1 /*
2  * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/queue.h>
18 
19 #include <stdlib.h>
20 #include <string.h>
21 #include <sha1.h>
22 #include <stdio.h>
23 #include <zlib.h>
24 #include <limits.h>
25 #include <time.h>
26 
27 #include "got_object.h"
28 #include "got_error.h"
29 
30 #include "got_lib_delta.h"
31 #include "got_lib_inflate.h"
32 #include "got_lib_object.h"
33 #include "got_lib_delta_cache.h"
34 
35 #ifndef nitems
36 #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
37 #endif
38 
39 struct got_delta_cache_element {
40 	TAILQ_ENTRY(got_delta_cache_element) entry;
41 	off_t delta_data_offset;
42 	uint8_t *delta_data;
43 	size_t delta_len;
44 };
45 
46 TAILQ_HEAD(got_delta_cache_head, got_delta_cache_element);
47 
48 struct got_delta_cache {
49 	struct got_delta_cache_head entries;
50 	int nelem;
51 	int maxelem;
52 	size_t maxelemsize;
53 	int cache_search;
54 	int cache_hit;
55 	int cache_miss;
56 	int cache_evict;
57 	int cache_toolarge;
58 };
59 
60 struct got_delta_cache *
61 got_delta_cache_alloc(int maxelem, size_t maxelemsize)
62 {
63 	struct got_delta_cache *cache;
64 
65 	cache = calloc(1, sizeof(*cache));
66 	if (cache == NULL)
67 		return NULL;
68 
69 	TAILQ_INIT(&cache->entries);
70 	cache->maxelem = maxelem;
71 	cache->maxelemsize = maxelemsize;
72 	return cache;
73 }
74 
75 void
76 got_delta_cache_free(struct got_delta_cache *cache)
77 {
78 	struct got_delta_cache_element *entry;
79 
80 #ifdef GOT_OBJ_CACHE_DEBUG
81 	fprintf(stderr, "%s: delta cache: %d elements, %d searches, %d hits, "
82 	    "%d missed, %d evicted, %d too large\n", getprogname(), cache->nelem,
83 	    cache->cache_search, cache->cache_hit, cache->cache_miss,
84 	    cache->cache_evict, cache->cache_toolarge);
85 #endif
86 	while (!TAILQ_EMPTY(&cache->entries)) {
87 		entry = TAILQ_FIRST(&cache->entries);
88 		TAILQ_REMOVE(&cache->entries, entry, entry);
89 		free(entry->delta_data);
90 		free(entry);
91 	}
92 	free(cache);
93 }
94 
95 static void
96 remove_least_used_element(struct got_delta_cache *cache)
97 {
98 	struct got_delta_cache_element *entry;
99 
100 	if (cache->nelem == 0)
101 		return;
102 
103 	entry = TAILQ_LAST(&cache->entries, got_delta_cache_head);
104 	TAILQ_REMOVE(&cache->entries, entry, entry);
105 	free(entry->delta_data);
106 	free(entry);
107 	cache->nelem--;
108 	cache->cache_evict++;
109 }
110 
111 
112 const struct got_error *
113 got_delta_cache_add(struct got_delta_cache *cache,
114     off_t delta_data_offset, uint8_t *delta_data, size_t delta_len)
115 {
116 	struct got_delta_cache_element *entry;
117 
118 	if (delta_len > cache->maxelemsize) {
119 		cache->cache_toolarge++;
120 		return got_error(GOT_ERR_NO_SPACE);
121 	}
122 
123 	if (cache->nelem >= cache->maxelem)
124 		remove_least_used_element(cache);
125 
126 	entry = calloc(1, sizeof(*entry));
127 	if (entry == NULL)
128 		return got_error_from_errno("calloc");
129 
130 	entry->delta_data_offset = delta_data_offset;
131 	entry->delta_data = delta_data;
132 	entry->delta_len = delta_len;
133 
134 	TAILQ_INSERT_HEAD(&cache->entries, entry, entry);
135 	cache->nelem++;
136 	return NULL;
137 }
138 
139 void
140 got_delta_cache_get(uint8_t **delta_data, size_t *delta_len,
141     struct got_delta_cache *cache, off_t delta_data_offset)
142 {
143 	struct got_delta_cache_element *entry;
144 
145 	cache->cache_search++;
146 	*delta_data = NULL;
147 	*delta_len = 0;
148 	TAILQ_FOREACH(entry, &cache->entries, entry) {
149 		if (entry->delta_data_offset != delta_data_offset)
150 			continue;
151 		cache->cache_hit++;
152 		if (entry != TAILQ_FIRST(&cache->entries)) {
153 			TAILQ_REMOVE(&cache->entries, entry, entry);
154 			TAILQ_INSERT_HEAD(&cache->entries, entry, entry);
155 		}
156 		*delta_data = entry->delta_data;
157 		*delta_len = entry->delta_len;
158 		return;
159 	}
160 
161 	cache->cache_miss++;
162 }