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140 lines
3.2 KiB
C++

/* Copyright (C) 2014 InfiniDB, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; version 2 of
the License.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */
/******************************************************************************************
* $Id$
*
******************************************************************************************/
/* This allocator is an attempt to consolidate small allocations and
deallocations to boost performance and reduce mem fragmentation. */
#pragma once
#include <unistd.h>
#include <stdint.h>
#include <vector>
#include <map>
#include <memory>
#include <atomic>
namespace utils
{
class PoolAllocator
{
public:
static const unsigned DEFAULT_WINDOW_SIZE = 4096 * 40; // should be an integral # of pages
explicit PoolAllocator(unsigned windowSize = DEFAULT_WINDOW_SIZE, bool isTmpSpace = false,
bool _useLock = false)
: allocSize(windowSize)
, tmpSpace(isTmpSpace)
, capacityRemaining(0)
, memUsage(0)
, nextAlloc(0)
, useLock(_useLock)
, lock(false)
{
}
PoolAllocator(const PoolAllocator& p)
: allocSize(p.allocSize)
, tmpSpace(p.tmpSpace)
, capacityRemaining(0)
, memUsage(0)
, nextAlloc(0)
, useLock(p.useLock)
, lock(false)
{
}
virtual ~PoolAllocator()
{
}
PoolAllocator& operator=(const PoolAllocator&);
void* allocate(uint64_t size);
void deallocate(void* p);
void deallocateAll();
inline uint64_t getMemUsage() const
{
return memUsage;
}
unsigned getWindowSize() const
{
return allocSize;
}
void setUseLock(bool ul)
{
useLock = ul;
}
private:
void newBlock();
void* allocOOB(uint64_t size);
unsigned allocSize;
std::vector<std::shared_ptr<uint8_t[]>> mem;
bool tmpSpace;
unsigned capacityRemaining;
uint64_t memUsage;
uint8_t* nextAlloc;
bool useLock;
std::atomic<bool> lock;
struct OOBMemInfo
{
std::shared_ptr<uint8_t[]> mem;
uint64_t size;
};
typedef std::map<void*, OOBMemInfo> OutOfBandMap;
OutOfBandMap oob; // for mem chunks bigger than the window size; these can be dealloc'd
};
inline void* PoolAllocator::allocate(uint64_t size)
{
void* ret;
bool _false = false;
if (useLock)
while (!lock.compare_exchange_weak(_false, true, std::memory_order_acquire))
_false = false;
if (size > allocSize)
{
ret = allocOOB(size);
if (useLock)
lock.store(false, std::memory_order_release);
return ret;
}
if (size > capacityRemaining)
newBlock();
ret = (void*)nextAlloc;
nextAlloc += size;
capacityRemaining -= size;
memUsage += size;
if (useLock)
lock.store(false, std::memory_order_release);
return ret;
}
} // namespace utils