> Berin Loritsch wrote:
>
> Carsten Ziegeler wrote:
> >
> > Thanks for your explanation, Berin!
> >
> > I understand the difference, but - as I'm not a java expert - does
> > not know, what makes a component SingleThreaded. Which circumstances
> > must occur to declare a component so?
>
> Honestly, it is very rare that a compoent can't be used again. However,
> Xerces happens to make one. I wish I new _why_ it was not reusable.
> Basically, if the complexity of the component is such that it cannot
> reset itself automatically, then you must implement it in a SingleThreaded
> manner.
>
Ok, this means the component is only usable exactly one-time. This has in
my opinion nothing to do with SingleThreaded. But ok, it's the way it is.
> The rest of the time Poolable or Recyclable will work.
>
> > One of the components I wanted to make singlethreaded is the JaxpParser
> > in Cocoon2 (and that's actually the reason why I ask this question).
> > I don't see any specific code in that class.
>
> JaxpParser is SingleThreaded--at least the last time I committed it was.
> It should be implementing the SingleThreaded interface.
>
It still is, but if I understand you right, we could make the Jaxp parser
Poolable when it instantiates a new (Xerces) parser object each time it
it is get from the pool. This would slightly reduce object creation (
and new configuration of the JaxpParser).
Am I correct here.
Carsten
>
> The mechanics are these:
>
> If a component implements a lifestyle interface (SingleThreaded, Poolable,
> or ThreadSafe) it is used. They are mutually exclusive--however there is
> no Java mechanism to enforce this in the compiler--so it will not
> complain.
>
> If a component does not declare any lifecycle interface then it is treated
> as SingleThreaded. This is not optimal, but it is the safest
> assumption that
> the CM can make. Therefore implementing Poolable or ThreadSafe
> are optimizations
> to the run-time.
>
> >
> > Carsten
> >
> > > Berin Loritsch wrote:
> > >
> > > Carsten Ziegeler wrote:
> > > >
> > > > Hi,
> > > >
> > > > I just wanted to make a SingleThreaded component poolable. Is this
> > > > not allowed?
> > >
> > > They are not allowed. Currently SingleThreaded marks interfaces that
> > > cannot be reused, and must be used in one thread at a time.
> Therefore,
> > > they are manufactured by the Factory method.
> > >
> > > Poolable components (inherently only run in one thread at a time) can
> > > be reused, therefore when one thread is done with it, it is returned
> > > to the pool.
> > >
> > > Notice the distinction.
> > >
> > > > I get an exception from the excalibur component manager, which does
> > > > the following test:
> > > > >>>
> > > > if (SingleThreaded.class.isAssignableFrom(componentClass))
> > > > {
> > > > numInterfaces++;
> > > > }
> > > >
> > > > if (ThreadSafe.class.isAssignableFrom(componentClass))
> > > > {
> > > > numInterfaces++;
> > > > }
> > > >
> > > > if (Poolable.class.isAssignableFrom(componentClass))
> > > > {
> > > > numInterfaces++;
> > > > }
> > > > <<<
> > > > This means these interfaces can not combined. I agree that
> > > > SingleThreaded and ThreadSafe are not possible and
> > > > ThreadSafe and Poolable don't make sense, but
> > > > Poolable and SingleThreaded seems ok to me.
> > > > Or am I wrong?
> > > >
> > > > Carsten
> > > >
> > > >
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