path: root/src/mongo/idl/cluster_server_parameter_op_observer.cpp

/**
 *    Copyright (C) 2022-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/idl/cluster_server_parameter_op_observer.h"

#include <memory>

#include "mongo/db/dbdirectclient.h"
#include "mongo/logv2/log.h"

#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kControl


namespace mongo {

namespace {
constexpr auto kIdField = "_id"_sd;
constexpr auto kCPTField = "clusterParameterTime"_sd;

/**
 * Per-operation scratch space indicating the document being deleted.
 * This is used in the aboutToDelte/onDelete handlers since the document
 * is not necessarily available in the latter.
 */
const auto aboutToDeleteDoc = OperationContext::declareDecoration<std::string>();

bool isConfigNamespace(const NamespaceString& nss) {
    return nss == NamespaceString::kClusterParametersNamespace;
}

constexpr auto kOplog = "oplog"_sd;
void updateParameter(BSONObj doc, StringData mode) {
    auto nameElem = doc[kIdField];
    if (nameElem.type() != String) {
        LOGV2_DEBUG(6226301,
                    1,
                    "Update with invalid cluster server parameter name",
                    "mode"_attr = mode,
                    "_id"_attr = nameElem);
        return;
    }

    auto name = doc[kIdField].valueStringData();
    auto* sp = ServerParameterSet::getClusterParameterSet()->getIfExists(name);
    if (!sp) {
        LOGV2_DEBUG(6226300,
                    3,
                    "Update to unknown cluster server parameter",
                    "mode"_attr = mode,
                    "name"_attr = name);
        return;
    }

    auto cptElem = doc[kCPTField];
    if ((cptElem.type() != mongo::Date) && (cptElem.type() != bsonTimestamp)) {
        LOGV2_DEBUG(6226302,
                    1,
                    "Update to cluster server parameter has invalid clusterParameterTime",
                    "mode"_attr = mode,
                    "name"_attr = name,
                    "clusterParameterTime"_attr = cptElem);
        return;
    }

    uassertStatusOK(sp->set(doc));
}

void clearParameter(ServerParameter* sp) {
    if (sp->getClusterParameterTime() == LogicalTime::kUninitialized) {
        // Nothing to clear.
        return;
    }

    uassertStatusOK(sp->reset());
}

void clearParameter(StringData id) {
    auto* sp = ServerParameterSet::getClusterParameterSet()->getIfExists(id);
    if (!sp) {
        LOGV2_DEBUG(6226303,
                    5,
                    "oplog event deletion of unknown cluster server parameter",
                    "name"_attr = id);
        return;
    }

    clearParameter(sp);
}

void clearAllParameters() {
    const auto& params = ServerParameterSet::getClusterParameterSet()->getMap();
    for (const auto& it : params) {
        clearParameter(it.second);
    }
}

template <typename OnEntry>
void doLoadAllParametersFromDisk(OperationContext* opCtx, StringData mode, OnEntry onEntry) try {
    std::vector<Status> failures;

    DBDirectClient client(opCtx);
    FindCommandRequest findRequest{NamespaceString::kClusterParametersNamespace};
    client.find(std::move(findRequest), ReadPreferenceSetting{}, [&](BSONObj doc) {
        try {
            onEntry(doc, mode);
        } catch (const DBException& ex) {
            failures.push_back(ex.toStatus());
        }
    });
    if (!failures.empty()) {
        StringBuilder msg;
        for (const auto& failure : failures) {
            msg << failure.toString() << ", ";
        }
        msg.reset(msg.len() - 2);
        uasserted(ErrorCodes::OperationFailed, msg.str());
    }
} catch (const DBException& ex) {
    uassertStatusOK(ex.toStatus().withContext(
        str::stream() << "Failed " << mode << " cluster server parameters from disk"));
}

/**
 * Used on rollback and rename with drop.
 * Updates settings which are present and clears settings which are not.
 */
void resynchronizeAllParametersFromDisk(OperationContext* opCtx) {
    const auto& allParams = ServerParameterSet::getClusterParameterSet()->getMap();
    std::set<std::string> unsetSettings;
    for (const auto& it : allParams) {
        unsetSettings.insert(it.second->name());
    }

    doLoadAllParametersFromDisk(
        opCtx, "resynchronizing"_sd, [&unsetSettings](BSONObj doc, StringData mode) {
            unsetSettings.erase(doc[kIdField].str());
            updateParameter(doc, mode);
        });

    // For all known settings which were not present in this resync,
    // explicitly clear any value which may be present in-memory.
    for (const auto& setting : unsetSettings) {
        clearParameter(setting);
    }
}
}  // namespace

void ClusterServerParameterOpObserver::initializeAllParametersFromDisk(OperationContext* opCtx) {
    doLoadAllParametersFromDisk(opCtx, "initializing"_sd, updateParameter);
}

void ClusterServerParameterOpObserver::onInserts(OperationContext* opCtx,
                                                 const NamespaceString& nss,
                                                 const UUID& uuid,
                                                 std::vector<InsertStatement>::const_iterator first,
                                                 std::vector<InsertStatement>::const_iterator last,
                                                 bool fromMigrate) {
    if (!isConfigNamespace(nss)) {
        return;
    }

    for (auto it = first; it != last; ++it) {
        updateParameter(it->doc, kOplog);
    }
}

void ClusterServerParameterOpObserver::onUpdate(OperationContext* opCtx,
                                                const OplogUpdateEntryArgs& args) {
    auto updatedDoc = args.updateArgs->updatedDoc;
    if (!isConfigNamespace(args.nss) || args.updateArgs->update.isEmpty()) {
        return;
    }

    updateParameter(updatedDoc, kOplog);
}

void ClusterServerParameterOpObserver::aboutToDelete(OperationContext* opCtx,
                                                     const NamespaceString& nss,
                                                     const UUID& uuid,
                                                     const BSONObj& doc) {
    std::string docBeingDeleted;

    if (isConfigNamespace(nss)) {
        auto elem = doc[kIdField];
        if (elem.type() == String) {
            docBeingDeleted = elem.str();
        } else {
            // This delete makes no sense,
            // but it's safe to ignore since the insert/update
            // would not have resulted in an in-memory update anyway.
            LOGV2_DEBUG(6226304,
                        3,
                        "Deleting a cluster-wide server parameter with non-string name",
                        "name"_attr = elem);
        }
    }

    // Stash the name of the config doc being deleted (if any)
    // in an opCtx decoration for use in the onDelete() hook below
    // since OpLogDeleteEntryArgs isn't guaranteed to have the deleted doc.
    aboutToDeleteDoc(opCtx) = std::move(docBeingDeleted);
}

void ClusterServerParameterOpObserver::onDelete(OperationContext* opCtx,
                                                const NamespaceString& nss,
                                                const UUID& uuid,
                                                StmtId stmtId,
                                                const OplogDeleteEntryArgs& args) {
    const auto& docName = aboutToDeleteDoc(opCtx);
    if (!docName.empty()) {
        clearParameter(docName);
    }
}

void ClusterServerParameterOpObserver::onDropDatabase(OperationContext* opCtx,
                                                      const std::string& dbName) {
    if (dbName == NamespaceString::kConfigDb) {
        // Entire config DB deleted, reset to default state.
        clearAllParameters();
    }
}

repl::OpTime ClusterServerParameterOpObserver::onDropCollection(
    OperationContext* opCtx,
    const NamespaceString& collectionName,
    const UUID& uuid,
    std::uint64_t numRecords,
    CollectionDropType dropType) {
    if (isConfigNamespace(collectionName)) {
        // Entire collection deleted, reset to default state.
        clearAllParameters();
    }

    return {};
}

void ClusterServerParameterOpObserver::postRenameCollection(
    OperationContext* opCtx,
    const NamespaceString& fromCollection,
    const NamespaceString& toCollection,
    const UUID& uuid,
    const boost::optional<UUID>& dropTargetUUID,
    bool stayTemp) {
    if (isConfigNamespace(fromCollection)) {
        // Same as collection dropped from a config point of view.
        clearAllParameters();
    }

    if (isConfigNamespace(toCollection)) {
        // Potentially many documents now set, perform full scan.
        if (dropTargetUUID) {
            // Possibly lost configurations in overwrite.
            resynchronizeAllParametersFromDisk(opCtx);
        } else {
            // Collection did not exist prior to rename.
            initializeAllParametersFromDisk(opCtx);
        }
    }
}

void ClusterServerParameterOpObserver::onImportCollection(OperationContext* opCtx,
                                                          const UUID& importUUID,
                                                          const NamespaceString& nss,
                                                          long long numRecords,
                                                          long long dataSize,
                                                          const BSONObj& catalogEntry,
                                                          const BSONObj& storageMetadata,
                                                          bool isDryRun) {
    if (!isDryRun && (numRecords > 0) && isConfigNamespace(nss)) {
        // Something was imported, do a full collection scan to sync up.
        // No need to apply rollback rules since nothing will have been deleted.
        initializeAllParametersFromDisk(opCtx);
    }
}

void ClusterServerParameterOpObserver::_onReplicationRollback(OperationContext* opCtx,
                                                              const RollbackObserverInfo& rbInfo) {
    if (rbInfo.rollbackNamespaces.count(NamespaceString::kClusterParametersNamespace)) {
        // Some kind of rollback happend in the settings collection.
        // Just reload from disk to be safe.
        resynchronizeAllParametersFromDisk(opCtx);
    }
}

}  // namespace mongo