PMDF Programmer's Reference Manual
PMDF-PRM-6.0

Specify the address of a procedure to call when a PMDF RESTART or PMDF SHUTDOWN command has been issued.

VMS FORMAT

status = PMDF_set_call_back

(proc, facility, facility_len)

C FORMAT

status = PMDFsetCallBack

(proc, facility, facility_len)

int PMDFsetCallBack (proc, facility, facility_len) 
         void (*proc)(); 
         char  *facility; 
         int    facility_len; 

ARGUMENTS

proc

An asynchronous procedure which will be called at AST level whenever a PMDF RESTART or SHUTDOWN command is issued. This procedure will be passed by reference a single integer parameter explaining the reason for the call back.

facility

Facility or component name to associate with the routine using this call back. When a RESTART or SHUTDOWN command specifying this facility name is issued, then the call back procedure will be invoked. The length of this string should not exceed 17 bytes.

facility_len

Length in bytes of facility.

DESCRIPTION

PMDF_cancel_call_back is only functional on OpenVMS systems. On other systems, it merely returns PMDF__OK and does nothing. Through a call back procedure, programs may be notified whenever a PMDF RESTART or PMDF SHUTDOWN command has been issued. Unless PMDF_cancel_call_back is called, the call back procedure will be called each and every time any of the five commands are issued

$ PMDF CACHE/CLOSE
$ PMDF RESTART
$ PMDF RESTART facility
$ PMDF SHUTDOWN
$ PMDF SHUTDOWN facility

where facility is the facility name. The call back procedure will be invoked at AST level and passed, by reference, a single argument. This argument is of type integer and has one of three values:

Symbolic name	Value	Command issued
PMDF_CACHE_CALLBACK	8	PMDF CACHE/CLOSE
PMDF_RESTART_CALLBACK	16	PMDF RESTART [facility]
PMDF_SHUTDOWN_CALLBACK	24	PMDF SHUTDOWN [facility]

In response to a PMDF_CACHE_CALLBACK call back, the program using the call back should close the queue cache as soon as is convenient by calling PMDF_close_queue_cache. In response to either of the other two call backs, the program should exit in an orderly fashion as soon as is convenient. In the case of PMDF_RESTART_CALLBACK, the program should be restarted (i.e., re-run). On OpenVMS systems, this routine will enqueue five resource locks each with blocking ASTs. In order to accomplish this, SYSLCK privilege as well as a sufficient enqueue and AST quotas are required. The call back procedure will be invoked at AST level. Note that the delivery of the blocking AST's used by PMDF_set_call_backs may be hindered in a program which itself spends most of its time at AST level.