bstr_data_point_lock(3) — Subroutines

Name

bstr_data_point_lock − Locks a Data_Point or a Data_Point_Set (VODB only).

Syntax

bstr_t_status   bstr_data_point_lock (
                                  bstr_t_reference   ∗data_point,
                                  bstr_t_lock_type   lock_type,
                                  bstr_t_rcb         ∗control);

Description

The bstr_data_point_lock procedure allows the calling application to lock the Data_Point or Data_Point_Set specified by data_point. The lock provides the calling application with control over concurrent access by other applications.

The type of access permitted for other applications on the locked Data_Point (or Data_Point_Set) is specified by lock_type.

An application that invokes the bstr_data_point_lock procedure, for an object that is already locked, is suspended until the Data_Point becomes free (that is, until it is unlocked by the user that locked it).

Arguments

data_point
access: read
The reference to the Data_Point or Data_Point_Set to be locked.

lock_type
access: read
Indicates the type of lock to be performed on the specified Data_Point. Depending on the lock type, other users are allowed to have no access or limited access to the locked object. Valid lock types are as follows:

Constant Name	Description
BSTR_C_READ_ONLY	Other users are only allowed to read the locked object.
BSTR_C_EXCLUSIVE	No other users can read or write the locked object.

control
access: read
The address of an optional request control block.

Return Values

BSTR_S_ABORTED	Operation aborted
BSTR_S_ANOTHER_TRANSACTION	Another transaction is already open
BSTR_S_BAD_PARAMETER	Bad parameter value
BSTR_S_BAD_REFERENCE	Bad reference
BSTR_S_COMMUNICATION_ERROR	Communication error
BSTR_S_COM_PC_SIZE_MISMATCH	Number of bytes requested does not match the number of bytes returned
BSTR_S_DEVICE_SERVICES_NOT_AVAILABLE	Device Services are not available
BSTR_S_FINISH	Request aborted by bstr_finish
BSTR_S_INTERNAL_ERROR	Internal error
BSTR_S_INTR	Operation interrupted
BSTR_S_INVALID_LOCK_TYPE	Invalid lock mode
BSTR_S_INVALID_OPERATION	Invalid operation
BSTR_S_INVALID_RCB	Invalid Request Control Block
BSTR_S_INVALID_USAGE	Invalid reference usage
BSTR_S_NORMAL	Normal successful completion
BSTR_S_NO_MEMORY	Insufficient virtual memory
BSTR_S_SERVER_NOT_REACHABLE	Server not reachable
BSTR_S_TIMEOUT	Timeout expired
BSTR_S_TOO_MANY_REQUESTS	Too many pending requests