DiskLoc CappedIterator::getNextCapped(const NamespaceDetails* nsd, const ExtentManager* em,
const DiskLoc& dl,
CollectionScanParams::Direction direction ) {
verify(!dl.isNull());
if (CollectionScanParams::FORWARD == direction) {
// If it's not looped, it's easy.
if (!nsd->capLooped()) { return em->getNextRecord( dl ); }
// TODO ELABORATE
// EOF.
if (dl == em->getExtent( nsd->capExtent() )->lastRecord) { return DiskLoc(); }
DiskLoc ret = nextLoop(nsd,em,dl);
// If we become capFirstNewRecord from same extent, advance to next extent.
if (ret == nsd->capFirstNewRecord() && ret != em->getExtent( nsd->capExtent() )->firstRecord) {
ret = nextLoop(nsd,em,em->getExtent( nsd->capExtent() )->lastRecord);
}
// If we have just gotten to beginning of capExtent, skip to capFirstNewRecord
if (ret == em->getExtent( nsd->capExtent() )->firstRecord) { ret = nsd->capFirstNewRecord(); }
return ret;
}
else {
if (!nsd->capLooped()) { return em->getPrevRecord( dl ); }
// TODO ELABORATE
// Last record
if (nsd->capFirstNewRecord() == em->getExtent( nsd->capExtent() )->firstRecord) {
if (dl == nextLoop(nsd,em,em->getExtent( nsd->capExtent() )->lastRecord)) {
return DiskLoc();
}
}
else {
if (dl == em->getExtent( nsd->capExtent() )->firstRecord) { return DiskLoc(); }
}
DiskLoc ret;
// If we are capFirstNewRecord, advance to prev extent, otherwise just get prev.
if (dl == nsd->capFirstNewRecord()) {
ret = prevLoop(nsd, em, em->getExtent( nsd->capExtent() )->firstRecord);
}
else {
ret = prevLoop(nsd, em, dl);
}
// If we just became last in cap extent, advance past capFirstNewRecord
// (We know capExtent.ext()->firstRecord != capFirstNewRecord, since would
// have returned DiskLoc() earlier otherwise.)
if (ret == em->getExtent( nsd->capExtent() )->lastRecord) {
ret = em->getPrevRecord( nsd->capFirstNewRecord() );
}
return ret;
}
}
xPL_Node* xPL_Node::prevLoop() {
if (_parent)
{
xPL_Node* n = _parent->child();
while(n->nextLoop()!=this) n=nextLoop();
return n;
}
return NULL;
}
CappedIterator::CappedIterator(const CollectionTemp* collection,
const DiskLoc& start, bool tailable,
const CollectionScanParams::Direction& dir)
: _collection(collection), _curr(start), _tailable(tailable),
_direction(dir), _killedByInvalidate(false) {
verify( collection->ok() );
if (_curr.isNull()) {
const NamespaceDetails* nsd = _collection->_details;
const ExtentManager* em = _collection->getExtentManager();
// If a start position isn't specified, we fill one out from the start of the
// collection.
if (CollectionScanParams::FORWARD == _direction) {
// Going forwards.
if (!nsd->capLooped()) {
// If our capped collection doesn't loop around, the first record is easy.
_curr = nsd->firstRecord();
}
else {
// Our capped collection has "looped' around.
// Copied verbatim from ForwardCappedCursor::init.
// TODO ELABORATE
_curr = em->getExtent( nsd->capExtent() )->firstRecord;
if (!_curr.isNull() && _curr == nsd->capFirstNewRecord()) {
_curr = em->getExtent( nsd->capExtent() )->lastRecord;
_curr = nextLoop(nsd,em,_curr);
}
}
}
else {
// Going backwards
if (!nsd->capLooped()) {
// Start at the end.
_curr = nsd->lastRecord();
}
else {
_curr = em->getExtent( nsd->capExtent() )->lastRecord;
}
}
}
}
//
// Capped collection traversal
//
CappedRecordStoreV1Iterator::CappedRecordStoreV1Iterator( OperationContext* txn,
const CappedRecordStoreV1* collection,
const DiskLoc& start, bool tailable,
const CollectionScanParams::Direction& dir)
: _txn(txn), _recordStore(collection), _curr(start), _tailable(tailable),
_direction(dir), _killedByInvalidate(false) {
if (_curr.isNull()) {
const RecordStoreV1MetaData* nsd = _recordStore->details();
// If a start position isn't specified, we fill one out from the start of the
// collection.
if (CollectionScanParams::FORWARD == _direction) {
// 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;
}
}
}
}
DiskLoc CappedRecordStoreV1Iterator::getNextCapped(const DiskLoc& dl) {
invariant(!dl.isNull());
const RecordStoreV1MetaData* details = _recordStore->details();
if (CollectionScanParams::FORWARD == _direction) {
// 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;
}
}
