void FindingStartCursor::next() {
if ( !_findingStartCursor || !_findingStartCursor->ok() ) {
_findingStart = false;
_c = _qp.newCursor(); // on error, start from beginning
destroyClientCursor();
return;
}
switch( _findingStartMode ) {
case Initial: {
if ( !_matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStart = false; // found first record out of query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
RARELY {
if ( _findingStartTimer.seconds() >= __findingStartInitialTimeout ) {
createClientCursor( startLoc( _findingStartCursor->currLoc() ) );
_findingStartMode = FindExtent;
return;
}
}
return;
}
case FindExtent: {
if ( !_matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStartMode = InExtent;
return;
}
DiskLoc prev = prevLoc( _findingStartCursor->currLoc() );
if ( prev.isNull() ) { // hit beginning, so start scanning from here
createClientCursor();
_findingStartMode = InExtent;
return;
}
// There might be a more efficient implementation than creating new cursor & client cursor each time,
// not worrying about that for now
createClientCursor( prev );
return;
}
case InExtent: {
if ( _matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStart = false; // found first record in query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
return;
}
default: {
massert( 14038, "invalid _findingStartMode", false );
}
}
}
void FindingStartCursor::next() {
if ( !_findingStartCursor || !_findingStartCursor->ok() ) {
_findingStart = false;
_c = _qp.newCursor(); // on error, start from beginning
destroyClientCursor();
return;
}
switch( _findingStartMode ) {
// Initial mode: scan backwards from end of collection
case Initial: {
if ( !_matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStart = false; // found first record out of query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
RARELY {
if ( _findingStartTimer.seconds() >= __findingStartInitialTimeout ) {
// If we've scanned enough, switch to find extent mode.
createClientCursor( extentFirstLoc( _findingStartCursor->currLoc() ) );
_findingStartMode = FindExtent;
return;
}
}
return;
}
// FindExtent mode: moving backwards through extents, check first
// document of each extent.
case FindExtent: {
if ( !_matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStartMode = InExtent;
return;
}
DiskLoc prev = prevExtentFirstLoc( _findingStartCursor->currLoc() );
if ( prev.isNull() ) { // hit beginning, so start scanning from here
createClientCursor();
_findingStartMode = InExtent;
return;
}
// There might be a more efficient implementation than creating new cursor & client cursor each time,
// not worrying about that for now
createClientCursor( prev );
return;
}
// InExtent mode: once an extent is chosen, find starting doc in the extent.
case InExtent: {
if ( _matcher->matchesCurrent( _findingStartCursor->c() ) ) {
_findingStart = false; // found first record in query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
return;
}
default: {
massert( 14038, "invalid _findingStartMode", false );
}
}
}
