DF12195 TPFDF ? Allow Optimistic Read Ahead

TPFUG_Req_Number: DF12195
ORIGIN DATE: 10/23/2012
REQUIREMENT ABSTRACT (required)

TPFDF Optimistic Read Ahead – TPFDF should read the next block in chain using asynchronous FINDC as soon as the current block is read. Provide an option to control this on DBOPN or DBRED.


REQUIREMENT DESCRIPTION (required)

Allow TPFDF to read chains using FINDC as soon as the file address for the next chain is known. This can be controlled by an option on DBOPN or DBRED macros.



CRITICAL SUCCESS FACTORS (optional)


ALTERNATIVE SOLUTIONS (optional)



SOLUTION CONSIDERATIONS (required)

When a LREC match is found, and TPFDF has been set to do the optimized read, then TPFDF issues a FINDC. When the application issues another DF macro, and DF needs the next block, it can check if that I/O is still pending, and if it is then do a WAITC. There may be more error checking that needs to be handled especially if the WAITC happens outside of TPFDF.