class_open man page on DigitalUNIX

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class_open(3)							 class_open(3)

NAME
       class_open - initialize the class scheduling database

SYNOPSIS
       #include <apar_types.h> #include <sys/class.h>

       class_open(
	       apar_t part_id,
	       class_apar_handle_t *handle );

LIBRARY
       Class Scheduling Library (libclass.a)

       This library is not available as a shared library.

PARAMETERS
       Input that describes the unique partition identifier.  Output that dis‐
       plays the descriptor used in calls to reference the partition.

DESCRIPTION
       The class_open() function is used to prepare the class database for use
       as  follows: Opening the disk file (if required) Creating (or attaching
       to) a shared memory section Creating (or attaching to) a semaphore Ini‐
       tializing the database if one does not aready exist

       Before class scheduling can be used for a partition, its class database
       must be initialized. At the first call of class_open() since the system
       last started, the function creates a shared memory segment for the par‐
       tition's database and, if it exists on disk, reads it into  the	shared
       memory.	A semaphore is also created that is used to synchronize poten‐
       tial simultaneous database updates (from class_admin and runclass,  for
       instance). If no database exists for the partition, one will be created
       with the default name and configuration.

       On subsequent calls to  class_open(),  the  function  attaches  to  the
       shared  memory and semaphore for the database most recently loaded into
       memory for the specified partition.

					Note

       It is possible for multiple databases to be set up on disk for use with
       the  same  partition  (to be applied at different times). In this case,
       the database currently loaded into memory or, if no database is loaded,
       the  default pathname assumed by the class_open() function when a data‐
       base is loaded from disk might not be appropriate. Therefore, the  pro‐
       gram must call class_load_database() to specify the target database.

RESTRICTIONS
       The caller must have root access rights.

RETURN VALUES
       The  operation  completed successfully.	The class_open() succeeded but
       no database existed.  A new database was created with default  configu‐
       ration  settings.  The calling process is not superuser (root) and per‐
       mission is denied.  The malloc function failed to get memory  for  han‐
       dle.   Failed  to  access disk file, if it exists.  Failed to create or
       attach to shared memory.	 Failed to create or attach to semaphore.

SEE ALSO
       Commands: runclass(1), class_admin(8)

       Functions: class_load_database(3)

       Files: class_scheduling(4)

       System Administration

								 class_open(3)
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