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/*-
* Copyright (c) 2005 Michael Bushkov <bushman@rsu.ru>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: src/usr.sbin/nscd/cacheplcs.c,v 1.3 2008/10/12 00:44:27 delphij Exp $
*/
#include <assert.h>
#include <string.h>
#include "cacheplcs.h"
#include "debug.h"
static void cache_fifo_policy_update_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static void cache_lfu_policy_add_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static struct cache_policy_item_ * cache_lfu_policy_create_item(void);
static void cache_lfu_policy_destroy_item(struct cache_policy_item_ *);
static struct cache_policy_item_ *cache_lfu_policy_get_first_item(
struct cache_policy_ *);
static struct cache_policy_item_ *cache_lfu_policy_get_last_item(
struct cache_policy_ *);
static struct cache_policy_item_ *cache_lfu_policy_get_next_item(
struct cache_policy_ *, struct cache_policy_item_ *);
static struct cache_policy_item_ *cache_lfu_policy_get_prev_item(
struct cache_policy_ *, struct cache_policy_item_ *);
static void cache_lfu_policy_remove_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static void cache_lfu_policy_update_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static void cache_lru_policy_update_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static void cache_queue_policy_add_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static struct cache_policy_item_ * cache_queue_policy_create_item();
static void cache_queue_policy_destroy_item(struct cache_policy_item_ *);
static struct cache_policy_item_ *cache_queue_policy_get_first_item(
struct cache_policy_ *);
static struct cache_policy_item_ *cache_queue_policy_get_last_item(
struct cache_policy_ *);
static struct cache_policy_item_ *cache_queue_policy_get_next_item(
struct cache_policy_ *, struct cache_policy_item_ *);
static struct cache_policy_item_ *cache_queue_policy_get_prev_item(
struct cache_policy_ *, struct cache_policy_item_ *);
static void cache_queue_policy_remove_item(struct cache_policy_ *,
struct cache_policy_item_ *);
static void destroy_cache_queue_policy(struct cache_queue_policy_ *);
static struct cache_queue_policy_ *init_cache_queue_policy(void);
/*
* All cache_queue_policy_XXX functions below will be used to fill
* the cache_queue_policy structure. They implement the most functionality of
* LRU and FIFO policies. LRU and FIFO policies are actually the
* cache_queue_policy_ with cache_update_item function changed.
*/
static struct cache_policy_item_ *
cache_queue_policy_create_item(void)
{
struct cache_queue_policy_item_ *retval;
TRACE_IN(cache_queue_policy_create_item);
retval = (struct cache_queue_policy_item_ *)calloc(1,
sizeof(struct cache_queue_policy_item_));
assert(retval != NULL);
TRACE_OUT(cache_queue_policy_create_item);
return ((struct cache_policy_item_ *)retval);
}
static void
cache_queue_policy_destroy_item(struct cache_policy_item_ *item)
{
TRACE_IN(cache_queue_policy_destroy_item);
assert(item != NULL);
free(item);
TRACE_OUT(cache_queue_policy_destroy_item);
}
static void
cache_queue_policy_add_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_queue_policy_ *queue_policy;
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(cache_queue_policy_add_item);
queue_policy = (struct cache_queue_policy_ *)policy;
queue_item = (struct cache_queue_policy_item_ *)item;
TAILQ_INSERT_TAIL(&queue_policy->head, queue_item, entries);
TRACE_OUT(cache_queue_policy_add_item);
}
static void
cache_queue_policy_remove_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_queue_policy_ *queue_policy;
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(cache_queue_policy_remove_item);
queue_policy = (struct cache_queue_policy_ *)policy;
queue_item = (struct cache_queue_policy_item_ *)item;
TAILQ_REMOVE(&queue_policy->head, queue_item, entries);
TRACE_OUT(cache_queue_policy_remove_item);
}
static struct cache_policy_item_ *
cache_queue_policy_get_first_item(struct cache_policy_ *policy)
{
struct cache_queue_policy_ *queue_policy;
TRACE_IN(cache_queue_policy_get_first_item);
queue_policy = (struct cache_queue_policy_ *)policy;
TRACE_OUT(cache_queue_policy_get_first_item);
return ((struct cache_policy_item_ *)TAILQ_FIRST(&queue_policy->head));
}
static struct cache_policy_item_ *
cache_queue_policy_get_last_item(struct cache_policy_ *policy)
{
struct cache_queue_policy_ *queue_policy;
TRACE_IN(cache_queue_policy_get_last_item);
queue_policy = (struct cache_queue_policy_ *)policy;
TRACE_OUT(cache_queue_policy_get_last_item);
return ((struct cache_policy_item_ *)TAILQ_LAST(&queue_policy->head,
cache_queue_policy_head_));
}
static struct cache_policy_item_ *
cache_queue_policy_get_next_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_queue_policy_ *queue_policy;
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(cache_queue_policy_get_next_item);
queue_policy = (struct cache_queue_policy_ *)policy;
queue_item = (struct cache_queue_policy_item_ *)item;
TRACE_OUT(cache_queue_policy_get_next_item);
return ((struct cache_policy_item_ *)TAILQ_NEXT(queue_item, entries));
}
static struct cache_policy_item_ *
cache_queue_policy_get_prev_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_queue_policy_ *queue_policy;
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(cache_queue_policy_get_prev_item);
queue_policy = (struct cache_queue_policy_ *)policy;
queue_item = (struct cache_queue_policy_item_ *)item;
TRACE_OUT(cache_queue_policy_get_prev_item);
return ((struct cache_policy_item_ *)TAILQ_PREV(queue_item,
cache_queue_policy_head_, entries));
}
/*
* Initializes cache_queue_policy_ by filling the structure with the functions
* pointers, defined above
*/
static struct cache_queue_policy_ *
init_cache_queue_policy(void)
{
struct cache_queue_policy_ *retval;
TRACE_IN(init_cache_queue_policy);
retval = (struct cache_queue_policy_ *)calloc(1,
sizeof(struct cache_queue_policy_));
assert(retval != NULL);
retval->parent_data.create_item_func = cache_queue_policy_create_item;
retval->parent_data.destroy_item_func = cache_queue_policy_destroy_item;
retval->parent_data.add_item_func = cache_queue_policy_add_item;
retval->parent_data.remove_item_func = cache_queue_policy_remove_item;
retval->parent_data.get_first_item_func =
cache_queue_policy_get_first_item;
retval->parent_data.get_last_item_func =
cache_queue_policy_get_last_item;
retval->parent_data.get_next_item_func =
cache_queue_policy_get_next_item;
retval->parent_data.get_prev_item_func =
cache_queue_policy_get_prev_item;
TAILQ_INIT(&retval->head);
TRACE_OUT(init_cache_queue_policy);
return (retval);
}
static void
destroy_cache_queue_policy(struct cache_queue_policy_ *queue_policy)
{
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(destroy_cache_queue_policy);
while (!TAILQ_EMPTY(&queue_policy->head)) {
queue_item = TAILQ_FIRST(&queue_policy->head);
TAILQ_REMOVE(&queue_policy->head, queue_item, entries);
cache_queue_policy_destroy_item(
(struct cache_policy_item_ *)queue_item);
}
free(queue_policy);
TRACE_OUT(destroy_cache_queue_policy);
}
/*
* Makes cache_queue_policy_ behave like FIFO policy - we don't do anything,
* when the cache element is updated. So it always stays in its initial
* position in the queue - that is exactly the FIFO functionality.
*/
static void
cache_fifo_policy_update_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
TRACE_IN(cache_fifo_policy_update_item);
/* policy and item arguments are ignored */
TRACE_OUT(cache_fifo_policy_update_item);
}
struct cache_policy_ *
init_cache_fifo_policy(void)
{
struct cache_queue_policy_ *retval;
TRACE_IN(init_cache_fifo_policy);
retval = init_cache_queue_policy();
retval->parent_data.update_item_func = cache_fifo_policy_update_item;
TRACE_OUT(init_cache_fifo_policy);
return ((struct cache_policy_ *)retval);
}
void
destroy_cache_fifo_policy(struct cache_policy_ *policy)
{
struct cache_queue_policy_ *queue_policy;
TRACE_IN(destroy_cache_fifo_policy);
queue_policy = (struct cache_queue_policy_ *)policy;
destroy_cache_queue_policy(queue_policy);
TRACE_OUT(destroy_cache_fifo_policy);
}
/*
* Makes cache_queue_policy_ behave like LRU policy. On each update, cache
* element is moved to the end of the queue - so it would be deleted in last
* turn. That is exactly the LRU policy functionality.
*/
static void
cache_lru_policy_update_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_queue_policy_ *queue_policy;
struct cache_queue_policy_item_ *queue_item;
TRACE_IN(cache_lru_policy_update_item);
queue_policy = (struct cache_queue_policy_ *)policy;
queue_item = (struct cache_queue_policy_item_ *)item;
TAILQ_REMOVE(&queue_policy->head, queue_item, entries);
TAILQ_INSERT_TAIL(&queue_policy->head, queue_item, entries);
TRACE_OUT(cache_lru_policy_update_item);
}
struct cache_policy_ *
init_cache_lru_policy(void)
{
struct cache_queue_policy_ *retval;
TRACE_IN(init_cache_lru_policy);
retval = init_cache_queue_policy();
retval->parent_data.update_item_func = cache_lru_policy_update_item;
TRACE_OUT(init_cache_lru_policy);
return ((struct cache_policy_ *)retval);
}
void
destroy_cache_lru_policy(struct cache_policy_ *policy)
{
struct cache_queue_policy_ *queue_policy;
TRACE_IN(destroy_cache_lru_policy);
queue_policy = (struct cache_queue_policy_ *)policy;
destroy_cache_queue_policy(queue_policy);
TRACE_OUT(destroy_cache_lru_policy);
}
/*
* LFU (least frequently used) policy implementation differs much from the
* LRU and FIFO (both based on cache_queue_policy_). Almost all cache_policy_
* functions are implemented specifically for this policy. The idea of this
* policy is to represent frequency (real number) as the integer number and
* use it as the index in the array. Each array's element is
* the list of elements. For example, if we have the 100-elements
* array for this policy, the elements with frequency 0.1 (calls per-second)
* would be in 10th element of the array.
*/
static struct cache_policy_item_ *
cache_lfu_policy_create_item(void)
{
struct cache_lfu_policy_item_ *retval;
TRACE_IN(cache_lfu_policy_create_item);
retval = (struct cache_lfu_policy_item_ *)calloc(1,
sizeof(struct cache_lfu_policy_item_));
assert(retval != NULL);
TRACE_OUT(cache_lfu_policy_create_item);
return ((struct cache_policy_item_ *)retval);
}
static void
cache_lfu_policy_destroy_item(struct cache_policy_item_ *item)
{
TRACE_IN(cache_lfu_policy_destroy_item);
assert(item != NULL);
free(item);
TRACE_OUT(cache_lfu_policy_destroy_item);
}
/*
* When placed in the LFU policy queue for the first time, the maximum
* frequency is assigned to the element
*/
static void
cache_lfu_policy_add_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
TRACE_IN(cache_lfu_policy_add_item);
lfu_policy = (struct cache_lfu_policy_ *)policy;
lfu_item = (struct cache_lfu_policy_item_ *)item;
lfu_item->frequency = CACHELIB_MAX_FREQUENCY - 1;
TAILQ_INSERT_HEAD(&(lfu_policy->groups[CACHELIB_MAX_FREQUENCY - 1]),
lfu_item, entries);
TRACE_OUT(cache_lfu_policy_add_item);
}
/*
* On each update the frequency of the element is recalculated and, if it
* changed, the element would be moved to the another place in the array.
*/
static void
cache_lfu_policy_update_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
int index;
TRACE_IN(cache_lfu_policy_update_item);
lfu_policy = (struct cache_lfu_policy_ *)policy;
lfu_item = (struct cache_lfu_policy_item_ *)item;
/*
* We calculate the square of the request_count to avoid grouping of
* all elements at the start of the array (for example, if array size is
* 100 and most of its elements has frequency below the 0.01, they
* all would be grouped in the first array's position). Other
* techniques should be used here later to ensure, that elements are
* equally distributed in the array and not grouped in its beginning.
*/
if (lfu_item->parent_data.last_request_time.tv_sec !=
lfu_item->parent_data.creation_time.tv_sec) {
index = ((double)lfu_item->parent_data.request_count *
(double)lfu_item->parent_data.request_count /
(lfu_item->parent_data.last_request_time.tv_sec -
lfu_item->parent_data.creation_time.tv_sec + 1)) *
CACHELIB_MAX_FREQUENCY;
if (index >= CACHELIB_MAX_FREQUENCY)
index = CACHELIB_MAX_FREQUENCY - 1;
} else
index = CACHELIB_MAX_FREQUENCY - 1;
TAILQ_REMOVE(&(lfu_policy->groups[lfu_item->frequency]), lfu_item,
entries);
lfu_item->frequency = index;
TAILQ_INSERT_HEAD(&(lfu_policy->groups[index]), lfu_item, entries);
TRACE_OUT(cache_lfu_policy_update_item);
}
static void
cache_lfu_policy_remove_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
TRACE_IN(cache_lfu_policy_remove_item);
lfu_policy = (struct cache_lfu_policy_ *)policy;
lfu_item = (struct cache_lfu_policy_item_ *)item;
TAILQ_REMOVE(&(lfu_policy->groups[lfu_item->frequency]), lfu_item,
entries);
TRACE_OUT(cache_lfu_policy_remove_item);
}
static struct cache_policy_item_ *
cache_lfu_policy_get_first_item(struct cache_policy_ *policy)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
int i;
TRACE_IN(cache_lfu_policy_get_first_item);
lfu_item = NULL;
lfu_policy = (struct cache_lfu_policy_ *)policy;
for (i = 0; i < CACHELIB_MAX_FREQUENCY; ++i)
if (!TAILQ_EMPTY(&(lfu_policy->groups[i]))) {
lfu_item = TAILQ_FIRST(&(lfu_policy->groups[i]));
break;
}
TRACE_OUT(cache_lfu_policy_get_first_item);
return ((struct cache_policy_item_ *)lfu_item);
}
static struct cache_policy_item_ *
cache_lfu_policy_get_last_item(struct cache_policy_ *policy)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
int i;
TRACE_IN(cache_lfu_policy_get_last_item);
lfu_item = NULL;
lfu_policy = (struct cache_lfu_policy_ *)policy;
for (i = CACHELIB_MAX_FREQUENCY - 1; i >= 0; --i)
if (!TAILQ_EMPTY(&(lfu_policy->groups[i]))) {
lfu_item = TAILQ_LAST(&(lfu_policy->groups[i]),
cache_lfu_policy_group_);
break;
}
TRACE_OUT(cache_lfu_policy_get_last_item);
return ((struct cache_policy_item_ *)lfu_item);
}
static struct cache_policy_item_ *
cache_lfu_policy_get_next_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
int i;
TRACE_IN(cache_lfu_policy_get_next_item);
lfu_policy = (struct cache_lfu_policy_ *)policy;
lfu_item = TAILQ_NEXT((struct cache_lfu_policy_item_ *)item, entries);
if (lfu_item == NULL)
{
for (i = ((struct cache_lfu_policy_item_ *)item)->frequency + 1;
i < CACHELIB_MAX_FREQUENCY; ++i) {
if (!TAILQ_EMPTY(&(lfu_policy->groups[i]))) {
lfu_item = TAILQ_FIRST(&(lfu_policy->groups[i]));
break;
}
}
}
TRACE_OUT(cache_lfu_policy_get_next_item);
return ((struct cache_policy_item_ *)lfu_item);
}
static struct cache_policy_item_ *
cache_lfu_policy_get_prev_item(struct cache_policy_ *policy,
struct cache_policy_item_ *item)
{
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
int i;
TRACE_IN(cache_lfu_policy_get_prev_item);
lfu_policy = (struct cache_lfu_policy_ *)policy;
lfu_item = TAILQ_PREV((struct cache_lfu_policy_item_ *)item,
cache_lfu_policy_group_, entries);
if (lfu_item == NULL)
{
for (i = ((struct cache_lfu_policy_item_ *)item)->frequency - 1;
i >= 0; --i)
if (!TAILQ_EMPTY(&(lfu_policy->groups[i]))) {
lfu_item = TAILQ_LAST(&(lfu_policy->groups[i]),
cache_lfu_policy_group_);
break;
}
}
TRACE_OUT(cache_lfu_policy_get_prev_item);
return ((struct cache_policy_item_ *)lfu_item);
}
/*
* Initializes the cache_policy_ structure by filling it with appropriate
* functions pointers
*/
struct cache_policy_ *
init_cache_lfu_policy(void)
{
int i;
struct cache_lfu_policy_ *retval;
TRACE_IN(init_cache_lfu_policy);
retval = (struct cache_lfu_policy_ *)calloc(1,
sizeof(struct cache_lfu_policy_));
assert(retval != NULL);
retval->parent_data.create_item_func = cache_lfu_policy_create_item;
retval->parent_data.destroy_item_func = cache_lfu_policy_destroy_item;
retval->parent_data.add_item_func = cache_lfu_policy_add_item;
retval->parent_data.update_item_func = cache_lfu_policy_update_item;
retval->parent_data.remove_item_func = cache_lfu_policy_remove_item;
retval->parent_data.get_first_item_func =
cache_lfu_policy_get_first_item;
retval->parent_data.get_last_item_func =
cache_lfu_policy_get_last_item;
retval->parent_data.get_next_item_func =
cache_lfu_policy_get_next_item;
retval->parent_data.get_prev_item_func =
cache_lfu_policy_get_prev_item;
for (i = 0; i < CACHELIB_MAX_FREQUENCY; ++i)
TAILQ_INIT(&(retval->groups[i]));
TRACE_OUT(init_cache_lfu_policy);
return ((struct cache_policy_ *)retval);
}
void
destroy_cache_lfu_policy(struct cache_policy_ *policy)
{
int i;
struct cache_lfu_policy_ *lfu_policy;
struct cache_lfu_policy_item_ *lfu_item;
TRACE_IN(destroy_cache_lfu_policy);
lfu_policy = (struct cache_lfu_policy_ *)policy;
for (i = 0; i < CACHELIB_MAX_FREQUENCY; ++i) {
while (!TAILQ_EMPTY(&(lfu_policy->groups[i]))) {
lfu_item = TAILQ_FIRST(&(lfu_policy->groups[i]));
TAILQ_REMOVE(&(lfu_policy->groups[i]), lfu_item,
entries);
cache_lfu_policy_destroy_item(
(struct cache_policy_item_ *)lfu_item);
}
}
free(policy);
TRACE_OUT(destroy_cache_lfu_policy);
}
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