Author's note. This is not meant to be patronizing or anything. It's kind
of an oversimplification, but it's intended to help you (and anyone else who
wants to read it) visualize the problems.
Okay. Pretend that data storage is a bunch of bins. Anyone can look at
shared bins, like the session, client, application, and server bins. Anyone
can write to them as well (for the most part).
Now, let's pretend that you've got a bunch of office workers who use these.
There are two problems associated with sharing all this stuff.
One: garbling things. Let's pretend that you have a long memo stored in
(what else?) application.memo. Bob the janitor is taking the memo out of
the bin a paragraph at a time (he's a slow reader). Normally, this isn't a
problem. Until Jim the manager starts rewriting the memo and sticks the
paragraphs in the bin while Bob isn't looking.. Unfortunately, Bob & Jim
aren't smart enough to co-ordinate this, so what Bob gets is the first half
of the old memo and the last half of the new memo. So he gets a garbled
memo.
Two: race conditions. Fred needs to remember something, so he sticks in in
application.something. Unfortunately, Herman needs to remember a slightly
different version, and sticks it in application.something just after Fred
does. Now, when Fred goes to read what he put there, he gets Herman's
version.
Okay, now we have CFLOCK. It's like a note on the front of the bin. If
it's a readonly lock, it says "You can read this, but don't change it until
I remove the note." If it's an exclusive lock, it says "I'm using this,
wait your turn!"
HTH.
-- Ben Doom
Programmer & General Lackey
Moonbow Software, Inc
: -----Original Message-----
: From: Scott Wilhelm [mailto:[EMAIL PROTECTED]]
: Sent: Tuesday, February 11, 2003 3:17 PM
: To: CF-Talk
: Subject: CFLOCK
:
:
: Can someone please explain to me, in very simply terms, what CFLOCK
: does, and why/when/where I should use it?
:
: I'm trying to build an application, and put it together as proper as can
: be, but for some reason, my brain doesn't want to comprehen CFLOCK.
:
: Thanks,
:
: Scott
:
:
: Scott Wilhelm
: Computer Technician/Web Developer
: St. Lawrence-Lewis BOCES
: PO Box 231, Outer State Street
: Canton, NY 13617
:
: P. 315-386-4504 x 164
: F. 315-386-3395
: W. http://www.sllboces.org
: E. [EMAIL PROTECTED]
:
:
:
:
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