 preserve_callbacks a boolean flag indicating if all registered
/// @c TrackingLeaseMgr callbacks should be copied to the new
/// instance.
static void recreate(const std::string& dbaccess,
bool preserve_callbacks = true);
/// @brief Return current lease manager
///
/// Returns an instance of the "current" lease manager. An exception
/// will be thrown if none is available.
///
/// @throw isc::dhcp::NoLeaseManager No lease manager is available: use
/// create() to create one before calling this method.
static TrackingLeaseMgr& instance();
/// @brief Indicates if the lease manager has been instantiated.
///
/// @return True if the lease manager instance exists, false otherwise.
static bool haveInstance();
private:
/// @brief Hold pointer to lease manager
///
/// Holds a pointer to the singleton lease manager. The singleton
/// is encapsulated in this method to avoid a "static initialization
/// fiasco" if defined in an external static variable.
static boost::scoped_ptr<TrackingLeaseMgr>& getLeaseMgrPtr();
};
} // end of isc::dhcp namespace
} // end of isc namespace
#endif // LEASE_MGR_FACTORY_H
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