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// Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.
#ifndef DATASRC_ZONE_ITERATOR_H
#define DATASRC_ZONE_ITERATOR_H 1
#include <dns/rrset.h>
#include <boost/noncopyable.hpp>
#include <datasrc/zone.h>
namespace isc {
namespace datasrc {
/**
* \brief Read-only iterator to a zone.
*
* You can get an instance of (descendand of) ZoneIterator from
* DataSourceClient::getIterator() method. The actual concrete implementation
* will be different depending on the actual data source used. This is the
* abstract interface.
*
* There's no way to start iterating from the beginning again or return.
*/
class ZoneIterator : public boost::noncopyable {
public:
/**
* \brief Destructor
*
* Virtual destructor. It is empty, but ensures the right destructor from
* descendant is called.
*/
virtual ~ ZoneIterator() { }
/**
* \brief Get next RRset from the zone.
*
* This returns the next RRset in the zone as a shared pointer. The
* shared pointer is used to allow both accessing in-memory data and
* automatic memory management.
*
* Any special order is not guaranteed.
*
* While this can potentially throw anything (including standard allocation
* errors), it should be rare.
*
* \return Pointer to the next RRset or NULL pointer when the iteration
* gets to the end of the zone.
*/
virtual isc::dns::ConstRRsetPtr getNextRRset() = 0;
/**
* \brief Return the SOA record of the zone in the iterator context.
*
* This method returns the zone's SOA record (if any, and a valid zone
* should have it) in the form of an RRset object. This SOA is identical
* to that (again, if any) contained in the sequence of RRsets returned
* by the iterator. In that sense this method is redundant, but is
* provided as a convenient utility for the application of the
* iterator; the application may need to know the SOA serial or the
* SOA RR itself for the purpose of protocol handling or skipping the
* expensive iteration processing.
*
* If the zone doesn't have an SOA (which is broken, but some data source
* may allow that situation), this method returns NULL. Also, in the
* normal and valid case, the SOA should have exactly one RDATA, but
* this API does not guarantee it as some data source may accept such an
* abnormal condition. It's up to the caller whether to check the number
* of RDATA and how to react to the unexpected case.
*
* Each concrete derived method must ensure that the SOA returned by this
* method is identical to the zone's SOA returned via the iteration.
* For example, even if another thread or process updates the SOA while
* the iterator is working, the result of this method must not be
* affected by the update. For database based data sources, this can
* be done by making the entire iterator operation as a single database
* transaction, but the actual implementation can differ.
*
* \exception None
*
* \return A shared pointer to an SOA RRset that would be returned
* from the iteration. It will be NULL if the zone doesn't have an SOA.
*/
virtual isc::dns::ConstRRsetPtr getSOA() const = 0;
};
}
}
#endif // DATASRC_ZONE_ITERATOR_H
// Local Variables:
// mode: c++
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