path: root/src/mongo/db/update/update_driver.cpp

/**
 *    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,
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 */

#include "mongo/db/update/update_driver.h"


#include "mongo/base/error_codes.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/mutable/algorithm.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/db/bson/dotted_path_support.h"
#include "mongo/db/curop_failpoint_helpers.h"
#include "mongo/db/field_ref.h"
#include "mongo/db/matcher/expression_leaf.h"
#include "mongo/db/matcher/extensions_callback_noop.h"
#include "mongo/db/server_options.h"
#include "mongo/db/update/delta_executor.h"
#include "mongo/db/update/modifier_table.h"
#include "mongo/db/update/object_replace_executor.h"
#include "mongo/db/update/path_support.h"
#include "mongo/db/update/storage_validation.h"
#include "mongo/db/update/update_oplog_entry_version.h"
#include "mongo/stdx/variant.h"
#include "mongo/util/embedded_builder.h"
#include "mongo/util/str.h"
#include "mongo/util/visit_helper.h"

namespace mongo {

MONGO_FAIL_POINT_DEFINE(hangAfterPipelineUpdateFCVCheck);

using pathsupport::EqualityMatches;

namespace {
modifiertable::ModifierType validateMod(BSONElement mod) {
    auto modType = modifiertable::getType(mod.fieldName());

    uassert(
        ErrorCodes::FailedToParse,
        str::stream()
            << "Unknown modifier: " << mod.fieldName()
            << ". Expected a valid update modifier or pipeline-style update specified as an array",
        modType != modifiertable::MOD_UNKNOWN);

    uassert(ErrorCodes::FailedToParse,
            str::stream() << "Modifiers operate on fields but we found type "
                          << typeName(mod.type()) << " instead. For example: {$mod: {<field>: ...}}"
                          << " not {" << mod << "}",
            mod.type() == BSONType::Object);

    return modType;
}

// Parses 'updateExpr' and merges it into 'root'. Returns whether 'updateExpr' is positional.
bool parseUpdateExpression(
    BSONObj updateExpr,
    UpdateObjectNode* root,
    const boost::intrusive_ptr<ExpressionContext>& expCtx,
    const std::map<StringData, std::unique_ptr<ExpressionWithPlaceholder>>& arrayFilters) {
    bool positional = false;
    std::set<std::string> foundIdentifiers;
    bool foundVersionField = false;
    for (auto&& mod : updateExpr) {
        // If there is a "$v" field among the modifiers, it should have already been used by the
        // caller to determine that this is the correct parsing function.
        if (mod.fieldNameStringData() == kUpdateOplogEntryVersionFieldName) {
            uassert(
                ErrorCodes::BadValue, "Duplicate $v in oplog update document", !foundVersionField);
            foundVersionField = true;
            invariant(mod.numberLong() ==
                      static_cast<long long>(UpdateOplogEntryVersion::kUpdateNodeV1));
            continue;
        }

        auto modType = validateMod(mod);
        for (auto&& field : mod.Obj()) {
            auto statusWithPositional = UpdateObjectNode::parseAndMerge(
                root, modType, field, expCtx, arrayFilters, foundIdentifiers);
            uassertStatusOK(statusWithPositional);
            positional = positional || statusWithPositional.getValue();
        }
    }

    for (const auto& arrayFilter : arrayFilters) {
        uassert(ErrorCodes::FailedToParse,
                str::stream() << "The array filter for identifier '" << arrayFilter.first
                              << "' was not used in the update " << updateExpr,
                foundIdentifiers.find(arrayFilter.first.toString()) != foundIdentifiers.end());
    }

    return positional;
}

}  // namespace

UpdateDriver::UpdateDriver(const boost::intrusive_ptr<ExpressionContext>& expCtx)
    : _expCtx(expCtx) {}

void UpdateDriver::parse(
    const write_ops::UpdateModification& updateMod,
    const std::map<StringData, std::unique_ptr<ExpressionWithPlaceholder>>& arrayFilters,
    boost::optional<BSONObj> constants,
    const bool multi) {
    invariant(!_updateExecutor, "Multiple calls to parse() on same UpdateDriver");

    if (updateMod.type() == write_ops::UpdateModification::Type::kPipeline) {
        uassert(ErrorCodes::FailedToParse,
                "arrayFilters may not be specified for pipeline-syle updates",
                arrayFilters.empty());
        _updateExecutor =
            std::make_unique<PipelineExecutor>(_expCtx, updateMod.getUpdatePipeline(), constants);
        _updateType = UpdateType::kPipeline;
        return;
    }

    if (updateMod.type() == write_ops::UpdateModification::Type::kDelta) {
        uassert(4772603,
                "arrayFilters may not be specified for delta-syle updates",
                arrayFilters.empty());

        _updateType = UpdateType::kDelta;
        _updateExecutor = std::make_unique<DeltaExecutor>(updateMod.getDiff());
        return;
    }

    uassert(51198, "Constant values may only be specified for pipeline updates", !constants);

    // Check if the update expression is a full object replacement.
    if (isDocReplacement(updateMod)) {
        uassert(ErrorCodes::FailedToParse,
                "multi update is not supported for replacement-style update",
                !multi);

        _updateExecutor = std::make_unique<ObjectReplaceExecutor>(updateMod.getUpdateClassic());

        // Register the fact that this driver will only do full object replacements.
        _updateType = UpdateType::kReplacement;
        return;
    }

    invariant(_updateType == UpdateType::kOperator);

    // By this point we are expecting a "classic" update. This version of mongod only supports $v:
    // 1 (modifier language) and $v: 2 (delta) (older versions support $v: 0). We've already
    // checked whether this is a delta update so we check that the $v field isn't present, or has a
    // value of 1.

    auto updateExpr = updateMod.getUpdateClassic();
    BSONElement versionElement = updateExpr[kUpdateOplogEntryVersionFieldName];
    if (versionElement) {
        uassert(ErrorCodes::FailedToParse,
                "The $v update field is only recognized internally",
                _fromOplogApplication);

        // The UpdateModification should have verified that the value of $v is valid.
        invariant(versionElement.numberInt() ==
                  static_cast<int>(UpdateOplogEntryVersion::kUpdateNodeV1));
    }

    auto root = std::make_unique<UpdateObjectNode>();
    _positional = parseUpdateExpression(updateExpr, root.get(), _expCtx, arrayFilters);
    _updateExecutor = std::make_unique<UpdateTreeExecutor>(std::move(root));
}

Status UpdateDriver::populateDocumentWithQueryFields(OperationContext* opCtx,
                                                     const BSONObj& query,
                                                     const FieldRefSet& immutablePaths,
                                                     mutablebson::Document& doc) const {
    // We canonicalize the query to collapse $and/$or, and the namespace is not needed.  Also,
    // because this is for the upsert case, where we insert a new document if one was not found, the
    // $where/$text clauses do not make sense, hence empty ExtensionsCallback.
    auto qr = std::make_unique<QueryRequest>(NamespaceString(""));
    qr->setFilter(query);
    const boost::intrusive_ptr<ExpressionContext> expCtx;
    // $expr is not allowed in the query for an upsert, since it is not clear what the equality
    // extraction behavior for $expr should be.
    auto statusWithCQ =
        CanonicalQuery::canonicalize(opCtx,
                                     std::move(qr),
                                     expCtx,
                                     ExtensionsCallbackNoop(),
                                     MatchExpressionParser::kAllowAllSpecialFeatures &
                                         ~MatchExpressionParser::AllowedFeatures::kExpr);
    if (!statusWithCQ.isOK()) {
        return statusWithCQ.getStatus();
    }
    std::unique_ptr<CanonicalQuery> cq = std::move(statusWithCQ.getValue());

    return populateDocumentWithQueryFields(*cq, immutablePaths, doc);
}

Status UpdateDriver::populateDocumentWithQueryFields(const CanonicalQuery& query,
                                                     const FieldRefSet& immutablePaths,
                                                     mutablebson::Document& doc) const {
    EqualityMatches equalities;
    Status status = Status::OK();

    if (_updateType == UpdateType::kReplacement) {
        // Extract only immutable fields.
        status =
            pathsupport::extractFullEqualityMatches(*query.root(), immutablePaths, &equalities);
    } else {
        // Extract all fields from op-style update.
        status = pathsupport::extractEqualityMatches(*query.root(), &equalities);
    }

    if (!status.isOK())
        return status;

    status = pathsupport::addEqualitiesToDoc(equalities, &doc);
    return status;
}

Status UpdateDriver::update(OperationContext* opCtx,
                            StringData matchedField,
                            mutablebson::Document* doc,
                            bool validateForStorage,
                            const FieldRefSet& immutablePaths,
                            bool isInsert,
                            BSONObj* logOpRec,
                            bool* docWasModified,
                            FieldRefSetWithStorage* modifiedPaths) {
    // TODO: assert that update() is called at most once in a !_multi case.

    _affectIndices = _updateType == UpdateType::kReplacement && _indexedFields != nullptr;

    _logDoc.reset();

    UpdateExecutor::ApplyParams applyParams(doc->root(), immutablePaths);
    applyParams.matchedField = matchedField;
    applyParams.insert = isInsert;
    applyParams.fromOplogApplication = _fromOplogApplication;
    applyParams.validateForStorage = validateForStorage;
    applyParams.indexData = _indexedFields;
    applyParams.modifiedPaths = modifiedPaths;
    // The supplied 'modifiedPaths' must be an empty set.
    invariant(!modifiedPaths || modifiedPaths->empty());

    if (_logOp && logOpRec) {
        const auto& fcvState = serverGlobalParams.featureCompatibility;

        // Updates may be run as part of the startup sequence, before the global FCV state has been
        // initialized. We conservatively do not permit the use of $v:2 oplog entries in these
        // situations.

        // TODO SERVER-51075: Remove FCV check for $v:2 delta oplog entries.
        const bool fcvAllowsV2Entries = fcvState.isVersionInitialized() &&
            fcvState.isGreaterThanOrEqualTo(
                ServerGlobalParams::FeatureCompatibility::Version::kVersion47);

        applyParams.logMode = fcvAllowsV2Entries && internalQueryEnableLoggingV2OplogEntries.load()
            ? ApplyParams::LogMode::kGenerateOplogEntry
            : ApplyParams::LogMode::kGenerateOnlyV1OplogEntry;

        if (MONGO_unlikely(hangAfterPipelineUpdateFCVCheck.shouldFail()) &&
            type() == UpdateType::kPipeline) {
            CurOpFailpointHelpers::waitWhileFailPointEnabled(
                &hangAfterPipelineUpdateFCVCheck, opCtx, "hangAfterPipelineUpdateFCVCheck");
        }
    }

    invariant(_updateExecutor);
    auto applyResult = _updateExecutor->applyUpdate(applyParams);
    if (applyResult.indexesAffected) {
        _affectIndices = true;
        doc->disableInPlaceUpdates();
    }
    if (docWasModified) {
        *docWasModified = !applyResult.noop;
    }

    if (_logOp && logOpRec && !applyResult.noop) {
        *logOpRec = applyResult.oplogEntry;
    }

    return Status::OK();
}

void UpdateDriver::setCollator(const CollatorInterface* collator) {
    if (_updateExecutor) {
        _updateExecutor->setCollator(collator);
    }
}

bool UpdateDriver::isDocReplacement(const write_ops::UpdateModification& updateMod) {
    return (updateMod.type() == write_ops::UpdateModification::Type::kClassic &&
            *updateMod.getUpdateClassic().firstElementFieldName() != '$') ||
        updateMod.type() == write_ops::UpdateModification::Type::kPipeline;
}

}  // namespace mongo