diff options
Diffstat (limited to 'src/mongo/rpc/metadata/server_selection_metadata.cpp')
| -rw-r--r-- | src/mongo/rpc/metadata/server_selection_metadata.cpp | 378 |
1 files changed, 177 insertions, 201 deletions
diff --git a/src/mongo/rpc/metadata/server_selection_metadata.cpp b/src/mongo/rpc/metadata/server_selection_metadata.cpp index 4222c88e895..1441243a4e7 100644 --- a/src/mongo/rpc/metadata/server_selection_metadata.cpp +++ b/src/mongo/rpc/metadata/server_selection_metadata.cpp @@ -45,244 +45,220 @@ namespace rpc { namespace { - const char kSecondaryOkFieldName[] = "$secondaryOk"; - const char kReadPreferenceFieldName[] = "$readPreference"; - - const char kQueryOptionsFieldName[] = "$queryOptions"; - - const char kDollarQueryWrapper[] = "$query"; - const char kQueryWrapper[] = "query"; - - /** - * Utility to unwrap a '$query' or 'query' wrapped command object. The first element of the - * return value indicates whether the command was unwrapped, and the second element is either - * the unwrapped command (if it was wrapped), or the original command if it was not. - */ - std::tuple<bool, BSONObj> unwrapCommand(const BSONObj& maybeWrapped) { - const auto firstElFieldName = maybeWrapped.firstElementFieldName(); - if ((firstElFieldName == StringData(kDollarQueryWrapper)) || - (firstElFieldName == StringData(kQueryWrapper))) { - // TODO: do we need getOwned here? - return std::make_tuple(true, maybeWrapped.firstElement().embeddedObject()); - } - return std::make_tuple(false, maybeWrapped); - } +const char kSecondaryOkFieldName[] = "$secondaryOk"; +const char kReadPreferenceFieldName[] = "$readPreference"; - /** - * Reads a top-level $readPreference field from a wrapped command. - */ - Status extractWrappedReadPreference(const BSONObj& wrappedCommand, - BSONObjBuilder* metadataBob) { - BSONElement readPrefEl; - auto rpExtractStatus = bsonExtractTypedField(wrappedCommand, - kReadPreferenceFieldName, - mongo::Object, - &readPrefEl); - if (rpExtractStatus.isOK()) { - metadataBob->append(readPrefEl); - } - else if (rpExtractStatus != ErrorCodes::NoSuchKey) { - return rpExtractStatus; - } +const char kQueryOptionsFieldName[] = "$queryOptions"; - return Status::OK(); - } +const char kDollarQueryWrapper[] = "$query"; +const char kQueryWrapper[] = "query"; - /** - * Reads a $readPreference from a $queryOptions subobject, if it exists, and writes it to - * metadataBob. Writes out the original command excluding the $queryOptions subobject. - */ - Status extractUnwrappedReadPreference(const BSONObj& unwrappedCommand, - BSONObjBuilder* commandBob, - BSONObjBuilder* metadataBob) { - BSONElement queryOptionsEl; - BSONElement readPrefEl; - - auto queryOptionsExtractStatus = bsonExtractTypedField(unwrappedCommand, - kQueryOptionsFieldName, - mongo::Object, - &queryOptionsEl); - - // If there is no queryOptions subobject, we write out the command and return. - if (queryOptionsExtractStatus == ErrorCodes::NoSuchKey) { - commandBob->appendElements(unwrappedCommand); - return Status::OK(); - } - else if (!queryOptionsExtractStatus.isOK()) { - return queryOptionsExtractStatus; - } - - // Write out the command excluding the $queryOptions field. - for (const auto& elem : unwrappedCommand) { - if (elem.fieldNameStringData() != kQueryOptionsFieldName) { - commandBob->append(elem); - } - } +/** + * Utility to unwrap a '$query' or 'query' wrapped command object. The first element of the + * return value indicates whether the command was unwrapped, and the second element is either + * the unwrapped command (if it was wrapped), or the original command if it was not. + */ +std::tuple<bool, BSONObj> unwrapCommand(const BSONObj& maybeWrapped) { + const auto firstElFieldName = maybeWrapped.firstElementFieldName(); + if ((firstElFieldName == StringData(kDollarQueryWrapper)) || + (firstElFieldName == StringData(kQueryWrapper))) { + // TODO: do we need getOwned here? + return std::make_tuple(true, maybeWrapped.firstElement().embeddedObject()); + } + return std::make_tuple(false, maybeWrapped); +} - auto rpExtractStatus = bsonExtractTypedField(queryOptionsEl.embeddedObject(), - kReadPreferenceFieldName, - mongo::Object, - &readPrefEl); +/** + * Reads a top-level $readPreference field from a wrapped command. + */ +Status extractWrappedReadPreference(const BSONObj& wrappedCommand, BSONObjBuilder* metadataBob) { + BSONElement readPrefEl; + auto rpExtractStatus = + bsonExtractTypedField(wrappedCommand, kReadPreferenceFieldName, mongo::Object, &readPrefEl); + if (rpExtractStatus.isOK()) { + metadataBob->append(readPrefEl); + } else if (rpExtractStatus != ErrorCodes::NoSuchKey) { + return rpExtractStatus; + } - // If there is a $queryOptions field, we expect there to be a $readPreference. - if (!rpExtractStatus.isOK()) { - return rpExtractStatus; - } + return Status::OK(); +} - metadataBob->append(readPrefEl); +/** + * Reads a $readPreference from a $queryOptions subobject, if it exists, and writes it to + * metadataBob. Writes out the original command excluding the $queryOptions subobject. + */ +Status extractUnwrappedReadPreference(const BSONObj& unwrappedCommand, + BSONObjBuilder* commandBob, + BSONObjBuilder* metadataBob) { + BSONElement queryOptionsEl; + BSONElement readPrefEl; + + auto queryOptionsExtractStatus = bsonExtractTypedField( + unwrappedCommand, kQueryOptionsFieldName, mongo::Object, &queryOptionsEl); + + // If there is no queryOptions subobject, we write out the command and return. + if (queryOptionsExtractStatus == ErrorCodes::NoSuchKey) { + commandBob->appendElements(unwrappedCommand); return Status::OK(); + } else if (!queryOptionsExtractStatus.isOK()) { + return queryOptionsExtractStatus; } -} // namespace - - const OperationContext::Decoration<ServerSelectionMetadata> ServerSelectionMetadata::get = - OperationContext::declareDecoration<ServerSelectionMetadata>(); + // Write out the command excluding the $queryOptions field. + for (const auto& elem : unwrappedCommand) { + if (elem.fieldNameStringData() != kQueryOptionsFieldName) { + commandBob->append(elem); + } + } - ServerSelectionMetadata::ServerSelectionMetadata( - bool secondaryOk, - boost::optional<ReadPreferenceSetting> readPreference - ) - : _secondaryOk(secondaryOk) - , _readPreference(std::move(readPreference)) - {} + auto rpExtractStatus = bsonExtractTypedField( + queryOptionsEl.embeddedObject(), kReadPreferenceFieldName, mongo::Object, &readPrefEl); - StatusWith<ServerSelectionMetadata> - ServerSelectionMetadata::readFromMetadata(const BSONObj& metadata) { - auto secondaryOkField = metadata.getField(kSecondaryOkFieldName); + // If there is a $queryOptions field, we expect there to be a $readPreference. + if (!rpExtractStatus.isOK()) { + return rpExtractStatus; + } - bool secondaryOk = !secondaryOkField.eoo(); + metadataBob->append(readPrefEl); + return Status::OK(); +} - boost::optional<ReadPreferenceSetting> readPreference; - BSONElement rpElem; - auto readPrefExtractStatus = bsonExtractTypedField(metadata, - kReadPreferenceFieldName, - mongo::Object, - &rpElem); +} // namespace - if (readPrefExtractStatus == ErrorCodes::NoSuchKey) { - // Do nothing, it's valid to have no ReadPreference - } - else if (!readPrefExtractStatus.isOK()) { - return readPrefExtractStatus; - } - else { - // We have a read preference in the metadata object. - auto parsedRps = ReadPreferenceSetting::fromBSON(rpElem.Obj()); - if (!parsedRps.isOK()) { - return parsedRps.getStatus(); - } - readPreference.emplace(std::move(parsedRps.getValue())); +const OperationContext::Decoration<ServerSelectionMetadata> ServerSelectionMetadata::get = + OperationContext::declareDecoration<ServerSelectionMetadata>(); + +ServerSelectionMetadata::ServerSelectionMetadata( + bool secondaryOk, boost::optional<ReadPreferenceSetting> readPreference) + : _secondaryOk(secondaryOk), _readPreference(std::move(readPreference)) {} + +StatusWith<ServerSelectionMetadata> ServerSelectionMetadata::readFromMetadata( + const BSONObj& metadata) { + auto secondaryOkField = metadata.getField(kSecondaryOkFieldName); + + bool secondaryOk = !secondaryOkField.eoo(); + + boost::optional<ReadPreferenceSetting> readPreference; + BSONElement rpElem; + auto readPrefExtractStatus = + bsonExtractTypedField(metadata, kReadPreferenceFieldName, mongo::Object, &rpElem); + + if (readPrefExtractStatus == ErrorCodes::NoSuchKey) { + // Do nothing, it's valid to have no ReadPreference + } else if (!readPrefExtractStatus.isOK()) { + return readPrefExtractStatus; + } else { + // We have a read preference in the metadata object. + auto parsedRps = ReadPreferenceSetting::fromBSON(rpElem.Obj()); + if (!parsedRps.isOK()) { + return parsedRps.getStatus(); } - - return ServerSelectionMetadata(secondaryOk, std::move(readPreference)); + readPreference.emplace(std::move(parsedRps.getValue())); } - Status ServerSelectionMetadata::writeToMetadata(BSONObjBuilder* metadataBob) const { - if (isSecondaryOk()) { - metadataBob->append(kSecondaryOkFieldName, 1); - } - - if (getReadPreference()) { - metadataBob->append(kReadPreferenceFieldName, getReadPreference()->toBSON()); - } + return ServerSelectionMetadata(secondaryOk, std::move(readPreference)); +} - return Status::OK(); +Status ServerSelectionMetadata::writeToMetadata(BSONObjBuilder* metadataBob) const { + if (isSecondaryOk()) { + metadataBob->append(kSecondaryOkFieldName, 1); } - Status ServerSelectionMetadata::downconvert(const BSONObj& command, - const BSONObj& metadata, - BSONObjBuilder* legacyCommand, - int* legacyQueryFlags) { + if (getReadPreference()) { + metadataBob->append(kReadPreferenceFieldName, getReadPreference()->toBSON()); + } - BSONElement secondaryOkElem = metadata.getField(kSecondaryOkFieldName); - BSONElement readPrefElem = metadata.getField(kReadPreferenceFieldName); + return Status::OK(); +} - if (!secondaryOkElem.eoo()) { - *legacyQueryFlags |= mongo::QueryOption_SlaveOk; - } - else { - *legacyQueryFlags &= ~mongo::QueryOption_SlaveOk; - } +Status ServerSelectionMetadata::downconvert(const BSONObj& command, + const BSONObj& metadata, + BSONObjBuilder* legacyCommand, + int* legacyQueryFlags) { + BSONElement secondaryOkElem = metadata.getField(kSecondaryOkFieldName); + BSONElement readPrefElem = metadata.getField(kReadPreferenceFieldName); - if (!readPrefElem.eoo()) { - // Use 'query' to wrap query, then append read preference. + if (!secondaryOkElem.eoo()) { + *legacyQueryFlags |= mongo::QueryOption_SlaveOk; + } else { + *legacyQueryFlags &= ~mongo::QueryOption_SlaveOk; + } - // NOTE(amidvidy): Oddly, the _isSecondaryQuery implementation in dbclient_rs does - // not unwrap the query properly - it only checks for 'query', and not - // '$query'. We should probably standardize on one - drivers use '$query', - // and the shell uses 'query'. See SERVER-18705 for details. + if (!readPrefElem.eoo()) { + // Use 'query' to wrap query, then append read preference. - // TODO: this may need to use the $queryOptions hack on mongos. - legacyCommand->append(kQueryWrapper, command); - legacyCommand->append(readPrefElem); - } - else { - legacyCommand->appendElements(command); - } + // NOTE(amidvidy): Oddly, the _isSecondaryQuery implementation in dbclient_rs does + // not unwrap the query properly - it only checks for 'query', and not + // '$query'. We should probably standardize on one - drivers use '$query', + // and the shell uses 'query'. See SERVER-18705 for details. - return Status::OK(); + // TODO: this may need to use the $queryOptions hack on mongos. + legacyCommand->append(kQueryWrapper, command); + legacyCommand->append(readPrefElem); + } else { + legacyCommand->appendElements(command); } - Status ServerSelectionMetadata::upconvert(const BSONObj& legacyCommand, - const int legacyQueryFlags, - BSONObjBuilder* commandBob, - BSONObjBuilder* metadataBob) { + return Status::OK(); +} - // The secondaryOK option is equivalent to the slaveOk bit being set on legacy commands. - if (legacyQueryFlags & QueryOption_SlaveOk) { - metadataBob->append(kSecondaryOkFieldName, 1); - } +Status ServerSelectionMetadata::upconvert(const BSONObj& legacyCommand, + const int legacyQueryFlags, + BSONObjBuilder* commandBob, + BSONObjBuilder* metadataBob) { + // The secondaryOK option is equivalent to the slaveOk bit being set on legacy commands. + if (legacyQueryFlags & QueryOption_SlaveOk) { + metadataBob->append(kSecondaryOkFieldName, 1); + } - // First we need to check if we have a wrapped command. That is, a command of the form - // {'$query': { 'commandName': 1, ...}, '$someOption': 5, ....}. Curiously, the field name - // of the wrapped query can be either '$query', or 'query'. - BSONObj maybeUnwrapped; - bool wasWrapped; - std::tie(wasWrapped, maybeUnwrapped) = unwrapCommand(legacyCommand); - - if (wasWrapped) { - // Check if legacyCommand has an invalid $maxTimeMS option. - // TODO: Move this check elsewhere when we handle upconverting/downconverting maxTimeMS. - if (legacyCommand.hasField("$maxTimeMS")) { - return Status(ErrorCodes::InvalidOptions, - "cannot use $maxTimeMS query option with " - "commands; use maxTimeMS command option " - "instead"); - } - - // If the command was wrapped, we can write out the upconverted command now, as there - // is nothing else we need to remove from it. - commandBob->appendElements(maybeUnwrapped); - - return extractWrappedReadPreference(legacyCommand, metadataBob); + // First we need to check if we have a wrapped command. That is, a command of the form + // {'$query': { 'commandName': 1, ...}, '$someOption': 5, ....}. Curiously, the field name + // of the wrapped query can be either '$query', or 'query'. + BSONObj maybeUnwrapped; + bool wasWrapped; + std::tie(wasWrapped, maybeUnwrapped) = unwrapCommand(legacyCommand); + + if (wasWrapped) { + // Check if legacyCommand has an invalid $maxTimeMS option. + // TODO: Move this check elsewhere when we handle upconverting/downconverting maxTimeMS. + if (legacyCommand.hasField("$maxTimeMS")) { + return Status(ErrorCodes::InvalidOptions, + "cannot use $maxTimeMS query option with " + "commands; use maxTimeMS command option " + "instead"); } - // If the command was not wrapped, we need to check for a readPreference sent by mongos - // on the $queryOptions field of the command. If it is set, we remove it from the - // upconverted command, so we need to pass the command builder along. - return extractUnwrappedReadPreference(maybeUnwrapped, commandBob, metadataBob); - } + // If the command was wrapped, we can write out the upconverted command now, as there + // is nothing else we need to remove from it. + commandBob->appendElements(maybeUnwrapped); - bool ServerSelectionMetadata::isSecondaryOk() const { - return _secondaryOk; + return extractWrappedReadPreference(legacyCommand, metadataBob); } - const boost::optional<ReadPreferenceSetting>& - ServerSelectionMetadata::getReadPreference() const { - return _readPreference; - } + // If the command was not wrapped, we need to check for a readPreference sent by mongos + // on the $queryOptions field of the command. If it is set, we remove it from the + // upconverted command, so we need to pass the command builder along. + return extractUnwrappedReadPreference(maybeUnwrapped, commandBob, metadataBob); +} + +bool ServerSelectionMetadata::isSecondaryOk() const { + return _secondaryOk; +} + +const boost::optional<ReadPreferenceSetting>& ServerSelectionMetadata::getReadPreference() const { + return _readPreference; +} #if defined(_MSC_VER) && _MSC_VER < 1900 - ServerSelectionMetadata::ServerSelectionMetadata(ServerSelectionMetadata&& ssm) - : _secondaryOk(ssm._secondaryOk) - , _readPreference(std::move(ssm._readPreference)) - {} - - ServerSelectionMetadata& ServerSelectionMetadata::operator=(ServerSelectionMetadata&& ssm) { - _secondaryOk = ssm._secondaryOk; - _readPreference = std::move(ssm._readPreference); - return *this; - } +ServerSelectionMetadata::ServerSelectionMetadata(ServerSelectionMetadata&& ssm) + : _secondaryOk(ssm._secondaryOk), _readPreference(std::move(ssm._readPreference)) {} + +ServerSelectionMetadata& ServerSelectionMetadata::operator=(ServerSelectionMetadata&& ssm) { + _secondaryOk = ssm._secondaryOk; + _readPreference = std::move(ssm._readPreference); + return *this; +} #endif } // rpc |