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// @file logfile.h simple file log writing / journaling
/**
* 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/client/export_macros.h"
namespace mongo {
class MONGO_CLIENT_API LogFile {
public:
/** create the file and open. must not already exist.
throws UserAssertion on i/o error
*/
LogFile(const std::string& name, bool readwrite = false);
/** closes */
~LogFile();
/** append to file. does not return until sync'd. uses direct i/o when possible.
throws UserAssertion on an i/o error
note direct i/o may have alignment requirements
*/
void synchronousAppend(const void* buf, size_t len);
/** write at specified offset. must be aligned. noreturn until physically written. thread safe */
void writeAt(unsigned long long offset, const void* _bug, size_t _len);
void readAt(unsigned long long offset, void* _buf, size_t _len);
const std::string _name;
void truncate(); // Removes extra data after current position
private:
#if defined(_WIN32)
typedef HANDLE fd_type;
#else
typedef int fd_type;
#endif
fd_type _fd;
bool _direct; // are we using direct I/O
// Block size, in case of direct I/O we need to test alignment against the page size,
// which can be different than 4kB.
size_t _blkSize;
};
}
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