sybperl-l Archive

From: Phil dot Moore at morganstanley dot com
Subject: Patch to DBD::SYbase 1.01 for nsql deadlock retry logic
Date: Nov 12 2003 4:55PM

Mike --

Please apply this patch to the next release of DBD::Sybase.  The
nsql() implementation has a critical flaw in the deadlock retry logic
upon which many of us depend.

When a failure occurs the errors is stashed in $err, and if that error
is a deadlock (Message 1205), and the application has configured the
various retry attributes, then the SQL is resubmitted correctly.

However, if a subsequent execute succeeds, the $err variable still has
the value from the previous failure, and the code then returns no
data.  $err needs to be reset per invocation od the DEADLOCK block.

The patch is trivial:

*** Sybase.pm.~1~       Mon Sep  8 17:30:22 2003
--- Sybase.pm   Mon Nov 10 17:05:21 2003
***************
*** 381,388 ****
  
  #     DBI->trace(3);
        
!     DEADLOCK: 
          {     
            # Use RaiseError technique to throw a fatal error if anything goes
            # wrong in the execute or fetch phase.
            eval { 
--- 381,395 ----
  
  #     DBI->trace(3);
        
!     DEADLOCK:
          {     
+ 
+           #
+           # Initialize $err before each iteration through this loop.
+           # Otherwise, we inherit the value from the previous failure.
+           #
+           $err = undef;
+ 
            # Use RaiseError technique to throw a fatal error if anything goes
            # wrong in the execute or fetch phase.
            eval {