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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 <map>
#include <set>
#include <string>
#include <vector>
#include "mongo/bson/simple_bsonobj_comparator.h"
#include "mongo/client/connpool.h"
#include "mongo/db/catalog/document_validation.h"
#include "mongo/db/command_generic_argument.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/mr.h"
#include "mongo/db/query/collation/collation_spec.h"
#include "mongo/s/balancer_configuration.h"
#include "mongo/s/catalog/dist_lock_manager.h"
#include "mongo/s/catalog/sharding_catalog_client.h"
#include "mongo/s/catalog_cache.h"
#include "mongo/s/client/shard_connection.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/cluster_commands_helpers.h"
#include "mongo/s/commands/strategy.h"
#include "mongo/s/grid.h"
#include "mongo/s/request_types/shard_collection_gen.h"
#include "mongo/s/write_ops/cluster_write.h"
#include "mongo/stdx/chrono.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"
namespace mongo {
namespace {
AtomicUInt32 JOB_NUMBER;
const Milliseconds kNoDistLockTimeout(-1);
/**
* Generates a unique name for the temporary M/R output collection.
*/
std::string getTmpName(StringData coll) {
return str::stream() << "tmp.mrs." << coll << "_" << time(0) << "_"
<< JOB_NUMBER.fetchAndAdd(1);
}
/**
* Given an input map/reduce command, this call generates the matching command which should
* be sent to the shards as part of the first phase of map/reduce.
*/
BSONObj fixForShards(const BSONObj& orig,
const std::string& output,
std::string& badShardedField,
int maxChunkSizeBytes) {
BSONObjBuilder b;
BSONObjIterator i(orig);
while (i.more()) {
BSONElement e = i.next();
const auto fn = e.fieldNameStringData();
if (fn == bypassDocumentValidationCommandOption() || fn == "map" || fn == "mapreduce" ||
fn == "mapReduce" || fn == "mapparams" || fn == "reduce" || fn == "query" ||
fn == "sort" || fn == "collation" || fn == "scope" || fn == "verbose" ||
fn == "$queryOptions" || fn == "readConcern" ||
fn == QueryRequest::cmdOptionMaxTimeMS) {
b.append(e);
} else if (fn == "out" || fn == "finalize" || fn == "writeConcern") {
// We don't want to copy these
} else if (!isGenericArgument(fn)) {
badShardedField = fn.toString();
return BSONObj();
}
}
b.append("out", output);
b.append("shardedFirstPass", true);
if (maxChunkSizeBytes > 0) {
// Will need to figure out chunks, ask shards for points
b.append("splitInfo", maxChunkSizeBytes);
}
// mapReduce creates temporary collections and renames them at the end, so it will handle
// cluster collection creation differently.
return appendAllowImplicitCreate(b.obj(), true);
}
/**
* Outline for sharded map reduce for sharded output, $out replace:
*
* ============= mongos =============
* 1. Send map reduce command to all relevant shards with some extra info like the value for
* the chunkSize and the name of the temporary output collection.
*
* ============= shard =============
* 2. Does normal map reduce.
*
* 3. Calls splitVector on itself against the output collection and puts the results into the
* response object.
*
* ============= mongos =============
* 4. If the output collection is *not* sharded, uses the information from splitVector to
* create a pre-split sharded collection.
*
* 5. Grabs the distributed lock for the final output collection.
*
* 6. Sends mapReduce.shardedfinish.
*
* ============= shard =============
* 7. Extracts the list of shards from the mapReduce.shardedfinish and performs a broadcast
* query against all of them to obtain all documents that this shard owns.
*
* 8. Performs the reduce operation against every document from step #7 and outputs them to
* another temporary collection. Also keeps track of the BSONObject size of every "reduced"
* document for each chunk range.
*
* 9. Atomically drops the old output collection and renames the temporary collection to the
* output collection.
*
* ============= mongos =============
* 10. Releases the distributed lock acquired at step #5.
*
* 11. Inspects the BSONObject size from step #8 and determines if it needs to split.
*/
class MRCmd : public ErrmsgCommandDeprecated {
public:
MRCmd() : ErrmsgCommandDeprecated("mapReduce", "mapreduce") {}
AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
return AllowedOnSecondary::kAlways;
}
bool adminOnly() const override {
return false;
}
std::string parseNs(const std::string& dbname, const BSONObj& cmdObj) const override {
return CommandHelpers::parseNsCollectionRequired(dbname, cmdObj).ns();
}
bool supportsWriteConcern(const BSONObj& cmd) const override {
return mr::mrSupportsWriteConcern(cmd);
}
std::string help() const override {
return "Runs the sharded map/reduce command";
}
void addRequiredPrivileges(const std::string& dbname,
const BSONObj& cmdObj,
std::vector<Privilege>* out) const override {
mr::addPrivilegesRequiredForMapReduce(this, dbname, cmdObj, out);
}
bool errmsgRun(OperationContext* opCtx,
const std::string& dbname,
const BSONObj& cmdObj,
std::string& errmsg,
BSONObjBuilder& result) override {
Timer t;
const NamespaceString nss(parseNs(dbname, cmdObj));
const std::string shardResultCollection = getTmpName(nss.coll());
bool shardedOutput = false;
bool customOutDB = false;
NamespaceString outputCollNss;
bool inlineOutput = false;
bool replaceOutput = false;
std::string outDB = dbname;
BSONElement outElmt = cmdObj.getField("out");
if (outElmt.type() == Object) {
// Check if there is a custom output
BSONObj customOut = outElmt.embeddedObject();
shardedOutput = customOut.getBoolField("sharded");
if (customOut.hasField("inline")) {
inlineOutput = true;
uassert(ErrorCodes::InvalidOptions,
"cannot specify inline and sharded output at the same time",
!shardedOutput);
uassert(ErrorCodes::InvalidOptions,
"cannot specify inline and output database at the same time",
!customOut.hasField("db"));
} else {
// Mode must be 1st element
const std::string finalColShort = customOut.firstElement().str();
if (customOut.hasField("replace")) {
replaceOutput = true;
}
if (customOut.hasField("db")) {
customOutDB = true;
outDB = customOut.getField("db").str();
}
outputCollNss = NamespaceString(outDB, finalColShort);
uassert(ErrorCodes::InvalidNamespace,
"Invalid output namespace",
outputCollNss.isValid());
}
}
auto const catalogCache = Grid::get(opCtx)->catalogCache();
// Ensure the input database exists and set up the input collection
auto inputRoutingInfo = uassertStatusOK(catalogCache->getCollectionRoutingInfo(opCtx, nss));
const bool shardedInput = inputRoutingInfo.cm() != nullptr;
// Create the output database implicitly if we have a custom output requested
if (customOutDB) {
uassertStatusOK(createShardDatabase(opCtx, outDB));
}
// Ensure that the output database doesn't reside on the config server
auto outputDbInfo = uassertStatusOK(catalogCache->getDatabase(opCtx, outDB));
uassert(ErrorCodes::CommandNotSupported,
str::stream() << "Can not execute mapReduce with output database " << outDB
<< " which lives on config servers",
inlineOutput || outputDbInfo.primaryId() != "config");
int64_t maxChunkSizeBytes = 0;
if (shardedOutput) {
// Will need to figure out chunks, ask shards for points
maxChunkSizeBytes = cmdObj["maxChunkSizeBytes"].numberLong();
if (maxChunkSizeBytes == 0) {
maxChunkSizeBytes =
Grid::get(opCtx)->getBalancerConfiguration()->getMaxChunkSizeBytes();
}
// maxChunkSizeBytes is sent as int BSON field
invariant(maxChunkSizeBytes < std::numeric_limits<int>::max());
} else if (outputCollNss.isValid()) {
auto outputRoutingInfo =
uassertStatusOK(catalogCache->getCollectionRoutingInfo(opCtx, outputCollNss));
uassert(15920,
"Cannot output to a non-sharded collection because "
"sharded collection exists already",
!outputRoutingInfo.cm());
// TODO: Should we also prevent going from non-sharded to sharded? During the
// transition client may see partial data.
}
const auto shardRegistry = Grid::get(opCtx)->shardRegistry();
// modify command to run on shards with output to tmp collection
std::string badShardedField;
BSONObj shardedCommand =
fixForShards(cmdObj, shardResultCollection, badShardedField, maxChunkSizeBytes);
if (!shardedInput && !shardedOutput && !customOutDB) {
LOG(1) << "simple MR, just passthrough";
invariant(inputRoutingInfo.db().primary());
ShardConnection conn(opCtx, inputRoutingInfo.db().primary()->getConnString(), "");
BSONObj res;
bool ok = conn->runCommand(
dbname,
appendAllowImplicitCreate(
CommandHelpers::filterCommandRequestForPassthrough(cmdObj), true),
res);
conn.done();
if (auto wcErrorElem = res["writeConcernError"]) {
appendWriteConcernErrorToCmdResponse(
inputRoutingInfo.db().primary()->getId(), wcErrorElem, result);
}
result.appendElementsUnique(CommandHelpers::filterCommandReplyForPassthrough(res));
return ok;
}
if (badShardedField.size()) {
errmsg = str::stream() << "unknown m/r field for sharding: " << badShardedField;
return false;
}
BSONObj q;
if (cmdObj["query"].type() == Object) {
q = cmdObj["query"].embeddedObjectUserCheck();
}
BSONObj collation;
if (cmdObj["collation"].type() == Object) {
collation = cmdObj["collation"].embeddedObjectUserCheck();
}
std::set<std::string> servers;
std::vector<Strategy::CommandResult> mrCommandResults;
BSONObjBuilder shardResultsB;
BSONObjBuilder shardCountsB;
std::map<std::string, int64_t> countsMap;
auto splitPts = SimpleBSONObjComparator::kInstance.makeBSONObjSet();
{
bool ok = true;
// TODO: take distributed lock to prevent split / migration?
try {
Strategy::commandOp(
opCtx, dbname, shardedCommand, nss.ns(), q, collation, &mrCommandResults);
} catch (DBException& e) {
e.addContext(str::stream() << "could not run map command on all shards for ns "
<< nss.ns()
<< " and query "
<< q);
throw;
}
for (const auto& mrResult : mrCommandResults) {
// Need to gather list of all servers even if an error happened
const auto server = [&]() {
const auto shard =
uassertStatusOK(shardRegistry->getShard(opCtx, mrResult.shardTargetId));
return shard->getConnString().toString();
}();
servers.insert(server);
if (!ok) {
continue;
}
BSONObj singleResult = mrResult.result;
ok = singleResult["ok"].trueValue();
if (!ok) {
// At this point we will return
errmsg = str::stream() << "MR parallel processing failed: "
<< singleResult.toString();
continue;
}
shardResultsB.append(server, singleResult);
BSONObj counts = singleResult["counts"].embeddedObjectUserCheck();
shardCountsB.append(server, counts);
// Add up the counts for each shard. Some of them will be fixed later like
// output and reduce.
BSONObjIterator j(counts);
while (j.more()) {
BSONElement temp = j.next();
countsMap[temp.fieldName()] += temp.numberLong();
}
if (singleResult.hasField("splitKeys")) {
BSONElement splitKeys = singleResult.getField("splitKeys");
for (const auto& splitPt : splitKeys.Array()) {
splitPts.insert(splitPt.Obj().getOwned());
}
}
}
if (!ok) {
cleanUp(servers, dbname, shardResultCollection);
// Add "code" to the top-level response, if the failure of the sharded command
// can be accounted to a single error.
int code = getUniqueCodeFromCommandResults(mrCommandResults);
if (code != 0) {
result.append("code", code);
result.append("codeName", ErrorCodes::errorString(ErrorCodes::Error(code)));
}
return false;
}
}
// Build the sharded finish command
BSONObjBuilder finalCmd;
finalCmd.append("mapreduce.shardedfinish", cmdObj);
finalCmd.append("inputDB", dbname);
finalCmd.append("shardedOutputCollection", shardResultCollection);
finalCmd.append("shards", shardResultsB.done());
finalCmd.append("writeConcern", opCtx->getWriteConcern().toBSON());
BSONObj shardCounts = shardCountsB.done();
finalCmd.append("shardCounts", shardCounts);
BSONObjBuilder timingBuilder;
timingBuilder.append("shardProcessing", t.millis());
BSONObjBuilder aggCountsB;
for (const auto& countEntry : countsMap) {
aggCountsB.append(countEntry.first, static_cast<long long>(countEntry.second));
}
BSONObj aggCounts = aggCountsB.done();
finalCmd.append("counts", aggCounts);
if (auto elem = cmdObj[QueryRequest::cmdOptionMaxTimeMS])
finalCmd.append(elem);
if (auto elem = cmdObj[bypassDocumentValidationCommandOption()])
finalCmd.append(elem);
Timer t2;
long long reduceCount = 0;
long long outputCount = 0;
BSONObjBuilder postCountsB;
bool ok = true;
BSONObj singleResult;
if (!shardedOutput) {
LOG(1) << "MR with single shard output, NS=" << outputCollNss
<< " primary=" << outputDbInfo.primaryId();
const auto outputShard =
uassertStatusOK(shardRegistry->getShard(opCtx, outputDbInfo.primaryId()));
ShardConnection conn(opCtx, outputShard->getConnString(), outputCollNss.ns());
ok = conn->runCommand(
outDB, appendAllowImplicitCreate(finalCmd.obj(), true), singleResult);
BSONObj counts = singleResult.getObjectField("counts");
postCountsB.append(conn->getServerAddress(), counts);
reduceCount = counts.getIntField("reduce");
outputCount = counts.getIntField("output");
conn.done();
if (auto wcErrorElem = singleResult["writeConcernError"]) {
appendWriteConcernErrorToCmdResponse(outputShard->getId(), wcErrorElem, result);
}
} else {
LOG(1) << "MR with sharded output, NS=" << outputCollNss.ns();
auto outputRoutingInfo = uassertStatusOK(
catalogCache->getCollectionRoutingInfoWithRefresh(opCtx, outputCollNss));
const auto catalogClient = Grid::get(opCtx)->catalogClient();
// We need to determine whether we need to drop and shard the output collection and
// send the UUID to the shards. We will always do this if we are using replace so we
// can skip this check in that case. If using merge or reduce, we only want to do this
// if the output collection does not exist or if it exists and is an empty sharded
// collection.
bool shouldDropAndShard = replaceOutput;
if (!replaceOutput && outputCollNss.isValid()) {
const auto primaryShard =
uassertStatusOK(shardRegistry->getShard(opCtx, outputDbInfo.primaryId()));
ScopedDbConnection conn(primaryShard->getConnString());
if (!outputRoutingInfo.cm()) {
// The output collection either exists and is unsharded, or does not exist. If
// the output collection exists and is unsharded, fail because we should not go
// from unsharded to sharded.
BSONObj listCollsCmdResponse;
ok = conn->runCommand(
outDB,
BSON("listCollections" << 1 << "filter"
<< BSON("name" << outputCollNss.coll())),
listCollsCmdResponse);
BSONObj cursorObj = listCollsCmdResponse.getObjectField("cursor");
BSONObj collections = cursorObj["firstBatch"].Obj();
uassert(ErrorCodes::IllegalOperation,
"Cannot output to a sharded collection because "
"non-sharded collection exists already",
collections.isEmpty());
// If we reach here, the collection does not exist at all.
shouldDropAndShard = true;
} else {
// The output collection exists and is sharded. We need to determine whether the
// collection is empty in order to decide whether we should drop and re-shard
// it.
// We don't want to do this if the collection is not empty.
shouldDropAndShard = (conn->count(outputCollNss.ns()) == 0);
}
conn.done();
}
// If we are using replace, the output collection exists and is sharded, or the output
// collection doesn't exist we need to drop and shard the output collection. We send the
// UUID generated during shardCollection to the shards to be used to create the temp
// collections.
boost::optional<UUID> shardedOutputCollUUID;
if (shouldDropAndShard) {
auto dropCmdResponse = uassertStatusOK(
Grid::get(opCtx)
->shardRegistry()
->getConfigShard()
->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting(ReadPreference::PrimaryOnly),
"admin",
BSON("_configsvrDropCollection" << outputCollNss.toString()),
Shard::RetryPolicy::kIdempotent));
uassertStatusOK(dropCmdResponse.commandStatus);
uassertStatusOK(dropCmdResponse.writeConcernStatus);
outputRoutingInfo = createShardedOutputCollection(
opCtx, outputCollNss, splitPts, &shardedOutputCollUUID);
}
// This mongos might not have seen a UUID if setFCV was called on the cluster just after
// this mongos tried to obtain the sharded output collection's UUID, so appending the
// UUID is optional. If setFCV=3.6 has been called on the shard, the shard will error.
// Else, the shard will pull the UUID from the config server on receiving setFCV=3.6.
if (shardedOutputCollUUID) {
shardedOutputCollUUID->appendToBuilder(&finalCmd, "shardedOutputCollUUID");
}
{
// Take distributed lock to prevent split / migration.
auto scopedDistLock = catalogClient->getDistLockManager()->lock(
opCtx, outputCollNss.ns(), "mr-post-process", kNoDistLockTimeout);
uassertStatusOK(scopedDistLock.getStatus());
BSONObj finalCmdObj = appendAllowImplicitCreate(finalCmd.obj(), true);
mrCommandResults.clear();
try {
const BSONObj query;
Strategy::commandOp(opCtx,
outDB,
finalCmdObj,
outputCollNss.ns(),
query,
CollationSpec::kSimpleSpec,
&mrCommandResults);
ok = true;
} catch (DBException& e) {
e.addContext(str::stream() << "could not run final reduce on all shards for "
<< nss.ns()
<< ", output "
<< outputCollNss.ns());
throw;
}
bool hasWCError = false;
for (const auto& mrResult : mrCommandResults) {
const auto server = [&]() {
const auto shard =
uassertStatusOK(Grid::get(opCtx)->shardRegistry()->getShard(
opCtx, mrResult.shardTargetId));
return shard->getConnString().toString();
}();
singleResult = mrResult.result;
if (!hasWCError) {
if (auto wcErrorElem = singleResult["writeConcernError"]) {
appendWriteConcernErrorToCmdResponse(
mrResult.shardTargetId, wcErrorElem, result);
hasWCError = true;
}
}
ok = singleResult["ok"].trueValue();
if (!ok) {
break;
}
BSONObj counts = singleResult.getObjectField("counts");
reduceCount += counts.getIntField("reduce");
outputCount += counts.getIntField("output");
postCountsB.append(server, counts);
}
}
// Do the splitting round
catalogCache->onStaleShardVersion(std::move(outputRoutingInfo));
outputRoutingInfo =
uassertStatusOK(catalogCache->getCollectionRoutingInfo(opCtx, outputCollNss));
uassert(34359,
str::stream() << "Failed to write mapreduce output to " << outputCollNss.ns()
<< "; expected that collection to be sharded, but it was not",
outputRoutingInfo.cm());
}
cleanUp(servers, dbname, shardResultCollection);
if (!ok) {
errmsg = str::stream() << "MR post processing failed: " << singleResult.toString();
return false;
}
// copy some elements from a single result
// annoying that we have to copy all results for inline, but no way around it
if (singleResult.hasField("result")) {
result.append(singleResult.getField("result"));
} else if (singleResult.hasField("results")) {
result.append(singleResult.getField("results"));
}
BSONObjBuilder countsB(32);
// input stat is determined by aggregate MR job
countsB.append("input", aggCounts.getField("input").numberLong());
countsB.append("emit", aggCounts.getField("emit").numberLong());
// reduce count is sum of all reduces that happened
countsB.append("reduce", aggCounts.getField("reduce").numberLong() + reduceCount);
// ouput is determined by post processing on each shard
countsB.append("output", outputCount);
result.append("counts", countsB.done());
timingBuilder.append("postProcessing", t2.millis());
result.append("timeMillis", t.millis());
result.append("timing", timingBuilder.done());
result.append("shardCounts", shardCounts);
result.append("postProcessCounts", postCountsB.done());
return true;
}
private:
/**
* Creates and shards the collection for the output results.
*/
static CachedCollectionRoutingInfo createShardedOutputCollection(
OperationContext* opCtx,
const NamespaceString& nss,
const BSONObjSet& splitPts,
boost::optional<UUID>* outUUID) {
auto const catalogCache = Grid::get(opCtx)->catalogCache();
// Enable sharding on the output db
auto status =
Grid::get(opCtx)->shardRegistry()->getConfigShard()->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting(ReadPreference::PrimaryOnly),
"admin",
BSON("_configsvrEnableSharding" << nss.db().toString()),
Shard::RetryPolicy::kIdempotent);
// If the database has sharding already enabled, we can ignore the error
if (status.isOK()) {
// Invalidate the output database so it gets reloaded on the next fetch attempt
catalogCache->purgeDatabase(nss.db());
} else if (status != ErrorCodes::AlreadyInitialized) {
uassertStatusOK(status);
}
// Points will be properly sorted using the set
const std::vector<BSONObj> sortedSplitPts(splitPts.begin(), splitPts.end());
// Specifying the initial split points explicitly will cause _configsvrShardCollection to
// distribute the initial chunks evenly across shards.
// Note that it's not safe to pre-split onto non-primary shards through shardCollection:
// a conflict may result if multiple map-reduces are writing to the same output collection,
//
// TODO: pre-split mapReduce output in a safer way.
// Invalidate the routing table cache entry for this collection so that we reload the
// collection the next time it's accessed, even if we receive a failure, e.g. NetworkError.
ON_BLOCK_EXIT([catalogCache, nss] { catalogCache->invalidateShardedCollection(nss); });
ConfigsvrShardCollectionRequest configShardCollRequest;
configShardCollRequest.set_configsvrShardCollection(nss);
configShardCollRequest.setKey(BSON("_id" << 1));
configShardCollRequest.setUnique(true);
configShardCollRequest.setInitialSplitPoints(sortedSplitPts);
configShardCollRequest.setGetUUIDfromPrimaryShard(false);
auto cmdResponse = uassertStatusOK(
Grid::get(opCtx)->shardRegistry()->getConfigShard()->runCommandWithFixedRetryAttempts(
opCtx,
ReadPreferenceSetting(ReadPreference::PrimaryOnly),
"admin",
configShardCollRequest.toBSON(),
Shard::RetryPolicy::kIdempotent));
uassertStatusOK(cmdResponse.commandStatus);
// Parse the UUID for the sharded collection from the shardCollection response.
auto shardCollResponse = ConfigsvrShardCollectionResponse::parse(
IDLParserErrorContext("ConfigsvrShardCollectionResponse"), cmdResponse.response);
*outUUID = std::move(shardCollResponse.getCollectionUUID());
// Make sure the cached metadata for the collection knows that we are now sharded
return uassertStatusOK(catalogCache->getCollectionRoutingInfo(opCtx, nss));
}
/**
* Drops the temporary results collections from each shard.
*/
static void cleanUp(const std::set<std::string>& servers,
const std::string& dbName,
const std::string& shardResultCollection) {
try {
// drop collections with tmp results on each shard
for (const auto& server : servers) {
ScopedDbConnection conn(server);
conn->dropCollection(dbName + "." + shardResultCollection);
conn.done();
}
} catch (const DBException& e) {
warning() << "Cannot cleanup shard results" << redact(e);
} catch (const std::exception& e) {
severe() << "Cannot cleanup shard results" << causedBy(redact(e.what()));
}
}
} clusterMapReduceCmd;
} // namespace
} // namespace mongo
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