PlanStage::StageState IndexScan::work(WorkingSetID* out) {
++_commonStats.works;
if (NULL == _indexCursor.get()) {
// First call to work(). Perform possibly heavy init.
initIndexScan();
checkEnd();
}
else if (_yieldMovedCursor) {
_yieldMovedCursor = false;
// Note that we're not calling next() here. We got the next thing when we recovered
// from yielding.
}
if (isEOF()) { return PlanStage::IS_EOF; }
// Grab the next (key, value) from the index.
BSONObj keyObj = _indexCursor->getKey();
DiskLoc loc = _indexCursor->getValue();
// Move to the next result.
// The underlying IndexCursor points at the *next* thing we want to return. We do this so
// that if we're scanning an index looking for docs to delete we don't continually clobber
// the thing we're pointing at.
_indexCursor->next();
checkEnd();
if (_shouldDedup) {
++_specificStats.dupsTested;
if (_returned.end() != _returned.find(loc)) {
++_specificStats.dupsDropped;
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else {
_returned.insert(loc);
}
}
if (Filter::passes(keyObj, _keyPattern, _filter)) {
if (NULL != _filter) {
++_specificStats.matchTested;
}
// We must make a copy of the on-disk data since it can mutate during the execution of
// this query.
BSONObj ownedKeyObj = keyObj.getOwned();
// Fill out the WSM.
WorkingSetID id = _workingSet->allocate();
WorkingSetMember* member = _workingSet->get(id);
member->loc = loc;
member->keyData.push_back(IndexKeyDatum(_keyPattern, ownedKeyObj));
member->state = WorkingSetMember::LOC_AND_IDX;
if (_params.addKeyMetadata) {
BSONObjBuilder bob;
bob.appendKeys(_keyPattern, ownedKeyObj);
member->addComputed(new IndexKeyComputedData(bob.obj()));
}
*out = id;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
PlanStage::StageState IndexScan::doWork(WorkingSetID* out) {
// Get the next kv pair from the index, if any.
boost::optional<IndexKeyEntry> kv;
try {
switch (_scanState) {
case INITIALIZING:
kv = initIndexScan();
break;
case GETTING_NEXT:
kv = _indexCursor->next();
break;
case NEED_SEEK:
++_specificStats.seeks;
kv = _indexCursor->seek(_seekPoint);
break;
case HIT_END:
return PlanStage::IS_EOF;
}
} catch (const WriteConflictException& wce) {
*out = WorkingSet::INVALID_ID;
return PlanStage::NEED_YIELD;
}
if (kv) {
// In debug mode, check that the cursor isn't lying to us.
if (kDebugBuild && !_endKey.isEmpty()) {
int cmp = kv->key.woCompare(_endKey,
Ordering::make(_params.descriptor->keyPattern()),
/*compareFieldNames*/ false);
if (cmp == 0)
dassert(_endKeyInclusive);
dassert(_forward ? cmp <= 0 : cmp >= 0);
}
++_specificStats.keysExamined;
if (_params.maxScan && _specificStats.keysExamined >= _params.maxScan) {
kv = boost::none;
}
}
if (kv && _checker) {
switch (_checker->checkKey(kv->key, &_seekPoint)) {
case IndexBoundsChecker::VALID:
break;
case IndexBoundsChecker::DONE:
kv = boost::none;
break;
case IndexBoundsChecker::MUST_ADVANCE:
_scanState = NEED_SEEK;
return PlanStage::NEED_TIME;
}
}
if (!kv) {
_scanState = HIT_END;
_commonStats.isEOF = true;
_indexCursor.reset();
return PlanStage::IS_EOF;
}
_scanState = GETTING_NEXT;
if (_shouldDedup) {
++_specificStats.dupsTested;
if (!_returned.insert(kv->loc).second) {
// We've seen this RecordId before. Skip it this time.
++_specificStats.dupsDropped;
return PlanStage::NEED_TIME;
}
}
if (_filter) {
if (!Filter::passes(kv->key, _keyPattern, _filter)) {
return PlanStage::NEED_TIME;
}
}
if (!kv->key.isOwned())
kv->key = kv->key.getOwned();
// We found something to return, so fill out the WSM.
WorkingSetID id = _workingSet->allocate();
WorkingSetMember* member = _workingSet->get(id);
member->recordId = kv->loc;
member->keyData.push_back(IndexKeyDatum(_keyPattern, kv->key, _iam));
_workingSet->transitionToRecordIdAndIdx(id);
if (_params.addKeyMetadata) {
BSONObjBuilder bob;
bob.appendKeys(_keyPattern, kv->key);
member->addComputed(new IndexKeyComputedData(bob.obj()));
}
*out = id;
return PlanStage::ADVANCED;
}
