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/*
* Copyright (c) 2011 Intel Corporation. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <config.h>
#include <errno.h>
#include <sys/types.h>
#include <stdlib.h>
#include "indexer.h"
/*
* Indexer - to find a structure given an index
*
* We store pointers using a double lookup and return an index to the
* user which is then used to retrieve the pointer. The upper bits of
* the index are itself an index into an array of memory allocations.
* The lower bits specify the offset into the allocated memory where
* the pointer is stored.
*
* This allows us to adjust the number of pointers stored by the index
* list without taking a lock during data lookups.
*/
static int idx_grow(struct indexer *idx)
{
union idx_entry *entry;
int i, start_index;
if (idx->size >= IDX_ARRAY_SIZE)
goto nomem;
idx->array[idx->size] = calloc(IDX_ENTRY_SIZE, sizeof(union idx_entry));
if (!idx->array[idx->size])
goto nomem;
entry = idx->array[idx->size];
start_index = idx->size << IDX_ENTRY_BITS;
entry[IDX_ENTRY_SIZE - 1].next = idx->free_list;
for (i = IDX_ENTRY_SIZE - 2; i >= 0; i--)
entry[i].next = start_index + i + 1;
/* Index 0 is reserved */
if (start_index == 0)
start_index++;
idx->free_list = start_index;
idx->size++;
return start_index;
nomem:
errno = ENOMEM;
return -1;
}
int idx_insert(struct indexer *idx, void *item)
{
union idx_entry *entry;
int index;
if ((index = idx->free_list) == 0) {
if ((index = idx_grow(idx)) <= 0)
return index;
}
entry = idx->array[idx_array_index(index)];
idx->free_list = entry[idx_entry_index(index)].next;
entry[idx_entry_index(index)].item = item;
return index;
}
void *idx_remove(struct indexer *idx, int index)
{
union idx_entry *entry;
void *item;
entry = idx->array[idx_array_index(index)];
item = entry[idx_entry_index(index)].item;
entry[idx_entry_index(index)].next = idx->free_list;
idx->free_list = index;
return item;
}
void idx_replace(struct indexer *idx, int index, void *item)
{
union idx_entry *entry;
entry = idx->array[idx_array_index(index)];
entry[idx_entry_index(index)].item = item;
}
static int idm_grow(struct index_map *idm, int index)
{
idm->array[idx_array_index(index)] = calloc(IDX_ENTRY_SIZE, sizeof(void *));
if (!idm->array[idx_array_index(index)])
goto nomem;
return index;
nomem:
errno = ENOMEM;
return -1;
}
int idm_set(struct index_map *idm, int index, void *item)
{
void **entry;
if (index > IDX_MAX_INDEX) {
errno = ENOMEM;
return -1;
}
if (!idm->array[idx_array_index(index)]) {
if (idm_grow(idm, index) < 0)
return -1;
}
entry = idm->array[idx_array_index(index)];
entry[idx_entry_index(index)] = item;
return index;
}
void *idm_clear(struct index_map *idm, int index)
{
void **entry;
void *item;
entry = idm->array[idx_array_index(index)];
item = entry[idx_entry_index(index)];
entry[idx_entry_index(index)] = NULL;
return item;
}
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