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// @file file_allocator.h
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mongo/pch.h"
#include <list>
#include <boost/filesystem/path.hpp>
#include <boost/thread/condition.hpp>
#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 : boost::noncopyable {
/*
* 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 string &name, long &size );
/**
* Returns when file has been allocated. If file exists, size is
* updated to match existing file size.
*/
void allocateAsap( const string &name, unsigned long long &size );
void waitUntilFinished() const;
bool hasFailed() 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 string &name ) const;
// caller must hold pendingMutex_ lock.
bool inProgress( const string &name ) const;
/** called from the worked thread */
static void run( FileAllocator * fa );
// generate a unique name for temporary files
string makeTempFileName( boost::filesystem::path root );
mutable mongo::mutex _pendingMutex;
mutable boost::condition _pendingUpdated;
std::list< string > _pending;
mutable map< string, long > _pendingSize;
// unique number for temporary files
static unsigned long long _uniqueNumber;
bool _failed;
static FileAllocator* _instance;
};
} // namespace mongo
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