Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
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CONTROL Procedure
26 Requests immediate completion of all outstanding
I/O requests without loss of data by the recipient of
the CONTROL 26 request.
None
27 Wait for DP2 disk file write.
This operation is not supported for queue files.
This operation finishes when a WRITE, WRITEUPDATE, or
WRITEUPDATEUNLOCK occurs on a DP2 disk file designated by
filenum.
Not valid for partitioned files.
Do not assume that the file contains any new data when a call to CONTROL
27 finishes; assume only that it is time to check the file for new data.
CONTROL 27 also finishes when a WRITE or WRITEUPDATE occurs as part
of a logical undo of a transaction by the backout process or when a volume
goes down.
If SETMODE 146 was specified, each write completes only one CONTROL
27; otherwise each write completes all pending CONTROL 27 operations.
To ensure that no updates are missed, you should issue a nowait CONTROL
27 call on one open to a file, then read data from the file on another open, and
finally wait for the CONTROL operation to finish. If CONTROL 27 were
executed after reading, a write by another process could occur between the
read and the CONTROL operations. The file open that is used for the
CONTROL operation should have a
syncdepth of 0. Path errors and network
errors might indicate successful completion.
Refer to the discussion of CONTROL operation 27 in the
Guardian
Programmer’s Guide.
Table 3-5. CONTROL Operations 2 Through 27 (page3of3)
Operation Description Description of <param>