Jason,
If that query is stored in the service object variables/this scope and
the service is stored in the app scope, then yes - you should use
duplicate() like you are outlining.
/H.
--
Hugo Ahlenius
-------------------------------------------------------------
Hugo Ahlenius E-Mail: [EMAIL PROTECTED]
Project Officer Phone: +46 8 412 1427
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Skype: callto:fraxxinus
-------------------------------------------------------------
| -----Original Message-----
| From: [EMAIL PROTECTED]
| [mailto:[EMAIL PROTECTED] On Behalf Of Jason Daiger
| Sent: Tuesday, March 21, 2006 18:28
| To: [email protected]
| Subject: Re: [CFCDev] application-scoped singletons and thread safety
|
| I've been following this thread w/ great interest and have a final
| question but first let me set the scenario. I have a service that
| stores a lookup collection. The service and all its member variables
| are stored in application scope. The lookup collection (one of the
| member variables stored by the
| service) returns a query to the caller.
| The caller then does whatever it wants (looping most likely) w/ the
| query it has received. So based on what I'm reading I should have the
| service use duplicate before returning the query. Something like this
| <cffunction name="getLookup"
| returntype="query">
| <cfargument name="lookupCode" type="string">
|
| <!--- The following uses the lookupsAggregator object to find the
| lookup and return all the lookup values for that lookup code. If
| nothing is found it returns an empty query --->
| <cfset var retVal =
| _me.lookupsAggregator.getLookupValues(arguments.lookupCode)>
| <cfreturn duplicate(retVal)
| </cffunction>
|
| Have I read and understood this thread correctly?
|
| -Jason
|
|
|
| Hugo Ahlenius wrote:
| > Barry,
| >
| > I don't think it is not that simple/obvious -- you store a
| query for
| > caching and ONLY reading, then it is not obvious that the
| > currentrow/loop cursor is written - I actually took for
| granted that
| > the cursor would be per request, and was not an integral
| part of the
| > actual variable/query.
| >
| > I would strongly recommend against cflock here, use duplicate.
| >
| > /H.
| >
| >
| > --
| > Hugo Ahlenius
| >
| > -------------------------------------------------------------
| > Hugo Ahlenius E-Mail: [EMAIL PROTECTED]
| > Project Officer Phone: +46 8 412 1427
| > UNEP GRID-Arendal Fax: +46 8 723 0348
| > Stockholm Office Mobile: +46 733 467111
| > WWW: http://www.grida.no
| > Skype: callto:fraxxinus
| > -------------------------------------------------------------
| >
| >
| >
| >
| >
| >
| >
| >
| >
| >
| > | -----Original Message-----
| > | From: [EMAIL PROTECTED]
| > | [mailto:[EMAIL PROTECTED] On Behalf Of Barry Beattie
| > | Sent: Tuesday, March 21, 2006 12:11
| > | To: [email protected]
| > | Subject: Re: [CFCDev] application-scoped singletons and thread
| > | safety
| > |
| > | the biggest issue is usually understanding what's happening.
| > |
| > | just because there's a couple of lines of code together
| with a loop
| > | only means those instructions are being executed sequentually
| > | _by_that_thread. In between which, other threads have
| their "slice
| > | of the processor" to run instructions and, in this case,
| access to
| > | common
| >
| > | memory (ie: Application scoped variables).
| > |
| > | All shared scopes have this issue to consider and that's
| why cflock
| > | (yeah it *is* an ugly way to go) works: deny other
| threads access to
| > | this shared scope until the first thread hits the
| </cflock>. copying
| > | the data and using the copy for processing avoids the issue.
| > |
| > | it's also related to the old
| > |
| > | if app var doesn't exist
| > | lock
| > | if it still really doesn't exist (not created by another thread
| > | while locking this thread)
| > | create app var
| > | end if
| > | end lock
| > | end if
| > |
| > |
| > | it's an easy thing to forget when you're deep in the
| innards of some
| > | code.
| > |
| > | my 2c
| > | barry.b
| > |
| > |
| > |
| > | On 3/21/06, Hugo Ahlenius <[EMAIL PROTECTED]> wrote:
| > | > I experimented a bit more, and it has nothing to do with
| > | CFCs really
| > | > -- in the application scope (and also likely in other
| > | shared scopes)
| > | > the currentrow cursor is shared with the queries, at least
| > | in CFMX 6.1
| > | > and BD 6.2.1 (which I have tested, don't have access to CFMX 7).
| > | >
| > | > Workarounds:
| > | > * Best is to duplicate (for encapsulation etc)
| > | > * One can also cflock (ugly!)
| > | > * Or do an index loop 1 to recordcount
| > | >
| > | >
| > | > --
| > | > Hugo Ahlenius
| > | >
| > | > -------------------------------------------------------------
| > | > Hugo Ahlenius E-Mail: [EMAIL PROTECTED]
| > | > Project Officer Phone: +46 8 412 1427
| > | > UNEP GRID-Arendal Fax: +46 8 723 0348
| > | > Stockholm Office Mobile: +46 733 467111
| > | > WWW: http://www.grida.no
| > | > Skype: callto:fraxxinus
| > | > -------------------------------------------------------------
| > | >
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| --
| Jason Daiger
| URL: www.jdaiger.com
| EML: [EMAIL PROTECTED]
|
|
|
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