Guardian Procedure Calls Reference Manual

CHECKPOINTX Procedure
Summary
Syntax for C Programmers
Syntax for TAL Programmers
Parameters
Returned Value
Considerations
Summary
The CHECKPOINTX procedure (like the CHECKPOINTMANYX procedure) is called by a primary
process to send information about its current executing state to its backup process. The checkpoint
information enables the backup process to recover from a failure of the primary process in an
orderly manner. The backup process must be in the "monitor" state (that is, in a call to the
CHECKMONITOR procedure) for the CHECKPOINTX call to be successful.
This procedure can be used to checkpoint:
• Stack data from a specified stack address to the tip of the stack
• Up to five data areas
• File synchronization blocks
The CHECKPOINTX procedure can be used by both TNS processes and native processes. It allows
checkpointing of data in extended data segments (flat or selectable) in addition to the user data
segment.
Use the CHECKPOINTMANYX procedure if you need to checkpoint more than five data areas.
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 := CHECKPOINTX ( [ stack-origin ] ! i
,[ segment-id1], [ bufferx-1 ], [ count-1 ] ! i,i,i
,[ segment-id2], [ bufferx-2 ], [ count-2 ] ! i,i,i
. .
. .
. .
,[ segment-id5 ], [ bufferx-5 ], [ count-5 ] ); ! i,i,i
Parameters
stack-origin
input
INT:ref:*
contains an address. CHECKPOINTX checkpoints the process' data stack from the address in
stack-origin through the current tip-of-stack location (‘S'). A checkpoint of the data stack
defines a restart point for the backup process.
See Considerations (page 157) for details.
CHECKPOINTX Procedure 155