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// extent.h
/**
* 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 <iosfwd>
#include <string>
#include <vector>
#include "mongo/db/storage/mmap_v1/catalog/namespace.h"
#include "mongo/db/storage/mmap_v1/diskloc.h"
namespace mongo {
/* extents are datafile regions where all the records within the region
belong to the same namespace.
(11:12:35 AM) dm10gen: when the extent is allocated, all its empty space is stuck into one big DeletedRecord
(11:12:55 AM) dm10gen: and that is placed on the free list
*/
#pragma pack(1)
struct Extent {
enum { extentSignature = 0x41424344 };
unsigned magic;
DiskLoc myLoc;
/* next/prev extent for this namespace */
DiskLoc xnext;
DiskLoc xprev;
/* which namespace this extent is for. this is just for troubleshooting really
and won't even be correct if the collection were renamed!
*/
Namespace nsDiagnostic;
int length; /* size of the extent, including these fields */
DiskLoc firstRecord;
DiskLoc lastRecord;
char _extentData[4];
// -----
bool validates(const DiskLoc diskLoc, std::vector<std::string>* errors = NULL) const;
BSONObj dump() const;
void dump(std::iostream& s) const;
bool isOk() const {
return magic == extentSignature;
}
void assertOk() const {
verify(isOk());
}
static int HeaderSize() {
return sizeof(Extent) - 4;
}
};
#pragma pack()
}
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