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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 <boost/optional.hpp>
#include "mongo/db/auth/user_name.h"
#include "mongo/db/jsobj.h"
#include "mongo/s/query/cluster_query_result.h"
#include "mongo/util/time_support.h"
namespace mongo {
class OperationContext;
template <typename T>
class StatusWith;
/**
* ClusterClientCursor is used to generate results from cursor-generating commands on one or
* more remote hosts. A cursor-generating command (e.g. the find command) is one that
* establishes a ClientCursor and a matching cursor id on the remote host. In order to retrieve
* all command results, getMores must be issued against each of the remote cursors until they
* are exhausted.
*
* Results are generated using a pipeline of mongoS query execution stages called RouterExecStage.
*
* Does not throw exceptions.
*/
class ClusterClientCursor {
public:
virtual ~ClusterClientCursor(){};
/**
* Returns the next available result document (along with an ok status). May block waiting
* for results from remote nodes.
*
* If there are no further results, the end of the stream is indicated with an empty
* QueryResult and an ok status.
*
* A non-ok status is returned in case of any error.
*/
virtual StatusWith<ClusterQueryResult> next(OperationContext* opCtx) = 0;
/**
* Must be called before destruction to abandon a not-yet-exhausted cursor. If next() has
* already returned boost::none, then the cursor is exhausted and is safe to destroy.
*
* May block waiting for responses from remote hosts.
*/
virtual void kill(OperationContext* opCtx) = 0;
/**
* Returns whether or not this cursor is tailing a capped collection on a shard.
*/
virtual bool isTailable() const = 0;
/**
* Returns the set of authenticated users when this cursor was created.
*/
virtual UserNameIterator getAuthenticatedUsers() const = 0;
/**
* Returns the view definition associated with this cursor, if any.
*/
virtual boost::optional<BSONObj> viewDefinition() const = 0;
/**
* Returns the number of result documents returned so far by this cursor via the next() method.
*/
virtual long long getNumReturnedSoFar() const = 0;
/**
* Stash the ClusterQueryResult so that it gets returned from the CCC on a later call to
* next().
*
* Queued documents are returned in FIFO order. The queued results are exhausted before
* generating further results from the underlying mongos query stages.
*
* 'obj' must be owned BSON.
*/
virtual void queueResult(const ClusterQueryResult& result) = 0;
/**
* Returns whether or not all the remote cursors underlying this cursor have been exhausted.
*/
virtual bool remotesExhausted() = 0;
/**
* Sets the maxTimeMS value that the cursor should forward with any internally issued getMore
* requests.
*
* Returns a non-OK status if this cursor type does not support maxTimeMS on getMore (i.e. if
* the cursor is not tailable + awaitData).
*/
virtual Status setAwaitDataTimeout(Milliseconds awaitDataTimeout) = 0;
};
} // namespace mongo
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