Hi,
On Wednesday, January 21, 2015, manfred riem <manfred.riem_at_oracle.com>
wrote:
> As noted at https://struberg.wordpress.com/tag/cdi/ we could have the CDI
> layer
> cache the value and achieve a speed up that way.
>
> Thoughts?
Okay, so to be clear, the assumption is that CDI is (potentially) so fast
at resolving beans from EL and/or their scope, that effectively nothing has
to be done here, right?
It's not the full outcome of an EL expression that's cached, but just the
CDI managed beans in the chain.
Eg
Suppose we have EL;
#{foo.bar.kaz.rendered}
With "foo" being say a CDI view scoped bean, and bar and kaz dependent
beans, then getBar().getKaz().isRendered() will still be called as often as
they are today, but the assumption is that calling 3 (in this case) getters
is so utterly cheap that it's not worth optimising for.
The real cost is in resolving "foo", but CDI is already so blazingly fast
there that JSF does not have to do anything.
Is it correct that this is the idea?
Kind regards,
Arjan
> Manfred
>
> On 1/15/15, 8:33 AM, arjan tijms wrote:
>
>> Hi there,
>>
>> On Thu, Jan 15, 2015 at 11:11 AM, Hanspeter<hampidu_at_gmail.com> wrote:
>>
>>> Hi all.
>>> A good thought this cache annotation, however, the called method to
>>> return
>>> the rendered boolean has no knowledge if the component is inside an
>>> iterating component. Cachong on phase level without respect to iteration
>>> will cause problems.
>>>
>> Yes, good point. There's definitely some more thinking needed there.
>>
>> Maybe the iterating component can reset the scoped cache (no need to
>> go up or down the children's chain), or maybe the cache's
>> (auto-generated) cache key can include the (virtual) component ID.
>>
>> As said, just thinking out loud here.
>>
>>
>> Also annotation lookup might cause more effort than simply cache rendered
>>> eval result within the encode* cycle.
>>>
>> Possibly yes. If the component itself does some caching and stores
>> this in a simple variable, it's almost always going to be faster and
>> as a bonus simpler and more automatic for the user as well.
>>
>> The idea about explicit caching tailored for JSF phases was just
>> thrown out there in case this automatic caching would appear to be too
>> invasive and the default has to be more conservative. It's a bit of a
>> backup plan thus.
>>
>> One thing that could limit the cost of annotation lookup is if this
>> would only be done once when the ValueExpression is created. Suppose
>> we would create a CachingValueExpression when the @Cached annotation
>> is present, and this CachingValueExpression would do the caching
>> (possibly using a scoped cache).
>>
>> Components which would not care about caching can then just obtain the
>> value from the VE as they always do, while components that do care can
>> do an instanceof check, and if needed call methods on
>> CachingValueExpression to bypass the cache, reset it, etc.
>>
>> Kind regards,
>> Arjan
>>
>>
>> Regards
>>> Hanspeter
>>>
>>> Am 14.01.2015 23:59 schrieb "arjan tijms"<arjan.tijms_at_gmail.com>:
>>>
>>> Hi,
>>>>
>>>> On Tuesday, January 13, 2015, Leonardo Uribe<leonardo.uribe_at_irian.at>
>>>> wrote:
>>>>
>>>>> Yes, the strategy done in MyFaces is far more simple, but since this is
>>>>> considered an implementation detail, how it works falls out of the
>>>>> scope of
>>>>> the discussion of the list.
>>>>>
>>>> I for one would be rather interested in the details regarding this far
>>>> more simple solution. Would it really not be a possible candidate for
>>>> standardization?
>>>>
>>>>
>>>> The thing you need to consider in this problem is EL evaluation is not
>>>>> as slow as you can imagine, compared with multiple hashmap.get()
>>>>> calls. On
>>>>> the other side isRendered() method can be called multiple times and
>>>>> most of
>>>>> them do not do any EL evaluation. If you have a component tree with
>>>>> multiple
>>>>> component and some of them has an EL on isRendered(), you will not gain
>>>>> anything if you add extra hashmap.get() calls on every isRendered()
>>>>> call
>>>>>
>>>> I generally agree with the statement that we should be careful that
>>>> any kind of cache lookup does not end up being roughly as expensive as
>>>> the thing we're trying to cache, let alone be more expensive.
>>>>
>>>> That said, caching the isRendered outcome does prevent users getting
>>>> surprised about why their bean is called multiple times, and lessens
>>>> the impact of doing any kind of expensive computation inside the
>>>> getter (which users of course shouldn't do, but especially beginners
>>>> are often tempted to do anyway).
>>>>
>>>> Just thinking out loud, but a potential additional solution could be
>>>> to put the caching behavior more in the hands of the user, for
>>>> instance with explicit cached EL expressions, or JCache like
>>>> annotations.
>>>>
>>>> Explicit cached value expressions are a bit like c:set or OmiFaces'
>>>> o:cacheValue (http://showcase.omnifaces.org/components/cache), but
>>>> would have more control over the phases. E.g.
>>>>
>>>> <o:cache key="foo" scope="request" phase="renderResponse">
>>>> <o:cacheValue name="isRendered"
>>>> value="#{someBean.something.isRendered}" />
>>>> </o:cache>
>>>>
>>>> ...
>>>>
>>>> <h:panelGroup rendered="#{isRendered}">
>>>> ...
>>>>
>>>> Or with a JCache-like annotation:
>>>>
>>>> @Cached(facesPhase="renderResponse")
>>>> public boolean isRendered() {
>>>> return ...
>>>> }
>>>>
>>>> Yet another option with EL 3 lambdas:
>>>>
>>>> <h:panelGroup rendered="#{fn:cached( () ->
>>>> someBean.something.isRendered, 'renderResponse') }">
>>>> ...
>>>>
>>>> Such constructs could be used together with the component caching as
>>>> mentioned in this thread; component caching could then be relatively
>>>> conservative, while for more elaborate caching an explicit user
>>>> controlled construct could be used.
>>>>
>>>> As said, just thinking out loud here ;)
>>>>
>>>> Kind regards,
>>>> Arjan Tijms
>>>>
>>>>
>>>>
>>>> , just to try to gain something on the components that use it (which
>>>>> can
>>>>> be just a couple of them).
>>>>>
>>>>> regards,
>>>>>
>>>>> Leonardo Uribe
>>>>>
>>>>> 2015-01-12 15:55 GMT-05:00 manfred riem<manfred.riem_at_oracle.com>:
>>>>>
>>>>>> Since you are telling me there are other tested strategies that are
>>>>>> far
>>>>>> more simple can you elaborate?
>>>>>>
>>>>>> Manfred
>>>>>>
>>>>>>
>>>>>> On 1/12/15, 2:53 PM, Leonardo Uribe wrote:
>>>>>>
>>>>>> Hi Manfred
>>>>>>
>>>>>> Well, you can make it work, but all that logic seems overkill to me.
>>>>>> It
>>>>>> could work, but I doubt about its convenience against other tested
>>>>>> strategies for the same problem that are far more simple.
>>>>>>
>>>>>> regards,
>>>>>>
>>>>>> Leonardo Uribe
>>>>>>
>>>>>> 2015-01-12 15:07 GMT-05:00 manfred riem<manfred.riem_at_oracle.com>:
>>>>>>
>>>>>>> Hi Leonardo,
>>>>>>>
>>>>>>> I disagree, as when the rendering starts in each encodeBegin it can
>>>>>>> get the elCacheable transientHelper attribute from the parent and
>>>>>>> then set
>>>>>>> is own elCacheable transientHelper attribute. And if you cannot find
>>>>>>> the
>>>>>>> elCacheable transientHelper attribute on the parent you err on the
>>>>>>> side of
>>>>>>> assuming it is not EL cacheable. And voila no going up many levels.
>>>>>>>
>>>>>>> Manfred
>>>>>>>
>>>>>>>
>>>>>>> On 1/12/15, 12:26 PM, Leonardo Uribe wrote:
>>>>>>>
>>>>>>> Hi
>>>>>>>
>>>>>>> It could be one, it could be many. The problem is the component
>>>>>>> doesn't know how many levels up should be checked to decide if there
>>>>>>> is an
>>>>>>> iteration, so it will be forced to go all levels to the top, over
>>>>>>> and over.
>>>>>>> There is no contextual information about the current iteration. I
>>>>>>> think it
>>>>>>> is quite easy to find examples where it will fail.
>>>>>>>
>>>>>>> regards,
>>>>>>>
>>>>>>> Leonardo Uribe
>>>>>>>
>>>>>>> 2015-01-12 13:08 GMT-05:00 manfred riem<manfred.riem_at_oracle.com>:
>>>>>>>
>>>>>>>> How so? It is just calling one component up?
>>>>>>>>
>>>>>>>> Manfred
>>>>>>>>
>>>>>>>>
>>>>>>>> On 1/12/15, 12:06 PM, Leonardo Uribe wrote:
>>>>>>>>
>>>>>>>> Hi Manfred
>>>>>>>>
>>>>>>>> MR>> The encodeBegin method has access to the parent component
>>>>>>>>
>>>>>>>> The problem is do that will increase the algorithm complexity. We
>>>>>>>> need to
>>>>>>>> keep it on lineal complexity (O(n)), otherwise the optimization will
>>>>>>>> not
>>>>>>>> be effective.
>>>>>>>>
>>>>>>>> regards,
>>>>>>>>
>>>>>>>> Leonardo Uribe
>>>>>>>>
>>>>>>>> 2015-01-12 12:44 GMT-05:00 manfred riem<manfred.riem_at_oracle.com>:
>>>>>>>>
>>>>>>>>> Hi Leonardo,
>>>>>>>>>
>>>>>>>>> The encodeBegin method has access to the parent component, so it
>>>>>>>>> can
>>>>>>>>> determine the parent ElCacheable from it. If the parent is not an
>>>>>>>>> ELCacheable instance the component itself cannot be either,
>>>>>>>>> otherwise it can
>>>>>>>>> look its getter.
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Manfred
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 1/12/15, 11:40 AM, Leonardo Uribe wrote:
>>>>>>>>>
>>>>>>>>> Hi
>>>>>>>>>
>>>>>>>>> I don't think an interface could work, because it is the parent,
>>>>>>>>> not
>>>>>>>>> the child who defines the iteration strategy. It is a fact that we
>>>>>>>>> reuse the
>>>>>>>>> same component instances for different rows (UIData).
>>>>>>>>>
>>>>>>>>> regards,
>>>>>>>>>
>>>>>>>>> Leonardo Uribe
>>>>>>>>>
>>>>>>>>> 2015-01-12 9:13 GMT-05:00 manfred riem<manfred.riem_at_oracle.com>:
>>>>>>>>>
>>>>>>>>>> Hi Hanspeter,
>>>>>>>>>>
>>>>>>>>>> I am trying to formalize it for the RenderPhase only, which would
>>>>>>>>>> mean stating something like the following:
>>>>>>>>>>
>>>>>>>>>> 1. ElCacheable would be defined by an interface
>>>>>>>>>> 2. ElCacheable would operate only in RENDER_RESPONSE
>>>>>>>>>> a. Which means a component would not be allowed to change the
>>>>>>>>>> value of an EL expression
>>>>>>>>>> b. For an iterating component it would not cache and thus not
>>>>>>>>>> implement ElCacheable
>>>>>>>>>> c. For components not implementing the ElCacheable interface
>>>>>>>>>> it
>>>>>>>>>> would operate as if it was not cacheable.
>>>>>>>>>> 3. Add a getter / setter that stores elCacheable on the
>>>>>>>>>> UIComponent
>>>>>>>>>>
>>>>>>>>>> Am I missing something here?
>>>>>>>>>>
>>>>>>>>>> Thoughts?
>>>>>>>>>> Manfred
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 1/9/15, 5:18 PM, Hanspeter wrote:
>>>>>>>>>>
>>>>>>>>>> Hi Experts.
>>>>>>>>>>
>>>>>>>>>> I think this is worth pushing +1.
>>>>>>>>>>
>>>>>>>>>> The multiple rendered attribute evaluation bothers most in the
>>>>>>>>>> render phase because isRendered() is called by every
>>>>>>>>>> UIComponent(Base).encode* method. So maybe a first step would be
>>>>>>>>>> to improve
>>>>>>>>>> the encode* methods such that for an encodeAll() cycle the
>>>>>>>>>> rendered
>>>>>>>>>> attribute is cached. That is possible with a few lines of code -
>>>>>>>>>> I happily
>>>>>>>>>> provide the changes.
>>>>>>>>>>
>>>>>>>>>> E.g. encodeAll() and/or encodeBegin() could enable
>>>>>>>>>> renderedCaching,
>>>>>>>>>> isRendered() stores the rendered result on a component private
>>>>>>>>>> Boolean, and
>>>>>>>>>> in encodeEnd() rendered caching is disabled and reset. That way
>>>>>>>>>> without
>>>>>>>>>> additional effort rendered is reset for the next iteration. But
>>>>>>>>>> still this
>>>>>>>>>> would reduce evaluate times by factor 3 to 4 per component
>>>>>>>>>> encoding.
>>>>>>>>>>
>>>>>>>>>> I'm not sure whether rendered caching on a broader scope makes
>>>>>>>>>> sense, e.g. for phases 2-5. In csJSF component library we did
>>>>>>>>>> some rendered
>>>>>>>>>> caching, but had to reset the cache once per phase and within
>>>>>>>>>> iterating
>>>>>>>>>> components as well. And I think rendered is rarely evaluated more
>>>>>>>>>> often as
>>>>>>>>>> it was reset in these execution phases.
>>>>>>>>>>
>>>>>>>>>> Best regards
>>>>>>>>>> Hanspeter
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> 2015-01-09 19:12 GMT+01:00 Bauke Scholtz<balusc_at_gmail.com>:
>>>>>>>>>>
>>>>>>>>>>> +1
>>>>>>>>>>>
>>>>>>>>>>> Ideally, the UIComponent#isRendered() should cache the value on a
>>>>>>>>>>> per-phase and per-iteration basis. It would be awesome too if
>>>>>>>>>>> iteration
>>>>>>>>>>> components implement a common interface or abstract class, which
>>>>>>>>>>> should also
>>>>>>>>>>> simplify a lot of other things related to a.o. setting the
>>>>>>>>>>> currently
>>>>>>>>>>> iterated item and state saving.
>>>>>>>>>>>
>>>>>>>>>>> Cheers, B
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Fri, Jan 9, 2015 at 7:00 PM, manfred riem
>>>>>>>>>>> <manfred.riem_at_oracle.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Whoops, sending to right list. Please ignore it on the other.
>>>>>>>>>>>>
>>>>>>>>>>>> -------- Original Message --------
>>>>>>>>>>>> Subject: [jsr344-experts] [941-ReduceELCalls] DISCUSSION
>>>>>>>>>>>> Date: Fri, 09 Jan 2015 11:51:14 -0600
>>>>>>>>>>>> From: manfred riem<manfred.riem_at_oracle.com>
>>>>>>>>>>>> Reply-To: jsr344-experts_at_javaserverfaces-spec-public.java.net
>>>>>>>>>>>> Organization: Oracle Corporation
>>>>>>>>>>>> To: jsr344-experts_at_javaserverfaces-spec-public.java.net
>>>>>>>>>>>> CC: Max Starets<max.starets_at_oracle.com>, Andy Schwartz
>>>>>>>>>>>> <andy.schwartz_at_oracle.com>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Hi all,
>>>>>>>>>>>>
>>>>>>>>>>>> As we all know the number of times an EL expression is evaluated
>>>>>>>>>>>> during render is higher than it could be.
>>>>>>>>>>>>
>>>>>>>>>>>> To see if there is a potential to reduce that number I want to
>>>>>>>>>>>> ask the most important question first as it determines whether
>>>>>>>>>>>> or not this
>>>>>>>>>>>> issue is even worth pursuing?
>>>>>>>>>>>>
>>>>>>>>>>>> Is it safe to assume that during rendering and not as a child of
>>>>>>>>>>>> an iterating component the value of the EL expression will stay
>>>>>>>>>>>> stable?
>>>>>>>>>>>>
>>>>>>>>>>>> Regards,
>>>>>>>>>>>> Manfred
>>>>>>>>>>>>
>>>>>>>>>>>>