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Bypassing a Locked Record, Take Two
Published: January 7, 2009
Hey, Ted:
I have a slightly different solution to the locked record problem your friends tackled in Bypassing a Locked Record. Like them, I have RPG programs that sequentially read a file and update some of the records. When a program tries to read a record that another job has locked, I sometimes bypass the locked record. Here's how.
Notice the READ operation in the second calculation of this example:
FSomeFile UF E K Disk Prefix(SR_)
D Forever S N inz(*On)
D Open C Const(' ')
D Closed C Const('Z')
/Free
DoW Forever;
Read(E) SomeRec;
If %Eof(SomeFile);
Leave;
EndIf;
If %Error();
Read(N) SomeRec;
Iter;
EndIf;
If SR_Status = Open and SR_Balance = *Zero;
Eval SR_Status = Closed;
Update SomeRec %Fields(SR_Status);
EndIf;
EndDo;
Eval *InLR = *On;
Return;
/End-Free
The READ includes an E extender, which tells the RPG compiler not to stop if the read ends in error. After the READ and the usual check for end-of-file, I use the %ERROR built-in function to trap the locked records. If the read failed, I read again, but this time without a lock. This second read allows me to move the file pointer to the next record.
In this example, I didn't verify that the read error was caused by a lock. If you need to get that granular, check the %STATUS built-in function for a value of 1218.
Thanks for writing about record locking. It's a big deal in my shop.
--Don
Thanks for the example, Don. We've run several tips about record locking, and I have more to cover when I can get to it.
--Ted
RELATED STORIES
Bypassing a Locked Record
Avoiding Record Locks in RPG
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Readers Insights and Feedback: Dealing with Record Locks
Release That Record Lock!
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