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/**
* Copyright (C) 2013 10gen 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 <string>
#include "mongo/db/clientcursor.h"
#include "mongo/db/dbmessage.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/query/canonical_query.h"
#include "mongo/util/net/message.h"
namespace mongo {
class NamespaceString;
class OperationContext;
class ScopedRecoveryUnitSwapper {
public:
ScopedRecoveryUnitSwapper(ClientCursor* cc, OperationContext* txn);
~ScopedRecoveryUnitSwapper();
/**
* Dismissing the RU swapper causes it to simply free the recovery unit rather than swapping
* it back into the ClientCursor.
*/
void dismiss();
private:
ClientCursor* _cc;
OperationContext* _txn;
bool _dismissed;
std::unique_ptr<RecoveryUnit> _txnPreviousRecoveryUnit;
OperationContext::RecoveryUnitState _txnPreviousRecoveryUnitState;
};
/**
* Returns true if enough results have been prepared to stop adding more to the first batch.
*
* Should be called *after* adding to the result set rather than before.
*/
bool enoughForFirstBatch(const LiteParsedQuery& pq, int numDocs, int bytesBuffered);
/**
* Returns true if enough results have been prepared to stop adding more to a getMore batch.
*
* Should be called *after* adding to the result set rather than before.
*/
bool enoughForGetMore(int ntoreturn, int numDocs, int bytesBuffered);
/**
* Whether or not the ClientCursor* is tailable.
*/
bool isCursorTailable(const ClientCursor* cursor);
/**
* Whether or not the ClientCursor* has the awaitData flag set.
*/
bool isCursorAwaitData(const ClientCursor* cursor);
/**
* Returns true if we should keep a cursor around because we're expecting to return more query
* results.
*
* If false, the caller should close the cursor and indicate this to the client by sending back
* a cursor ID of 0.
*/
bool shouldSaveCursor(OperationContext* txn,
const Collection* collection,
PlanExecutor::ExecState finalState,
PlanExecutor* exec);
/**
* Similar to shouldSaveCursor(), but used in getMore to determine whether we should keep
* the cursor around for additional getMores().
*
* If false, the caller should close the cursor and indicate this to the client by sending back
* a cursor ID of 0.
*/
bool shouldSaveCursorGetMore(PlanExecutor::ExecState finalState,
PlanExecutor* exec,
bool isTailable);
/**
* Fills out the CurOp for "txn" with information about this query.
*/
void beginQueryOp(OperationContext* txn,
const NamespaceString& nss,
const BSONObj& queryObj,
int ntoreturn,
int ntoskip);
/**
* Fills out CurOp for "txn" with information regarding this query's execution.
*
* Uses explain functionality to extract stats from 'exec'.
*
* The database profiling level, 'dbProfilingLevel', is used to conditionalize whether or not we
* do expensive stats gathering.
*/
void endQueryOp(OperationContext* txn,
const PlanExecutor& exec,
int dbProfilingLevel,
int numResults,
CursorId cursorId);
/**
* Constructs a PlanExecutor for a query with the oplogReplay option set to true,
* for the query 'cq' over the collection 'collection'. The PlanExecutor will
* wrap a singleton OplogStart stage.
*
* The oplog start finding hack requires that 'cq' has a $gt or $gte predicate over
* a field named 'ts'.
*/
StatusWith<std::unique_ptr<PlanExecutor>> getOplogStartHack(OperationContext* txn,
Collection* collection,
std::unique_ptr<CanonicalQuery> cq);
/**
* Called from the getMore entry point in ops/query.cpp.
*/
QueryResult::View getMore(OperationContext* txn,
const char* ns,
int ntoreturn,
long long cursorid,
int pass,
bool& exhaust,
bool* isCursorAuthorized);
/**
* Run the query 'q' and place the result in 'result'.
*/
std::string runQuery(OperationContext* txn,
QueryMessage& q,
const NamespaceString& ns,
Message& result);
} // namespace mongo
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