RCU support for consumer's hash tables
[lttng-tools.git] / include / lttng / lttng-consumer.h
1 /*
2 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
3 * Copyright (C) 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; only version 2
8 * of the License.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 */
19
20 #ifndef _LTTNG_CONSUMER_H
21 #define _LTTNG_CONSUMER_H
22
23 #include <limits.h>
24 #include <poll.h>
25 #include <unistd.h>
26
27 #include <lttng/lttng.h>
28 #include <lttng-ht.h>
29
30 /*
31 * When the receiving thread dies, we need to have a way to make the polling
32 * thread exit eventually. If all FDs hang up (normal case when the
33 * lttng-sessiond stops), we can exit cleanly, but if there is a problem and
34 * for whatever reason some FDs remain open, the consumer should still exit
35 * eventually.
36 *
37 * If the timeout is reached, it means that during this period no events
38 * occurred on the FDs so we need to force an exit. This case should not happen
39 * but it is a safety to ensure we won't block the consumer indefinitely.
40 *
41 * The value of 2 seconds is an arbitrary choice.
42 */
43 #define LTTNG_CONSUMER_POLL_TIMEOUT 2000
44
45 /* Commands for consumer */
46 enum lttng_consumer_command {
47 LTTNG_CONSUMER_ADD_CHANNEL,
48 LTTNG_CONSUMER_ADD_STREAM,
49 /* pause, delete, active depending on fd state */
50 LTTNG_CONSUMER_UPDATE_STREAM,
51 /* inform the consumer to quit when all fd has hang up */
52 LTTNG_CONSUMER_STOP,
53 };
54
55 /* State of each fd in consumer */
56 enum lttng_consumer_stream_state {
57 LTTNG_CONSUMER_ACTIVE_STREAM,
58 LTTNG_CONSUMER_PAUSE_STREAM,
59 LTTNG_CONSUMER_DELETE_STREAM,
60 };
61
62 enum lttng_consumer_type {
63 LTTNG_CONSUMER_UNKNOWN = 0,
64 LTTNG_CONSUMER_KERNEL,
65 LTTNG_CONSUMER64_UST,
66 LTTNG_CONSUMER32_UST,
67 };
68
69 struct lttng_consumer_channel {
70 struct lttng_ht_node_ulong node;
71 int key;
72 uint64_t max_sb_size; /* the subbuffer size for this channel */
73 int refcount; /* Number of streams referencing this channel */
74 /* For UST */
75 int shm_fd;
76 int wait_fd;
77 void *mmap_base;
78 size_t mmap_len;
79 struct lttng_ust_shm_handle *handle;
80 int nr_streams;
81 int shm_fd_is_copy;
82 int wait_fd_is_copy;
83 int cpucount;
84 };
85
86 /* Forward declaration for UST. */
87 struct lttng_ust_lib_ring_buffer;
88
89 /*
90 * Internal representation of the streams, sessiond_key is used to identify
91 * uniquely a stream.
92 */
93 struct lttng_consumer_stream {
94 struct lttng_ht_node_ulong node;
95 struct lttng_consumer_channel *chan; /* associated channel */
96 /*
97 * key is the key used by the session daemon to refer to the
98 * object in the consumer daemon.
99 */
100 int key;
101 int shm_fd;
102 int wait_fd;
103 int out_fd; /* output file to write the data */
104 off_t out_fd_offset; /* write position in the output file descriptor */
105 char path_name[PATH_MAX]; /* tracefile name */
106 enum lttng_consumer_stream_state state;
107 size_t shm_len;
108 void *mmap_base;
109 size_t mmap_len;
110 enum lttng_event_output output; /* splice or mmap */
111 int shm_fd_is_copy;
112 int wait_fd_is_copy;
113 /* For UST */
114 struct lttng_ust_lib_ring_buffer *buf;
115 int cpu;
116 int hangup_flush_done;
117 /* UID/GID of the user owning the session to which stream belongs */
118 uid_t uid;
119 gid_t gid;
120 };
121
122 /*
123 * UST consumer local data to the program. One or more instance per
124 * process.
125 */
126 struct lttng_consumer_local_data {
127 /* function to call when data is available on a buffer */
128 int (*on_buffer_ready)(struct lttng_consumer_stream *stream,
129 struct lttng_consumer_local_data *ctx);
130 /*
131 * function to call when we receive a new channel, it receives a
132 * newly allocated channel, depending on the return code of this
133 * function, the new channel will be handled by the application
134 * or the library.
135 *
136 * Returns:
137 * > 0 (success, FD is kept by application)
138 * == 0 (success, FD is left to library)
139 * < 0 (error)
140 */
141 int (*on_recv_channel)(struct lttng_consumer_channel *channel);
142 /*
143 * function to call when we receive a new stream, it receives a
144 * newly allocated stream, depending on the return code of this
145 * function, the new stream will be handled by the application
146 * or the library.
147 *
148 * Returns:
149 * > 0 (success, FD is kept by application)
150 * == 0 (success, FD is left to library)
151 * < 0 (error)
152 */
153 int (*on_recv_stream)(struct lttng_consumer_stream *stream);
154 /*
155 * function to call when a stream is getting updated by the session
156 * daemon, this function receives the sessiond key and the new
157 * state, depending on the return code of this function the
158 * update of state for the stream is handled by the application
159 * or the library.
160 *
161 * Returns:
162 * > 0 (success, FD is kept by application)
163 * == 0 (success, FD is left to library)
164 * < 0 (error)
165 */
166 int (*on_update_stream)(int sessiond_key, uint32_t state);
167 /* socket to communicate errors with sessiond */
168 int consumer_error_socket;
169 /* socket to exchange commands with sessiond */
170 char *consumer_command_sock_path;
171 /* communication with splice */
172 int consumer_thread_pipe[2];
173 /* pipe to wake the poll thread when necessary */
174 int consumer_poll_pipe[2];
175 /* to let the signal handler wake up the fd receiver thread */
176 int consumer_should_quit[2];
177 };
178
179 /*
180 * Library-level data. One instance per process.
181 */
182 struct lttng_consumer_global_data {
183
184 /*
185 * At this time, this lock is used to ensure coherence between the count
186 * and number of element in the hash table. It's also a protection for
187 * concurrent read/write between threads.
188 *
189 * XXX: We need to see if this lock is still needed with the lockless RCU
190 * hash tables.
191 */
192 pthread_mutex_t lock;
193
194 /*
195 * Number of streams in the hash table. Protected by consumer_data.lock.
196 */
197 int stream_count;
198 /*
199 * Hash tables of streams and channels. Protected by consumer_data.lock.
200 */
201 struct lttng_ht *stream_ht;
202 struct lttng_ht *channel_ht;
203 /*
204 * Flag specifying if the local array of FDs needs update in the
205 * poll function. Protected by consumer_data.lock.
206 */
207 unsigned int need_update;
208 enum lttng_consumer_type type;
209 };
210
211 /*
212 * Init consumer data structures.
213 */
214 extern void lttng_consumer_init(void);
215
216 /*
217 * Set the error socket for communication with a session daemon.
218 */
219 extern void lttng_consumer_set_error_sock(
220 struct lttng_consumer_local_data *ctx, int sock);
221
222 /*
223 * Set the command socket path for communication with a session daemon.
224 */
225 extern void lttng_consumer_set_command_sock_path(
226 struct lttng_consumer_local_data *ctx, char *sock);
227
228 /*
229 * Send return code to session daemon.
230 *
231 * Returns the return code of sendmsg : the number of bytes transmitted or -1
232 * on error.
233 */
234 extern int lttng_consumer_send_error(
235 struct lttng_consumer_local_data *ctx, int cmd);
236
237 /*
238 * Called from signal handler to ensure a clean exit.
239 */
240 extern void lttng_consumer_should_exit(
241 struct lttng_consumer_local_data *ctx);
242
243 /*
244 * Cleanup the daemon's socket on exit.
245 */
246 extern void lttng_consumer_cleanup(void);
247
248 /*
249 * Flush pending writes to trace output disk file.
250 */
251 extern void lttng_consumer_sync_trace_file(
252 struct lttng_consumer_stream *stream, off_t orig_offset);
253
254 /*
255 * Poll on the should_quit pipe and the command socket return -1 on error and
256 * should exit, 0 if data is available on the command socket
257 */
258 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
259
260 extern int consumer_update_poll_array(
261 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
262 struct lttng_consumer_stream **local_consumer_streams);
263
264 extern struct lttng_consumer_stream *consumer_allocate_stream(
265 int channel_key, int stream_key,
266 int shm_fd, int wait_fd,
267 enum lttng_consumer_stream_state state,
268 uint64_t mmap_len,
269 enum lttng_event_output output,
270 const char *path_name,
271 uid_t uid,
272 gid_t gid);
273 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
274 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
275 extern void consumer_change_stream_state(int stream_key,
276 enum lttng_consumer_stream_state state);
277 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
278 extern struct lttng_consumer_channel *consumer_allocate_channel(
279 int channel_key,
280 int shm_fd, int wait_fd,
281 uint64_t mmap_len,
282 uint64_t max_sb_size);
283 int consumer_add_channel(struct lttng_consumer_channel *channel);
284
285 extern struct lttng_consumer_local_data *lttng_consumer_create(
286 enum lttng_consumer_type type,
287 int (*buffer_ready)(struct lttng_consumer_stream *stream,
288 struct lttng_consumer_local_data *ctx),
289 int (*recv_channel)(struct lttng_consumer_channel *channel),
290 int (*recv_stream)(struct lttng_consumer_stream *stream),
291 int (*update_stream)(int sessiond_key, uint32_t state));
292 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
293 extern int lttng_consumer_on_read_subbuffer_mmap(
294 struct lttng_consumer_local_data *ctx,
295 struct lttng_consumer_stream *stream, unsigned long len);
296 extern int lttng_consumer_on_read_subbuffer_splice(
297 struct lttng_consumer_local_data *ctx,
298 struct lttng_consumer_stream *stream, unsigned long len);
299 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
300 struct lttng_consumer_stream *stream);
301 extern int lttng_consumer_get_produced_snapshot(
302 struct lttng_consumer_local_data *ctx,
303 struct lttng_consumer_stream *stream,
304 unsigned long *pos);
305 extern void *lttng_consumer_thread_poll_fds(void *data);
306 extern void *lttng_consumer_thread_receive_fds(void *data);
307 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
308 int sock, struct pollfd *consumer_sockpoll);
309
310 int lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
311 struct lttng_consumer_local_data *ctx);
312 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
313
314 #endif /* _LTTNG_CONSUMER_H */
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