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/*
* Pooling Allocator
* (C) 1999-2008 Jack Lloyd
* 2005 Matthew Gregan
* 2005-2006 Matt Johnston
*
* Distributed under the terms of the Botan license
*/
#include <botan/mem_pool.h>
#include <botan/util.h>
#include <botan/mem_ops.h>
#include <algorithm>
#include <exception>
namespace Botan {
namespace {
/*
* Memory Allocation Exception
*/
struct Memory_Exhaustion : public std::bad_alloc
{
const char* what() const throw()
{ return "Ran out of memory, allocation failed"; }
};
}
/*
* Memory_Block Constructor
*/
Pooling_Allocator::Memory_Block::Memory_Block(void* buf)
{
buffer = static_cast<byte*>(buf);
bitmap = 0;
buffer_end = buffer + (BLOCK_SIZE * BITMAP_SIZE);
}
/*
* See if ptr is contained by this block
*/
bool Pooling_Allocator::Memory_Block::contains(void* ptr,
u32bit length) const throw()
{
return ((buffer <= ptr) &&
(buffer_end >= static_cast<byte*>(ptr) + length * BLOCK_SIZE));
}
/*
* Allocate some memory, if possible
*/
byte* Pooling_Allocator::Memory_Block::alloc(u32bit n) throw()
{
if(n == 0 || n > BITMAP_SIZE)
return 0;
if(n == BITMAP_SIZE)
{
if(bitmap)
return 0;
else
{
bitmap = ~bitmap;
return buffer;
}
}
bitmap_type mask = (static_cast<bitmap_type>(1) << n) - 1;
u32bit offset = 0;
while(bitmap & mask)
{
mask <<= 1;
++offset;
if((bitmap & mask) == 0)
break;
if(mask >> 63)
break;
}
if(bitmap & mask)
return 0;
bitmap |= mask;
return buffer + offset * BLOCK_SIZE;
}
/*
* Mark this memory as free, if we own it
*/
void Pooling_Allocator::Memory_Block::free(void* ptr, u32bit blocks) throw()
{
clear_mem(static_cast<byte*>(ptr), blocks * BLOCK_SIZE);
const u32bit offset = (static_cast<byte*>(ptr) - buffer) / BLOCK_SIZE;
if(offset == 0 && blocks == BITMAP_SIZE)
bitmap = ~bitmap;
else
{
for(u32bit j = 0; j != blocks; ++j)
bitmap &= ~(static_cast<bitmap_type>(1) << (j+offset));
}
}
/*
* Pooling_Allocator Constructor
*/
Pooling_Allocator::Pooling_Allocator(Mutex* m) : mutex(m)
{
last_used = blocks.begin();
}
/*
* Pooling_Allocator Destructor
*/
Pooling_Allocator::~Pooling_Allocator()
{
delete mutex;
if(blocks.size())
throw Invalid_State("Pooling_Allocator: Never released memory");
}
/*
* Free all remaining memory
*/
void Pooling_Allocator::destroy()
{
Mutex_Holder lock(mutex);
blocks.clear();
for(u32bit j = 0; j != allocated.size(); ++j)
dealloc_block(allocated[j].first, allocated[j].second);
allocated.clear();
}
/*
* Allocation
*/
void* Pooling_Allocator::allocate(u32bit n)
{
const u32bit BITMAP_SIZE = Memory_Block::bitmap_size();
const u32bit BLOCK_SIZE = Memory_Block::block_size();
Mutex_Holder lock(mutex);
if(n <= BITMAP_SIZE * BLOCK_SIZE)
{
const u32bit block_no = round_up(n, BLOCK_SIZE) / BLOCK_SIZE;
byte* mem = allocate_blocks(block_no);
if(mem)
return mem;
get_more_core(BOTAN_MEM_POOL_CHUNK_SIZE);
mem = allocate_blocks(block_no);
if(mem)
return mem;
throw Memory_Exhaustion();
}
void* new_buf = alloc_block(n);
if(new_buf)
return new_buf;
throw Memory_Exhaustion();
}
/*
* Deallocation
*/
void Pooling_Allocator::deallocate(void* ptr, u32bit n)
{
const u32bit BITMAP_SIZE = Memory_Block::bitmap_size();
const u32bit BLOCK_SIZE = Memory_Block::block_size();
if(ptr == 0 || n == 0)
return;
Mutex_Holder lock(mutex);
if(n > BITMAP_SIZE * BLOCK_SIZE)
dealloc_block(ptr, n);
else
{
const u32bit block_no = round_up(n, BLOCK_SIZE) / BLOCK_SIZE;
std::vector<Memory_Block>::iterator i =
std::lower_bound(blocks.begin(), blocks.end(), Memory_Block(ptr));
if(i == blocks.end() || !i->contains(ptr, block_no))
throw Invalid_State("Pointer released to the wrong allocator");
i->free(ptr, block_no);
}
}
/*
* Try to get some memory from an existing block
*/
byte* Pooling_Allocator::allocate_blocks(u32bit n)
{
if(blocks.empty())
return 0;
std::vector<Memory_Block>::iterator i = last_used;
do
{
byte* mem = i->alloc(n);
if(mem)
{
last_used = i;
return mem;
}
++i;
if(i == blocks.end())
i = blocks.begin();
}
while(i != last_used);
return 0;
}
/*
* Allocate more memory for the pool
*/
void Pooling_Allocator::get_more_core(u32bit in_bytes)
{
const u32bit BITMAP_SIZE = Memory_Block::bitmap_size();
const u32bit BLOCK_SIZE = Memory_Block::block_size();
const u32bit TOTAL_BLOCK_SIZE = BLOCK_SIZE * BITMAP_SIZE;
// upper bound on allocation is 1 MiB
in_bytes = std::min<u32bit>(in_bytes, 1024 * 1024);
const u32bit in_blocks = round_up(in_bytes, BLOCK_SIZE) / TOTAL_BLOCK_SIZE;
const u32bit to_allocate = in_blocks * TOTAL_BLOCK_SIZE;
void* ptr = alloc_block(to_allocate);
if(ptr == 0)
throw Memory_Exhaustion();
allocated.push_back(std::make_pair(ptr, to_allocate));
for(u32bit j = 0; j != in_blocks; ++j)
{
byte* byte_ptr = static_cast<byte*>(ptr);
blocks.push_back(Memory_Block(byte_ptr + j * TOTAL_BLOCK_SIZE));
}
std::sort(blocks.begin(), blocks.end());
last_used = std::lower_bound(blocks.begin(), blocks.end(),
Memory_Block(ptr));
}
}
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