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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/exec/working_set.h"
#include "mongo/db/bson/dotted_path_support.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/service_context.h"
namespace mongo {
using std::string;
namespace dps = ::mongo::dotted_path_support;
WorkingSet::WorkingSet() : _freeList(INVALID_ID) {}
WorkingSetID WorkingSet::allocate() {
if (_freeList == INVALID_ID) {
// The free list is empty so we need to make a single new WSM to return. This relies on
// vector::resize being amortized O(1) for efficient allocation. Note that the free list
// remains empty until something is returned by a call to free().
WorkingSetID id = _data.size();
_data.resize(_data.size() + 1);
_data.back().nextFreeOrSelf = id;
return id;
}
// Pop the head off the free list and return it.
WorkingSetID id = _freeList;
_freeList = _data[id].nextFreeOrSelf;
_data[id].nextFreeOrSelf = id; // set to self to mark as in-use
return id;
}
void WorkingSet::free(WorkingSetID i) {
MemberHolder& holder = _data[i];
verify(i < _data.size()); // ID has been allocated.
verify(holder.nextFreeOrSelf == i); // ID currently in use.
// Free resources and push this WSM to the head of the freelist.
holder.member.clear();
holder.nextFreeOrSelf = _freeList;
_freeList = i;
}
void WorkingSet::clear() {
_data.clear();
// Since working set is now empty, the free list pointer should
// point to nothing.
_freeList = INVALID_ID;
}
void WorkingSet::transitionToRecordIdAndIdx(WorkingSetID id) {
WorkingSetMember* member = get(id);
member->_state = WorkingSetMember::RID_AND_IDX;
}
void WorkingSet::transitionToRecordIdAndObj(WorkingSetID id) {
WorkingSetMember* member = get(id);
member->transitionToRecordIdAndObj();
}
void WorkingSet::transitionToOwnedObj(WorkingSetID id) {
WorkingSetMember* member = get(id);
member->transitionToOwnedObj();
}
WorkingSetMember WorkingSet::extract(WorkingSetID wsid) {
invariant(wsid < _data.size());
WorkingSetMember ret = std::move(_data[wsid].member);
free(wsid);
return ret;
}
WorkingSetID WorkingSet::emplace(WorkingSetMember&& wsm) {
auto wsid = allocate();
*get(wsid) = std::move(wsm);
return wsid;
}
//
// WorkingSetMember
//
void WorkingSetMember::clear() {
_metadata = DocumentMetadataFields{};
keyData.clear();
if (doc.value().hasExclusivelyOwnedStorage()) {
// Reset the document to point to an empty BSON, which will preserve its underlying
// DocumentStorage for future users of this WSM.
resetDocument(SnapshotId(), BSONObj());
} else {
// If the Document doesn't exclusively own its storage, don't do anything. Attempting to
// assign it a value (even an empty one) would result in an allocation, which we don't want
// here, since this function is very much on the hot path.
}
_state = WorkingSetMember::INVALID;
}
WorkingSetMember::MemberState WorkingSetMember::getState() const {
return _state;
}
void WorkingSetMember::transitionToOwnedObj() {
invariant(doc.value().isOwned());
_state = OWNED_OBJ;
}
void WorkingSetMember::transitionToRecordIdAndObj() {
_state = WorkingSetMember::RID_AND_OBJ;
}
bool WorkingSetMember::hasRecordId() const {
return _state == RID_AND_IDX || _state == RID_AND_OBJ;
}
bool WorkingSetMember::hasObj() const {
return _state == OWNED_OBJ || _state == RID_AND_OBJ;
}
bool WorkingSetMember::hasOwnedObj() const {
return _state == OWNED_OBJ || _state == RID_AND_OBJ;
}
void WorkingSetMember::makeObjOwnedIfNeeded() {
if (_state == RID_AND_OBJ && !doc.value().isOwned()) {
doc.value() = doc.value().getOwned();
}
}
bool WorkingSetMember::getFieldDotted(const string& field, BSONElement* out) const {
// If our state is such that we have an object, use it.
if (hasObj()) {
// The document must not be modified. Otherwise toBson() call would create a temporary BSON
// that would get destroyed at the end of this function. *out would then point to dangling
// memory.
invariant(!doc.value().isModified());
*out = dps::extractElementAtPath(doc.value().toBson(), field);
return true;
}
// Our state should be such that we have index data/are covered.
if (auto outOpt = IndexKeyDatum::getFieldDotted(keyData, field)) {
*out = outOpt.get();
return true;
} else {
return false;
}
}
size_t WorkingSetMember::getMemUsage() const {
size_t memUsage = 0;
if (hasRecordId()) {
memUsage += sizeof(RecordId);
}
if (hasObj()) {
memUsage += doc.value().getApproximateSize();
}
for (size_t i = 0; i < keyData.size(); ++i) {
const IndexKeyDatum& keyDatum = keyData[i];
memUsage += keyDatum.keyData.objsize();
}
return memUsage;
}
void WorkingSetMember::resetDocument(SnapshotId snapshot, const BSONObj& obj) {
doc.setSnapshotId(snapshot);
MutableDocument md(std::move(doc.value()));
md.reset(obj, false);
doc.value() = md.freeze();
}
void WorkingSetMember::serialize(BufBuilder& buf) const {
// It is not legal to serialize a Document which has metadata attached to it. Any metadata must
// reside directly in the WorkingSetMember.
invariant(!doc.value().metadata());
buf.appendChar(static_cast<char>(_state));
if (hasObj()) {
doc.value().serializeForSorter(buf);
buf.appendNum(static_cast<unsigned long long>(doc.snapshotId().toNumber()));
}
if (_state == RID_AND_IDX) {
// First append the number of index keys, and then encode them in series.
buf.appendNum(static_cast<char>(keyData.size()));
for (auto&& indexKeyDatum : keyData) {
indexKeyDatum.indexKeyPattern.serializeForSorter(buf);
indexKeyDatum.keyData.serializeForSorter(buf);
buf.appendNum(indexKeyDatum.indexId);
buf.appendNum(static_cast<unsigned long long>(indexKeyDatum.snapshotId.toNumber()));
}
}
if (hasRecordId()) {
buf.appendNum(recordId.repr());
}
_metadata.serializeForSorter(buf);
}
WorkingSetMember WorkingSetMember::deserialize(BufReader& buf) {
WorkingSetMember wsm;
// First decode the state, which instructs us on how to interpret the rest of the buffer.
wsm._state = static_cast<MemberState>(buf.read<char>());
if (wsm.hasObj()) {
wsm.doc.setValue(
Document::deserializeForSorter(buf, Document::SorterDeserializeSettings{}));
auto snapshotIdRepr = buf.read<LittleEndian<uint64_t>>();
auto snapshotId = snapshotIdRepr ? SnapshotId{snapshotIdRepr} : SnapshotId{};
wsm.doc.setSnapshotId(snapshotId);
}
if (wsm.getState() == WorkingSetMember::RID_AND_IDX) {
auto numKeys = buf.read<char>();
wsm.keyData.reserve(numKeys);
for (auto i = 0; i < numKeys; ++i) {
auto indexKeyPattern =
BSONObj::deserializeForSorter(buf, BSONObj::SorterDeserializeSettings{}).getOwned();
auto indexKey =
BSONObj::deserializeForSorter(buf, BSONObj::SorterDeserializeSettings{}).getOwned();
auto indexId = buf.read<LittleEndian<unsigned int>>();
auto snapshotIdRepr = buf.read<LittleEndian<uint64_t>>();
auto snapshotId = snapshotIdRepr ? SnapshotId{snapshotIdRepr} : SnapshotId{};
wsm.keyData.push_back(IndexKeyDatum{
std::move(indexKeyPattern), std::move(indexKey), indexId, snapshotId});
}
}
if (wsm.hasRecordId()) {
wsm.recordId = RecordId{buf.read<LittleEndian<int64_t>>()};
}
DocumentMetadataFields::deserializeForSorter(buf, &wsm._metadata);
return wsm;
}
SortableWorkingSetMember SortableWorkingSetMember::getOwned() const {
auto ret = *this;
ret._holder->makeObjOwnedIfNeeded();
return ret;
}
WorkingSetRegisteredIndexId WorkingSet::registerIndexAccessMethod(
const IndexAccessMethod* indexAccess) {
for (WorkingSetRegisteredIndexId i = 0; i < _registeredIndexes.size(); ++i) {
if (_registeredIndexes[i] == indexAccess) {
return i;
}
}
_registeredIndexes.push_back(indexAccess);
return _registeredIndexes.size() - 1;
}
} // namespace mongo
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