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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.
*/
#pragma once
#include <boost/optional.hpp>
#include <functional>
#include <memory>
#include <vector>
#include "mongo/bson/bsonobj.h"
#include "mongo/client/read_preference.h"
#include "mongo/db/auth/user_name.h"
#include "mongo/db/cursor_id.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/pipeline/pipeline.h"
#include "mongo/db/query/cursor_response.h"
#include "mongo/db/query/tailable_mode.h"
#include "mongo/s/client/shard.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
namespace executor {
class TaskExecutor;
}
class OperationContext;
class RouterExecStage;
/**
* The resulting ClusterClientCursor will take ownership of the existing remote cursor, generating
* results based on the cursor's current state.
*
* Note that any results already generated from this cursor will not be returned by the resulting
* ClusterClientCursor. The caller is responsible for ensuring that results previously generated by
* this cursor have been processed.
*/
struct ClusterClientCursorParams {
// When mongos has to do a merge in order to return results to the client in the correct sort
// order, it requests a sortKey meta-projection using this field name.
static const char kSortKeyField[];
struct RemoteCursor {
RemoteCursor(ShardId shardId, HostAndPort hostAndPort, CursorResponse cursorResponse)
: shardId(std::move(shardId)),
hostAndPort(std::move(hostAndPort)),
cursorResponse(std::move(cursorResponse)) {}
// The shardId of the shard on which the cursor resides.
ShardId shardId;
// The exact host (within the shard) on which the cursor resides.
HostAndPort hostAndPort;
// Encompasses the state of the established cursor.
CursorResponse cursorResponse;
};
ClusterClientCursorParams(NamespaceString nss,
UserNameIterator authenticatedUsersIter,
boost::optional<ReadPreferenceSetting> readPref = boost::none)
: nsString(std::move(nss)) {
while (authenticatedUsersIter.more()) {
authenticatedUsers.emplace_back(authenticatedUsersIter.next());
}
if (readPref) {
readPreference = std::move(readPref.get());
}
}
// Namespace against which the cursors exist.
NamespaceString nsString;
// The set of authenticated users when this cursor was created.
std::vector<UserName> authenticatedUsers;
// Per-remote node data.
std::vector<RemoteCursor> remotes;
// The sort specification. Leave empty if there is no sort.
BSONObj sort;
// The number of results to skip. Optional. Should not be forwarded to the remote hosts in
// 'cmdObj'.
boost::optional<long long> skip;
// The number of results per batch. Optional. If specified, will be specified as the batch for
// each getMore.
boost::optional<long long> batchSize;
// Limits the number of results returned by the ClusterClientCursor to this many. Optional.
// Should be forwarded to the remote hosts in 'cmdObj'.
boost::optional<long long> limit;
// If set, we use this pipeline to merge the output of aggregations on each remote.
std::unique_ptr<Pipeline, Pipeline::Deleter> mergePipeline;
// Whether this cursor is tailing a capped collection, and whether it has the awaitData option
// set.
TailableMode tailableMode = TailableMode::kNormal;
// Set if a readPreference must be respected throughout the lifetime of the cursor.
boost::optional<ReadPreferenceSetting> readPreference;
// If valid, is called to return the RouterExecStage which becomes the initial source in this
// cursor's execution plan. Otherwise, a RouterStageMerge is used.
stdx::function<std::unique_ptr<RouterExecStage>(
OperationContext*, executor::TaskExecutor*, ClusterClientCursorParams*)>
createCustomCursorSource;
// Whether the client indicated that it is willing to receive partial results in the case of an
// unreachable host.
bool isAllowPartialResults = false;
};
} // mongo
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