4 * Babeltrace - File descriptor cache
6 * Copyright 2019 Francis Deslauriers <francis.deslauriers@efficios.com>
8 * Author: Francis Deslauriers <francis.deslauriers@efficios.com>
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:
17 * The above copyright notice and this permission notice shall be included in
18 * all copies or substantial portions of the Software.
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
29 #define BT_LOG_TAG "FD-CACHE"
34 #include <sys/types.h>
38 #include <babeltrace/assert-internal.h>
39 #include <babeltrace/fd-cache-internal.h>
46 struct fd_handle_internal
{
47 struct bt_fd_cache_handle fd_handle
;
53 void fd_cache_handle_internal_destroy(
54 struct fd_handle_internal
*internal_fd
)
60 if (internal_fd
->fd_handle
.fd
>= 0) {
61 close(internal_fd
->fd_handle
.fd
);
62 internal_fd
->fd_handle
.fd
= -1;
70 * Using simple hash algorithm found on stackoverflow:
71 * https://stackoverflow.com/questions/664014/
74 uint64_t hash_uint64_t(uint64_t x
) {
75 x
= (x
^ (x
>> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
76 x
= (x
^ (x
>> 27)) * UINT64_C(0x94d049bb133111eb);
82 guint
file_key_hash(gconstpointer v
)
84 const struct file_key
*fk
= v
;
85 return hash_uint64_t(fk
->dev
) ^ hash_uint64_t(fk
->ino
);
89 gboolean
file_key_equal(gconstpointer v1
, gconstpointer v2
)
91 const struct file_key
*fk1
= v1
;
92 const struct file_key
*fk2
= v2
;
94 return (fk1
->dev
== fk2
->dev
) && (fk1
->ino
== fk2
->ino
);
98 void file_key_destroy(gpointer data
)
100 struct file_key
*fk
= data
;
105 int bt_fd_cache_init(struct bt_fd_cache
*fdc
)
109 fdc
->cache
= g_hash_table_new_full(file_key_hash
, file_key_equal
,
110 file_key_destroy
, (GDestroyNotify
) fd_cache_handle_internal_destroy
);
119 void bt_fd_cache_fini(struct bt_fd_cache
*fdc
)
121 BT_ASSERT(fdc
->cache
);
123 * All handle should have been removed for the hashtable at this point.
125 BT_ASSERT(g_hash_table_size(fdc
->cache
) == 0);
126 g_hash_table_destroy(fdc
->cache
);
132 struct bt_fd_cache_handle
*bt_fd_cache_get_handle(struct bt_fd_cache
*fdc
,
135 struct fd_handle_internal
*fd_internal
= NULL
;
140 ret
= stat(path
, &statbuf
);
142 BT_LOGE_ERRNO("Failed to stat file", ": path=%s", path
);
147 * Use the device number and inode number to uniquely identify a file.
148 * Even if the file as the same path, it may have been replaced so we
149 * must open a new FD for it. This replacement of file is more likely
150 * to happen with a lttng-live source component.
152 fk
.dev
= statbuf
.st_dev
;
153 fk
.ino
= statbuf
.st_ino
;
155 fd_internal
= g_hash_table_lookup(fdc
->cache
, &fk
);
158 struct file_key
*file_key
;
160 int fd
= open(path
, O_RDONLY
);
162 BT_LOGE_ERRNO("Failed to open file", "path=%s", path
);
166 fd_internal
= g_new0(struct fd_handle_internal
, 1);
168 BT_LOGE("Failed to allocate fd internal handle");
172 file_key
= g_new0(struct file_key
, 1);
174 BT_LOGE("Failed to allocate file key");
180 fd_internal
->fd_handle
.fd
= fd
;
181 fd_internal
->ref_count
= 0;
182 fd_internal
->key
= file_key
;
184 /* Insert the newly created fd handle. */
185 ret
= g_hash_table_insert(fdc
->cache
, fd_internal
->key
,
190 BT_ASSERT(fd_internal
->ref_count
>= 0);
192 fd_internal
->ref_count
++;
196 fd_cache_handle_internal_destroy(fd_internal
);
199 return (struct bt_fd_cache_handle
*) fd_internal
;
203 void bt_fd_cache_put_handle(struct bt_fd_cache
*fdc
,
204 struct bt_fd_cache_handle
*handle
)
206 struct fd_handle_internal
*fd_internal
;
212 fd_internal
= (struct fd_handle_internal
*) handle
;
214 BT_ASSERT(fd_internal
->ref_count
> 0);
216 if (fd_internal
->ref_count
> 1) {
217 fd_internal
->ref_count
--;
222 close_ret
= close(fd_internal
->fd_handle
.fd
);
223 if (close_ret
== -1) {
224 BT_LOGW_ERRNO("Failed to close file descriptor",
225 ": fd=%d", fd_internal
->fd_handle
.fd
);
227 ret
= g_hash_table_remove(fdc
->cache
, fd_internal
->key
);