(Non-Win32 users: The real issue here is not Win32-specific.)
I'm trying to write an mp1/Apache::Registry script on Win32 that uses
the Win32::Shortcut module, and I find that it works fine under CGI but
not mod_perl.
I think the problem is this:
Win32::Shortcut in an XS module. The XS file has a BOOT: section which
calls a Win32 API function called CoInitialize(). This is called by
"bootstrap Win32::Shortcut;" when the module is require()'d/use()'d.
The PM file has an END block which calls an XS routine which calls
another Win32 API function called CoUninitialize().
Nothing else in this module works unless it is called *between* those
calls to CoInit and CoUninit.
Under CGI, when my script starts running it runs "use Win32::Shortcut;"
which calls CoInit, then it does whatever it has to do, then exits,
causing the END block to be run, which calls CoUninit. The next time
the script is run we just do it all again:
----------
CoInit
# do stuff for request 1
CoUninit
----------
CoInit
# do stuff for request 2
CoUninit
----------
...
However, under Apache::Registry the CoInit call only gets done once
because the module is only loaded once and thereafter gets cached, but
the END block is still run at the end of every script run, so now we have:
----------
CoInit
# do stuff for request 1
CoUninit
----------
# do stuff for request 2
CoUninit
----------
...
You can see why request 2 doesn't work: CoUninit was called at the end
of request 1 and CoInit hasn't been called since.
I tried placing a "use Win32::Shortcut;" line in my mp1 startup.pl
script (and I also tried "PerlModule Win32::Shortcut" in the httpd.conf
file instead, which I believe amounts to the same thing) to see if this
would help, but it doesn't:
As explained in the mod_perl manpage, the END block will now only get
run once (at server shutdown) because it was encountered during server
startup. I thought that this would solve the problem since now we have
one call to CoInit at startup and one call to CoUninit at shutdown and
neither gets called any other time, but I now find that *no* requests to
the script work, not even the first request!
I think the reason is that the parent Apache.exe loaded the module,
doing the CoInit call (and will later run the END block, doing the
CoUninit too), but the child Apache.exe actually serves the request, and
the CoInit/CoUninit calls have to be made from the same process that
wants to be doing stuff in-between, so now the child doesn't work at all
since it never called CoInit to start with.
The only way that I've got this working so far is to simulate what
Apache::StatINC would do if the module was changed between every
request: I've deleted the loading of the module from server startup,
and now have this in my script:
use Win32::Shortcut;
delete $INC{'Win32/Shortcut.pm'};
require 'Win32/Shortcut.pm';
...
The use() line there gets an END block installed to be run at the end of
every script run, while the delete()/require() calls force the bootstrap
code to be re-run at the start of every script run.
This seems to work (so far!), but is there a more elegant way of doing this?
- Steve
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