On Apr 8, 2013, at 1:46 PM, Sanne Grinovero <sanne(a)infinispan.org> wrote:
I fail to understand the purpose of the feature then. What prevents
me
to use the existing code today just storing some extra fields in my
custom values?
^ You avoid the need of the wrapper since we already have a wrapper internally, which is
ICE. ICEs can already keep versions around, why do I need a wrapper class that stores a
version for Hot Rod server?
Down the line, we could decide to leave the metadata around to better support use cases
like this:
- The tombstones that Max refers
to could potentially be tombstone ICEs with only metadata info.
Cheers,
Sanne
On 8 April 2013 12:40, Galder Zamarreño <galder(a)redhat.com> wrote:
>
> On Apr 8, 2013, at 1:26 PM, Sanne Grinovero <sanne(a)infinispan.org> wrote:
>
>> On 8 April 2013 12:06, Galder Zamarreño <galder(a)redhat.com> wrote:
>>>
>>> On Apr 8, 2013, at 12:56 PM, Sanne Grinovero <sanne(a)infinispan.org>
wrote:
>>>
>>>>
>>>>
>>>>
>>>> On 8 April 2013 11:44, Galder Zamarreño <galder(a)redhat.com> wrote:
>>>>
>>>> On Apr 8, 2013, at 12:35 PM, Galder Zamarreño <galder(a)redhat.com>
wrote:
>>>>
>>>>>
>>>>> On Apr 8, 2013, at 11:17 AM, Manik Surtani
<msurtani(a)redhat.com> wrote:
>>>>>
>>>>>> All sounds very good. One important thing to consider is that the
reference to Metadata passed in by the client app will be tied to the ICE for the entire
lifespan of the ICE. You'll need to think about a defensive copy or some other form
of making the Metadata immutable (by the user application, at least) the moment it is
passed in.
>>>>>
>>>>> ^ Excellent point, it could be a nightmare if users could change the
metadata reference by the ICE at will. I'll have a think on how to best achieve this.
>>>>
>>>> ^ The metadata is gonna have to be marshalled somehow to ship to other
nodes, so that could be a way to achieve it, by enforcing this somehow. When the cache
receives it, it can marshaller/unmarshall it to make a copy
>>>>
>>>> One way would be to make Metadata extend Serializable, but not keen on
that. Another would be to somehow force the interface to define the Externalizer to use
(i.e. an interface method like getExternalizer()), but that's akward when it comes to
unmarshalling… what about forcing the Metadata object to be provided with a @SerializeWith
annotation?
>>>>
>>>> Why is getExternalizer() awkward for unmarshalling?
>>>
>>> ^ Because you don't have an instance yet, so what's the Externalizer
for it? IOW, there's no much point to doing that, simply register it depending on your
desire:
>>>
https://docs.jboss.org/author/display/ISPN/Plugging+Infinispan+With+User+...
>>
>> That's what I would expect.
>>
>>>
>>>> I would expect you to have the marshaller already known during
deserialization.
>>>
>>> You would, as long as you follow the instructions in
https://docs.jboss.org/author/display/ISPN/Plugging+Infinispan+With+User+...
>>>
>>>> Agreed that extensing Serializable is not a good idea.
>>>>
>>>> Are you thinking about the impact on CacheStore(s) and state transfer?
>>>
>>> ^ What about it in particular?
>>>
>>>> Eviction of no longer used metadata ?
>>>
>>> ^ Since the metadata is part of the entry, it'd initially go when the
entry is evicted. We might wanna leave it around in some cases… but it'd be for other
use cases.
>>
>> I thought the plan was to have entries refer to the metadata, but that
>> different entries sharing the same metadata would point to the same
>> instance.
>
> ^ Could be, but most likely not.
>
>> So this metadata needs to be stored separately in the CacheStore,
>> preloaded as appropriate, transferred during state transfer,
>> passivated when convenient and cleaned up when no longer referred to.
>
> ^ Well, it's part of the internal cache entry, so it'd be treated just like
ICE.
>
>> Am I wrong? Seems you plan to store a copy of the metadata within each ICE.
>
> ^ The idea is to store it alongside right now, but maybe at some point it might make
sense to leave it around (i.e. for 2LC use case), but this won't be done yet.
>
>>
>>
>>>
>>> I'm also considering separating the serialization/marshalling concerns
from the defensive copying concerns. IOW, add a copy() method to the Metadata interface,
or have a separate interface for those externally provided objects that require to be
defensive copied. IOW, do something like what Scala Case Classes do with their copy()
method, but without the issues of clone… I need to investigate this further to come up
with a nice solution.
>>>
>>> One positive side to splitting both concerns is speed. A Metadata
implementation might have ways to make a copy of itself which are more efficient than
marshalling/unmarshalling.
>>>
>>> Thoughts?
>>>
>>>>
>>>> Sanne
>>>>
>>>>
>>>> Any other ideas?
>>>>
>>>>>
>>>>> Cheers,
>>>>>
>>>>>>
>>>>>> On 8 Apr 2013, at 09:24, Galder Zamarreño
<galder(a)redhat.com> wrote:
>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> As mentioned in
http://lists.jboss.org/pipermail/infinispan-dev/2013-March/012348.html, in paralell to the
switch to Equivalent* collections, I was also working on being able to pass metadata into
Infinispan caches. This is done to better support the ability to store custom metadata in
Infinispan without the need of extra wrappers. So, the idea is that InternalCacheEntry
instances will have a a reference to this Metadata.
>>>>>>>
>>>>>>> One of that metadata is version, which I've been using as
test bed to see if clients could pass succesfully version information via metadata. As you
already know, Hot Rod requires to store version information. Before, this was stored in a
class called CacheValue alongside the value itself, but the work I've done in [1],
this is passed via the new API I've added in [2].
>>>>>>>
>>>>>>> So, I'd like to get some thoughts on this new API. I hope
that with these new put/replace versions, we can get rid of the nightmare which is all the
other put/replace calls taking lifespan and/or maxIdle information. In the end, I think
there should be two basic puts:
>>>>>>>
>>>>>>> - put(K, V)
>>>>>>> - put(K, V, Metadata)
>>>>>>>
>>>>>>> And their equivalents.
>>>>>>>
>>>>>>> IMPORTANT NOTE 1: The implementation details are bound to
change, because the entire Metadata needs to be stored in InternalCacheEntry, not just
version, lifespan..etc. I'll further develop the implementation once I get into adding
more metadata, i.e. when working on interoperability with REST. So, don't pay too much
attention to the implementation itself, focus on the AdvancedCache API itself and
let's refine that.
>>>>>>>
>>>>>>> IMPORTANT NOTE 2: The interoperability work in commit in [1]
is WIP, so please let's avoid discussing it in this email thread. Once I have a more
final version I'll send an email about it.
>>>>>>>
>>>>>>> Apart from working on enhancements to the API, I'm now
carry on tackling the interoperability work with aim to have an initial version of the
Embedded <-> Hot Rod interoperability as first step. Once that's in, it can be
released to get early feedback while the rest of interoperability modes are developed.
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> [1]
https://github.com/galderz/infinispan/commit/a35956fe291d2b2dc3b7fa7bf44d...
>>>>>>> [2]
https://github.com/galderz/infinispan/commit/a35956fe291d2b2dc3b7fa7bf44d...
>>>>>>> --
>>>>>>> Galder Zamarreño
>>>>>>> galder(a)redhat.com
>>>>>>>
twitter.com/galderz
>>>>>>>
>>>>>>> Project Lead, Escalante
>>>>>>>
http://escalante.io
>>>>>>>
>>>>>>> Engineer, Infinispan
>>>>>>>
http://infinispan.org
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> infinispan-dev mailing list
>>>>>>> infinispan-dev(a)lists.jboss.org
>>>>>>>
https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>>
>>>>>> --
>>>>>> Manik Surtani
>>>>>> manik(a)jboss.org
>>>>>>
twitter.com/maniksurtani
>>>>>>
>>>>>> Platform Architect, JBoss Data Grid
>>>>>>
http://red.ht/data-grid
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> infinispan-dev(a)lists.jboss.org
>>>>>>
https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>
>>>>>
>>>>> --
>>>>> Galder Zamarreño
>>>>> galder(a)redhat.com
>>>>>
twitter.com/galderz
>>>>>
>>>>> Project Lead, Escalante
>>>>>
http://escalante.io
>>>>>
>>>>> Engineer, Infinispan
>>>>>
http://infinispan.org
>>>>>
>>>>
>>>>
>>>> --
>>>> Galder Zamarreño
>>>> galder(a)redhat.com
>>>>
twitter.com/galderz
>>>>
>>>> Project Lead, Escalante
>>>>
http://escalante.io
>>>>
>>>> Engineer, Infinispan
>>>>
http://infinispan.org
>>>>
>>>>
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>>>
>>>
>>> --
>>> Galder Zamarreño
>>> galder(a)redhat.com
>>>
twitter.com/galderz
>>>
>>> Project Lead, Escalante
>>>
http://escalante.io
>>>
>>> Engineer, Infinispan
>>>
http://infinispan.org
>>>
>>>
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>>> infinispan-dev(a)lists.jboss.org
>>>
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>>
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>
>
> --
> Galder Zamarreño
> galder(a)redhat.com
>
twitter.com/galderz
>
> Project Lead, Escalante
>
http://escalante.io
>
> Engineer, Infinispan
>
http://infinispan.org
>
>
> _______________________________________________
> infinispan-dev mailing list
> infinispan-dev(a)lists.jboss.org
>
https://lists.jboss.org/mailman/listinfo/infinispan-dev
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