Spooler Plus Programmer's Guide

Using the Spooler Interface Procedures

Spooler Plus Programmer’s Guide—522293-003

2-21

Spooling—Levels 1 and 2

Spooling With a Nonzero Sync Depth

To prevent a line from being duplicated, you can take advantage of the sync depth

feature of the file system.

To use this feature, you should open the collector with a nonzero sync depth. The

program should perform a checkpoint before every nth write to the collector, where n is

the sync depth. At that time, the following should be checkpointed:



The data stack



The data line about to be written to the collector



The synchronization block of the file to the collector, including the current sync ID

and the access control block

The collector will keep track of up to 15 sync IDs; therefore, an application program

can open the collector with any sync depth up to and including 15.

Example 2-6 is an example of level-2 spooling with a nonzero sync depth.

Example 2-6. Annotated Example of Level-2 Spooling From a NonStop Process

Pair With a Nonzero Sync Depth

(page 1 of 4)

! This program is an example of level-2 NonStop spooling with a

! sync depth of 5. It consists of 6 procedures: cherror,

! stbackup, error, sperror, getline, and root, and it calls the

! Guardian procedures OPEN, CLOSE, WRITE, STOP, CHECKOPEN, and

! CHECKPOINT. It also calls SPOOLSTART to specify the attributes

! of the job.

! cherror --this procedure handles checkpointing errors.

! It performs the necessary steps for recovery or it aborts the

! program. It has a single INT parameter that is the back error

! returned from CHECKOPEN or the status word returned from

! CHECKPOINT. If it is called with a 0 value, it will stop the

! backup process.

! stbackup --this procedure decides whether this program is the

! primary or backup procedure. If it is the primary, it starts a

! backup. Otherwise, it waits for checkpointing information from

! the primary. Opens $RECEIVE and reads the Startup message.

! error --this procedure handles I/O errors. It performs the

! necessary steps for recovery or it aborts the program.

! sperror --this procedure handles spooler errors. It performs the

! necessary steps for recovery or it aborts the program. It has

! a single INT parameter that is the error code returned from the

! spooler interface procedure.