text: /**
   * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
   * SPDX-License-Identifier: Apache-2.0.
   */
  #include <aws/common/lifo_cache.h>
  static int s_lifo_cache_put(struct aws_cache *cache, const void *key, void *p_value);
  
  static struct aws_cache_vtable s_lifo_cache_vtable = {
      .destroy = aws_cache_base_default_destroy,
      .find = aws_cache_base_default_find,
      .put = s_lifo_cache_put,
      .remove = aws_cache_base_default_remove,
      .clear = aws_cache_base_default_clear,
      .get_element_count = aws_cache_base_default_get_element_count,
  };
  
  struct aws_cache *aws_cache_new_lifo(
      struct aws_allocator *allocator,
      aws_hash_fn *hash_fn,
      aws_hash_callback_eq_fn *equals_fn,
      aws_hash_callback_destroy_fn *destroy_key_fn,
      aws_hash_callback_destroy_fn *destroy_value_fn,
      size_t max_items) {
      AWS_ASSERT(allocator);
      AWS_ASSERT(max_items);
  
      struct aws_cache *lifo_cache = aws_mem_calloc(allocator, 1, sizeof(struct aws_cache));
      if (!lifo_cache) {
          return NULL;
      }
      lifo_cache->allocator = allocator;
      lifo_cache->max_items = max_items;
      lifo_cache->vtable = &s_lifo_cache_vtable;
      if (aws_linked_hash_table_init(
              &lifo_cache->table, allocator, hash_fn, equals_fn, destroy_key_fn, destroy_value_fn, max_items)) {
          return NULL;
      }
      return lifo_cache;
  }
  
  /* lifo cache put implementation */
  static int s_lifo_cache_put(struct aws_cache *cache, const void *key, void *p_value) {
      if (aws_linked_hash_table_put(&cache->table, key, p_value)) {
          return AWS_OP_ERR;
      }
  
      /* Manage the space if we actually added a new element and the cache is full. */
      if (aws_linked_hash_table_get_element_count(&cache->table) > cache->max_items) {
          /* we're over the cache size limit. Remove whatever is in the one before the back of the linked_hash_table,
           * which was the latest element before we put the new one */
          const struct aws_linked_list *list = aws_linked_hash_table_get_iteration_list(&cache->table);
          struct aws_linked_list_node *node = aws_linked_list_back(list);
          if (!node->prev) {
              return AWS_OP_SUCCESS;
          }
          struct aws_linked_hash_table_node *table_node =
              AWS_CONTAINER_OF(node->prev, struct aws_linked_hash_table_node, node);
          return aws_linked_hash_table_remove(&cache->table, table_node->key);
      }
  
      return AWS_OP_SUCCESS;
  }
  