struts-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From theron.kou...@webmd.net
Subject Re: Hi Folks, 2 questions about Actions and their instance
Date Mon, 01 Apr 2002 17:13:51 GMT

>> There are 2 different path elements but both refer to the same Action
class
>> instance...    Does this mean 2 static instances of
>> BillingActionPreloadForm will exist or will only just 1 exist between
the 2
>> different action mappings that link to the same class?

> I don't know, but it doesn't matter.  You should always assume that
> any specific instance of an Action class could potentially serve multiple
> threads at once.  Or else what's the point of putting your app on the
> web?  ;-)

Reason I brought this up is that I plan to use mysql.    Mysql has those
AUTO INCREMENT fields and I want to insert a record and immediately call
last_index_id()  to get the newly inserted row.    If I do this is just one
and only one action, I may be able to prevent a timing/race condition by
which last_index_id() may accidentally be returned from the wrong insert.
I definitely want to prevent that from happening.

thanks,
Theron



                                                                                         
              
                    Jim Crossley                                                         
              
                    <jcrossley@if        To:     Struts Users Mailing List            
                 
                    leet.com>            <struts-user@jakarta.apache.org>       
                       
                                         cc:                                             
              
                    04/01/02             Subject:     Re: Hi Folks, 2 questions about Actions
and their 
                    09:02 AM             instance                                        
              
                    Please                                                               
              
                    respond to                                                           
              
                    Struts Users                                                         
              
                    Mailing List                                                         
              
                                                                                         
              
                                                                                         
              



theron.kousek@webmd.net writes:

[...]

> So here's my 2 question(s):
>
> 1.   I then assume that "perform()" is synchronized

No.  If all data objects are local to the perform method, there's no
reason for it to be synchronized.  If the data objects referred to in
perform are shared, then their access should probably be synchronized,
but not necessarily.

> 2.  What about those cases where 2 different action mappings resort to
the
> same action class?

[...]

> There are 2 different path elements but both refer to the same Action
class
> instance...    Does this mean 2 static instances of
> BillingActionPreloadForm will exist or will only just 1 exist between the
2
> different action mappings that link to the same class?

I don't know, but it doesn't matter.  You should always assume that
any specific instance of an Action class could potentially serve multiple
threads at once.  Or else what's the point of putting your app on the
web?  ;-)

-- Jim

--
To unsubscribe, e-mail:   <
mailto:struts-user-unsubscribe@jakarta.apache.org>
For additional commands, e-mail: <
mailto:struts-user-help@jakarta.apache.org>




--
To unsubscribe, e-mail:   <mailto:struts-user-unsubscribe@jakarta.apache.org>
For additional commands, e-mail: <mailto:struts-user-help@jakarta.apache.org>


Mime
View raw message