Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (C)
Guardian Procedure Calls Reference Manual—522629-013
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CHECKSWITCH Procedure
2 Primarys process processor failed
3 Primary process called CHECKSWITCH
Considerations
•
When to use CHECKSWITCH
Use CHECKSWITCH following the reload of a processor module. The purpose is
to switch the process pair’s work back to the original primary processor module.
CHECKSWITCH causes the current backup to become the primary process and to
begin processing from the latest call to the CHECKPOINT[MANY][X] procedure.
•
Identification of the backup process
The system identifies the process to be affected by the CHECKSWITCH operation
from the process’s mom field in the process control block (PCB). For named
process pairs, this field is automatically set up during the creation of a backup
process.
Note. The normal return from a call to CHECKSWITCH is to the statement following a call to
the CHECKPOINT[MANY][X] procedure. The return corresponds to the latest call to
CHECKPOINT[MANY][X] by the primary process in which its stack was checkpointed.
The backup process executes the statement following the call to CHECKSWITCH only if the
primary process has not checkpointed its stack through a call to CHECKPOINT[MANY][X].