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// durable_mapped_file.h
/*
*
* Copyright (C) 2008 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 "mongo/util/mmap.h"
#include "mongo/util/paths.h"
namespace mongo {
/** DurableMappedFile adds some layers atop memory mapped files - specifically our handling of private views & such.
if you don't care about journaling/durability (temp sort files & such) use MemoryMappedFile class,
not this.
*/
class DurableMappedFile : private MemoryMappedFile {
protected:
virtual void* viewForFlushing() { return _view_write; }
public:
DurableMappedFile();
virtual ~DurableMappedFile();
virtual void close();
/** @return true if opened ok. */
bool open(const std::string& fname, bool sequentialHint /*typically we open with this false*/);
/** @return file length */
unsigned long long length() const { return MemoryMappedFile::length(); }
string filename() const { return MemoryMappedFile::filename(); }
void flush(bool sync) { MemoryMappedFile::flush(sync); }
/* Creates with length if DNE, otherwise uses existing file length,
passed length.
@param sequentialHint if true will be sequentially accessed
@return true for ok
*/
bool create(const std::string& fname, unsigned long long& len, bool sequentialHint);
/* Get the "standard" view (which is the private one).
@return the private view.
*/
void* getView() const { return _view_private; }
/* Get the "write" view (which is required for writing).
@return the write view.
*/
void* view_write() const { return _view_write; }
/** for a filename a/b/c.3
filePath() is "a/b/c"
fileSuffixNo() is 3
if the suffix is "ns", fileSuffixNo -1
*/
const RelativePath& relativePath() const {
DEV verify( !_p._p.empty() );
return _p;
}
int fileSuffixNo() const { return _fileSuffixNo; }
HANDLE getFd() { return MemoryMappedFile::getFd(); }
/** true if we have written.
set in PREPLOGBUFFER, it is NOT set immediately on write intent declaration.
reset to false in REMAPPRIVATEVIEW
*/
bool willNeedRemap() { return _willNeedRemap; }
void setWillNeedRemap() { _willNeedRemap = true; }
void remapThePrivateView();
virtual bool isDurableMappedFile() { return true; }
private:
void *_view_write;
void *_view_private;
bool _willNeedRemap;
RelativePath _p; // e.g. "somepath/dbname"
int _fileSuffixNo; // e.g. 3. -1="ns"
void setPath(const std::string& pathAndFileName);
bool finishOpening();
};
/** for durability support we want to be able to map pointers to specific DurableMappedFile objects.
*/
class PointerToDurableMappedFile : boost::noncopyable {
public:
PointerToDurableMappedFile();
/** register view.
threadsafe
*/
void add(void *view, DurableMappedFile *f);
/** de-register view.
threadsafe
*/
void remove(void *view);
/** find associated MMF object for a given pointer.
threadsafe
@param ofs out returns offset into the view of the pointer, if found.
@return the DurableMappedFile to which this pointer belongs. null if not found.
*/
DurableMappedFile* find(void *p, /*out*/ size_t& ofs);
/** for doing many finds in a row with one lock operation */
mutex& _mutex() { return _m; }
DurableMappedFile* find_inlock(void *p, /*out*/ size_t& ofs);
map<void*,DurableMappedFile*>::iterator finditer_inlock(void *p) { return _views.upper_bound(p); }
unsigned numberOfViews_inlock() const { return _views.size(); }
private:
mutex _m;
map<void*, DurableMappedFile*> _views;
};
// allows a pointer into any private view of a DurableMappedFile to be resolved to the DurableMappedFile object
extern PointerToDurableMappedFile privateViews;
}
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