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/* Copyright (C) 20012 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/>.
*/
/**
* Defines CursorId and defines ByLocKey, which pairs up a DiskLoc
* and a CursorId and provides a comparison operation.
*/
#pragma once
#include <limits>
#include <map>
#include "mongo/db/diskloc.h"
namespace mongo {
typedef long long CursorId; /* passed to the client so it can send back on getMore */
static const CursorId INVALID_CURSOR_ID = -1; // But see SERVER-5726.
// TODO(acm|mathias): ByLocKey allows constructing a map so we can
// invalidate or advance all cursors pointing to a DiskLoc when we
// remove that record. During review of moving this class to this
// header, Mathias said: "On further thought, I think this need
// would be better served by an unordered_map<DiskLoc,
// unordered_map<CursorId, ClientCursor*>>." At which point, this
// class should be removed.
struct ByLocKey {
ByLocKey(const DiskLoc& l, const CursorId& i) : loc(l), id(i) {}
static ByLocKey min(const DiskLoc& l) {
return ByLocKey(l, std::numeric_limits<long long>::min());
}
static ByLocKey max(const DiskLoc& l) {
return ByLocKey(l, std::numeric_limits<long long>::max());
}
const DiskLoc loc;
const CursorId id;
};
inline bool operator<(const ByLocKey& lhs, const ByLocKey& rhs) {
int x = lhs.loc.compare(rhs.loc);
if (x)
return x < 0;
return lhs.id < rhs.id;
}
class ClientCursor;
typedef std::map<ByLocKey, ClientCursor*> CCByLoc;
} // namespace mongo
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