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/*
* Copyright (c) 2021 Cisco and/or its affiliates.
* 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.
*/
#ifndef _WIN32
#include <sys/queue.h>
#endif
#include <hicn/util/log.h>
#include <hicn/hicn-light/config.h>
#include <stdio.h>
#include <hicn/core/packet_cache.h>
#include "lru.h"
void cs_lru_initialize(cs_t *cs) {
/* We start with an empty double-linked list */
cs->lru.head = INVALID_ENTRY_ID;
cs->lru.tail = INVALID_ENTRY_ID;
}
void cs_lru_finalize(cs_t *cs) {
// Nothing to do
}
cs_entry_t *_cs_entry_at(pkt_cache_t *pkt_cache, off_t entry_id) {
pkt_cache_entry_t *entry = pkt_cache_entry_at(pkt_cache, entry_id);
assert(entry->entry_type == PKT_CACHE_CS_TYPE);
return &entry->u.cs_entry;
}
/**
* Remove a cs_entry_t from all tables and indices.
*/
static int cs_lru_remove_entry(pkt_cache_t *pkt_cache,
pkt_cache_entry_t *entry) {
assert(pkt_cache);
assert(entry);
off_t entry_id = pkt_cache_get_entry_id(pkt_cache, entry);
cs_t *cs = pkt_cache_get_cs(pkt_cache);
cs_entry_t *cs_entry = &entry->u.cs_entry;
// If node to be deleted is head node
if (cs->lru.head == entry_id) cs->lru.head = cs_entry->lru.next;
// If node to be deleted is tail node
if (cs->lru.tail == entry_id) cs->lru.tail = cs_entry->lru.prev;
// If node to be deleted is not the last node
if (cs_entry->lru.next != INVALID_ENTRY_ID) {
cs_entry_t *next_cs_entry = _cs_entry_at(pkt_cache, cs_entry->lru.next);
assert(next_cs_entry);
next_cs_entry->lru.prev = cs_entry->lru.prev;
}
// If node to be deleted is not the first node
if (cs_entry->lru.prev != INVALID_ENTRY_ID) {
cs_entry_t *prev_entry = _cs_entry_at(pkt_cache, cs_entry->lru.prev);
assert(prev_entry);
prev_entry->lru.next = cs_entry->lru.next;
}
cs->stats.lru.countLruDeletions++;
return LRU_SUCCESS;
}
/**
* @brief LRU processing related to the insertion of a new entry in the content
* store (helper).
* @param[in] cs Content store.
* @param[in] entry_id Identifier of the entry in the content store entry pool.
* @param[in] is_update Boolean value to distinguish update from add operations
* since an update involves removing an entry and adding it again
*
* @return int Error code : 0 if succesful, a negative value otherwise.
*
* NOTE:
* - We insert the new element at the head of the double-linked list.
*/
int _cs_lru_add_entry(pkt_cache_t *pkt_cache, off_t entry_id, bool is_update) {
assert(pkt_cache);
cs_t *cs = pkt_cache_get_cs(pkt_cache);
cs_entry_t *entry = _cs_entry_at(pkt_cache, entry_id);
assert(entry);
// Add at the front of the LRU doubly linked list
if (cs->lru.head != INVALID_ENTRY_ID) {
cs_entry_t *head_entry = _cs_entry_at(pkt_cache, cs->lru.head);
assert(head_entry->lru.prev == INVALID_ENTRY_ID);
head_entry->lru.prev = entry_id;
entry->lru.next = cs->lru.head;
entry->lru.prev = INVALID_ENTRY_ID;
cs->lru.head = entry_id;
} else { /* The list is empty */
assert(cs->lru.tail == INVALID_ENTRY_ID);
entry->lru.next = INVALID_ENTRY_ID;
entry->lru.prev = INVALID_ENTRY_ID;
cs->lru.head = cs->lru.tail = entry_id;
}
if (!is_update) cs->stats.lru.countAdds++;
// Handle LRU eviction
if (cs->num_entries > cs->max_size) {
DEBUG("LRU eviction");
cs->stats.lru.countLruEvictions++;
// Remove from LRU tail
pkt_cache_entry_t *tail = pkt_cache_entry_at(pkt_cache, cs->lru.tail);
cs_lru_remove_entry(pkt_cache, tail);
return LRU_EVICTION;
}
return LRU_SUCCESS;
}
/**
* @brief LRU processing related to the insertion of a new entry in the content
* store.
* @param[in] cs Content store.
* @param[in] entry_id Identifier of the entry in the content store entry pool.
*
* @return int Error code : 0 if succesful, a negative value otherwise.
*
* NOTE:
* - We insert the new element at the head of the double-linked list.
*/
static int cs_lru_add_entry(pkt_cache_t *pkt_cache, off_t entry_id) {
return _cs_lru_add_entry(pkt_cache, entry_id, false);
}
/**
* Move a cs_entry_t to the LRU head.
*/
static void cs_lru_update_entry(pkt_cache_t *pkt_cache,
pkt_cache_entry_t *entry) {
assert(pkt_cache);
assert(entry);
cs_t *cs = pkt_cache_get_cs(pkt_cache);
cs->stats.lru.countUpdates++;
// Remove from LRU
cs_lru_remove_entry(pkt_cache, entry);
// Attach at the LRU head
off_t entry_id = pkt_cache_get_entry_id(pkt_cache, entry);
_cs_lru_add_entry(pkt_cache, entry_id, true);
}
DECLARE_CS(lru);
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