Re: [Firebird-devel] Providers, yvalve, external engines and object lifecycle

[Alex P. <pes...@ma...>]

 On 03/28/11 19:04, Adriano dos Santos Fernandes wrote:
>
> ---------------------
> Revision: 52587
>           http://firebird.svn.sourceforge.net/firebird/?rev=52587&view=rev
> Author:   asfernandes
> Date:     2011-03-21 21:56:47 +0000 (Mon, 21 Mar 2011)
>
> Log Message:
> -----------
> Move transactRequest, createBlob, openBlob, getSlice, putSlice and ddl
> from ITransaction to IAttachment.
>
> It's better to have one standard than two, and "ddl" was broken from API
> POV.
> So make the IAttachment always the caller, explicit or implicit (via
> IStatement or IRequest), and pass the ITransaction as parameter.
> ---------------------
>
> What you were doing was to make possible to call
> transaction->createBlob(..., attachment = NULL) for single transactions,
> but sure this is impossible to work with multidb transactions.

Definitely yes. I've blindly kept ISC API functionality, I was wrong.
But I do not see big need in moving this calls from ITransaction to
IAttachment. What did you achieve with it?

> So you needed the IAttachment for them, and it would be need to be
> casted as we were talking. 

No, there is no need in casts.
Instead I suggest to keep openBlob in ITransaction.

SingleDB implementation stores a pointer to an YAttachment in which it
was started. Let it be:

YAttachment* myAttachment;

Therefore:

YTransaction::openBlob(BLOB_ID_TYPE blobId, IAttachment* att)
{
    if (myAttachment == att)
    {
        next->openBlob(bolbId, myAttachment->next);
        return;
    }
    // raise error
}


Multi DB transaction stores pairs (IAttachment*, ITransaction*). Lete it be:

Array<Pair<IAttachment*, ITransaction*> > pairs;

And:

MultiTransaction::openBlob(BLOB_ID_TYPE blobId, IAttachment* att)
{
    for (i=0; I<pairs.count(); ++i)
    {
        if (pairs[i].left == att)
        {
            pairs[i].right->openBlob(bolbId, att);
            return;
        }
    }
    // raise error
}

That's all - and no casts.