1/*
2 * libwebsockets - small server side websockets and web server implementation
3 *
4 * Copyright (C) 2010 - 2021 Andy Green <andy@warmcat.com>
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22 * IN THE SOFTWARE.
23 */
24
25#define lwsl_cache lwsl_debug
26#define lwsl_hexdump_cache lwsl_hexdump_debug
27
28#define LWS_CACHE_MAX_LEVELS 3
29
30/*
31 * If we need structure inside the cache tag names, use this character as a
32 * separator
33 */
34#define LWSCTAG_SEP '|'
35
36/*
37 * Our synthetic cache result items all have tags starting with this char
38 */
39#define META_ITEM_LEADING '!'
40
41typedef struct lws_cache_ttl_item_heap {
42	lws_dll2_t			list_expiry;
43	lws_dll2_t			list_lru;
44
45	lws_usec_t			expiry;
46	size_t				key_len;
47	size_t				size;
48
49	/*
50	 * len + key_len + 1 bytes of data overcommitted, user object first
51	 * so it is well-aligned, then the NUL-terminated key name
52	 */
53} lws_cache_ttl_item_heap_t;
54
55/* this is a "base class", all cache implementations have one at the start */
56
57typedef struct lws_cache_ttl_lru {
58	struct lws_cache_creation_info	info;
59	lws_sorted_usec_list_t		sul;
60	struct lws_cache_ttl_lru	*child;
61	uint64_t			current_footprint;
62} lws_cache_ttl_lru_t;
63
64/*
65 * The heap-backed cache uses lws_dll2 linked-lists to track items that are
66 * in it.
67 */
68
69typedef struct lws_cache_ttl_lru_heap {
70	lws_cache_ttl_lru_t		cache;
71
72	lws_dll2_owner_t		items_expiry;
73	lws_dll2_owner_t		items_lru;
74} lws_cache_ttl_lru_t_heap_t;
75
76/*
77 * We want to be able to work with a large file-backed implementation even on
78 * devices that don't have heap to track what is in it.  It means if lookups
79 * reach this cache layer, we will be scanning a potentially large file.
80 *
81 * L1 caching of lookups (including null result list) reduces the expense of
82 * this on average.  We keep a copy of the last computed earliest expiry.
83 *
84 * We can't keep an open file handle here.  Because other processes may change
85 * the cookie file by deleting and replacing it, we have to open it fresh each
86 * time.
87 */
88typedef struct lws_cache_nscookiejar {
89	lws_cache_ttl_lru_t		cache;
90
91	lws_usec_t			earliest_expiry;
92} lws_cache_nscookiejar_t;
93
94void
95lws_cache_clear_matches(lws_dll2_owner_t *results_owner);
96
97void
98lws_cache_schedule(struct lws_cache_ttl_lru *cache, sul_cb_t cb, lws_usec_t e);
99