[Koha-devel] Restructuring C4

[Ian Walls]

Fellow Developers,


Last night, I stayed up late running circ/circulation.pl through NYTProf, to
get an idea where we may be able to optimize circulation for speed.  After
much frustration (darn session IDs...), I was able to get a report.  The
results were... not exactly what I expected.

It seems that much of the time spent running circ/circulation.pl is spent
BEGINing the various C4 modules, multiple times.  C4::Items, for example, is
BEGuN 14 times in the execution of circ/circulation.pl.  More stats:

C4::Accounts - 8 BEGINs
C4::Acquisition - 14 BEGINs
C4::Auth        - 14 BEGINs
C4::Biblio       - 14 BEGINs
C4::Branch     - 5 BEGINs
C4::Circulation - 22 BEGINs
C4::Context     - 18 BEGINs
C4::Dates       - 12 BEGINs

... and so on.  Even modules like C4::XSLT, C4::SMS, C4::Suggestions, and
C4::Search::PazPar2 are BEGuN several times, without any calls to any of
their subroutines.  Some modules, it seems, don't have an END at the end...

I was also able to get a Graphviz file out, showing all the package calls
(folks may remember my keen interest in such things from KohaCon).  Running
it through sccmap to detect cycles, I found a very long one between several
of the modules.  About 8 packages long.

All this indicate to me that we REALLY need to start thinking about imposing
some kind of structure on C4.  I'm thinking something with two-levels:

Level 1 :  Calls to the database, other direct interaction with stored data
Level 2:   Calls to Level 1 functions to manipulate data

all our scripts would then be modified to call only Level 2, which would
take care of talking to Level 1.  At the worst, a particular Level 1 package
would be BEGuN as many times as there were Level 2 packages BEGuN in the
script (and we could certainly do better).  It would eliminate all the
cycles, as well.

I can provide access to my report for anyone who needs it, or more details
about how I obtained it.  Whatever any of you need to keep this conversation
going.  This is a big deal, in my opinion, and we need to start detangling
our code before too much long, or we're going to get seriously bogged down.

Cheers,


-Ian

-- 
Ian Walls
Lead Development Specialist
ByWater Solutions
Phone # (888) 900-8944
http://bywatersolutions.com
ian.walls at bywatersolutions.com
Twitter: @sekjal
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