Guardian Procedure Calls Reference Manual

CHECKMONITOR Procedure
Summary
Syntax for C Programmers
Syntax for TAL Programmers
Returned Value
Considerations
Messages
Summary
The CHECKMONITOR procedure is called by a backup process to monitor the state of the primary
process and to return control to the appropriate point (in the backup process) in the event of a
failure of the primary process.
Syntax for C Programmers
This passive backup procedure is not supported in C programs. For a comparison of active backup
and passive backup, see the Guardian Programmer's Guide.
Syntax for TAL Programmers
status := CHECKMONITOR;
Returned Value
INT
A status word of this form:
2<0:7>=
Primary process stopped.0<8:15> =
Primary process abnormally ended.1
Primary process processor failed.2
Primary process called CHECKSWITCH.3
NOTE: The normal return from a call to CHECKMONITOR 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 CHECKMONITOR only if the
primary process has not checkpointed its stack through a call to the CHECKPOINT[MANY][X]
procedure.
138 Guardian Procedure Calls (C)