class DD_factory

Class DD_factory: Class to handle create and delete of DDs.

Public Methods

DD_factory()

(only) ctor

~DD_factory()

dtor, calls cleanup

DD* create_dd( const char* dd_name = DD::pccDefaultDDName, const char* mode = "r", const char* config_file = NULL )

Creates a DD system.

DD* get_dd( const char* dd_name ) const

Given the name of the DD system, return pointer to it.

int delete_dd( const char* dd_name )

Deletes the DD system.

int remove_dd( const char* dd_name )

Removes the DD system.

static void cleanup()

static cleanup member function.

Documentation

Class DD_factory: Class to handle create and delete of DDs. Its main purpose is to keep track which DDs have been created or to which DDs the process has been attached. This is done using static variables nDDs and theDDs. Atexit we call the cleanup routine that makes sure that we detached from all DDs (and deletes them if necesary).

Comments:

• Is not really necessary to call these routines but one can equally well just call the DD member functions. However one then looses the automatic cleanup upon exit, so this is the preferred way.
• There is a sublety in static member functions between DD_factory and DD. The DD_factory member functions are only used for handling the creation and deletion of the DD systems for that particular process. The class DD has in addition the following static member functions:
  1. bool DD::exists( char *name ): returns true if the DD systems (i.e. the IPC resources exist)
  2. DD* DD::create_dd: the static member function that decides which DD to create how

Modifications:

DD_factory()

(only) ctor

~DD_factory()

dtor, calls cleanup

DD* create_dd( const char* dd_name = DD::pccDefaultDDName, const char* mode = "r", const char* config_file = NULL )

Creates a DD system. Using this memberfunction garantees that the DD system will be properly detached/deleted when the process exits. The arguments are:

Parameters:

dd_name - : name of the DD system
mode - : "w" to create the DD if it doesn't exits, "r" (=default): attaches to the DD
config_file - : (optional) configuration file of the DD @ return Pointer to the DD system or NULL

DD* get_dd( const char* dd_name ) const

Given the name of the DD system, return pointer to it.

Returns:

Pointer *DD or NULL if we never attached the to the system

int delete_dd( const char* dd_name )

Deletes the DD system. Note: delete_dd does only detach the current process from the DD system if there are still other processes attached to it. Removes the IPC resources if we are the last process.

Returns:

ddcSuccess if ok, ddcFailure if we never attached/created the DD system

int remove_dd( const char* dd_name )

Removes the DD system. In contrast to delete_dd we now enforce the removal (cleanup) of all IPC resources

Returns:

ddcSuccess if ok, ddcFailure if we never attached/created the DD system

static void cleanup()

static cleanup member function. This member function is called at exit and makes sure that all connections to existing DD systems are closed

This class has no child classes.

Author:

C.Witzig
Date: Mar 17, 98

Version:

Last update: Mar 17, 98

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