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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/db/storage/mmap_v1/record_store_v1_capped_iterator.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/storage/mmap_v1/extent.h"
#include "mongo/db/storage/mmap_v1/extent_manager.h"
#include "mongo/db/storage/mmap_v1/record_store_v1_capped.h"
namespace mongo {
//
// Capped collection traversal
//
CappedRecordStoreV1Iterator::CappedRecordStoreV1Iterator(OperationContext* txn,
const CappedRecordStoreV1* collection,
bool forward)
: _txn(txn), _recordStore(collection), _forward(forward) {
const RecordStoreV1MetaData* nsd = _recordStore->details();
// If a start position isn't specified, we fill one out from the start of the
// collection.
if (_forward) {
// Going forwards.
if (!nsd->capLooped()) {
// If our capped collection doesn't loop around, the first record is easy.
_curr = collection->firstRecord(_txn);
} else {
// Our capped collection has "looped' around.
// Copied verbatim from ForwardCappedCursor::init.
// TODO ELABORATE
_curr = _getExtent(nsd->capExtent())->firstRecord;
if (!_curr.isNull() && _curr == nsd->capFirstNewRecord()) {
_curr = _getExtent(nsd->capExtent())->lastRecord;
_curr = nextLoop(_curr);
}
}
} else {
// Going backwards
if (!nsd->capLooped()) {
// Start at the end.
_curr = collection->lastRecord(_txn);
} else {
_curr = _getExtent(nsd->capExtent())->lastRecord;
}
}
}
boost::optional<Record> CappedRecordStoreV1Iterator::next() {
if (isEOF())
return {};
auto toReturn = _curr.toRecordId();
_curr = getNextCapped(_curr);
return {{toReturn, _recordStore->RecordStore::dataFor(_txn, toReturn)}};
}
boost::optional<Record> CappedRecordStoreV1Iterator::seekExact(const RecordId& id) {
_curr = getNextCapped(DiskLoc::fromRecordId(id));
return {{id, _recordStore->RecordStore::dataFor(_txn, id)}};
}
void CappedRecordStoreV1Iterator::invalidate(const RecordId& id) {
const DiskLoc dl = DiskLoc::fromRecordId(id);
if (dl == _curr) {
// We *could* move to the next thing, since there is actually a next
// thing, but according to clientcursor.cpp:
// "note we cannot advance here. if this condition occurs, writes to the oplog
// have "caught" the reader. skipping ahead, the reader would miss potentially
// important data."
_curr = DiskLoc();
_killedByInvalidate = true;
}
}
void CappedRecordStoreV1Iterator::savePositioned() {
_txn = nullptr;
}
bool CappedRecordStoreV1Iterator::restore(OperationContext* txn) {
_txn = txn;
return !_killedByInvalidate;
}
DiskLoc CappedRecordStoreV1Iterator::getNextCapped(const DiskLoc& dl) {
invariant(!dl.isNull());
const RecordStoreV1MetaData* details = _recordStore->details();
if (_forward) {
// If it's not looped, it's easy.
if (!_recordStore->details()->capLooped()) {
return _getNextRecord(dl);
}
// TODO ELABORATE
// EOF.
if (dl == _getExtent(details->capExtent())->lastRecord) {
return DiskLoc();
}
DiskLoc ret = nextLoop(dl);
// If we become capFirstNewRecord from same extent, advance to next extent.
if (ret == details->capFirstNewRecord() &&
ret != _getExtent(details->capExtent())->firstRecord) {
ret = nextLoop(_getExtent(details->capExtent())->lastRecord);
}
// If we have just gotten to beginning of capExtent, skip to capFirstNewRecord
if (ret == _getExtent(details->capExtent())->firstRecord) {
ret = details->capFirstNewRecord();
}
return ret;
} else {
if (!details->capLooped()) {
return _getPrevRecord(dl);
}
// TODO ELABORATE
// Last record
if (details->capFirstNewRecord() == _getExtent(details->capExtent())->firstRecord) {
if (dl == nextLoop(_getExtent(details->capExtent())->lastRecord)) {
return DiskLoc();
}
} else {
if (dl == _getExtent(details->capExtent())->firstRecord) {
return DiskLoc();
}
}
DiskLoc ret;
// If we are capFirstNewRecord, advance to prev extent, otherwise just get prev.
if (dl == details->capFirstNewRecord()) {
ret = prevLoop(_getExtent(details->capExtent())->firstRecord);
} else {
ret = prevLoop(dl);
}
// If we just became last in cap extent, advance past capFirstNewRecord
// (We know ext(capExtent)->firstRecord != capFirstNewRecord, since would
// have returned DiskLoc() earlier otherwise.)
if (ret == _getExtent(details->capExtent())->lastRecord) {
ret = _getPrevRecord(details->capFirstNewRecord());
}
return ret;
}
}
DiskLoc CappedRecordStoreV1Iterator::nextLoop(const DiskLoc& prev) {
// TODO ELABORATE
DiskLoc next = _getNextRecord(prev);
if (!next.isNull()) {
return next;
}
return _recordStore->firstRecord(_txn);
}
DiskLoc CappedRecordStoreV1Iterator::prevLoop(const DiskLoc& curr) {
// TODO ELABORATE
DiskLoc prev = _getPrevRecord(curr);
if (!prev.isNull()) {
return prev;
}
return _recordStore->lastRecord(_txn);
}
Extent* CappedRecordStoreV1Iterator::_getExtent(const DiskLoc& loc) {
return _recordStore->_extentManager->getExtent(loc);
}
DiskLoc CappedRecordStoreV1Iterator::_getNextRecord(const DiskLoc& loc) {
return _recordStore->getNextRecord(_txn, loc);
}
DiskLoc CappedRecordStoreV1Iterator::_getPrevRecord(const DiskLoc& loc) {
return _recordStore->getPrevRecord(_txn, loc);
}
std::unique_ptr<RecordFetcher> CappedRecordStoreV1Iterator::fetcherForNext() const {
return _recordStore->_extentManager->recordNeedsFetch(_curr);
}
std::unique_ptr<RecordFetcher> CappedRecordStoreV1Iterator::fetcherForId(const RecordId& id) const {
return _recordStore->_extentManager->recordNeedsFetch(DiskLoc::fromRecordId(id));
}
} // namespace mongo
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