scopes (this is a change from previous versions). Now you only need to
worry about race conditions.
Think of your shared scopes as a primitive database, with each scope as a
table, and each individual variable as a record. The session scope is kind
of special, because it is bound to a user, so you'd actually have a "table"
for each user's session. You still need to lock though, in case they have
two browsers open, you're using a frameset, or whatever.
CFLOCK is required any place you would need to use a transaction to ensure
atomicity if you were actually talking to a database. If you're modifying a
single variable, you don't need a transaction (a single statement is always
atomic). If you're setting multiple unrelated variables, same thing,
because each can be treated as an individual action. If you're doing any
kind of relative thing (such as reading, perforing an operation, and writing
the result), you'd need a transaction, and therefore need CFLOCK.
Keep in mind that CFLOCK can only lock entire scopes (I'm ignoring the
'name' attribute), which is equivalent to locking an ENTIRE TABLE in our
database analogy. That means that using too much locking has a definite
negative effect, as it will cause access to the shared scopes to become
single-threaded, greatly reducing concurrency. So just like with income
tax, lock as little as possible, but never less than you have to.
Cheers,
barneyb
> -----Original Message-----
> From: Hoe [mailto:[EMAIL PROTECTED]
> Sent: Thursday, June 10, 2004 9:56 AM
> To: CF-Talk
> Subject: re: Using <cflock and when under different circumstances
>
> Hello,
>
> I'm having difficulty grasping when and when not to use
> <cflock>? I've been using the following for session variables.
>
> <cflock timeout="10" type="EXCLUSIVE" scope="SESSION">
> <cfset SESSION.aaa = "aaa">
> <cfset SESSION.bbb = "bbb">
> </cflock>
>
>
> Let's say I'm checking a session varaible using <cfif>
>
> <cfif SESSION.aaa eq "?>
> ...
> </cfif>
>
> Should I also be wrapping ALL my <cfif> statements with <cflock>?
>
>
> What about the below?
>
> <cflock timeout="10" type="READONLY" scope="SESSION">
> <CFX_Users ACTION=""
> USER="#SESSION.auth#" PASSWORD="#FORM.OldPassword#">
> </cflock>
>
> I'm using alot of <cfloop>. Should I be wrapping all these
> with <cflock> also>
>
> <cflock timeout="10" type="EXCLUSIVE" scope="SESSION">
> <cfloop index=List list="#SESSION.name#">
> ...</cfloop>
> </cflock>
>
>
>
>
>
>
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