Guardian Procedure Calls Reference Manual

CHECKPOINT Procedure (Superseded by CHECKPOINTX Procedure)
Summary
Syntax for C Programmers
Syntax for TAL Programmers
Parameters
Returned Value
Considerations
Summary
NOTE: This procedure cannot be called by native processes. Although this procedure is supported
for TNS processes, it should not be used for new development.
The CHECKPOINT 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 checkpoint to
be successful.
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 := CHECKPOINT ( [ stack-origin ] ! i
,[ buffer-1 ], [ count-1 ] ! i,i
,[ buffer-2 ], [ count-2 ] ! i,i
. .
. .
. .
,[ buffer-13], [ count-13] ); ! i,i
Parameters
stack-origin
input
INT:ref:*
checkpoints the process' data stack from stack-origin through the current tip-of-stack
location (‘S'). A checkpoint of the data stack defines a restart point for the backup process.
buffer-n
input
INT:ref:*
checkpoints a block of the process' data area (usually a file buffer) from buffer-n for the
number of words specified by the corresponding count-n parameter. If you omit buffer-n,
count-n is treated as filenum and that file's file synchronization block is checkpointed.
142 Guardian Procedure Calls (C)