1 // Copyright (C) 2012-2020 Internet Systems Consortium, Inc. ("ISC") 2 // 3 // This Source Code Form is subject to the terms of the Mozilla Public 4 // License, v. 2.0. If a copy of the MPL was not distributed with this 5 // file, You can obtain one at http://mozilla.org/MPL/2.0/. 6 7 #ifndef LEASE_MGR_FACTORY_H 8 #define LEASE_MGR_FACTORY_H 9 10 #include <database/database_connection.h> 11 #include <dhcpsrv/lease_mgr.h> 12 #include <exceptions/exceptions.h> 13 14 #include <boost/scoped_ptr.hpp> 15 16 #include <string> 17 18 namespace isc { 19 namespace dhcp { 20 21 22 /// @brief No lease manager exception 23 /// 24 /// Thrown if an attempt is made to get a reference to the current lease 25 /// manager and none is currently available. 26 class NoLeaseManager : public Exception { 27 public: NoLeaseManager(const char * file,size_t line,const char * what)28 NoLeaseManager(const char* file, size_t line, const char* what) : 29 isc::Exception(file, line, what) {} 30 }; 31 32 /// @brief Lease Manager Factory 33 /// 34 /// This class comprises nothing but static methods used to create a lease 35 /// manager. It analyzes the database information passed to the creation 36 /// function and instantiates an appropriate lease manager based on the type 37 /// requested. 38 /// 39 /// Strictly speaking these functions could be stand-alone functions. However, 40 /// it is convenient to encapsulate them in a class for naming purposes. 41 /// 42 /// @todo: Will need to develop some form of registration mechanism for 43 /// user-supplied backends (so that there is no need to modify the code). 44 class LeaseMgrFactory { 45 public: 46 /// @brief Create an instance of a lease manager. 47 /// 48 /// Each database backend has its own lease manager type. This static 49 /// method sets the "current" lease manager to be a manager of the 50 /// appropriate type. The actual lease manager is returned by the 51 /// "instance" method. 52 /// 53 /// @note When called, the current lease manager is <b>always</b> destroyed 54 /// and a new one created - even if the parameters are the same. 55 /// 56 /// dbaccess is a generic way of passing parameters. Parameters are passed 57 /// in the "name=value" format, separated by spaces. The data MUST include 58 /// a keyword/value pair of the form "type=dbtype" giving the database 59 /// type, e.q. "mysql" or "sqlite3". 60 /// 61 /// @param dbaccess Database access parameters. These are in the form of 62 /// "keyword=value" pairs, separated by spaces. They are backend- 63 /// -end specific, although must include the "type" keyword which 64 /// gives the backend in use. 65 /// 66 /// @throw isc::InvalidParameter dbaccess string does not contain the "type" 67 /// keyword. 68 /// @throw isc::dhcp::InvalidType The "type" keyword in dbaccess does not 69 /// identify a supported backend. 70 static void create(const std::string& dbaccess); 71 72 /// @brief Destroy lease manager 73 /// 74 /// Destroys the current lease manager object. This should have the effect 75 /// of closing the database connection. The method is a no-op if no 76 /// lease manager is available. 77 static void destroy(); 78 79 /// @brief Return current lease manager 80 /// 81 /// Returns an instance of the "current" lease manager. An exception 82 /// will be thrown if none is available. 83 /// 84 /// @throw isc::dhcp::NoLeaseManager No lease manager is available: use 85 /// create() to create one before calling this method. 86 static LeaseMgr& instance(); 87 88 /// @brief Indicates if the lease manager has been instantiated. 89 /// 90 /// @return True if the lease manager instance exists, false otherwise. 91 static bool haveInstance(); 92 93 private: 94 /// @brief Hold pointer to lease manager 95 /// 96 /// Holds a pointer to the singleton lease manager. The singleton 97 /// is encapsulated in this method to avoid a "static initialization 98 /// fiasco" if defined in an external static variable. 99 static boost::scoped_ptr<LeaseMgr>& getLeaseMgrPtr(); 100 101 }; 102 103 } // end of isc::dhcp namespace 104 } // end of isc namespace 105 106 #endif // LEASE_MGR_FACTORY_H 107