// static
void Explain::getSummaryStats(PlanExecutor* exec, PlanSummaryStats* statsOut) {
invariant(NULL != statsOut);
PlanStage* root = exec->getRootStage();
// We can get some of the fields we need from the common stats stored in the
// root stage of the plan tree.
const CommonStats* common = root->getCommonStats();
statsOut->nReturned = common->advanced;
statsOut->executionTimeMillis = common->executionTimeMillis;
// Generate the plan summary string.
statsOut->summaryStr = getPlanSummary(root);
// The other fields are aggregations over the stages in the plan tree. We flatten
// the tree into a list and then compute these aggregations.
vector<PlanStage*> stages;
flattenExecTree(root, &stages);
for (size_t i = 0; i < stages.size(); i++) {
statsOut->totalKeysExamined += getKeysExamined(stages[i]->stageType(),
stages[i]->getSpecificStats());
statsOut->totalDocsExamined += getDocsExamined(stages[i]->stageType(),
stages[i]->getSpecificStats());
if (STAGE_IDHACK == stages[i]->stageType()) {
statsOut->isIdhack = true;
}
if (STAGE_SORT == stages[i]->stageType()) {
statsOut->hasSortStage = true;
}
}
}
void Explain::getSummaryStats(PlanExecutor* exec, PlanSummaryStats* statsOut) {
invariant(NULL != statsOut);
PlanStage* root = exec->getStages();
// We can get some of the fields we need from the common stats stored in the
// root stage of the plan tree.
const CommonStats* common = root->getCommonStats();
statsOut->nReturned = common->advanced;
statsOut->executionTimeMillis = common->executionTimeMillis;
// The other fields are aggregations over the stages in the plan tree. We flatten
// the tree into a list and then compute these aggregations.
vector<PlanStage*> stages;
flattenExecTree(root, &stages);
// Use this stream to build the plan summary string.
mongoutils::str::stream ss;
bool seenLeaf = false;
for (size_t i = 0; i < stages.size(); i++) {
statsOut->totalKeysExamined += getKeysExamined(stages[i]->stageType(),
stages[i]->getSpecificStats());
statsOut->totalDocsExamined += getDocsExamined(stages[i]->stageType(),
stages[i]->getSpecificStats());
if (STAGE_IDHACK == stages[i]->stageType()) {
statsOut->isIdhack = true;
}
if (STAGE_SORT == stages[i]->stageType()) {
statsOut->hasSortStage = true;
}
if (stages[i]->getChildren().empty()) {
// This is a leaf node. Add to the plan summary string accordingly. Unless
// this is the first leaf we've seen, add a delimiting string first.
if (seenLeaf) {
ss << ", ";
}
else {
seenLeaf = true;
}
addStageSummaryStr(stages[i], ss);
}
}
statsOut->summaryStr = ss;
}
PlanStage::StageState MergeSortStage::work(WorkingSetID* out) {
++_commonStats.works;
// Adds the amount of time taken by work() to executionTimeMillis.
ScopedTimer timer(&_commonStats.executionTimeMillis);
if (isEOF()) {
return PlanStage::IS_EOF;
}
if (!_noResultToMerge.empty()) {
// We have some child that we don't have a result from. Each child must have a result
// in order to pick the minimum result among all our children. Work a child.
PlanStage* child = _noResultToMerge.front();
WorkingSetID id = WorkingSet::INVALID_ID;
StageState code = child->work(&id);
if (PlanStage::ADVANCED == code) {
WorkingSetMember* member = _ws->get(id);
// If we're deduping...
if (_dedup) {
if (!member->hasLoc()) {
// Can't dedup data unless there's a RecordId. We go ahead and use its
// result.
_noResultToMerge.pop();
} else {
++_specificStats.dupsTested;
// ...and there's a diskloc and and we've seen the RecordId before
if (_seen.end() != _seen.find(member->loc)) {
// ...drop it.
_ws->free(id);
++_commonStats.needTime;
++_specificStats.dupsDropped;
return PlanStage::NEED_TIME;
} else {
// Otherwise, note that we've seen it.
_seen.insert(member->loc);
// We're going to use the result from the child, so we remove it from
// the queue of children without a result.
_noResultToMerge.pop();
}
}
} else {
// Not deduping. We use any result we get from the child. Remove the child
// from the queue of things without a result.
_noResultToMerge.pop();
}
// Store the result in our list.
StageWithValue value;
value.id = id;
value.stage = child;
// Ensure that the BSONObj underlying the WorkingSetMember is owned in case we yield.
member->makeObjOwned();
_mergingData.push_front(value);
// Insert the result (indirectly) into our priority queue.
_merging.push(_mergingData.begin());
++_commonStats.needTime;
return PlanStage::NEED_TIME;
} else if (PlanStage::IS_EOF == code) {
// There are no more results possible from this child. Don't bother with it
// anymore.
_noResultToMerge.pop();
++_commonStats.needTime;
return PlanStage::NEED_TIME;
} else if (PlanStage::FAILURE == code || PlanStage::DEAD == code) {
*out = id;
// If a stage fails, it may create a status WSM to indicate why it
// failed, in which case 'id' is valid. If ID is invalid, we
// create our own error message.
if (WorkingSet::INVALID_ID == id) {
mongoutils::str::stream ss;
ss << "merge sort stage failed to read in results from child";
Status status(ErrorCodes::InternalError, ss);
*out = WorkingSetCommon::allocateStatusMember(_ws, status);
}
return code;
} else {
if (PlanStage::NEED_TIME == code) {
++_commonStats.needTime;
} else if (PlanStage::NEED_YIELD == code) {
*out = id;
++_commonStats.needYield;
}
return code;
}
}
// If we're here, for each non-EOF child, we have a valid WSID.
verify(!_merging.empty());
// Get the 'min' WSID. _merging is a priority queue so its top is the smallest.
MergingRef top = _merging.top();
_merging.pop();
// Since we're returning the WSID that came from top->stage, we need to work(...) it again
// to get a new result.
_noResultToMerge.push(top->stage);
// Save the ID that we're returning and remove the returned result from our data.
WorkingSetID idToTest = top->id;
_mergingData.erase(top);
// Return the min.
*out = idToTest;
++_commonStats.advanced;
// But don't return it if it's flagged.
if (_ws->isFlagged(*out)) {
return PlanStage::NEED_TIME;
}
return PlanStage::ADVANCED;
}
PlanStage::StageState AndSortedStage::moveTowardTargetLoc(WorkingSetID* out) {
verify(numeric_limits<size_t>::max() != _targetNode);
verify(WorkingSet::INVALID_ID != _targetId);
// We have nodes that haven't hit _targetLoc yet.
size_t workingChildNumber = _workingTowardRep.front();
PlanStage* next = _children[workingChildNumber];
WorkingSetID id = WorkingSet::INVALID_ID;
StageState state = next->work(&id);
if (PlanStage::ADVANCED == state) {
WorkingSetMember* member = _ws->get(id);
// Maybe the child had an invalidation. We intersect DiskLoc(s) so we can't do anything
// with this WSM.
if (!member->hasLoc()) {
_ws->flagForReview(id);
return PlanStage::NEED_TIME;
}
verify(member->hasLoc());
if (member->loc == _targetLoc) {
// The front element has hit _targetLoc. Don't move it forward anymore/work on
// another element.
_workingTowardRep.pop();
AndCommon::mergeFrom(_ws->get(_targetId), *member);
_ws->free(id);
if (0 == _workingTowardRep.size()) {
WorkingSetID toReturn = _targetId;
WorkingSetMember* toMatchTest = _ws->get(toReturn);
_targetNode = numeric_limits<size_t>::max();
_targetId = WorkingSet::INVALID_ID;
_targetLoc = DiskLoc();
// Everyone hit it, hooray. Return it, if it matches.
if (Filter::passes(toMatchTest, _filter)) {
if (NULL != _filter) {
++_specificStats.matchTested;
}
*out = toReturn;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
else {
_ws->free(toReturn);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
}
// More children need to be advanced to _targetLoc.
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else if (member->loc < _targetLoc) {
// The front element of _workingTowardRep hasn't hit the thing we're AND-ing with
// yet. Try again later.
_ws->free(id);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else {
// member->loc > _targetLoc.
// _targetLoc wasn't successfully AND-ed with the other sub-plans. We toss it and
// try AND-ing with the next value.
_specificStats.failedAnd[_targetNode]++;
_ws->free(_targetId);
_targetNode = workingChildNumber;
_targetLoc = member->loc;
_targetId = id;
_workingTowardRep = std::queue<size_t>();
for (size_t i = 0; i < _children.size(); ++i) {
if (workingChildNumber != i) {
_workingTowardRep.push(i);
}
}
// Need time to chase after the new _targetLoc.
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
}
else if (PlanStage::IS_EOF == state) {
_isEOF = true;
_ws->free(_targetId);
return state;
}
else if (PlanStage::FAILURE == state) {
*out = id;
// If a stage fails, it may create a status WSM to indicate why it
// failed, in which case 'id' is valid. If ID is invalid, we
// create our own error message.
if (WorkingSet::INVALID_ID == id) {
mongoutils::str::stream ss;
ss << "sorted AND stage failed to read in results from child " << workingChildNumber;
Status status(ErrorCodes::InternalError, ss);
*out = WorkingSetCommon::allocateStatusMember( _ws, status);
}
_isEOF = true;
_ws->free(_targetId);
return state;
}
else {
if (PlanStage::NEED_TIME == state) {
++_commonStats.needTime;
}
else if (PlanStage::NEED_FETCH == state) {
++_commonStats.needFetch;
*out = id;
}
return state;
}
}
PlanStage::StageState AndHashStage::work(WorkingSetID* out) {
++_commonStats.works;
// Adds the amount of time taken by work() to executionTimeMillis.
ScopedTimer timer(&_commonStats.executionTimeMillis);
if (isEOF()) { return PlanStage::IS_EOF; }
// Fast-path for one of our children being EOF immediately. We work each child a few times.
// If it hits EOF, the AND cannot output anything. If it produces a result, we stash that
// result in _lookAheadResults.
if (_lookAheadResults.empty()) {
// INVALID_ID means that the child didn't produce a valid result.
// We specifically are not using .resize(size, value) here because C++11 builds don't
// seem to resolve WorkingSet::INVALID_ID during linking.
_lookAheadResults.resize(_children.size());
for (size_t i = 0; i < _children.size(); ++i) {
_lookAheadResults[i] = WorkingSet::INVALID_ID;
}
// Work each child some number of times until it's either EOF or produces
// a result. If it's EOF this whole stage will be EOF. If it produces a
// result we cache it for later.
for (size_t i = 0; i < _children.size(); ++i) {
PlanStage* child = _children[i];
for (size_t j = 0; j < kLookAheadWorks; ++j) {
StageState childStatus = child->work(&_lookAheadResults[i]);
if (PlanStage::IS_EOF == childStatus || PlanStage::DEAD == childStatus) {
// A child went right to EOF. Bail out.
_hashingChildren = false;
_dataMap.clear();
return PlanStage::IS_EOF;
}
else if (PlanStage::ADVANCED == childStatus) {
// We have a result cached in _lookAheadResults[i]. Stop looking at this
// child.
break;
}
else if (PlanStage::FAILURE == childStatus) {
// Propage error to parent.
*out = _lookAheadResults[i];
// If a stage fails, it may create a status WSM to indicate why it
// failed, in which case 'id' is valid. If ID is invalid, we
// create our own error message.
if (WorkingSet::INVALID_ID == *out) {
mongoutils::str::stream ss;
ss << "hashed AND stage failed to read in look ahead results "
<< "from child " << i;
Status status(ErrorCodes::InternalError, ss);
*out = WorkingSetCommon::allocateStatusMember( _ws, status);
}
_hashingChildren = false;
_dataMap.clear();
return PlanStage::FAILURE;
}
// We ignore NEED_TIME. TODO: what do we want to do if we get NEED_YIELD here?
}
}
// We did a bunch of work above, return NEED_TIME to be fair.
return PlanStage::NEED_TIME;
}
// An AND is either reading the first child into the hash table, probing against the hash
// table with subsequent children, or checking the last child's results to see if they're
// in the hash table.
// We read the first child into our hash table.
if (_hashingChildren) {
// Check memory usage of previously hashed results.
if (_memUsage > _maxMemUsage) {
mongoutils::str::stream ss;
ss << "hashed AND stage buffered data usage of " << _memUsage
<< " bytes exceeds internal limit of " << kDefaultMaxMemUsageBytes << " bytes";
Status status(ErrorCodes::Overflow, ss);
*out = WorkingSetCommon::allocateStatusMember( _ws, status);
return PlanStage::FAILURE;
}
if (0 == _currentChild) {
return readFirstChild(out);
}
else if (_currentChild < _children.size() - 1) {
return hashOtherChildren(out);
}
else {
_hashingChildren = false;
// We don't hash our last child. Instead, we probe the table created from the
// previous children, returning results in the order of the last child.
// Fall through to below.
}
}
// Returning results. We read from the last child and return the results that are in our
// hash map.
// We should be EOF if we're not hashing results and the dataMap is empty.
verify(!_dataMap.empty());
// We probe _dataMap with the last child.
verify(_currentChild == _children.size() - 1);
// Get the next result for the (_children.size() - 1)-th child.
StageState childStatus = workChild(_children.size() - 1, out);
if (PlanStage::ADVANCED != childStatus) {
return childStatus;
}
// We know that we've ADVANCED. See if the WSM is in our table.
WorkingSetMember* member = _ws->get(*out);
// Maybe the child had an invalidation. We intersect RecordId(s) so we can't do anything
// with this WSM.
if (!member->hasLoc()) {
_ws->flagForReview(*out);
return PlanStage::NEED_TIME;
}
DataMap::iterator it = _dataMap.find(member->loc);
if (_dataMap.end() == it) {
// Child's output wasn't in every previous child. Throw it out.
_ws->free(*out);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else {
// Child's output was in every previous child. Merge any key data in
// the child's output and free the child's just-outputted WSM.
WorkingSetID hashID = it->second;
_dataMap.erase(it);
WorkingSetMember* olderMember = _ws->get(hashID);
AndCommon::mergeFrom(olderMember, *member);
_ws->free(*out);
// We should check for matching at the end so the matcher can use information in the
// indices of all our children.
if (Filter::passes(olderMember, _filter)) {
*out = hashID;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
else {
_ws->free(hashID);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
}
}
PlanStage::StageState MergeSortStage::doWork(WorkingSetID* out) {
if (isEOF()) {
return PlanStage::IS_EOF;
}
if (!_noResultToMerge.empty()) {
// We have some child that we don't have a result from. Each child must have a result
// in order to pick the minimum result among all our children. Work a child.
PlanStage* child = _noResultToMerge.front();
WorkingSetID id = WorkingSet::INVALID_ID;
StageState code = child->work(&id);
if (PlanStage::ADVANCED == code) {
WorkingSetMember* member = _ws->get(id);
// If we're deduping...
if (_dedup) {
if (!member->hasRecordId()) {
// Can't dedup data unless there's a RecordId. We go ahead and use its
// result.
_noResultToMerge.pop();
} else {
++_specificStats.dupsTested;
// ...and there's a RecordId and and we've seen the RecordId before
if (_seen.end() != _seen.find(member->recordId)) {
// ...drop it.
_ws->free(id);
++_specificStats.dupsDropped;
return PlanStage::NEED_TIME;
} else {
// Otherwise, note that we've seen it.
_seen.insert(member->recordId);
// We're going to use the result from the child, so we remove it from
// the queue of children without a result.
_noResultToMerge.pop();
}
}
} else {
// Not deduping. We use any result we get from the child. Remove the child
// from the queue of things without a result.
_noResultToMerge.pop();
}
// Store the result in our list.
StageWithValue value;
value.id = id;
value.stage = child;
// Ensure that the BSONObj underlying the WorkingSetMember is owned in case we yield.
member->makeObjOwnedIfNeeded();
_mergingData.push_front(value);
// Insert the result (indirectly) into our priority queue.
_merging.push(_mergingData.begin());
return PlanStage::NEED_TIME;
} else if (PlanStage::IS_EOF == code) {
// There are no more results possible from this child. Don't bother with it
// anymore.
_noResultToMerge.pop();
return PlanStage::NEED_TIME;
} else if (PlanStage::FAILURE == code) {
// The stage which produces a failure is responsible for allocating a working set member
// with error details.
invariant(WorkingSet::INVALID_ID != id);
*out = id;
return code;
} else if (PlanStage::NEED_YIELD == code) {
*out = id;
return code;
} else {
return code;
}
}
// If we're here, for each non-EOF child, we have a valid WSID.
verify(!_merging.empty());
// Get the 'min' WSID. _merging is a priority queue so its top is the smallest.
MergingRef top = _merging.top();
_merging.pop();
// Since we're returning the WSID that came from top->stage, we need to work(...) it again
// to get a new result.
_noResultToMerge.push(top->stage);
// Save the ID that we're returning and remove the returned result from our data.
WorkingSetID idToTest = top->id;
_mergingData.erase(top);
// Return the min.
*out = idToTest;
return PlanStage::ADVANCED;
}
PlanStage::StageState MergeSortStage::work(WorkingSetID* out) {
++_commonStats.works;
if (isEOF()) { return PlanStage::IS_EOF; }
if (!_noResultToMerge.empty()) {
// We have some child that we don't have a result from. Each child must have a result
// in order to pick the minimum result among all our children. Work a child.
PlanStage* child = _noResultToMerge.front();
WorkingSetID id = WorkingSet::INVALID_ID;
StageState code = child->work(&id);
if (PlanStage::ADVANCED == code) {
// If we're deduping...
if (_dedup) {
WorkingSetMember* member = _ws->get(id);
if (!member->hasLoc()) {
// Can't dedup data unless there's a DiskLoc. We go ahead and use its
// result.
_noResultToMerge.pop();
}
else {
++_specificStats.dupsTested;
// ...and there's a diskloc and and we've seen the DiskLoc before
if (_seen.end() != _seen.find(member->loc)) {
// ...drop it.
_ws->free(id);
++_commonStats.needTime;
++_specificStats.dupsDropped;
return PlanStage::NEED_TIME;
}
else {
// Otherwise, note that we've seen it.
_seen.insert(member->loc);
// We're going to use the result from the child, so we remove it from
// the queue of children without a result.
_noResultToMerge.pop();
}
}
}
else {
// Not deduping. We use any result we get from the child. Remove the child
// from the queue of things without a result.
_noResultToMerge.pop();
}
// Store the result in our list.
StageWithValue value;
value.id = id;
value.stage = child;
_mergingData.push_front(value);
// Insert the result (indirectly) into our priority queue.
_merging.push(_mergingData.begin());
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else if (PlanStage::IS_EOF == code) {
// There are no more results possible from this child. Don't bother with it
// anymore.
_noResultToMerge.pop();
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else if (PlanStage::FAILURE == code) {
*out = id;
return code;
}
else {
if (PlanStage::NEED_FETCH == code) {
*out = id;
++_commonStats.needFetch;
}
else if (PlanStage::NEED_TIME == code) {
++_commonStats.needTime;
}
return code;
}
}
// If we're here, for each non-EOF child, we have a valid WSID.
verify(!_merging.empty());
// Get the 'min' WSID. _merging is a priority queue so its top is the smallest.
MergingRef top = _merging.top();
_merging.pop();
// Since we're returning the WSID that came from top->stage, we need to work(...) it again
// to get a new result.
_noResultToMerge.push(top->stage);
// Save the ID that we're returning and remove the returned result from our data.
WorkingSetID idToTest = top->id;
_mergingData.erase(top);
// Return the min.
*out = idToTest;
++_commonStats.advanced;
// But don't return it if it's flagged.
if (_ws->isFlagged(*out)) {
_ws->free(*out);
return PlanStage::NEED_TIME;
}
return PlanStage::ADVANCED;
}
PlanStage::StageState AndHashStage::work(WorkingSetID* out) {
++_commonStats.works;
if (isEOF()) { return PlanStage::IS_EOF; }
// Fast-path for one of our children being EOF immediately. We work each child a few times.
// If it hits EOF, the AND cannot output anything. If it produces a result, we stash that
// result in _lookAheadResults.
if (_lookAheadResults.empty()) {
// INVALID_ID means that the child didn't produce a valid result.
_lookAheadResults.resize(_children.size(), WorkingSet::INVALID_ID);
// Work each child some number of times until it's either EOF or produces
// a result. If it's EOF this whole stage will be EOF. If it produces a
// result we cache it for later.
for (size_t i = 0; i < _children.size(); ++i) {
PlanStage* child = _children[i];
for (size_t j = 0; j < kLookAheadWorks; ++j) {
StageState childStatus = child->work(&_lookAheadResults[i]);
if (PlanStage::IS_EOF == childStatus || PlanStage::DEAD == childStatus ||
PlanStage::FAILURE == childStatus) {
// A child went right to EOF. Bail out.
_hashingChildren = false;
_dataMap.clear();
return PlanStage::IS_EOF;
}
else if (PlanStage::ADVANCED == childStatus) {
// We have a result cached in _lookAheadResults[i]. Stop looking at this
// child.
break;
}
// We ignore NEED_TIME. TODO: What do we want to do if the child provides
// NEED_FETCH?
}
}
// We did a bunch of work above, return NEED_TIME to be fair.
return PlanStage::NEED_TIME;
}
// An AND is either reading the first child into the hash table, probing against the hash
// table with subsequent children, or checking the last child's results to see if they're
// in the hash table.
// We read the first child into our hash table.
if (_hashingChildren) {
if (0 == _currentChild) {
return readFirstChild(out);
}
else if (_currentChild < _children.size() - 1) {
return hashOtherChildren(out);
}
else {
_hashingChildren = false;
// We don't hash our last child. Instead, we probe the table created from the
// previous children, returning results in the order of the last child.
// Fall through to below.
}
}
// Returning results. We read from the last child and return the results that are in our
// hash map.
// We should be EOF if we're not hashing results and the dataMap is empty.
verify(!_dataMap.empty());
// We probe _dataMap with the last child.
verify(_currentChild == _children.size() - 1);
// Get the next result for the (_children.size() - 1)-th child.
StageState childStatus = workChild(_children.size() - 1, out);
if (PlanStage::ADVANCED != childStatus) {
return childStatus;
}
// We know that we've ADVANCED. See if the WSM is in our table.
WorkingSetMember* member = _ws->get(*out);
// Maybe the child had an invalidation. We intersect DiskLoc(s) so we can't do anything
// with this WSM.
if (!member->hasLoc()) {
_ws->flagForReview(*out);
return PlanStage::NEED_TIME;
}
DataMap::iterator it = _dataMap.find(member->loc);
if (_dataMap.end() == it) {
// Child's output wasn't in every previous child. Throw it out.
_ws->free(*out);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
else {
// Child's output was in every previous child. Merge any key data in
// the child's output and free the child's just-outputted WSM.
WorkingSetID hashID = it->second;
_dataMap.erase(it);
WorkingSetMember* olderMember = _ws->get(hashID);
AndCommon::mergeFrom(olderMember, *member);
_ws->free(*out);
// We should check for matching at the end so the matcher can use information in the
// indices of all our children.
if (Filter::passes(olderMember, _filter)) {
*out = hashID;
++_commonStats.advanced;
return PlanStage::ADVANCED;
}
else {
_ws->free(hashID);
++_commonStats.needTime;
return PlanStage::NEED_TIME;
}
}
}
