Dima,
Here is how proposed design works:
class A {
int x = 1;
}
class B {
int x = 2;
}
BinaryObject obj = ...;
Object val = obj.field("A.x"); // Returns "1";
Object val = obj.field("B.x"); // Returns "2";
Object val = obj.field("x"); // Returns null;
boolean exists = obj.hasField("A.x"); // Returns "true";
boolean exists = obj.hasField("B.x"); // Returns "true";
boolean exists = obj.hasField("x"); // Returns "false";
Looks clean and consistent for me. Remember that we are talking about very
specific use case. It is very unlikely that user will operate on objects
conflicting fields in binary form.
Also, there will be no parsing at all. We use field name passed by user
directly.
Vladimir.
On Mon, Dec 21, 2015 at 12:10 PM, Dmitriy Setrakyan <[email protected]>
wrote:
> Vova,
>
> We cannot return null in case of a conflict, as user won’t be able to
> differentiate between a conflict and missing field. We should throw an
> exception.
>
> Also, I don’t like parsing field names looking for a dot for every field.
> It will introduce a performance overhead for the cases that do not have
> conflicts. Instead, we should add another API for this use case, something
> like field(typeName, fieldName).
>
> D.
>
> On Mon, Dec 21, 2015 at 1:01 AM, Vladimir Ozerov <[email protected]>
> wrote:
>
> > Denis,
> > Yes, as we do not know which field to pick, we return null.
> >
> > On Mon, Dec 21, 2015 at 12:00 PM, Denis Magda <[email protected]>
> wrote:
> >
> > > Sounds good for me. I would go for this approach.
> > >
> > > In addition if to consider your example below and the user decides to
> > look
> > > up a field by its simple name then he/she will get nothing or exception
> > > (depending on the API), correct?
> > > As an example for this case the method will return null
> > >
> > > BinaryObject obj = ...;
> > > Object val = obj.field("x"); // null will be returned cause we don't
> know
> > > what particular 'x' we have to return
> > >
> > >
> > > --
> > > Denis
> > >
> > > On 12/21/2015 11:48 AM, Vladimir Ozerov wrote:
> > >
> > >> Folks,
> > >>
> > >> I thought about the solution a bit more and came to the following
> > design.
> > >>
> > >> *Scenario:*
> > >> class A {
> > >> int x;
> > >> }
> > >> class B : extends A {
> > >> int y;
> > >> }
> > >>
> > >> *Solution:*
> > >> 1) Field A.x is written as *"A.x"*, field B.x is written as *"B.x"*.
> > I.e.
> > >> *both
> > >> conflicting fields are prefixed* with simple name of the owning class.
> > >> 2) API is unchanged. User manipulates these fields on all public
> methods
> > >> in
> > >> exactly the same way: "A.x" and "B.x".
> > >>
> > >> *Rationale:*
> > >> 1) We cannot prefix only some of conflicting fields. E.g. if decide to
> > >> prefix only A.x, then it is not clear how to handle this case:
> > >>
> > >> class B extends A implements Binarylizable {
> > >> void write(BinaryWriter writer) {
> > >> writer.writeInt("B.x", x); // User intentionally written
> field
> > as
> > >> "B.x".
> > >> }
> > >> }
> > >>
> > >> BinaryObject obj = ...;
> > >> Object val = obj.field("B.x"); // Should we lookup for "B.x" as user
> > asked
> > >> us, or just for "x"?
> > >>
> > >> Prefixing all conflicting fields with class name resolves the problem.
> > >>
> > >> 2) If we add methods to manipulate fields not only by name, but by
> > >> (typeName + fieldName) as well, then we will have to add *9 new
> methods*
> > >> to
> > >>
> > >> API:
> > >> BinaryType.fieldTypeName(String typeName, String fieldName);
> > >> BinaryType.field(String typeName, String fieldName);
> > >> BinaryObject.field(String typeName, String fieldName);
> > >> BinaryObject.hasField(String typeName, String fieldName);
> > >> BinaryObjectBuilder.getField(String typeName, String fieldName);
> > >> BinaryObjectBuilder.setField(String typeName, String fieldName, ...);
> > // 3
> > >> overloads
> > >> BinaryObjectBuilder.removeField(String typeName, String fieldName);
> > >>
> > >> This is definitely an overkill for such a rare scenario.
> > >>
> > >> Thoughts?
> > >>
> > >> On Mon, Dec 21, 2015 at 11:22 AM, Vladimir Ozerov <
> [email protected]
> > >
> > >> wrote:
> > >>
> > >> Agree, prefixing parent class fields sound like a better option.
> > >>> Regarding aliases - I need some time to understand internal
> mechanics.
> > >>> Will answer this a bit later.
> > >>>
> > >>> On Mon, Dec 21, 2015 at 11:18 AM, Dmitriy Setrakyan <
> > >>> [email protected]
> > >>>
> > >>>> wrote:
> > >>>> Vova,
> > >>>>
> > >>>> Shouldn’t it be the other way around? Class B writes the field as
> “a”,
> > >>>> and
> > >>>> class A writes it with a prefix (possibly the hash code of the class
> > >>>> name).
> > >>>>
> > >>>> Also, we should clearly document how the SQL queries are affected by
> > >>>> this.
> > >>>> AFAIK, we should be using field aliases here, no?
> > >>>>
> > >>>> D.
> > >>>>
> > >>>> On Sun, Dec 20, 2015 at 10:08 AM, Vladimir Ozerov <
> > [email protected]
> > >>>> >
> > >>>> wrote:
> > >>>>
> > >>>> May be we can use normal field names by default and add some
> > >>>>>
> > >>>> prefix/suffix
> > >>>>
> > >>>>> if conflict is found? E.g.:
> > >>>>>
> > >>>>> class A {
> > >>>>> int a; // Write as "a";
> > >>>>> }
> > >>>>>
> > >>>>> class B extends A {
> > >>>>> int a; // Write as "B_a";
> > >>>>> }
> > >>>>>
> > >>>>> On Fri, Dec 18, 2015 at 10:34 PM, Valentin Kulichenko <
> > >>>>> [email protected]> wrote:
> > >>>>>
> > >>>>> Folks,
> > >>>>>>
> > >>>>>> It seems to me that issue here is not with 3rd-party libraries. We
> > >>>>>>
> > >>>>> just
> > >>>>
> > >>>>> don't properly support class hierarchy in binary format. Any class
> > >>>>>>
> > >>>>> that
> > >>>>
> > >>>>> extends another class and has the field with the same name as
> parent
> > >>>>>>
> > >>>>> has
> > >>>>
> > >>>>> will fail unless user provides custom serialization logic that will
> > >>>>>>
> > >>>>> handle
> > >>>>>
> > >>>>>> it.
> > >>>>>>
> > >>>>>> What if we prepend the field name with the simple class name in
> this
> > >>>>>>
> > >>>>> case?
> > >>>>>
> > >>>>>> Say, we have two classes:
> > >>>>>>
> > >>>>>> class A {
> > >>>>>> private int id;
> > >>>>>> }
> > >>>>>>
> > >>>>>> class B extends A {
> > >>>>>> private int id;
> > >>>>>> }
> > >>>>>>
> > >>>>>> In this case we will get two fields: "A.id" and "B.id". The only
> > >>>>>>
> > >>>>> issue is
> > >>>>
> > >>>>> that if there are no name conflict, we should be able to resolve by
> > >>>>>>
> > >>>>> both
> > >>>>
> > >>>>> names - with or without prepended type name. I.e., if A is
> > serialized,
> > >>>>>>
> > >>>>> you
> > >>>>>
> > >>>>>> can get the field value by "id" or "A.id". This is similar to how
> it
> > >>>>>>
> > >>>>> works
> > >>>>>
> > >>>>>> if you join two SQL tables with the same column names.
> > >>>>>>
> > >>>>>> Any thoughts on whether it's doable or not?
> > >>>>>>
> > >>>>>> -Val
> > >>>>>>
> > >>>>>> On Fri, Dec 18, 2015 at 10:05 AM, Andrey Kornev <
> > >>>>>>
> > >>>>> [email protected]>
> > >>>>>
> > >>>>>> wrote:
> > >>>>>>
> > >>>>>> In this particular case, the class that fails is a non-static
> inner
> > >>>>>>>
> > >>>>>> class
> > >>>>>
> > >>>>>> that extends another non-static inner class, so they both end up
> > >>>>>>>
> > >>>>>> having
> > >>>>
> > >>>>> the
> > >>>>>>
> > >>>>>>> compiler-generated "this$0" field.
> > >>>>>>>
> > >>>>>>> Regards
> > >>>>>>> Andrey
> > >>>>>>>
> > >>>>>>> Date: Fri, 18 Dec 2015 20:44:12 +0300
> > >>>>>>>> Subject: Re: CacheEntry serialization failure
> > >>>>>>>> From: [email protected]
> > >>>>>>>> To: [email protected]
> > >>>>>>>>
> > >>>>>>>> The most straightforward solution which comes to my mind - *do
> not
> > >>>>>>>>
> > >>>>>>> ever
> > >>>>>
> > >>>>>> use
> > >>>>>>>
> > >>>>>>>> BinaryMarshaller by default*. Always fallback to
> > >>>>>>>>
> > >>>>>>> OptimizedMarshaller
> > >>>>
> > >>>>> unless
> > >>>>>>>
> > >>>>>>>> user explicitly asked us to use binary format (e.g. through
> > >>>>>>>>
> > >>>>>>> package
> > >>>>
> > >>>>> wildcards).
> > >>>>>>>>
> > >>>>>>>> BTW, we already do this for Externalizable and
> > >>>>>>>>
> > >>>>>>> readObject/writeObject.
> > >>>>>
> > >>>>>> On Fri, Dec 18, 2015 at 8:41 PM, Vladimir Ozerov <
> > >>>>>>>>
> > >>>>>>> [email protected]
> > >>>>>
> > >>>>>> wrote:
> > >>>>>>>>
> > >>>>>>>> Ah, I saw your problem with DirectedSpecifics. We need to think
> > >>>>>>>>>
> > >>>>>>>> about
> > >>>>>
> > >>>>>> how
> > >>>>>>>
> > >>>>>>>> to solve it. Here is the case:
> > >>>>>>>>> 1) Class is Serilzable and cannot be changed;
> > >>>>>>>>> 2) There are several duplicated field names;
> > >>>>>>>>> => BinaryMarshaller cannot handle it.
> > >>>>>>>>>
> > >>>>>>>>> Any thoughts?
> > >>>>>>>>>
> > >>>>>>>>> On Fri, Dec 18, 2015 at 8:34 PM, Vladimir Ozerov <
> > >>>>>>>>>
> > >>>>>>>> [email protected]
> > >>>>>>
> > >>>>>>> wrote:
> > >>>>>>>>>
> > >>>>>>>>> I fixed the problem, it was a bug actually.
> > >>>>>>>>>>
> > >>>>>>>>>> By default classes which has some custom Java logic (e.g.
> > >>>>>>>>>>
> > >>>>>>>>> Externalizable,
> > >>>>>>>
> > >>>>>>>> or with writeObject/readObject methods) will be written using
> > >>>>>>>>>> OptimizedMarshaller, so similar field names is not a problem.
> > >>>>>>>>>> If you want to serialize such class in binary format and have
> > >>>>>>>>>>
> > >>>>>>>>> duplicate
> > >>>>>>>
> > >>>>>>>> field names, you should provide your own BinarySerializer,
> > >>>>>>>>>>
> > >>>>>>>>> which
> > >>>>
> > >>>>> will
> > >>>>>>
> > >>>>>>> write
> > >>>>>>>
> > >>>>>>>> these fields with different names.
> > >>>>>>>>>>
> > >>>>>>>>>> On Fri, Dec 18, 2015 at 8:07 PM, Andrey Kornev <
> > >>>>>>>>>>
> > >>>>>>>>> [email protected]>
> > >>>>>>>
> > >>>>>>>> wrote:
> > >>>>>>>>>>
> > >>>>>>>>>> How am I supposed to handle this situation if the class comes
> > >>>>>>>>>>>
> > >>>>>>>>>> from
> > >>>>>
> > >>>>>> a
> > >>>>>>
> > >>>>>>> 3d
> > >>>>>>>
> > >>>>>>>> party I can't modify?
> > >>>>>>>>>>>
> > >>>>>>>>>>> Thanks
> > >>>>>>>>>>> Andrey
> > >>>>>>>>>>>
> > >>>>>>>>>>> Date: Fri, 18 Dec 2015 09:12:22 +0300
> > >>>>>>>>>>>> Subject: Re: CacheEntry serialization failure
> > >>>>>>>>>>>> From: [email protected]
> > >>>>>>>>>>>> To: [email protected]
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> I'll take a look.
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> On Fri, Dec 18, 2015 at 4:37 AM, Valentin Kulichenko <
> > >>>>>>>>>>>> [email protected]> wrote:
> > >>>>>>>>>>>>
> > >>>>>>>>>>>> Folks,
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> It looks like CacheEntry implementation (i.e., the entry
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>> that
> > >>>>
> > >>>>> contains
> > >>>>>>>>>>>
> > >>>>>>>>>>>> version) can't be properly serialized with the
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>> BinaryMarshaller.
> > >>>>>>
> > >>>>>>> I
> > >>>>>>>
> > >>>>>>>> created
> > >>>>>>>>>>>
> > >>>>>>>>>>>> the test and the ticket:
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>> https://issues.apache.org/jira/browse/IGNITE-2203
> > >>>>>>>>>>>
> > >>>>>>>>>>>> Can someone take a look?
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>> -Val
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>>>
> > >>>>>>>>>>>
> > >>>>>>>>>>
> > >>>>>>>
> > >>>
> > >
> >
>
