Jiři,
I've already had to go through the pain of getting the IResultSet and
IStatement interface to work when developing the Firebird Pascal API
that is distributed with IBX. The strategy that I found that works is:
1. A cursor (IResultSet) is best disposed of with "close" unless the
transaction is no longer active when "release" will do.
2. A statement (IStatement) is disposed of with a "release".
3. A transaction (ITransaction) is disposed of with a "release"
4. An attachment (IAttachment) is disposed of with a "detach".
In all cases, you should null the pointer to the interface after
disposing of it.
The Firebird Pascal API is object oriented and more than one copy of an
object can reference the same underlying Firebird interface, hence it
always uses reference counter interfaces to dispose of objects.
Regards
Tony Whyman
MWA
On 05/12/2019 09:01, Jiří Činčura wrote:
Maybe better to show some code (simplified). Expecting the free and release to
have separate responsibilities I wrote initially (the variables with underscore
are class fields). The Execute is called at some point and Free is called
either after the IExternalFunctionImpl finished executing or in
IExternalResultSetImpl::dispose (because that's the only place I'm aware of I
know no more fetching will occur and the fetching might end up in the middle
not reading all the results (otherwise I would know it because fetchNext would
return != IStatus::RESULT_OK).
void Execute(const char* stmt)
{
auto status = ThrowStatusWrapper(_context->getMaster()->getStatus());
_attachment = _context->getAttachment(&status);
_transaction = _context->getTransaction(&status);
_statement = _attachment->prepare(&status, _transaction, 0, stmt,
SQL_DIALECT_CURRENT, 0);
_cursor = _statement->openCursor(&status, _transaction, nullptr,
nullptr, outMetadata, 0);
_msg = new unsigned char[outMetadata->getMessageLength(&status)];
// other method does the fetchNext
}
void Free()
{
_cursor->close(&status);
_statement->free(&status);
delete _msg;
_msg = nullptr;
_cursor->release();
_cursor = nullptr;
_statement->release();
_statement = nullptr;
_transaction->release();
_transaction = nullptr;
_attachment->release();
_attachment = nullptr;
}
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