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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.
*/
#include "mongo/platform/basic.h"
#include <boost/optional.hpp>
#include "mongo/client/read_preference.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/commands.h"
#include "mongo/db/matcher/extensions_callback_noop.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/db/stats/counters.h"
#include "mongo/db/views/resolved_view.h"
#include "mongo/rpc/get_status_from_command_result.h"
#include "mongo/s/catalog_cache.h"
#include "mongo/s/cluster_commands_helpers.h"
#include "mongo/s/commands/cluster_explain.h"
#include "mongo/s/grid.h"
#include "mongo/s/query/cluster_aggregate.h"
#include "mongo/s/query/cluster_find.h"
namespace mongo {
namespace {
using std::unique_ptr;
using std::string;
using std::vector;
const char kTermField[] = "term";
/**
* Implements the find command on mongos.
*/
class ClusterFindCmd final : public Command {
public:
ClusterFindCmd() : Command("find") {}
std::unique_ptr<CommandInvocation> parse(OperationContext* opCtx,
const OpMsgRequest& opMsgRequest) override {
// TODO: Parse into a QueryRequest here.
return std::make_unique<Invocation>(this, opMsgRequest, opMsgRequest.getDatabase());
}
AllowedOnSecondary secondaryAllowed(ServiceContext* context) const override {
return AllowedOnSecondary::kOptIn;
}
bool maintenanceOk() const final {
return false;
}
bool adminOnly() const final {
return false;
}
bool shouldAffectCommandCounter() const final {
return false;
}
std::string help() const override {
return "query for documents";
}
class Invocation final : public CommandInvocation {
public:
Invocation(const ClusterFindCmd* definition, const OpMsgRequest& request, StringData dbName)
: CommandInvocation(definition), _request(request), _dbName(dbName) {}
private:
bool supportsWriteConcern() const override {
return false;
}
bool supportsReadConcern(repl::ReadConcernLevel level) const final {
return true;
}
NamespaceString ns() const override {
// TODO get the ns from the parsed QueryRequest.
return NamespaceString(
CommandHelpers::parseNsCollectionRequired(_dbName, _request.body));
}
/**
* In order to run the find command, you must be authorized for the "find" action
* type on the collection.
*/
void doCheckAuthorization(OperationContext* opCtx) const final {
auto hasTerm = _request.body.hasField(kTermField);
uassertStatusOK(
AuthorizationSession::get(opCtx->getClient())->checkAuthForFind(ns(), hasTerm));
}
void explain(OperationContext* opCtx,
ExplainOptions::Verbosity verbosity,
rpc::ReplyBuilderInterface* result) override {
// Parse the command BSON to a QueryRequest.
bool isExplain = true;
auto qr =
uassertStatusOK(QueryRequest::makeFromFindCommand(ns(), _request.body, isExplain));
try {
const auto explainCmd = ClusterExplain::wrapAsExplain(_request.body, verbosity);
long long millisElapsed;
std::vector<AsyncRequestsSender::Response> shardResponses;
// We will time how long it takes to run the commands on the shards.
Timer timer;
const auto routingInfo = uassertStatusOK(
Grid::get(opCtx)->catalogCache()->getCollectionRoutingInfo(opCtx, qr->nss()));
shardResponses =
scatterGatherVersionedTargetByRoutingTable(opCtx,
qr->nss().db(),
qr->nss(),
routingInfo,
explainCmd,
ReadPreferenceSetting::get(opCtx),
Shard::RetryPolicy::kIdempotent,
qr->getFilter(),
qr->getCollation());
millisElapsed = timer.millis();
const char* mongosStageName =
ClusterExplain::getStageNameForReadOp(shardResponses.size(), _request.body);
auto bodyBuilder = result->getBodyBuilder();
uassertStatusOK(ClusterExplain::buildExplainResult(
opCtx,
ClusterExplain::downconvert(opCtx, shardResponses),
mongosStageName,
millisElapsed,
&bodyBuilder));
} catch (const ExceptionFor<ErrorCodes::CommandOnShardedViewNotSupportedOnMongod>& ex) {
auto bodyBuilder = result->getBodyBuilder();
bodyBuilder.resetToEmpty();
auto aggCmdOnView = uassertStatusOK(qr->asAggregationCommand());
auto aggRequestOnView = uassertStatusOK(
AggregationRequest::parseFromBSON(ns(), aggCmdOnView, verbosity));
uassertStatusOK(ClusterAggregate::retryOnViewError(
opCtx, aggRequestOnView, *ex.extraInfo<ResolvedView>(), ns(), &bodyBuilder));
}
}
void run(OperationContext* opCtx, rpc::ReplyBuilderInterface* result) {
// We count find command as a query op.
globalOpCounters.gotQuery();
const bool isExplain = false;
auto qr =
uassertStatusOK(QueryRequest::makeFromFindCommand(ns(), _request.body, isExplain));
const boost::intrusive_ptr<ExpressionContext> expCtx;
auto cq = uassertStatusOK(
CanonicalQuery::canonicalize(opCtx,
std::move(qr),
expCtx,
ExtensionsCallbackNoop(),
MatchExpressionParser::kAllowAllSpecialFeatures));
try {
// Do the work to generate the first batch of results. This blocks waiting to get
// responses from the shard(s).
std::vector<BSONObj> batch;
auto cursorId =
ClusterFind::runQuery(opCtx, *cq, ReadPreferenceSetting::get(opCtx), &batch);
// Build the response document.
CursorResponseBuilder::Options options;
options.isInitialResponse = true;
CursorResponseBuilder firstBatch(result, options);
for (const auto& obj : batch) {
firstBatch.append(obj);
}
firstBatch.done(cursorId, cq->ns());
} catch (const ExceptionFor<ErrorCodes::CommandOnShardedViewNotSupportedOnMongod>& ex) {
result->reset();
auto aggCmdOnView = uassertStatusOK(cq->getQueryRequest().asAggregationCommand());
auto aggRequestOnView =
uassertStatusOK(AggregationRequest::parseFromBSON(ns(), aggCmdOnView));
auto bodyBuilder = result->getBodyBuilder();
uassertStatusOK(ClusterAggregate::retryOnViewError(
opCtx, aggRequestOnView, *ex.extraInfo<ResolvedView>(), ns(), &bodyBuilder));
}
}
private:
const OpMsgRequest& _request;
const StringData _dbName;
};
} cmdFindCluster;
} // namespace
} // namespace mongo
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