Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (D-E)
Guardian Procedure Calls Reference Manual—522629-013
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DEVICEINFO2 Procedure
(Superseded by FILE_GETINFOBYNAME_
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If you call this procedure in a nowait manner (options <13> is set to 1), the
results are returned in the nowait DEVICEINFO2 completion message (-41), not in
the output parameters of the procedure. The format of this completion message is
described in the
Guardian Procedure Errors and Messages Manual. If error is
not 0, no completion message is sent to $RECEIVE. Errors can be reported either
on return from the procedure, in which case
error might be meaningful, or
through the completion message sent to $RECEIVE.
The system reports a path error only after automatically making retries.
The nowait option allows any step of the inquiry process to execute
asynchronously to the caller. However, this option guarantees only that simulation
inquiries to subtype 30 processes will be asynchronous. Other parts of the function
may or may not be asynchronous.
Process pairs using the nowait option should handle the fact that a DEVICEINFO2
completion message is delivered only to the process that initiates it, not to the
other member of the pair. You might have the primary process keep the backup
process ignorant of outstanding inquiries, or you might have equivalent
DEVICEINFO2 calls at the point where a backup takes over from the primary
process.
For interprocess messages directed to a process pair, file-system errors 200
(ownership) and 201 (path down) are retried automatically to the other member of
the pair.
Switching ownership from the primary to the backup process can leave outstanding
inquiries. The CHECKSWITCH procedure automatically discards these as it
becomes the backup process. Programs using another method of switching
should tolerate the completions of these irrelevant inquiries.
Example
CALL DEVICEINFO2 ( INFILE, DEVTYPE, RECLENGTH, D^VERSION );