Ken, others,
now for the definitive answer:
There is one instance per interceptor ref, thus interceptor instances
being unique within the scope they are referenced in.
Example:
<package name="foo" extends="struts-default" namespace="/foo">
<interceptors>
<interceptor name="foo" class="FooInterceptor"/>
</interceptors>
<action name="bar1" class="com.opensymphony.xwork2.ActionSupport">
<interceptor-ref name="foo">
<param name="bar">barfoobar</param>
</interceptor-ref>
<result name="success">/index.jsp</result>
</action>
<action name="bar2" class="com.opensymphony.xwork2.ActionSupport">
<interceptor-ref name="foo">
<param name="bar">barfoo</param>
</interceptor-ref>
<result name="success">/index.jsp</result>
</action>
</package>
This will cause two instances of FooInterceptor being created, one with
bar property set to "barfoobar" and one with "barfoo". The interceptors
parameters given in struts.xml are only set once per instance, which
means that there are no thread safety issues with interceptor instance
variables.
HTH,
Rene
Rene Gielen schrieb:
Uahhh,
thanks for pointing out this information, I was way to fast to reply on
the said question - I recalled it wrong. Indeed documentation is right
here, they need to be thread safe - sorry for causing misunderstanding
here.
Anyway, this does not answer the question if interceptor parameters
introduce thread safety issues. The builder mechanism is a little
complicated here, but AFAIK Interceptor instances are unique to the scope
they are configured in. I will check this tonight to ensure we do not face
a problem here with current implementation and hopefully can provide a
reliable answer then.
Regards,
Rene
<interceptor name="
Am Mo, 9.07.2007, 15:01, schrieb Hoying, Ken:
Thanks, Rene!
Someone might want to update the documentation to make this clearer.
The following document seems to indicate otherwise:
http://struts.apache.org/2.x/docs/writing-interceptors.html
Thread Safety
Interceptors must be thread-safe!
A Struts 2 Action instance is created for every request and do not need
to be thread-safe. Conversely, Interceptors are shared between requests
and must be thread-safe.
-----Original Message-----
From: Rene Gielen [mailto:[EMAIL PROTECTED]
Sent: Sunday, July 08, 2007 7:00 AM
To: Struts Users Mailing List
Subject: Re: [S2] Interceptor Question (Thread Safety)
Ken,
there is no problem at all since s2 interceptor instances, as well as
action instances, are created per ActionInvokation, which means they are
always operated in a single thread.
Regards,
Rene
Hoying, Ken schrieb:
From what I understand from reading the documentation, interceptors
are suppose to be thread safe. However, I have noticed that some of
the interceptors do contain instance variables and I have seen some
examples where these variables are set or modified from with in the
action configurations.
For example, the File Upload interceptor allows you to set the
maximumSize and allowedTypes. Is this going to work if I have 2
different actions each allowing different maximumSize and
allowedTypes?
This does not seem thread safe to me. Is there only one instance of
the interceptors or does maybe each action mapping have its own
instance of the interceptors?
Thanks in advance,
Ken
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