Commit | Line | Data |
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8d7183bd 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 | ||
c864e29a | 29 | #define BT_LOG_OUTPUT_LEVEL (fdc->log_level) |
8d7183bd | 30 | #define BT_LOG_TAG "FD-CACHE" |
c864e29a | 31 | #include "logging/log.h" |
8d7183bd 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 | ||
57952005 MJ |
39 | #include "common/assert.h" |
40 | #include "fd-cache.h" | |
8d7183bd 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 | |
c864e29a | 106 | int bt_fd_cache_init(struct bt_fd_cache *fdc, int log_level) |
8d7183bd FD |
107 | { |
108 | int ret = 0; | |
109 | ||
c864e29a | 110 | fdc->log_level = log_level; |
8d7183bd 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 | { | |
555c125c FD |
123 | if (!fdc->cache) { |
124 | goto end; | |
125 | } | |
126 | ||
8d7183bd FD |
127 | /* |
128 | * All handle should have been removed for the hashtable at this point. | |
129 | */ | |
130 | BT_ASSERT(g_hash_table_size(fdc->cache) == 0); | |
131 | g_hash_table_destroy(fdc->cache); | |
132 | ||
555c125c | 133 | end: |
8d7183bd FD |
134 | return; |
135 | } | |
136 | ||
137 | BT_HIDDEN | |
138 | struct bt_fd_cache_handle *bt_fd_cache_get_handle(struct bt_fd_cache *fdc, | |
139 | const char *path) | |
140 | { | |
141 | struct fd_handle_internal *fd_internal = NULL; | |
142 | struct stat statbuf; | |
143 | struct file_key fk; | |
c938519d | 144 | int ret, fd = -1; |
8d7183bd FD |
145 | |
146 | ret = stat(path, &statbuf); | |
147 | if (ret < 0) { | |
a7ac2d3a FD |
148 | /* |
149 | * This is not necessarily an error as we sometimes try to open | |
150 | * files to see if they exist. Log the error as DEBUG severity | |
151 | * level. | |
152 | */ | |
153 | BT_LOGD_ERRNO("Failed to stat file", ": path=%s", path); | |
8d7183bd FD |
154 | goto end; |
155 | } | |
156 | ||
157 | /* | |
158 | * Use the device number and inode number to uniquely identify a file. | |
a7ac2d3a | 159 | * Even if the file has the same path, it may have been replaced so we |
8d7183bd FD |
160 | * must open a new FD for it. This replacement of file is more likely |
161 | * to happen with a lttng-live source component. | |
162 | */ | |
163 | fk.dev = statbuf.st_dev; | |
164 | fk.ino = statbuf.st_ino; | |
165 | ||
166 | fd_internal = g_hash_table_lookup(fdc->cache, &fk); | |
167 | if (!fd_internal) { | |
8d7183bd FD |
168 | struct file_key *file_key; |
169 | ||
c938519d | 170 | fd = open(path, O_RDONLY); |
8d7183bd FD |
171 | if (fd < 0) { |
172 | BT_LOGE_ERRNO("Failed to open file", "path=%s", path); | |
173 | goto error; | |
174 | } | |
175 | ||
176 | fd_internal = g_new0(struct fd_handle_internal, 1); | |
177 | if (!fd_internal) { | |
a684a357 | 178 | BT_LOGE_STR("Failed to allocate internal FD handle."); |
8d7183bd FD |
179 | goto error; |
180 | } | |
181 | ||
182 | file_key = g_new0(struct file_key, 1); | |
183 | if (!fd_internal) { | |
a684a357 | 184 | BT_LOGE_STR("Failed to allocate file key."); |
8d7183bd FD |
185 | goto error; |
186 | } | |
187 | ||
188 | *file_key = fk; | |
189 | ||
190 | fd_internal->fd_handle.fd = fd; | |
191 | fd_internal->ref_count = 0; | |
192 | fd_internal->key = file_key; | |
193 | ||
194 | /* Insert the newly created fd handle. */ | |
c8f043d2 | 195 | g_hash_table_insert(fdc->cache, fd_internal->key, fd_internal); |
8d7183bd FD |
196 | } |
197 | ||
8d7183bd FD |
198 | fd_internal->ref_count++; |
199 | goto end; | |
200 | ||
201 | error: | |
c938519d FD |
202 | /* |
203 | * Close file descriptor if it was open() and we are currently on error | |
204 | * path. | |
205 | */ | |
206 | if (fd != -1) { | |
207 | ret = close(fd); | |
208 | if (ret) { | |
209 | BT_LOGE_ERRNO("Failed to close file descriptor", | |
210 | ": fd=%i, path=%s", fd, path); | |
211 | } | |
212 | } | |
213 | ||
8d7183bd FD |
214 | fd_cache_handle_internal_destroy(fd_internal); |
215 | fd_internal = NULL; | |
216 | end: | |
217 | return (struct bt_fd_cache_handle *) fd_internal; | |
218 | } | |
219 | ||
220 | BT_HIDDEN | |
221 | void bt_fd_cache_put_handle(struct bt_fd_cache *fdc, | |
222 | struct bt_fd_cache_handle *handle) | |
223 | { | |
224 | struct fd_handle_internal *fd_internal; | |
225 | ||
226 | if (!handle) { | |
227 | goto end; | |
228 | } | |
229 | ||
230 | fd_internal = (struct fd_handle_internal *) handle; | |
231 | ||
232 | BT_ASSERT(fd_internal->ref_count > 0); | |
233 | ||
234 | if (fd_internal->ref_count > 1) { | |
235 | fd_internal->ref_count--; | |
236 | } else { | |
237 | gboolean ret; | |
238 | int close_ret; | |
239 | ||
240 | close_ret = close(fd_internal->fd_handle.fd); | |
241 | if (close_ret == -1) { | |
a684a357 | 242 | BT_LOGE_ERRNO("Failed to close file descriptor", |
8d7183bd FD |
243 | ": fd=%d", fd_internal->fd_handle.fd); |
244 | } | |
245 | ret = g_hash_table_remove(fdc->cache, fd_internal->key); | |
246 | BT_ASSERT(ret); | |
247 | } | |
248 | ||
249 | end: | |
250 | return; | |
251 | } |