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From Jeff Trawick <>
Subject Re: cvs commit: apache-2.0/src/lib/apr/dso/os2 dso.c dso.h
Date Tue, 28 Mar 2000 02:36:19 GMT
> One other thing, the OS/2 API call DosLoadModule() returns a valuable
> piece of information on failure, the name of the module that failed to
> load. When loading a DLL, that DLL may depend on a whole chain of other
> DLLs, any one of which may fail. Knowing which one did can save a whole
> lotta time. 
> In 1.3, this information is put in the static error string for later
> retrieval by ap_os_dso_error(). For APR I'm thinking that it could be
> stored in the dso_handle_t for later retrieval by a suitable accessor
> function.

There are plenty of other situations where a particular os has special
information which, if available, greatly simplifies problem
determination.  OS/390, for example, has a secondary error indicator
for every system call which provides more information about the
error.  In many cases it is able to pinpoint the error.  This is
particularly helpful in the case of configuration problems.  

We could invent ways particular to different data types for saving
this information; we could add code to our favorite APR app for
checking to see if any such information was available.  

An alternate idea (shot down very quickly a few weeks ago) would be
for an APR app to give APR a function to call to record error
information.  This dispenses with some issues completely, such as how
to store the error info in the object for later retrieval and when the
APR app should query the object for such info (all this multiplied by
the number of objects that should support this type of information).

One platform-independent aspect of the trace is the use of a text
string to record the diagnostic information.  The text string could be
used on any platform.  If get-last-error functions are added to
various objects, they could return a text string for passing to

Jeff Trawick | | PGP public key at web site:
          Born in Roswell... married an alien...

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