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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.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kCommand
#include "mongo/platform/basic.h"
#include <boost/optional.hpp>
#include "mongo/s/cluster_commands_helpers.h"
#include "mongo/bson/util/bson_extract.h"
#include "mongo/db/commands.h"
#include "mongo/db/curop.h"
#include "mongo/db/error_labels.h"
#include "mongo/db/logical_clock.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/db/repl/read_concern_args.h"
#include "mongo/executor/task_executor_pool.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/rpc/write_concern_error_detail.h"
#include "mongo/s/catalog/type_collection.h"
#include "mongo/s/catalog_cache.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/database_version_helpers.h"
#include "mongo/s/grid.h"
#include "mongo/s/multi_statement_transaction_requests_sender.h"
#include "mongo/s/request_types/create_database_gen.h"
#include "mongo/s/shard_id.h"
#include "mongo/s/stale_exception.h"
#include "mongo/s/transaction_router.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
WriteConcernErrorDetail getWriteConcernErrorDetail(const BSONElement& wcErrorElem) {
WriteConcernErrorDetail wcError;
std::string errMsg;
auto wcErrorObj = wcErrorElem.Obj();
if (!wcError.parseBSON(wcErrorObj, &errMsg)) {
wcError.clear();
wcError.setStatus({ErrorCodes::FailedToParse,
"Failed to parse writeConcernError: " + wcErrorObj.toString() +
", Received error: " + errMsg});
}
return wcError;
}
void appendWriteConcernErrorToCmdResponse(const ShardId& shardId,
const BSONElement& wcErrorElem,
BSONObjBuilder& responseBuilder) {
WriteConcernErrorDetail wcError = getWriteConcernErrorDetail(wcErrorElem);
auto status = wcError.toStatus();
wcError.setStatus(
status.withReason(str::stream() << status.reason() << " at " << shardId.toString()));
responseBuilder.append("writeConcernError", wcError.toBSON());
}
std::unique_ptr<WriteConcernErrorDetail> getWriteConcernErrorDetailFromBSONObj(const BSONObj& obj) {
BSONElement wcErrorElem;
Status status = bsonExtractTypedField(obj, "writeConcernError", Object, &wcErrorElem);
if (!status.isOK()) {
if (status == ErrorCodes::NoSuchKey) {
return nullptr;
} else {
uassertStatusOK(status);
}
}
return std::make_unique<WriteConcernErrorDetail>(getWriteConcernErrorDetail(wcErrorElem));
}
namespace {
const auto kAllowImplicitCollectionCreation = "allowImplicitCollectionCreation"_sd;
/**
* Constructs a requests vector targeting each of the specified shard ids. Each request contains the
* same cmdObj combined with the default sharding parameters.
*/
std::vector<AsyncRequestsSender::Request> buildUnversionedRequestsForShards(
OperationContext* opCtx, std::vector<ShardId> shardIds, const BSONObj& cmdObj) {
auto cmdToSend = cmdObj;
std::vector<AsyncRequestsSender::Request> requests;
for (auto&& shardId : shardIds)
requests.emplace_back(std::move(shardId), cmdToSend);
return requests;
}
std::vector<AsyncRequestsSender::Request> buildUnversionedRequestsForAllShards(
OperationContext* opCtx, const BSONObj& cmdObj) {
std::vector<ShardId> shardIds;
Grid::get(opCtx)->shardRegistry()->getAllShardIdsNoReload(&shardIds);
return buildUnversionedRequestsForShards(opCtx, std::move(shardIds), cmdObj);
}
std::vector<AsyncRequestsSender::Request> buildVersionedRequestsForTargetedShards(
OperationContext* opCtx,
const NamespaceString& nss,
const CachedCollectionRoutingInfo& routingInfo,
const BSONObj& cmdObj,
const BSONObj& query,
const BSONObj& collation) {
auto cmdToSend = cmdObj;
if (!routingInfo.cm()) {
// The collection is unsharded. Target only the primary shard for the database.
// Attach shardVersion "UNSHARDED", unless targeting the config server.
const auto cmdObjWithShardVersion = (routingInfo.db().primaryId() != "config")
? appendShardVersion(cmdToSend, ChunkVersion::UNSHARDED())
: cmdToSend;
return buildUnversionedRequestsForShards(
opCtx,
{routingInfo.db().primaryId()},
appendDbVersionIfPresent(cmdObjWithShardVersion, routingInfo.db()));
}
std::vector<AsyncRequestsSender::Request> requests;
// The collection is sharded. Target all shards that own chunks that match the query.
std::set<ShardId> shardIds;
routingInfo.cm()->getShardIdsForQuery(opCtx, query, collation, &shardIds);
for (const ShardId& shardId : shardIds) {
requests.emplace_back(shardId,
appendShardVersion(cmdToSend, routingInfo.cm()->getVersion(shardId)));
}
return requests;
}
} // namespace
std::vector<AsyncRequestsSender::Response> gatherResponses(
OperationContext* opCtx,
StringData dbName,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy,
const std::vector<AsyncRequestsSender::Request>& requests,
const std::set<ErrorCodes::Error>& ignorableErrors) {
// Send the requests.
MultiStatementTransactionRequestsSender ars(
opCtx,
Grid::get(opCtx)->getExecutorPool()->getArbitraryExecutor(),
dbName,
requests,
readPref,
retryPolicy);
// Get the responses.
std::vector<AsyncRequestsSender::Response> responses; // Stores results by ShardId
while (!ars.done()) {
auto response = ars.next();
auto status = response.swResponse.getStatus();
if (status.isOK()) {
// We successfully received a response.
// Check for special errors that require throwing out any accumulated results.
auto& responseObj = response.swResponse.getValue().data;
status = getStatusFromCommandResult(responseObj);
// Failing to establish a consistent shardVersion means no results should be examined.
if (ErrorCodes::isStaleShardVersionError(status.code())) {
uassertStatusOK(status.withContext(str::stream()
<< "got stale shardVersion response from shard "
<< response.shardId << " at host "
<< response.shardHostAndPort->toString()));
}
if (ErrorCodes::StaleDbVersion == status) {
uassertStatusOK(status.withContext(
str::stream() << "got stale databaseVersion response from shard "
<< response.shardId << " at host "
<< response.shardHostAndPort->toString()));
}
// In the case a read is performed against a view, the server can return an error
// indicating that the underlying collection may be sharded. When this occurs the return
// message will include an expanded view definition and collection namespace. We pass
// the definition back to the caller by throwing the error. This allows the caller to
// rewrite the request as an aggregation and retry it.
if (ErrorCodes::CommandOnShardedViewNotSupportedOnMongod == status) {
uassertStatusOK(status);
}
}
responses.push_back(std::move(response));
}
return responses;
}
BSONObj appendDbVersionIfPresent(BSONObj cmdObj, const CachedDatabaseInfo& dbInfo) {
return appendDbVersionIfPresent(std::move(cmdObj), dbInfo.databaseVersion());
}
BSONObj appendDbVersionIfPresent(BSONObj cmdObj, DatabaseVersion dbVersion) {
if (databaseVersion::isFixed(dbVersion)) {
return cmdObj;
}
BSONObjBuilder cmdWithDbVersion(std::move(cmdObj));
cmdWithDbVersion.append("databaseVersion", dbVersion.toBSON());
return cmdWithDbVersion.obj();
}
BSONObj appendShardVersion(BSONObj cmdObj, ChunkVersion version) {
BSONObjBuilder cmdWithVersionBob(std::move(cmdObj));
version.appendToCommand(&cmdWithVersionBob);
return cmdWithVersionBob.obj();
}
BSONObj appendAllowImplicitCreate(BSONObj cmdObj, bool allow) {
BSONObjBuilder newCmdBuilder(std::move(cmdObj));
newCmdBuilder.append(kAllowImplicitCollectionCreation, allow);
return newCmdBuilder.obj();
}
BSONObj applyReadWriteConcern(OperationContext* opCtx,
bool appendRC,
bool appendWC,
const BSONObj& cmdObj) {
if (TransactionRouter::get(opCtx)) {
// When running in a transaction, the rules are:
// - Never apply writeConcern. Applying writeConcern to terminal operations such as
// abortTransaction and commitTransaction is done directly by the TransactionRouter.
// - Apply readConcern only if this is the first operation in the transaction.
if (!opCtx->isStartingMultiDocumentTransaction()) {
// Cannot apply either read or writeConcern, so short-circuit.
return cmdObj;
}
if (!appendRC) {
// First operation in transaction, but the caller has not requested readConcern be
// applied, so there's nothing to do.
return cmdObj;
}
// First operation in transaction, so ensure that writeConcern is not applied, then continue
// and apply the readConcern.
appendWC = false;
}
// Append all original fields except the readConcern/writeConcern field to the new command.
BSONObjBuilder output;
bool seenReadConcern = false;
bool seenWriteConcern = false;
for (const auto& elem : cmdObj) {
const auto name = elem.fieldNameStringData();
if (appendRC && name == repl::ReadConcernArgs::kReadConcernFieldName) {
seenReadConcern = true;
}
if (appendWC && name == WriteConcernOptions::kWriteConcernField) {
seenWriteConcern = true;
}
if (!output.hasField(name)) {
output.append(elem);
}
}
// Finally, add the new read/write concern.
if (appendRC && !seenReadConcern) {
const auto& readConcernArgs = repl::ReadConcernArgs::get(opCtx);
output.appendElements(readConcernArgs.toBSON());
}
if (appendWC && !seenWriteConcern) {
output.append(WriteConcernOptions::kWriteConcernField, opCtx->getWriteConcern().toBSON());
}
return output.obj();
}
BSONObj applyReadWriteConcern(OperationContext* opCtx,
CommandInvocation* invocation,
const BSONObj& cmdObj) {
const auto& readConcernArgs = repl::ReadConcernArgs::get(opCtx);
const auto readConcernSupport = invocation->supportsReadConcern(readConcernArgs.getLevel());
return applyReadWriteConcern(opCtx,
readConcernSupport.readConcernSupport.isOK(),
invocation->supportsWriteConcern(),
cmdObj);
}
BSONObj applyReadWriteConcern(OperationContext* opCtx, BasicCommand* cmd, const BSONObj& cmdObj) {
const auto& readConcernArgs = repl::ReadConcernArgs::get(opCtx);
const auto readConcernSupport = cmd->supportsReadConcern(cmdObj, readConcernArgs.getLevel());
return applyReadWriteConcern(opCtx,
readConcernSupport.readConcernSupport.isOK(),
cmd->supportsWriteConcern(cmdObj),
cmdObj);
}
BSONObj stripWriteConcern(const BSONObj& cmdObj) {
BSONObjBuilder output;
for (const auto& elem : cmdObj) {
const auto name = elem.fieldNameStringData();
if (name == WriteConcernOptions::kWriteConcernField) {
continue;
}
output.append(elem);
}
return output.obj();
}
std::vector<AsyncRequestsSender::Response> scatterGatherUnversionedTargetAllShards(
OperationContext* opCtx,
StringData dbName,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy) {
return gatherResponses(
opCtx, dbName, readPref, retryPolicy, buildUnversionedRequestsForAllShards(opCtx, cmdObj));
}
std::vector<AsyncRequestsSender::Response> scatterGatherVersionedTargetByRoutingTable(
OperationContext* opCtx,
StringData dbName,
const NamespaceString& nss,
const CachedCollectionRoutingInfo& routingInfo,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy,
const BSONObj& query,
const BSONObj& collation) {
const auto requests =
buildVersionedRequestsForTargetedShards(opCtx, nss, routingInfo, cmdObj, query, collation);
return gatherResponses(opCtx, dbName, readPref, retryPolicy, requests);
}
std::vector<AsyncRequestsSender::Response> scatterGatherOnlyVersionIfUnsharded(
OperationContext* opCtx,
const NamespaceString& nss,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy,
const std::set<ErrorCodes::Error>& ignorableErrors) {
auto routingInfo =
uassertStatusOK(Grid::get(opCtx)->catalogCache()->getCollectionRoutingInfo(opCtx, nss));
std::vector<AsyncRequestsSender::Request> requests;
if (routingInfo.cm()) {
// An unversioned request on a sharded collection can cause a shard that has not owned data
// for the collection yet to implicitly create the collection without all the collection
// options. So, we signal to shards that they should not implicitly create the collection.
requests = buildUnversionedRequestsForAllShards(opCtx, cmdObj);
} else {
requests = buildVersionedRequestsForTargetedShards(
opCtx, nss, routingInfo, cmdObj, BSONObj(), BSONObj());
}
return gatherResponses(opCtx, nss.db(), readPref, retryPolicy, requests, ignorableErrors);
}
AsyncRequestsSender::Response executeCommandAgainstDatabasePrimary(
OperationContext* opCtx,
StringData dbName,
const CachedDatabaseInfo& dbInfo,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy) {
auto responses =
gatherResponses(opCtx,
dbName,
readPref,
retryPolicy,
buildUnversionedRequestsForShards(
opCtx, {dbInfo.primaryId()}, appendDbVersionIfPresent(cmdObj, dbInfo)));
return std::move(responses.front());
}
AsyncRequestsSender::Response executeCommandAgainstShardWithMinKeyChunk(
OperationContext* opCtx,
const NamespaceString& nss,
const CachedCollectionRoutingInfo& routingInfo,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy) {
const auto query = routingInfo.cm()
? routingInfo.cm()->getShardKeyPattern().getKeyPattern().globalMin()
: BSONObj();
auto responses =
gatherResponses(opCtx,
nss.db(),
readPref,
retryPolicy,
buildVersionedRequestsForTargetedShards(
opCtx, nss, routingInfo, cmdObj, query, BSONObj() /* collation */));
return std::move(responses.front());
}
bool appendRawResponses(OperationContext* opCtx,
std::string* errmsg,
BSONObjBuilder* output,
const std::vector<AsyncRequestsSender::Response>& shardResponses,
std::set<ErrorCodes::Error> ignorableErrors) {
// Always include ShardNotFound as an ignorable error, since this node may not have realized a
// shard has been removed.
ignorableErrors.insert(ErrorCodes::ShardNotFound);
std::vector<std::pair<ShardId, BSONObj>> successResponsesReceived;
std::vector<std::pair<ShardId, Status>> ignorableErrorsReceived;
std::vector<std::pair<ShardId, Status>> nonIgnorableErrorsReceived;
boost::optional<std::pair<ShardId, BSONElement>> firstWriteConcernErrorReceived;
const auto processError = [&](const ShardId& shardId, const Status& status) {
invariant(!status.isOK());
// It is safe to pass `hasWriteConcernError` as false in the below check because operations
// run inside transactions do not wait for write concern, except for commit and abort.
if (TransactionRouter::get(opCtx) &&
isTransientTransactionError(
status.code(), false /*hasWriteConcernError*/, false /*isCommitOrAbort*/)) {
// Re-throw on transient transaction errors to make sure appropriate error labels are
// appended to the result.
uassertStatusOK(status);
}
if (ignorableErrors.find(status.code()) != ignorableErrors.end()) {
ignorableErrorsReceived.emplace_back(std::move(shardId), std::move(status));
return;
}
nonIgnorableErrorsReceived.emplace_back(shardId, status);
};
// Do a pass through all the received responses and group them into success, ignorable, and
// non-ignorable.
for (const auto& shardResponse : shardResponses) {
const auto& shardId = shardResponse.shardId;
const auto sendStatus = shardResponse.swResponse.getStatus();
if (!sendStatus.isOK()) {
processError(shardId, sendStatus);
continue;
}
const auto& resObj = shardResponse.swResponse.getValue().data;
const auto commandStatus = getStatusFromCommandResult(resObj);
if (!commandStatus.isOK()) {
processError(shardId, commandStatus);
continue;
}
if (!firstWriteConcernErrorReceived && resObj["writeConcernError"]) {
firstWriteConcernErrorReceived.emplace(shardId, resObj["writeConcernError"]);
}
successResponsesReceived.emplace_back(shardId, resObj);
}
// If all shards reported ignorable errors, promote them all to non-ignorable errors.
if (ignorableErrorsReceived.size() == shardResponses.size()) {
invariant(nonIgnorableErrorsReceived.empty());
nonIgnorableErrorsReceived = std::move(ignorableErrorsReceived);
}
// Append a 'raw' field containing the success responses and non-ignorable error responses.
BSONObjBuilder rawShardResponses;
const auto appendRawResponse = [&](const ShardId& shardId, const BSONObj& response) {
// Try to report the response by the shard's full connection string.
try {
const auto shardConnString =
uassertStatusOK(Grid::get(opCtx)->shardRegistry()->getShard(opCtx, shardId))
->getConnString();
rawShardResponses.append(shardConnString.toString(),
CommandHelpers::filterCommandReplyForPassthrough(response));
} catch (const ExceptionFor<ErrorCodes::ShardNotFound>&) {
// If we could not get the shard's connection string, fall back to reporting the
// response by shard id.
rawShardResponses.append(shardId, response);
}
};
for (const auto& success : successResponsesReceived) {
appendRawResponse(success.first, success.second);
}
for (const auto& error : nonIgnorableErrorsReceived) {
BSONObjBuilder statusObjBob;
CommandHelpers::appendCommandStatusNoThrow(statusObjBob, error.second);
appendRawResponse(error.first, statusObjBob.obj());
}
output->append("raw", rawShardResponses.done());
// If there were no non-ignorable errors, report success (possibly with a writeConcern error).
if (nonIgnorableErrorsReceived.empty()) {
if (firstWriteConcernErrorReceived) {
appendWriteConcernErrorToCmdResponse(firstWriteConcernErrorReceived->first,
firstWriteConcernErrorReceived->second,
*output);
}
return true;
}
// There was a non-ignorable error. Choose the first non-ignorable error as the top-level error.
const auto& firstNonIgnorableError = nonIgnorableErrorsReceived.front().second;
output->append("code", firstNonIgnorableError.code());
output->append("codeName", ErrorCodes::errorString(firstNonIgnorableError.code()));
*errmsg = firstNonIgnorableError.reason();
return false;
}
BSONObj extractQuery(const BSONObj& cmdObj) {
auto queryElem = cmdObj["query"];
if (!queryElem)
queryElem = cmdObj["q"];
if (!queryElem || queryElem.isNull())
return BSONObj();
uassert(ErrorCodes::TypeMismatch,
str::stream() << "Illegal type specified for query " << queryElem,
queryElem.type() == Object);
return queryElem.embeddedObject();
}
BSONObj extractCollation(const BSONObj& cmdObj) {
const auto collationElem = cmdObj["collation"];
if (!collationElem)
return BSONObj();
uassert(ErrorCodes::TypeMismatch,
str::stream() << "Illegal type specified for collation " << collationElem,
collationElem.type() == Object);
return collationElem.embeddedObject();
}
int getUniqueCodeFromCommandResults(const std::vector<Strategy::CommandResult>& results) {
int commonErrCode = -1;
for (std::vector<Strategy::CommandResult>::const_iterator it = results.begin();
it != results.end();
++it) {
// Only look at shards with errors.
if (!it->result["ok"].trueValue()) {
int errCode = it->result["code"].numberInt();
if (commonErrCode == -1) {
commonErrCode = errCode;
} else if (commonErrCode != errCode) {
// At least two shards with errors disagree on the error code
commonErrCode = 0;
}
}
}
// If no error encountered or shards with errors disagree on the error code, return 0
if (commonErrCode == -1 || commonErrCode == 0) {
return 0;
}
// Otherwise, shards with errors agree on the error code; return that code
return commonErrCode;
}
bool appendEmptyResultSet(OperationContext* opCtx,
BSONObjBuilder& result,
Status status,
const std::string& ns) {
invariant(!status.isOK());
CurOp::get(opCtx)->debug().nreturned = 0;
CurOp::get(opCtx)->debug().nShards = 0;
if (status == ErrorCodes::NamespaceNotFound) {
// Old style reply
result << "result" << BSONArray();
// New (command) style reply
appendCursorResponseObject(0LL, ns, BSONArray(), &result);
return true;
}
uassertStatusOK(status);
return true;
}
void createShardDatabase(OperationContext* opCtx, StringData dbName) {
auto dbStatus = Grid::get(opCtx)->catalogCache()->getDatabase(opCtx, dbName);
if (dbStatus == ErrorCodes::NamespaceNotFound) {
ConfigsvrCreateDatabase configCreateDatabaseRequest(dbName.toString());
configCreateDatabaseRequest.setDbName(NamespaceString::kAdminDb);
auto configShard = Grid::get(opCtx)->shardRegistry()->getConfigShard();
auto createDbResponse = uassertStatusOK(configShard->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting(ReadPreference::PrimaryOnly),
"admin",
CommandHelpers::appendMajorityWriteConcern(configCreateDatabaseRequest.toBSON({})),
Shard::RetryPolicy::kIdempotent));
uassertStatusOK(createDbResponse.writeConcernStatus);
if (createDbResponse.commandStatus != ErrorCodes::NamespaceExists) {
uassertStatusOKWithContext(createDbResponse.commandStatus,
str::stream()
<< "Database " << dbName << " could not be created");
}
dbStatus = Grid::get(opCtx)->catalogCache()->getDatabase(opCtx, dbName);
}
uassertStatusOKWithContext(dbStatus, str::stream() << "Database " << dbName << " not found");
}
std::set<ShardId> getTargetedShardsForQuery(OperationContext* opCtx,
const CachedCollectionRoutingInfo& routingInfo,
const BSONObj& query,
const BSONObj& collation) {
if (routingInfo.cm()) {
// The collection is sharded. Use the routing table to decide which shards to target
// based on the query and collation.
std::set<ShardId> shardIds;
routingInfo.cm()->getShardIdsForQuery(opCtx, query, collation, &shardIds);
return shardIds;
}
// The collection is unsharded. Target only the primary shard for the database.
return {routingInfo.db().primaryId()};
}
std::vector<std::pair<ShardId, BSONObj>> getVersionedRequestsForTargetedShards(
OperationContext* opCtx,
const NamespaceString& nss,
const CachedCollectionRoutingInfo& routingInfo,
const BSONObj& cmdObj,
const BSONObj& query,
const BSONObj& collation) {
std::vector<std::pair<ShardId, BSONObj>> requests;
auto ars_requests =
buildVersionedRequestsForTargetedShards(opCtx, nss, routingInfo, cmdObj, query, collation);
std::transform(std::make_move_iterator(ars_requests.begin()),
std::make_move_iterator(ars_requests.end()),
std::back_inserter(requests),
[](auto&& ars) {
return std::pair<ShardId, BSONObj>(std::move(ars.shardId),
std::move(ars.cmdObj));
});
return requests;
}
StatusWith<CachedCollectionRoutingInfo> getCollectionRoutingInfoForTxnCmd(
OperationContext* opCtx, const NamespaceString& nss) {
auto catalogCache = Grid::get(opCtx)->catalogCache();
invariant(catalogCache);
// Return the latest routing table if not running in a transaction with snapshot level read
// concern.
auto txnRouter = TransactionRouter::get(opCtx);
if (!txnRouter || !txnRouter.mustUseAtClusterTime()) {
return catalogCache->getCollectionRoutingInfo(opCtx, nss);
}
auto atClusterTime = txnRouter.getSelectedAtClusterTime();
return catalogCache->getCollectionRoutingInfoAt(opCtx, nss, atClusterTime.asTimestamp());
}
} // namespace mongo
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