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1e638f98 FD |
1 | /* |
2 | * fd-cache.c | |
3 | * | |
4 | * Babeltrace - File descriptor cache | |
5 | * | |
6 | * Copyright 2019 Francis Deslauriers <francis.deslauriers@efficios.com> | |
7 | * | |
8 | * Author: Francis Deslauriers <francis.deslauriers@efficios.com> | |
9 | * | |
10 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
11 | * of this software and associated documentation files (the "Software"), to deal | |
12 | * in the Software without restriction, including without limitation the rights | |
13 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
14 | * copies of the Software, and to permit persons to whom the Software is | |
15 | * furnished to do so, subject to the following conditions: | |
16 | * | |
17 | * The above copyright notice and this permission notice shall be included in | |
18 | * all copies or substantial portions of the Software. | |
19 | * | |
20 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
21 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
22 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
23 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
24 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
25 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
26 | * SOFTWARE. | |
27 | */ | |
28 | ||
86d8b7b8 | 29 | #define BT_LOG_OUTPUT_LEVEL (fdc->log_level) |
1e638f98 | 30 | #define BT_LOG_TAG "FD-CACHE" |
86d8b7b8 | 31 | #include "logging/log.h" |
1e638f98 FD |
32 | |
33 | #include <fcntl.h> | |
34 | #include <sys/stat.h> | |
35 | #include <sys/types.h> | |
36 | #include <unistd.h> | |
37 | #include <glib.h> | |
38 | ||
578e048b MJ |
39 | #include "common/assert.h" |
40 | #include "fd-cache.h" | |
1e638f98 FD |
41 | |
42 | struct file_key { | |
43 | uint64_t dev; | |
44 | uint64_t ino; | |
45 | }; | |
46 | ||
47 | struct fd_handle_internal { | |
48 | struct bt_fd_cache_handle fd_handle; | |
49 | uint64_t ref_count; | |
50 | struct file_key *key; | |
51 | }; | |
52 | ||
53 | static | |
54 | void fd_cache_handle_internal_destroy( | |
55 | struct fd_handle_internal *internal_fd) | |
56 | { | |
57 | if (!internal_fd) { | |
58 | goto end; | |
59 | } | |
60 | ||
61 | if (internal_fd->fd_handle.fd >= 0) { | |
62 | close(internal_fd->fd_handle.fd); | |
63 | internal_fd->fd_handle.fd = -1; | |
64 | } | |
65 | ||
66 | end: | |
67 | g_free(internal_fd); | |
68 | } | |
69 | ||
70 | /* | |
71 | * Using simple hash algorithm found on stackoverflow: | |
72 | * https://stackoverflow.com/questions/664014/ | |
73 | */ | |
74 | static inline | |
75 | uint64_t hash_uint64_t(uint64_t x) { | |
76 | x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9); | |
77 | x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb); | |
78 | x = x ^ (x >> 31); | |
79 | return x; | |
80 | } | |
81 | ||
82 | static | |
83 | guint file_key_hash(gconstpointer v) | |
84 | { | |
85 | const struct file_key *fk = v; | |
86 | return hash_uint64_t(fk->dev) ^ hash_uint64_t(fk->ino); | |
87 | } | |
88 | ||
89 | static | |
90 | gboolean file_key_equal(gconstpointer v1, gconstpointer v2) | |
91 | { | |
92 | const struct file_key *fk1 = v1; | |
93 | const struct file_key *fk2 = v2; | |
94 | ||
95 | return (fk1->dev == fk2->dev) && (fk1->ino == fk2->ino); | |
96 | } | |
97 | ||
98 | static | |
99 | void file_key_destroy(gpointer data) | |
100 | { | |
101 | struct file_key *fk = data; | |
102 | g_free(fk); | |
103 | } | |
104 | ||
105 | BT_HIDDEN | |
86d8b7b8 | 106 | int bt_fd_cache_init(struct bt_fd_cache *fdc, int log_level) |
1e638f98 FD |
107 | { |
108 | int ret = 0; | |
109 | ||
86d8b7b8 | 110 | fdc->log_level = log_level; |
1e638f98 FD |
111 | fdc->cache = g_hash_table_new_full(file_key_hash, file_key_equal, |
112 | file_key_destroy, (GDestroyNotify) fd_cache_handle_internal_destroy); | |
113 | if (!fdc->cache) { | |
114 | ret = -1; | |
115 | } | |
116 | ||
117 | return ret; | |
118 | } | |
119 | ||
120 | BT_HIDDEN | |
121 | void bt_fd_cache_fini(struct bt_fd_cache *fdc) | |
122 | { | |
123 | BT_ASSERT(fdc->cache); | |
124 | /* | |
125 | * All handle should have been removed for the hashtable at this point. | |
126 | */ | |
127 | BT_ASSERT(g_hash_table_size(fdc->cache) == 0); | |
128 | g_hash_table_destroy(fdc->cache); | |
129 | ||
130 | return; | |
131 | } | |
132 | ||
133 | BT_HIDDEN | |
134 | struct bt_fd_cache_handle *bt_fd_cache_get_handle(struct bt_fd_cache *fdc, | |
135 | const char *path) | |
136 | { | |
137 | struct fd_handle_internal *fd_internal = NULL; | |
138 | struct stat statbuf; | |
139 | struct file_key fk; | |
2431859f | 140 | int ret, fd = -1; |
1e638f98 FD |
141 | |
142 | ret = stat(path, &statbuf); | |
143 | if (ret < 0) { | |
093946c0 FD |
144 | /* |
145 | * This is not necessarily an error as we sometimes try to open | |
146 | * files to see if they exist. Log the error as DEBUG severity | |
147 | * level. | |
148 | */ | |
149 | BT_LOGD_ERRNO("Failed to stat file", ": path=%s", path); | |
1e638f98 FD |
150 | goto end; |
151 | } | |
152 | ||
153 | /* | |
154 | * Use the device number and inode number to uniquely identify a file. | |
093946c0 | 155 | * Even if the file has the same path, it may have been replaced so we |
1e638f98 FD |
156 | * must open a new FD for it. This replacement of file is more likely |
157 | * to happen with a lttng-live source component. | |
158 | */ | |
159 | fk.dev = statbuf.st_dev; | |
160 | fk.ino = statbuf.st_ino; | |
161 | ||
162 | fd_internal = g_hash_table_lookup(fdc->cache, &fk); | |
163 | if (!fd_internal) { | |
1e638f98 FD |
164 | struct file_key *file_key; |
165 | ||
2431859f | 166 | fd = open(path, O_RDONLY); |
1e638f98 FD |
167 | if (fd < 0) { |
168 | BT_LOGE_ERRNO("Failed to open file", "path=%s", path); | |
169 | goto error; | |
170 | } | |
171 | ||
172 | fd_internal = g_new0(struct fd_handle_internal, 1); | |
173 | if (!fd_internal) { | |
3f7d4d90 | 174 | BT_LOGE_STR("Failed to allocate internal FD handle."); |
1e638f98 FD |
175 | goto error; |
176 | } | |
177 | ||
178 | file_key = g_new0(struct file_key, 1); | |
179 | if (!fd_internal) { | |
3f7d4d90 | 180 | BT_LOGE_STR("Failed to allocate file key."); |
1e638f98 FD |
181 | goto error; |
182 | } | |
183 | ||
184 | *file_key = fk; | |
185 | ||
186 | fd_internal->fd_handle.fd = fd; | |
187 | fd_internal->ref_count = 0; | |
188 | fd_internal->key = file_key; | |
189 | ||
190 | /* Insert the newly created fd handle. */ | |
95dc9c84 | 191 | g_hash_table_insert(fdc->cache, fd_internal->key, fd_internal); |
1e638f98 FD |
192 | } |
193 | ||
1e638f98 FD |
194 | fd_internal->ref_count++; |
195 | goto end; | |
196 | ||
197 | error: | |
2431859f FD |
198 | /* |
199 | * Close file descriptor if it was open() and we are currently on error | |
200 | * path. | |
201 | */ | |
202 | if (fd != -1) { | |
203 | ret = close(fd); | |
204 | if (ret) { | |
205 | BT_LOGE_ERRNO("Failed to close file descriptor", | |
206 | ": fd=%i, path=%s", fd, path); | |
207 | } | |
208 | } | |
209 | ||
1e638f98 FD |
210 | fd_cache_handle_internal_destroy(fd_internal); |
211 | fd_internal = NULL; | |
212 | end: | |
213 | return (struct bt_fd_cache_handle *) fd_internal; | |
214 | } | |
215 | ||
216 | BT_HIDDEN | |
217 | void bt_fd_cache_put_handle(struct bt_fd_cache *fdc, | |
218 | struct bt_fd_cache_handle *handle) | |
219 | { | |
220 | struct fd_handle_internal *fd_internal; | |
221 | ||
222 | if (!handle) { | |
223 | goto end; | |
224 | } | |
225 | ||
226 | fd_internal = (struct fd_handle_internal *) handle; | |
227 | ||
228 | BT_ASSERT(fd_internal->ref_count > 0); | |
229 | ||
230 | if (fd_internal->ref_count > 1) { | |
231 | fd_internal->ref_count--; | |
232 | } else { | |
233 | gboolean ret; | |
234 | int close_ret; | |
235 | ||
236 | close_ret = close(fd_internal->fd_handle.fd); | |
237 | if (close_ret == -1) { | |
3f7d4d90 | 238 | BT_LOGE_ERRNO("Failed to close file descriptor", |
1e638f98 FD |
239 | ": fd=%d", fd_internal->fd_handle.fd); |
240 | } | |
241 | ret = g_hash_table_remove(fdc->cache, fd_internal->key); | |
242 | BT_ASSERT(ret); | |
243 | } | |
244 | ||
245 | end: | |
246 | return; | |
247 | } |