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// cursors.h
/*
* Copyright (C) 2010 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/base/disallow_copying.h"
#include "mongo/client/parallel.h"
#include "mongo/platform/random.h"
namespace mongo {
class QueryMessage;
class ShardedClientCursor {
MONGO_DISALLOW_COPYING(ShardedClientCursor);
public:
ShardedClientCursor(QueryMessage& q, ParallelSortClusteredCursor* cursor);
~ShardedClientCursor();
long long getId();
/**
* @return the cumulative number of documents seen by this cursor.
*/
int getTotalSent() const;
/**
* Sends queries to the shards and gather the result for this batch.
*
* @param r The request object from the client
* @param ntoreturn Number of documents to return
* @param buffer The buffer to use to store the results.
* @param docCount This will contain the number of documents gathered for this batch after
* a successful call.
*
* @return true if this is not the final batch.
*/
bool sendNextBatch(int ntoreturn, BufBuilder& buffer, int& docCount);
void accessed();
/** @return idle time in ms */
long long idleTime(long long now);
std::string getNS() {
return _cursor->getNS();
}
// The default initial buffer size for sending responses.
static const int INIT_REPLY_BUFFER_SIZE;
protected:
ParallelSortClusteredCursor* _cursor;
int _skip;
int _ntoreturn;
int _totalSent;
bool _done;
long long _id;
long long _lastAccessMillis; // 0 means no timeout
};
typedef std::shared_ptr<ShardedClientCursor> ShardedClientCursorPtr;
class CursorCache {
public:
static long long TIMEOUT;
typedef std::map<long long, ShardedClientCursorPtr> MapSharded;
typedef std::map<long long, int> MapShardedInt;
typedef std::map<long long, std::string> MapNormal;
CursorCache();
~CursorCache();
ShardedClientCursorPtr get(long long id) const;
int getMaxTimeMS(long long id) const;
void store(ShardedClientCursorPtr cursor, int maxTimeMS);
void updateMaxTimeMS(long long id, int maxTimeMS);
void remove(long long id);
void storeRef(const std::string& server, long long id, const std::string& ns);
void removeRef(long long id);
/** @return the server for id or "" */
std::string getRef(long long id) const;
/** @return the ns for id or "" */
std::string getRefNS(long long id) const;
void gotKillCursors(Message& m);
void appendInfo(BSONObjBuilder& result) const;
long long genId();
void doTimeouts();
void startTimeoutThread();
private:
mutable stdx::mutex _mutex;
PseudoRandom _random;
// Maps sharded cursor ID to ShardedClientCursorPtr.
MapSharded _cursors;
// Maps sharded cursor ID to remaining max time. Value can be any of:
// - the constant "kMaxTimeCursorNoTimeLimit", or
// - the constant "kMaxTimeCursorTimeLimitExpired", or
// - a positive integer representing milliseconds of remaining time
MapShardedInt _cursorsMaxTimeMS;
// Maps passthrough cursor ID to shard name.
MapNormal _refs;
// Maps passthrough cursor ID to namespace.
MapNormal _refsNS;
long long _shardedTotal;
static const int _myLogLevel;
};
extern CursorCache cursorCache;
}
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