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/**
* @file test_allocator.cpp
* @brief quick and dirty allocator for tracking memory allocations
*
* $LicenseInfo:firstyear=2012&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2012, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#include "test_allocator.h"
#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
#include <libkern/OSAtomic.h>
#elif defined(_MSC_VER)
#include <Windows.h>
#elif (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ ) > 40100
// atomic extensions are built into GCC on posix platforms
#endif
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <iostream>
#include <new>
#include <boost/thread.hpp>
struct BlockHeader
{
struct Block * next;
std::size_t size;
bool in_use;
};
struct Block
{
BlockHeader hdr;
unsigned char data[1];
};
#define TRACE_MSG(val) std::cout << __FUNCTION__ << "(" << val << ") [" << __FILE__ << ":" << __LINE__ << "]" << std::endl;
static unsigned char MemBuf[ 4096 * 1024 ];
Block * pNext = static_cast<Block *>(static_cast<void *>(MemBuf));
volatile std::size_t MemTotal = 0;
// cross-platform compare and swap operation
static bool CAS(void * volatile * ptr, void * expected, void * new_value)
{
#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
return OSAtomicCompareAndSwapPtr( expected, new_value, ptr );
#elif defined(_MSC_VER)
return expected == InterlockedCompareExchangePointer( ptr, new_value, expected );
#elif (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ ) > 40100
return __sync_bool_compare_and_swap( ptr, expected, new_value );
#endif
}
static void * GetMem(std::size_t size)
{
// TRACE_MSG(size);
volatile Block * pBlock = NULL;
volatile Block * pNewNext = NULL;
// do a lock-free update of the global next pointer
do
{
pBlock = pNext;
pNewNext = (volatile Block *)(pBlock->data + size);
} while(! CAS((void * volatile *) &pNext, (void *) pBlock, (void *) pNewNext));
// if we get here, we safely carved out a block of memory in the
// memory pool...
// initialize our block
pBlock->hdr.next = (Block *)(pBlock->data + size);
pBlock->hdr.size = size;
pBlock->hdr.in_use = true;
memset((void *) pBlock->data, 0, pBlock->hdr.size);
// do a lock-free update of the global memory total
volatile size_t total = 0;
volatile size_t new_total = 0;
do
{
total = MemTotal;
new_total = total + size;
} while (! CAS((void * volatile *) &MemTotal, (void *) total, (void *) new_total));
return (void *) pBlock->data;
}
static void FreeMem(void * p)
{
// get the pointer to the block record
Block * pBlock = (Block *)((unsigned char *) p - sizeof(BlockHeader));
// TRACE_MSG(pBlock->hdr.size);
bool * cur_in_use = &(pBlock->hdr.in_use);
volatile bool in_use = false;
bool new_in_use = false;
do
{
in_use = pBlock->hdr.in_use;
} while (! CAS((void * volatile *) cur_in_use, (void *) in_use, (void *) new_in_use));
// do a lock-free update of the global memory total
volatile size_t total = 0;
volatile size_t new_total = 0;
do
{
total = MemTotal;
new_total = total - pBlock->hdr.size;
} while (! CAS((void * volatile *)&MemTotal, (void *) total, (void *) new_total));
}
std::size_t GetMemTotal()
{
return MemTotal;
}
void * operator new(std::size_t size) //throw(std::bad_alloc)
{
return GetMem( size );
}
void * operator new[](std::size_t size) //throw(std::bad_alloc)
{
return GetMem( size );
}
void operator delete(void * p) throw()
{
if (p)
{
FreeMem( p );
}
}
void operator delete[](void * p) throw()
{
if (p)
{
FreeMem( p );
}
}
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