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/*
Copyright (c) 2008-2009 Z RESEARCH, Inc. <http://www.zresearch.com>
This file is part of GlusterFS.
GlusterFS 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; either version 3 of the License,
or (at your option) any later version.
GlusterFS 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, see
<http://www.gnu.org/licenses/>.
*/
#include "mem-pool.h"
#include "logging.h"
#include <stdlib.h>
#define GF_MEM_POOL_PAD_BOUNDARY (sizeof(struct list_head))
#define mem_pool_chunkhead2ptr(head) ((head) + GF_MEM_POOL_PAD_BOUNDARY)
#define mem_pool_ptr2chunkhead(ptr) ((ptr) - GF_MEM_POOL_PAD_BOUNDARY)
struct mem_pool *
mem_pool_new_fn (unsigned long sizeof_type,
unsigned long count)
{
struct mem_pool *mem_pool = NULL;
unsigned long padded_sizeof_type = 0;
void *pool = NULL;
int i = 0;
struct list_head *list = NULL;
if (!sizeof_type || !count) {
gf_log ("mem-pool", GF_LOG_ERROR, "invalid argument");
return NULL;
}
padded_sizeof_type = sizeof_type + GF_MEM_POOL_PAD_BOUNDARY;
mem_pool = CALLOC (sizeof (*mem_pool), 1);
if (!mem_pool)
return NULL;
LOCK_INIT (&mem_pool->lock);
INIT_LIST_HEAD (&mem_pool->list);
mem_pool->padded_sizeof_type = padded_sizeof_type;
mem_pool->cold_count = count;
mem_pool->real_sizeof_type = sizeof_type;
pool = CALLOC (count, padded_sizeof_type);
if (!pool) {
FREE (mem_pool);
return NULL;
}
for (i = 0; i < count; i++) {
list = pool + (i * (padded_sizeof_type));
INIT_LIST_HEAD (list);
list_add_tail (list, &mem_pool->list);
}
mem_pool->pool = pool;
mem_pool->pool_end = pool + (count * (padded_sizeof_type));
return mem_pool;
}
void *
mem_get (struct mem_pool *mem_pool)
{
struct list_head *list = NULL;
void *ptr = NULL;
if (!mem_pool) {
gf_log ("mem-pool", GF_LOG_ERROR, "invalid argument");
return NULL;
}
LOCK (&mem_pool->lock);
{
if (mem_pool->cold_count) {
list = mem_pool->list.next;
list_del (list);
mem_pool->hot_count++;
mem_pool->cold_count--;
ptr = list;
goto fwd_addr_out;
}
/* This is a problem area. If we've run out of
* chunks in our slab above, we need to allocate
* enough memory to service this request.
* The problem is, these indvidual chunks will fail
* the first address range check in __is_member. Now, since
* we're not allocating a full second slab, we wont have
* enough info perform the range check in __is_member.
*
* I am working around this by performing a regular allocation
* , just the way the caller would've done when not using the
* mem-pool. That also means, we're not padding the size with
* the list_head structure because, this will not be added to
* the list of chunks that belong to the mem-pool allocated
* initially.
*
* This is the best we can do without adding functionality for
* managing multiple slabs. That does not interest us at present
* because it is too much work knowing that a better slab
* allocator is coming RSN.
*/
ptr = MALLOC (mem_pool->real_sizeof_type);
if (!ptr)
goto unlocked_out;
}
fwd_addr_out:
ptr = mem_pool_chunkhead2ptr (ptr);
unlocked_out:
UNLOCK (&mem_pool->lock);
return ptr;
}
static int
__is_member (struct mem_pool *pool, void *ptr)
{
if (!pool || !ptr) {
gf_log ("mem-pool", GF_LOG_ERROR, "invalid argument");
return -1;
}
if (ptr < pool->pool || ptr >= pool->pool_end)
return 0;
if ((mem_pool_ptr2chunkhead (ptr) - pool->pool)
% pool->padded_sizeof_type)
return -1;
return 1;
}
void
mem_put (struct mem_pool *pool, void *ptr)
{
struct list_head *list = NULL;
if (!pool || !ptr) {
gf_log ("mem-pool", GF_LOG_ERROR, "invalid argument");
return;
}
LOCK (&pool->lock);
{
switch (__is_member (pool, ptr))
{
case 1:
list = mem_pool_ptr2chunkhead (ptr);
pool->hot_count--;
pool->cold_count++;
list_add (list, &pool->list);
break;
case -1:
/* For some reason, the address given is within
* the address range of the mem-pool but does not align
* with the expected start of a chunk that includes
* the list headers also. Sounds like a problem in
* layers of clouds up above us. ;)
*/
abort ();
break;
case 0:
/* The address is outside the range of the mem-pool. We
* assume here that this address was allocated at a
* point when the mem-pool was out of chunks in mem_get
* or the programmer has made a mistake by calling the
* wrong de-allocation interface. We do
* not have enough info to distinguish between the two
* situations.
*/
FREE (ptr);
break;
default:
/* log error */
break;
}
}
UNLOCK (&pool->lock);
}
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