HP 3000 Manuals HP 3000 Manuals
DBXEND
INTRINSIC NUMBER 421
Designates the end of a sequence of TurboIMAGE/XL procedure calls
regarded as a dynamic transaction for the purposes of logging and dynamic
roll-back recovery. The text parameter can be used to log user
information to the log file. DBXEND is used in conjunction with DBXBEGIN
to begin and end a dynamic transaction.
Syntax
DBXEND,base,text,mode,status,textlen
Parameters
base is the name of the array used as the base parameter
when opening the database. The first element of
the array must contain the base ID returned by
DBOPEN. (Refer to DBOPEN for more information about
the base ID.)
text is an array up to 256 halfwords long that contains
user ASCII or binary data to be written to the log
file as part of the DBXEND log record.
mode must be a halfword equal to 1 or 2.
Mode 1: End of dynamic transaction.
Mode 2: End dynamic transaction and write
contents of the logging buffer in memory
to disk. If logging is enabled, the
contents of the logging buffer in memory
will also be written to disk.
status is the name of an array of 10 halfwords in which
TurboIMAGE/XL returns status information about the
procedure. If the procedure executes successfully,
the status array contents are as follows:
Element Contents
1 If the procedure succeeds, the return
status is 0. Table 5-25 describes
the contents of element 1 when the
procedure does not succeed.
2-4 Unchanged from previous procedure call
using this array.
5-10 Procedure call information. Refer to
"Library Procedure Error Messages" in
appendix A for a description of this
information.
textlen is an integer equal to the number of halfwords to
be logged from the text parameter, or is a negative
integer equal to the number of bytes. Length can
be zero.
Discussion
[REV BEG]
DBXEND is called to designate the end of a sequence of TurboIMAGE/XL
procedure calls that are collectively considered a dynamic transaction.
If an intrinsic fails within a dynamic transaction, you may use DBXEND to
end the dynamic transaction at that point. The modifications completed
until that point will remain in the database. The beginning of such a
sequence is designated by a previous call to DBXBEGIN. DBXEND cannot be
called to end a transaction started by DBBEGIN.[REV END]
Logging and DBRECOV are not needed with dynamic transactions, because the
database can be recovered dynamically. However, if the calling process
is logging, DBXEND causes a record to be written to the log file to
identify the end of a dynamic transaction.
If you call DBXEND with mode 2, DBXEND forces the XM log buffer (and user
log buffer if the process is logging) to be written from memory to disk
before returning to the calling process. Use this option only for
critical transactions; too many mode 2 DBXEND calls can degrade
performance by causing a disk access each time a dynamic transaction
ends.
DBXEND returns an error condition if it is called without a prior
matching call to DBXBEGIN. [REV BEG] DBXEND is not necessary after a
DBXUNDO.[REV END]
Table 5-25. DBXEND Return Status Values
----------------------------------------------------------------------------------------------
| File System, Memory | -213 | DBXEND encountered XM error nn when ending dynamic |
| Management, and | | transaction. |
| Transaction Management | | |
| Failures: | | |
----------------------------------------------------------------------------------------------
| Calling Errors: | -11 | Bad database reference. |
| | -31 | Bad (unrecognized) DBXEND mode: n. |
| | -151 | Text length greater than 512 bytes. |
| | -219 | Remote database access incompatible with Dynamic |
| | | Rollback. |
| | -222 | Only DBXUNDO allowed when a dynamic transaction |
| | | encounters an error. |
| | -223 | Cannot DBXEND or DBXUNDO a transaction which was |
| | | not active. |
| | -237 | Cannot DBXEND or DBXUNDO a DBBEGIN transaction. |
----------------------------------------------------------------------------------------------
- Logging System Failures: - -111 - WRITELOG failure. -
----------------------------------------------------------------------------------------------
| Exceptional Conditions: | 67 | DBU disabled; potential damage; only DBCLOSE |
| | | allowed. |
----------------------------------------------------------------------------------------------
Consult appendix A for more information about these conditions.