Commit | Line | Data |
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1e638f98 | 1 | /* |
0235b0db | 2 | * SPDX-License-Identifier: MIT |
1e638f98 FD |
3 | * |
4 | * Copyright 2019 Francis Deslauriers <francis.deslauriers@efficios.com> | |
5 | * | |
0235b0db | 6 | * Babeltrace - File descriptor cache |
1e638f98 FD |
7 | */ |
8 | ||
86d8b7b8 | 9 | #define BT_LOG_OUTPUT_LEVEL (fdc->log_level) |
1e638f98 | 10 | #define BT_LOG_TAG "FD-CACHE" |
86d8b7b8 | 11 | #include "logging/log.h" |
1e638f98 FD |
12 | |
13 | #include <fcntl.h> | |
14 | #include <sys/stat.h> | |
15 | #include <sys/types.h> | |
16 | #include <unistd.h> | |
17 | #include <glib.h> | |
18 | ||
578e048b MJ |
19 | #include "common/assert.h" |
20 | #include "fd-cache.h" | |
1e638f98 FD |
21 | |
22 | struct file_key { | |
23 | uint64_t dev; | |
24 | uint64_t ino; | |
25 | }; | |
26 | ||
27 | struct fd_handle_internal { | |
28 | struct bt_fd_cache_handle fd_handle; | |
29 | uint64_t ref_count; | |
30 | struct file_key *key; | |
31 | }; | |
32 | ||
33 | static | |
34 | void fd_cache_handle_internal_destroy( | |
35 | struct fd_handle_internal *internal_fd) | |
36 | { | |
37 | if (!internal_fd) { | |
38 | goto end; | |
39 | } | |
40 | ||
41 | if (internal_fd->fd_handle.fd >= 0) { | |
42 | close(internal_fd->fd_handle.fd); | |
43 | internal_fd->fd_handle.fd = -1; | |
44 | } | |
45 | ||
46 | end: | |
47 | g_free(internal_fd); | |
48 | } | |
49 | ||
50 | /* | |
51 | * Using simple hash algorithm found on stackoverflow: | |
52 | * https://stackoverflow.com/questions/664014/ | |
53 | */ | |
54 | static inline | |
55 | uint64_t hash_uint64_t(uint64_t x) { | |
56 | x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9); | |
57 | x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb); | |
58 | x = x ^ (x >> 31); | |
59 | return x; | |
60 | } | |
61 | ||
62 | static | |
63 | guint file_key_hash(gconstpointer v) | |
64 | { | |
65 | const struct file_key *fk = v; | |
66 | return hash_uint64_t(fk->dev) ^ hash_uint64_t(fk->ino); | |
67 | } | |
68 | ||
69 | static | |
70 | gboolean file_key_equal(gconstpointer v1, gconstpointer v2) | |
71 | { | |
72 | const struct file_key *fk1 = v1; | |
73 | const struct file_key *fk2 = v2; | |
74 | ||
75 | return (fk1->dev == fk2->dev) && (fk1->ino == fk2->ino); | |
76 | } | |
77 | ||
78 | static | |
79 | void file_key_destroy(gpointer data) | |
80 | { | |
81 | struct file_key *fk = data; | |
82 | g_free(fk); | |
83 | } | |
84 | ||
85 | BT_HIDDEN | |
86d8b7b8 | 86 | int bt_fd_cache_init(struct bt_fd_cache *fdc, int log_level) |
1e638f98 FD |
87 | { |
88 | int ret = 0; | |
89 | ||
86d8b7b8 | 90 | fdc->log_level = log_level; |
1e638f98 FD |
91 | fdc->cache = g_hash_table_new_full(file_key_hash, file_key_equal, |
92 | file_key_destroy, (GDestroyNotify) fd_cache_handle_internal_destroy); | |
93 | if (!fdc->cache) { | |
94 | ret = -1; | |
95 | } | |
96 | ||
97 | return ret; | |
98 | } | |
99 | ||
100 | BT_HIDDEN | |
101 | void bt_fd_cache_fini(struct bt_fd_cache *fdc) | |
102 | { | |
9f7cf1d2 FD |
103 | if (!fdc->cache) { |
104 | goto end; | |
105 | } | |
106 | ||
1e638f98 FD |
107 | /* |
108 | * All handle should have been removed for the hashtable at this point. | |
109 | */ | |
110 | BT_ASSERT(g_hash_table_size(fdc->cache) == 0); | |
111 | g_hash_table_destroy(fdc->cache); | |
112 | ||
9f7cf1d2 | 113 | end: |
1e638f98 FD |
114 | return; |
115 | } | |
116 | ||
117 | BT_HIDDEN | |
118 | struct bt_fd_cache_handle *bt_fd_cache_get_handle(struct bt_fd_cache *fdc, | |
119 | const char *path) | |
120 | { | |
121 | struct fd_handle_internal *fd_internal = NULL; | |
122 | struct stat statbuf; | |
123 | struct file_key fk; | |
2431859f | 124 | int ret, fd = -1; |
1e638f98 FD |
125 | |
126 | ret = stat(path, &statbuf); | |
127 | if (ret < 0) { | |
093946c0 FD |
128 | /* |
129 | * This is not necessarily an error as we sometimes try to open | |
130 | * files to see if they exist. Log the error as DEBUG severity | |
131 | * level. | |
132 | */ | |
133 | BT_LOGD_ERRNO("Failed to stat file", ": path=%s", path); | |
1e638f98 FD |
134 | goto end; |
135 | } | |
136 | ||
137 | /* | |
138 | * Use the device number and inode number to uniquely identify a file. | |
093946c0 | 139 | * Even if the file has the same path, it may have been replaced so we |
1e638f98 FD |
140 | * must open a new FD for it. This replacement of file is more likely |
141 | * to happen with a lttng-live source component. | |
142 | */ | |
143 | fk.dev = statbuf.st_dev; | |
144 | fk.ino = statbuf.st_ino; | |
145 | ||
146 | fd_internal = g_hash_table_lookup(fdc->cache, &fk); | |
147 | if (!fd_internal) { | |
1e638f98 FD |
148 | struct file_key *file_key; |
149 | ||
2431859f | 150 | fd = open(path, O_RDONLY); |
1e638f98 FD |
151 | if (fd < 0) { |
152 | BT_LOGE_ERRNO("Failed to open file", "path=%s", path); | |
153 | goto error; | |
154 | } | |
155 | ||
156 | fd_internal = g_new0(struct fd_handle_internal, 1); | |
157 | if (!fd_internal) { | |
3f7d4d90 | 158 | BT_LOGE_STR("Failed to allocate internal FD handle."); |
1e638f98 FD |
159 | goto error; |
160 | } | |
161 | ||
162 | file_key = g_new0(struct file_key, 1); | |
163 | if (!fd_internal) { | |
3f7d4d90 | 164 | BT_LOGE_STR("Failed to allocate file key."); |
1e638f98 FD |
165 | goto error; |
166 | } | |
167 | ||
168 | *file_key = fk; | |
169 | ||
170 | fd_internal->fd_handle.fd = fd; | |
171 | fd_internal->ref_count = 0; | |
172 | fd_internal->key = file_key; | |
173 | ||
174 | /* Insert the newly created fd handle. */ | |
95dc9c84 | 175 | g_hash_table_insert(fdc->cache, fd_internal->key, fd_internal); |
1e638f98 FD |
176 | } |
177 | ||
1e638f98 FD |
178 | fd_internal->ref_count++; |
179 | goto end; | |
180 | ||
181 | error: | |
2431859f FD |
182 | /* |
183 | * Close file descriptor if it was open() and we are currently on error | |
184 | * path. | |
185 | */ | |
186 | if (fd != -1) { | |
187 | ret = close(fd); | |
188 | if (ret) { | |
189 | BT_LOGE_ERRNO("Failed to close file descriptor", | |
190 | ": fd=%i, path=%s", fd, path); | |
191 | } | |
192 | } | |
193 | ||
1e638f98 FD |
194 | fd_cache_handle_internal_destroy(fd_internal); |
195 | fd_internal = NULL; | |
196 | end: | |
197 | return (struct bt_fd_cache_handle *) fd_internal; | |
198 | } | |
199 | ||
200 | BT_HIDDEN | |
201 | void bt_fd_cache_put_handle(struct bt_fd_cache *fdc, | |
202 | struct bt_fd_cache_handle *handle) | |
203 | { | |
204 | struct fd_handle_internal *fd_internal; | |
205 | ||
206 | if (!handle) { | |
207 | goto end; | |
208 | } | |
209 | ||
210 | fd_internal = (struct fd_handle_internal *) handle; | |
211 | ||
212 | BT_ASSERT(fd_internal->ref_count > 0); | |
213 | ||
214 | if (fd_internal->ref_count > 1) { | |
215 | fd_internal->ref_count--; | |
216 | } else { | |
217 | gboolean ret; | |
218 | int close_ret; | |
219 | ||
220 | close_ret = close(fd_internal->fd_handle.fd); | |
221 | if (close_ret == -1) { | |
3f7d4d90 | 222 | BT_LOGE_ERRNO("Failed to close file descriptor", |
1e638f98 FD |
223 | ": fd=%d", fd_internal->fd_handle.fd); |
224 | } | |
225 | ret = g_hash_table_remove(fdc->cache, fd_internal->key); | |
226 | BT_ASSERT(ret); | |
227 | } | |
228 | ||
229 | end: | |
230 | return; | |
231 | } |