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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
  part_id
      Input that describes the unique partition identifier.

  handle
      Output that displays 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

    ·  Initializing 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
  partition's database and, if it exists on disk, reads it into the shared
  memory. A semaphore is also created that is used to synchronize potential
  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 database is loaded from disk might not be appropriate. Therefore,
       the program must call class_load_database() to specify the target
       database.

RESTRICTIONS
  The caller must have root access rights.

RETURN VALUES
  CLASS_SUCCESS
      The operation completed successfully.

  CLASS_DEFAULT_CONFIGURED
      The class_open() succeeded but no database existed.  A new database was
      created with default configuration settings.

  CLASS_NOT_SUSER
      The calling process is not superuser (root) and permission is denied.

  CLASS_MEM_ALLOC_FAILURE
      The malloc function failed to get memory for handle.

  CLASS_FILE_FAILURE
      Failed to access disk file, if it exists.

  CLASS_SHARED_MEM_FAILURE
      Failed to create or attach to shared memory.

  CLASS_SEMAPHORE_FAILURE
      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

Index for Section 3

Alphabetical listing for C

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