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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/platform/basic.h"
#include "mongo/db/query/wildcard_multikey_paths.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/index/wildcard_access_method.h"
#include "mongo/db/query/index_bounds_builder.h"
#include "mongo/db/record_id_helpers.h"
namespace mongo {
/**
* Extracts the multikey path from a metadata key stored within a wildcard index.
*/
static FieldRef extractMultikeyPathFromIndexKey(const IndexKeyEntry& entry) {
invariant(record_id_helpers::isReserved(entry.loc));
invariant(
!entry.loc.isLong() ||
entry.loc ==
record_id_helpers::reservedIdFor(
record_id_helpers::ReservationId::kWildcardMultikeyMetadataId, KeyFormat::Long));
invariant(
!entry.loc.isStr() ||
entry.loc ==
record_id_helpers::reservedIdFor(
record_id_helpers::ReservationId::kWildcardMultikeyMetadataId, KeyFormat::String));
// Validate that the first piece of the key is the integer 1.
BSONObjIterator iter(entry.key);
invariant(iter.more());
const auto firstElem = iter.next();
invariant(firstElem.isNumber());
invariant(firstElem.numberInt() == 1);
invariant(iter.more());
// Extract the path from the second piece of the key.
const auto secondElem = iter.next();
invariant(!iter.more());
invariant(secondElem.type() == BSONType::String);
return FieldRef(secondElem.valueStringData());
}
/**
* Retrieves from the wildcard index the set of multikey path metadata keys bounded by
* 'indexBounds'. Returns the set of multikey paths represented by the keys.
*/
static std::set<FieldRef> getWildcardMultikeyPathSetHelper(const WildcardAccessMethod* wam,
OperationContext* opCtx,
const IndexBounds& indexBounds,
MultikeyMetadataAccessStats* stats) {
return writeConflictRetry(
opCtx, "wildcard multikey path retrieval", "", [&]() -> std::set<FieldRef> {
stats->numSeeks = 0;
stats->keysExamined = 0;
auto cursor = wam->newCursor(opCtx);
constexpr int kForward = 1;
const auto keyPattern = BSON("" << 1 << "" << 1);
IndexBoundsChecker checker(&indexBounds, keyPattern, kForward);
IndexSeekPoint seekPoint;
if (!checker.getStartSeekPoint(&seekPoint)) {
return {};
}
std::set<FieldRef> multikeyPaths{};
auto entry = cursor->seek(IndexEntryComparison::makeKeyStringFromSeekPointForSeek(
seekPoint,
wam->getSortedDataInterface()->getKeyStringVersion(),
wam->getSortedDataInterface()->getOrdering(),
kForward));
++stats->numSeeks;
while (entry) {
++stats->keysExamined;
switch (checker.checkKey(entry->key, &seekPoint)) {
case IndexBoundsChecker::VALID:
multikeyPaths.emplace(extractMultikeyPathFromIndexKey(*entry));
entry = cursor->next();
break;
case IndexBoundsChecker::MUST_ADVANCE:
++stats->numSeeks;
entry =
cursor->seek(IndexEntryComparison::makeKeyStringFromSeekPointForSeek(
seekPoint,
wam->getSortedDataInterface()->getKeyStringVersion(),
wam->getSortedDataInterface()->getOrdering(),
kForward));
break;
case IndexBoundsChecker::DONE:
entry = boost::none;
break;
default:
MONGO_UNREACHABLE;
}
}
return multikeyPaths;
});
}
std::vector<Interval> getMultikeyPathIndexIntervalsForField(FieldRef field) {
std::vector<Interval> intervals;
size_t pointIntervalPrefixParts = field.numParts();
const size_t skipFirstFieldElement = 1;
const auto numericPathComponents = field.getNumericPathComponents(skipFirstFieldElement);
const auto hasNumericPathComponent = !numericPathComponents.empty();
if (hasNumericPathComponent) {
pointIntervalPrefixParts = *numericPathComponents.begin();
invariant(pointIntervalPrefixParts > 0);
}
constexpr bool inclusive = true;
constexpr bool exclusive = false;
// Add a point interval for each path up to the first numeric path component. Field "a.b.c"
// would produce point intervals ["a", "a"], ["a.b", "a.b"] and ["a.b.c", "a.b.c"]. Field
// "a.b.0.c" would produce point intervals ["a", "a"] and ["a.b", "a.b"].
for (size_t i = 1; i <= pointIntervalPrefixParts; ++i) {
auto multikeyPath = field.dottedSubstring(0, i);
intervals.push_back(IndexBoundsBuilder::makePointInterval(multikeyPath));
}
// If "field" contains a numeric path component then we add a range covering all subfields
// of the non-numeric prefix.
if (hasNumericPathComponent) {
auto rangeBase = field.dottedSubstring(0, pointIntervalPrefixParts);
StringBuilder multikeyPathStart;
multikeyPathStart << rangeBase << ".";
StringBuilder multikeyPathEnd;
multikeyPathEnd << rangeBase << static_cast<char>('.' + 1);
intervals.emplace_back(BSON("" << multikeyPathStart.str() << "" << multikeyPathEnd.str()),
inclusive,
exclusive);
}
return intervals;
}
std::set<FieldRef> getWildcardMultikeyPathSet(const WildcardAccessMethod* wam,
OperationContext* opCtx,
const stdx::unordered_set<std::string>& fieldSet,
MultikeyMetadataAccessStats* stats) {
invariant(stats);
IndexBounds indexBounds;
// Multikey metadata keys are stored with the number "1" in the first position of the index to
// differentiate them from user-data keys, which contain a string representing the path.
OrderedIntervalList multikeyPathFlagOil;
multikeyPathFlagOil.intervals.push_back(IndexBoundsBuilder::makePointInterval(BSON("" << 1)));
indexBounds.fields.push_back(std::move(multikeyPathFlagOil));
OrderedIntervalList fieldNameOil;
for (const auto& field : fieldSet) {
auto intervals = getMultikeyPathIndexIntervalsForField(FieldRef(field));
fieldNameOil.intervals.insert(fieldNameOil.intervals.end(),
std::make_move_iterator(intervals.begin()),
std::make_move_iterator(intervals.end()));
}
// IndexBoundsBuilder::unionize() sorts the OrderedIntervalList allowing for in order index
// traversal.
IndexBoundsBuilder::unionize(&fieldNameOil);
indexBounds.fields.push_back(std::move(fieldNameOil));
return getWildcardMultikeyPathSetHelper(wam, opCtx, indexBounds, stats);
}
std::set<FieldRef> getWildcardMultikeyPathSet(const WildcardAccessMethod* wam,
OperationContext* opCtx,
MultikeyMetadataAccessStats* stats) {
return writeConflictRetry(opCtx, "wildcard multikey path retrieval", "", [&]() {
invariant(stats);
stats->numSeeks = 0;
stats->keysExamined = 0;
auto cursor = wam->newCursor(opCtx);
// All of the keys storing multikeyness metadata are prefixed by a value of 1. Establish
// an index cursor which will scan this range.
const BSONObj metadataKeyRangeBegin = BSON("" << 1 << "" << MINKEY);
const BSONObj metadataKeyRangeEnd = BSON("" << 1 << "" << MAXKEY);
constexpr bool inclusive = true;
cursor->setEndPosition(metadataKeyRangeEnd, inclusive);
auto keyStringForSeek = IndexEntryComparison::makeKeyStringFromBSONKeyForSeek(
metadataKeyRangeBegin,
wam->getSortedDataInterface()->getKeyStringVersion(),
wam->getSortedDataInterface()->getOrdering(),
true, /* forward */
inclusive);
auto entry = cursor->seek(keyStringForSeek);
++stats->numSeeks;
// Iterate the cursor, copying the multikey paths into an in-memory set.
std::set<FieldRef> multikeyPaths{};
while (entry) {
++stats->keysExamined;
multikeyPaths.emplace(extractMultikeyPathFromIndexKey(*entry));
entry = cursor->next();
}
return multikeyPaths;
});
}
} // namespace mongo
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