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//
// MemoryPool.h
//
// Library: Foundation
// Package: Core
// Module: MemoryPool
//
// Definition of the MemoryPool class.
//
// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_MemoryPool_INCLUDED
#define Foundation_MemoryPool_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include <vector>
#include <cstddef>
namespace Poco {
class Foundation_API MemoryPool
/// A simple pool for fixed-size memory blocks.
///
/// The main purpose of this class is to speed-up
/// memory allocations, as well as to reduce memory
/// fragmentation in situations where the same blocks
/// are allocated all over again, such as in server
/// applications.
///
/// All allocated blocks are retained for future use.
/// A limit on the number of blocks can be specified.
/// Blocks can be preallocated.
{
public:
MemoryPool(std::size_t blockSize, int preAlloc = 0, int maxAlloc = 0);
/// Creates a MemoryPool for blocks with the given blockSize.
/// The number of blocks given in preAlloc are preallocated.
~MemoryPool();
void* get();
/// Returns a memory block. If there are no more blocks
/// in the pool, a new block will be allocated.
///
/// If maxAlloc blocks are already allocated, an
/// OutOfMemoryException is thrown.
void release(void* ptr);
/// Releases a memory block and returns it to the pool.
std::size_t blockSize() const;
/// Returns the block size.
int allocated() const;
/// Returns the number of allocated blocks.
int available() const;
/// Returns the number of available blocks in the pool.
private:
MemoryPool();
MemoryPool(const MemoryPool&);
MemoryPool& operator = (const MemoryPool&);
void clear();
enum
{
BLOCK_RESERVE = 128
};
typedef std::vector<char*> BlockVec;
std::size_t _blockSize;
int _maxAlloc;
int _allocated;
BlockVec _blocks;
FastMutex _mutex;
};
//
// inlines
//
inline std::size_t MemoryPool::blockSize() const
{
return _blockSize;
}
inline int MemoryPool::allocated() const
{
return _allocated;
}
inline int MemoryPool::available() const
{
return (int) _blocks.size();
}
} // namespace Poco
#endif // Foundation_MemoryPool_INCLUDED
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