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/**
* Copyright (C) 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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.
*/
#pragma once
#include <memory>
#include <queue>
#include "mongo/executor/task_executor.h"
#include "mongo/s/query/cluster_client_cursor.h"
#include "mongo/s/query/cluster_client_cursor_params.h"
#include "mongo/s/query/cluster_query_result.h"
#include "mongo/s/query/router_exec_stage.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
class RouterStageMock;
/**
* An RAII object which owns a ClusterClientCursor and kills the cursor if it is not explicitly
* released.
*/
class ClusterClientCursorGuard final {
MONGO_DISALLOW_COPYING(ClusterClientCursorGuard);
public:
ClusterClientCursorGuard(OperationContext* opCtx, std::unique_ptr<ClusterClientCursor> ccc);
/**
* If a cursor is owned, safely destroys the cursor, cleaning up remote cursor state if
* necessary. May block waiting for remote cursor cleanup.
*
* If no cursor is owned, does nothing.
*/
~ClusterClientCursorGuard();
ClusterClientCursorGuard(ClusterClientCursorGuard&&) = default;
ClusterClientCursorGuard& operator=(ClusterClientCursorGuard&&) = default;
/**
* Returns a pointer to the underlying cursor.
*/
ClusterClientCursor* operator->();
/**
* Transfers ownership of the underlying cursor to the caller.
*/
std::unique_ptr<ClusterClientCursor> releaseCursor();
private:
OperationContext* _opCtx;
std::unique_ptr<ClusterClientCursor> _ccc;
};
class ClusterClientCursorImpl final : public ClusterClientCursor {
MONGO_DISALLOW_COPYING(ClusterClientCursorImpl);
public:
/**
* Constructs a CCC whose safe cleanup is ensured by an RAII object.
*/
static ClusterClientCursorGuard make(OperationContext* opCtx,
executor::TaskExecutor* executor,
ClusterClientCursorParams&& params);
StatusWith<ClusterQueryResult> next(RouterExecStage::ExecContext) final;
void kill(OperationContext* opCtx) final;
void reattachToOperationContext(OperationContext* opCtx) final;
void detachFromOperationContext() final;
OperationContext* getCurrentOperationContext() const final;
bool isTailable() const final;
bool isTailableAndAwaitData() const final;
BSONObj getOriginatingCommand() const final;
std::size_t getNumRemotes() const final;
long long getNumReturnedSoFar() const final;
void queueResult(const ClusterQueryResult& result) final;
bool remotesExhausted() final;
Status setAwaitDataTimeout(Milliseconds awaitDataTimeout) final;
boost::optional<LogicalSessionId> getLsid() const final;
boost::optional<TxnNumber> getTxnNumber() const final;
boost::optional<ReadPreferenceSetting> getReadPreference() const final;
public:
/** private for tests */
/**
* Constructs a CCC whose result set is generated by a mock execution stage.
*/
ClusterClientCursorImpl(OperationContext* opCtx,
std::unique_ptr<RouterStageMock> root,
ClusterClientCursorParams&& params,
boost::optional<LogicalSessionId> lsid);
/**
* Constructs a cluster client cursor.
*/
ClusterClientCursorImpl(OperationContext* opCtx,
executor::TaskExecutor* executor,
ClusterClientCursorParams&& params,
boost::optional<LogicalSessionId> lsid);
private:
/**
* Constructs the pipeline of MergerPlanStages which will be used to answer the query.
*/
std::unique_ptr<RouterExecStage> buildMergerPlan(OperationContext* opCtx,
executor::TaskExecutor* executor,
ClusterClientCursorParams* params);
ClusterClientCursorParams _params;
// Number of documents already returned by next().
long long _numReturnedSoFar = 0;
// The root stage of the pipeline used to return the result set, merged from the remote nodes.
std::unique_ptr<RouterExecStage> _root;
// Stores documents queued by queueResult(). BSONObjs within the stashed results must be owned.
std::queue<ClusterQueryResult> _stash;
// Stores the logical session id for this cursor.
boost::optional<LogicalSessionId> _lsid;
// The OperationContext that we're executing within. This can be updated if necessary by using
// detachFromOperationContext() and reattachToOperationContext().
OperationContext* _opCtx = nullptr;
};
} // namespace mongo
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