On 7/13/00, Dave Watts penned:
> > The also recommend <name="#session.sessionid#"> when locking
>> session vars; do you agree, or if not, what do you recommend?
>
>No, again, this causes the same problem. You want a unique name to apply to
>an individual session, but you don't want to store it in a session variable.
>If you're using CF's cookies for state management, you could do this:
>
><cflock name="#Cookie.CFID##Cookie.CFTOKEN#" ....>
OK. I'm still having a hard time getting a grasp on this (so, what
else is new?).
I thought the whole idea of naming a lock was so nobody else would be
able to read or write to that memory space and it would lock other
users out based on the name of the lock.
So, if I'm setting a session variable named "total":
<cfset session.total = session.subtotal + tax>
If I lock that cfset and name the lock #Cookie.CFID##Cookie.CFTOKEN#,
won't that mean that anyone else would still be able to write to
session.total and session.subtotal seeing as how using that method
everyone would have the same lock named differently? I mean, why name
a lock if every user has the lock named differently? Won't ColdFusion
look and see if a lock by that name is being written and if it's not,
go ahead and write it?
And a question about names across different application, or even the
same application, but named differently:
When accessing or writing an application or session variable, does
the danger lie only within duplicate named variables within the same
application? Or across the whole server? Example:
I have 3 instances of my shopping cart on a server which uses the
session variable "session.total", all 3 with the application name
unique (I always name the application the same name as the main
datasource of the app so there's no chance I can accidentally name 2
applications the same). Joe Blow has his totally different shopping
cart and it also uses a session variable of "session.total".
If none of these were locked, and there is a single user using each
shopping cart, and each cart has a diffent application name, and they
are all writing a session.total at the exact same time, is there a
danger in that? Or would there only be a danger if 2 people were
writing to session.total in the SAME NAMED APPLICATION at the same
time?
If it's based upon the session variable name across the server and
not within an application, then there's no way of knowing that you
could ever have a uniquely named lock. I am HOPING it's based on the
name in cfapplication.
And one more question:
If you are locking all session variables with the same name by using
a unique local variable, will that cause all writing to all sessions
to be postponed until the lock is released?
For instance, I have these 2 cfsets:
<cflock name="#variables.mylock# type="Exclusive" timeout="10">
<cfset session.total = session.subtotal + tax>
</cflock>
<cflock name="#variables.mylock# type="Exclusive" timeout="10">
<cfset session.user_id = somequery.user_id>
</cflock>
Would the second query be locked out while the first is being written
since the locks are named the same (even though they are accessing
different session variables)? If so, then it seems like it would be
detrimental to name any 2 locks the same that don't contain
references to the same session variable. I'm assuming this is the
case.
I'm hoping this will clear things up for me once and for all. I read
BF's CFLOCK article in CFDJ and although it was a little useful,
there was really no clear cut explanation about what happens across
different applications on the server. Sadly, that is what the
majority of us are faced with. I have alot of copies of the same
application running on my server and if I need to lock session.total
with the same name on all instances of the application to stop all
users from writing to session.total no matter what application it is
in, then that's REALLY going to be a performance hit. If I can at
least name the lock different on each copy of the application, and
not worry about a user writing to session.total on application A
while other users are writing to session.total on applications B, C,
D, and E, that would be somewhat helpful.
I hope somebody understood that. LOL
--
Bud Schneehagen - Tropical Web Creations
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
ColdFusion Solutions / eCommerce Development
[EMAIL PROTECTED]
http://www.twcreations.com/
954.721.3452
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