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// @file file_allocator.h
/* Copyright 2009 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.
*/
#include "mongo/platform/basic.h"
#include <list>
#include <boost/filesystem/path.hpp>
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/concurrency/mutex.h"
namespace mongo {
/*
* Handles allocation of contiguous files on disk. Allocation may be
* requested asynchronously or synchronously.
* singleton
*/
class FileAllocator {
MONGO_DISALLOW_COPYING(FileAllocator);
/*
* The public functions may not be called concurrently. The allocation
* functions may be called multiple times per file, but only the first
* size specified per file will be used.
*/
public:
void start();
/**
* May be called if file exists. If file exists, or its allocation has
* been requested, size is updated to match existing file size.
*/
void requestAllocation(const std::string& name, long& size);
/**
* Returns when file has been allocated. If file exists, size is
* updated to match existing file size.
*/
void allocateAsap(const std::string& name, unsigned long long& size);
void waitUntilFinished() const;
static void ensureLength(int fd, long size);
/** @return the singleton */
static FileAllocator* get();
private:
FileAllocator();
void checkFailure();
// caller must hold pendingMutex_ lock. Returns size if allocated or
// allocation requested, -1 otherwise.
long prevSize(const std::string& name) const;
// caller must hold pendingMutex_ lock.
bool inProgress(const std::string& name) const;
/** called from the worked thread */
static void run(FileAllocator* fa);
// generate a unique name for temporary files
std::string makeTempFileName(boost::filesystem::path root);
mutable stdx::mutex _pendingMutex;
mutable stdx::condition_variable _pendingUpdated;
std::list<std::string> _pending;
mutable std::map<std::string, long> _pendingSize;
// unique number for temporary files
static unsigned long long _uniqueNumber;
bool _failed;
static FileAllocator* _instance;
};
} // namespace mongo
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