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// data_file.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/>.
*/
#pragma once
#include "mongo/db/diskloc.h"
#include "mongo/db/pdfile_version.h"
#include "mongo/db/storage/durable_mapped_file.h"
namespace mongo {
class ExtentManager;
/* a datafile - i.e. the "dbname.<#>" files :
----------------------
DataFileHeader
----------------------
Extent (for a particular namespace)
Record
...
Record (some chained for unused space)
----------------------
more Extents...
----------------------
*/
#pragma pack(1)
class DataFileHeader {
public:
int version;
int versionMinor;
int fileLength;
DiskLoc unused; /* unused is the portion of the file that doesn't belong to any allocated extents. -1 = no more */
int unusedLength;
char reserved[8192 - 4*4 - 8];
char data[4]; // first extent starts here
enum { HeaderSize = 8192 };
bool isCurrentVersion() const {
return version == PDFILE_VERSION && ( versionMinor == PDFILE_VERSION_MINOR_22_AND_OLDER
|| versionMinor == PDFILE_VERSION_MINOR_24_AND_NEWER
);
}
bool uninitialized() const { return version == 0; }
void init(int fileno, int filelength, const char* filename);
bool isEmpty() const {
return uninitialized() || ( unusedLength == fileLength - HeaderSize - 16 );
}
};
#pragma pack()
class DataFile {
friend class DataFileMgr;
friend class BasicCursor;
friend class ExtentManager;
public:
DataFile(int fn) : _mb(0), fileNo(fn) { }
/** @return true if found and opened. if uninitialized (prealloc only) does not open. */
Status openExisting( const char *filename );
/** creates if DNE */
void open(const char *filename, int requestedDataSize = 0, bool preallocateOnly = false);
DiskLoc allocExtentArea( int size );
DataFileHeader *getHeader() { return header(); }
HANDLE getFd() { return mmf.getFd(); }
unsigned long long length() const { return mmf.length(); }
/* return max size an extent may be */
static int maxSize();
/** fsync */
void flush( bool sync );
private:
void badOfs(int) const;
void badOfs2(int) const;
int defaultSize( const char *filename ) const;
void grow(DiskLoc dl, int size);
char* p() const { return (char *) _mb; }
DataFileHeader* header() { return (DataFileHeader*) _mb; }
DurableMappedFile mmf;
void *_mb; // the memory mapped view
int fileNo;
};
}
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