Re: Object serialization patch

[Guilhem Lavaux <guilhem at kaffe dot org>]

Jeroen Frijters wrote:
> Hi, 
>
>
> > Here is a new patch I propose. I've taken the suggestion 
> > into account and fix another small error reporting problem.
>
>
> I don't understand checkTypeConsistency, it looks odd and I'm having a
> hard time believing that it is correct. BTW, Shouldn't "nonPrimitive" be
> named "primitive"?

The problem if you sort fields using 
ObjectStreamField.compareTo is that you separate names which 
are alphabetically sorted. I will explain this on the 
following example.

Imagine that in the stream you have the following field names:

int a;
int e;
String b;
String d;

They will be sorted as: a, e, b, d. (They will be written as 
a1, e1, b1, d1).

Now the class may declare the same field names but with 
different types:

int a;
String e;
String b;
String d;

And they will be sorted as: a, b, d, e. (They will be 
written as a2, b2, d2, e2).

Now we want to check that the types are consistent between 
the stream and the class. Previously we compared a1 with a2, 
b1 with b2, d1 with d2 and the code was generating two more 
extra fields: e1 and e2 (aka int e and String e). They 
represent the same field but with two different types which 
is wrong.

Now checkTypeConsistency compares two field pools. We 
extract the non primitive fields F1 from the first pool and 
the primitive fields F2 from the second pool. If we find a 
field which has the same name both in F1 and F2 there is an 
inconsistency.

This operation must be done both when the first pool is the 
"stream" fields and the second pool the "class" fields, and 
when the roles are reversed.

I think that 'nonPrimitive' is correctly named as the 
primitive fields came in first and we are looking for the 
non primitive fields.

> Also, I really don't like the type checking being done in the various
> setXxxField methods, there is no reason to do this every time, it can be
> done once when the fields are mapped.

Yes, I'm also not completely satisfied with this method. But 
there exists cases where it is needed. For example, if 
serialPersistentFields declares class types wrongly. The 
types are not checked previously in that case and this 
results in an IllegalArgumentException (which is wrong). The 
solution would be to check the types of all fields when we 
are building the ObjectStreamClass from serialPersistentFields.


Regards,
Guilhem.