I would agree that a lock is not necessary. However, I'm really not sure
how CF performs an IsDefined() function. My guess is that somewhere CF
knows what variables are in existence, and it looks to that memory space - I
really don't think it looks at the values, and I seriously doubt it's as low
level as the CF structure.
---
Billy Cravens
HR Web Systems, EDS
[EMAIL PROTECTED]
----- Original Message -----
From: "Hinojosa, Robert A" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, July 31, 2001 10:07 AM
Subject: RE: question.
> woops, i guess i forgot to paste the code portion of the email. Yes
billy,
> definately persistant vars, particularly session vars. I understand the
> need to lock, but what he is saying is that since your only doing a lookup
> in the session structure, you don't need to lock the
> isDefined("session.var"). Is this a true statement?
>
> CODE PORTION OF EMAIL:
>
> <cfif IsDefined("Session.MyVar")> <!--- check it exists --->
> <!--- note: this is longhand as you can read variables in an
> exclusive --->
> <!--- lock but for this example a more verbose demonstration is
> needed --->
> <!--- read from the variable --->
> <cflock scope="session" type="readonly" timeout="10">
> <cfset V_MyVar = Session.MyVar>
> </cflock>
> <!--- write to the variable --->
> <cflock scope="session" type="exclusive" timeout="10">
> <cfset Session.MyVar = 52>
> </cflock>
> </cfif>
>
>
>
> -----Original Message-----
> From: Billy Cravens [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, July 31, 2001 9:55 AM
> To: [EMAIL PROTECTED]
> Subject: Re: question.
>
>
> It may do a read, or it may simply be a pointer to memory where existing
> variables are defined, with the actual value of the variable in a
different
> location.
>
> However, I can't understand why you'd need to a lock on a variable read
> I'm assuming you're referring to locking persistent-scope variables, like
> application). The whole purpose of the lock is to ensure data integrity
> (prevent writing to a variable while another user is reading it).
However,
> this shouldn't be the case with reading a variable.
>
> ---
> Billy Cravens
> HR Web Systems, EDS
> [EMAIL PROTECTED]
>
> ----- Original Message -----
> From: "Hinojosa, Robert A" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, July 31, 2001 9:17 AM
> Subject: question.
>
>
> > I received this email on another list and I am almost positive he is
> wrong.
> > I've read nearly everything there is to know about locking and cf, but I
> > wanted to make sure, so I am asking the greats here in this list.
> Checking
> > for an isDefined("") is actually doing a type of a read, isn't it, so
you
> > would need a lock around it?
> >
> > EMAIL:
> > Just as a quick note, you don't need to lock variables in an
IsDefined("")
> > the reason being, you are not reading from it or writing to it.... just
> > checking its there.....
> >
> >
> > Robert Hinojosa
> > [EMAIL PROTECTED]
> > 972.243.4343 x7446
> >
> >
>
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