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/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* This file provides some functions to manage a pool of pre-allocated
* objects. It also provides a method to reserve a pre-defined number
* of objects for higher priorty requests. The allocations follow the
* following rules:
*
* 1. An allocation will succeed at any priority if there is more than
* the reserved number of objects free.
* 2. Only high priority allocations will succeed when there are less
* than the reserved number of objects free.
* 3. When an allocation is freed it is always added to the high priority
* pool if there are less than the reserved number of allocations
* available.
*/
#include <pool.h>
#include <string.h>
#include <stdlib.h>
#include <ccan/list/list.h>
void* pool_get(struct pool *pool, enum pool_priority priority)
{
void *obj;
if (!pool->free_count ||
((pool->free_count <= pool->reserved) && priority == POOL_NORMAL))
return NULL;
pool->free_count--;
obj = (void *) list_pop_(&pool->free_list, 0);
assert(obj);
memset(obj, 0, pool->obj_size);
return obj;
}
void pool_free_object(struct pool *pool, void *obj)
{
pool->free_count++;
list_add_tail(&pool->free_list,
(struct list_node *) (obj));
}
int pool_init(struct pool *pool, size_t obj_size, int count, int reserved)
{
int i;
if (obj_size < sizeof(struct list_node))
obj_size = sizeof(struct list_node);
assert(count >= reserved);
pool->buf = malloc(obj_size*count);
if (!pool->buf)
return -1;
pool->obj_size = obj_size;
pool->free_count = count;
pool->reserved = reserved;
list_head_init(&pool->free_list);
for(i = 0; i < count; i++)
list_add_tail(&pool->free_list,
(struct list_node *) (pool->buf + obj_size*i));
return 0;
}
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