Add stream lock comment for nesting
[lttng-tools.git] / src / common / consumer.h
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1/*
2 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
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3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 * 2012 - David Goulet <dgoulet@efficios.com>
3bd1e081 5 *
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6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License, version 2 only,
8 * as published by the Free Software Foundation.
3bd1e081 9 *
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10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
3bd1e081 14 *
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15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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18 */
19
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20#ifndef LIB_CONSUMER_H
21#define LIB_CONSUMER_H
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22
23#include <limits.h>
24#include <poll.h>
6df2e2c9 25#include <unistd.h>
e4421fec 26
3bd1e081 27#include <lttng/lttng.h>
10a8a223 28
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29#include <common/hashtable/hashtable.h>
30#include <common/compat/fcntl.h>
00e2e675 31#include <common/sessiond-comm/sessiond-comm.h>
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32
33/*
34 * When the receiving thread dies, we need to have a way to make the polling
35 * thread exit eventually. If all FDs hang up (normal case when the
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36 * lttng-sessiond stops), we can exit cleanly, but if there is a problem and
37 * for whatever reason some FDs remain open, the consumer should still exit
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38 * eventually.
39 *
40 * If the timeout is reached, it means that during this period no events
41 * occurred on the FDs so we need to force an exit. This case should not happen
42 * but it is a safety to ensure we won't block the consumer indefinitely.
43 *
44 * The value of 2 seconds is an arbitrary choice.
45 */
46#define LTTNG_CONSUMER_POLL_TIMEOUT 2000
47
48/* Commands for consumer */
49enum lttng_consumer_command {
50 LTTNG_CONSUMER_ADD_CHANNEL,
51 LTTNG_CONSUMER_ADD_STREAM,
52 /* pause, delete, active depending on fd state */
53 LTTNG_CONSUMER_UPDATE_STREAM,
54 /* inform the consumer to quit when all fd has hang up */
55 LTTNG_CONSUMER_STOP,
00e2e675 56 LTTNG_CONSUMER_ADD_RELAYD_SOCKET,
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57 /* Inform the consumer to kill a specific relayd connection */
58 LTTNG_CONSUMER_DESTROY_RELAYD,
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59 /* Return to the sessiond if there is data pending for a session */
60 LTTNG_CONSUMER_DATA_AVAILABLE,
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61};
62
63/* State of each fd in consumer */
64enum lttng_consumer_stream_state {
65 LTTNG_CONSUMER_ACTIVE_STREAM,
66 LTTNG_CONSUMER_PAUSE_STREAM,
67 LTTNG_CONSUMER_DELETE_STREAM,
68};
69
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70enum lttng_consumer_type {
71 LTTNG_CONSUMER_UNKNOWN = 0,
72 LTTNG_CONSUMER_KERNEL,
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73 LTTNG_CONSUMER64_UST,
74 LTTNG_CONSUMER32_UST,
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75};
76
77struct lttng_consumer_channel {
e4421fec 78 struct lttng_ht_node_ulong node;
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79 int key;
80 uint64_t max_sb_size; /* the subbuffer size for this channel */
81 int refcount; /* Number of streams referencing this channel */
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82 /*
83 * The number of streams to receive initially. Used to guarantee that we do
84 * not destroy a channel before receiving all its associated streams.
85 */
86 unsigned int nb_init_streams;
87
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88 /* For UST */
89 int shm_fd;
90 int wait_fd;
91 void *mmap_base;
92 size_t mmap_len;
13161846 93 struct lttng_ust_shm_handle *handle;
b5c5fc29 94 int wait_fd_is_copy;
5af2f756 95 int cpucount;
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96};
97
98/* Forward declaration for UST. */
13161846 99struct lttng_ust_lib_ring_buffer;
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100
101/*
102 * Internal representation of the streams, sessiond_key is used to identify
103 * uniquely a stream.
104 */
105struct lttng_consumer_stream {
53632229 106 /* HT node used by the data_ht and metadata_ht */
e4421fec 107 struct lttng_ht_node_ulong node;
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108 /* HT node used in consumer_data.stream_list_ht */
109 struct lttng_ht_node_ulong node_session_id;
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110 struct lttng_consumer_channel *chan; /* associated channel */
111 /*
112 * key is the key used by the session daemon to refer to the
113 * object in the consumer daemon.
114 */
115 int key;
116 int shm_fd;
117 int wait_fd;
118 int out_fd; /* output file to write the data */
119 off_t out_fd_offset; /* write position in the output file descriptor */
120 char path_name[PATH_MAX]; /* tracefile name */
121 enum lttng_consumer_stream_state state;
122 size_t shm_len;
123 void *mmap_base;
124 size_t mmap_len;
125 enum lttng_event_output output; /* splice or mmap */
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126 int shm_fd_is_copy;
127 int wait_fd_is_copy;
3bd1e081 128 /* For UST */
13161846 129 struct lttng_ust_lib_ring_buffer *buf;
3bd1e081 130 int cpu;
4078b776 131 int data_read;
d056b477 132 int hangup_flush_done;
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133 /* UID/GID of the user owning the session to which stream belongs */
134 uid_t uid;
135 gid_t gid;
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136 /* Network sequence number. Indicating on which relayd socket it goes. */
137 int net_seq_idx;
138 /* Identify if the stream is the metadata */
139 unsigned int metadata_flag;
140 /* Used when the stream is set for network streaming */
141 uint64_t relayd_stream_id;
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142 /* Next sequence number to use for trace packet */
143 uint64_t next_net_seq_num;
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144 /*
145 * Lock to use the stream FDs since they are used between threads. Using
146 * this lock with network streaming, when using the control mutex of a
147 * consumer_relayd_sock_pair, make sure to acquire this lock BEFORE locking
148 * it and releasing it AFTER the control mutex unlock.
149 */
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150 pthread_mutex_t lock;
151 /* Tracing session id */
152 uint64_t session_id;
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153};
154
155/*
156 * Internal representation of a relayd socket pair.
157 */
158struct consumer_relayd_sock_pair {
159 /* Network sequence number. */
160 int net_seq_idx;
161 /* Number of stream associated with this relayd */
162 unsigned int refcount;
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163
164 /*
165 * This flag indicates whether or not we should destroy this object. The
166 * destruction should ONLY occurs when this flag is set and the refcount is
167 * set to zero.
168 */
169 unsigned int destroy_flag;
170
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171 /*
172 * Mutex protecting the control socket to avoid out of order packets
173 * between threads sending data to the relayd. Since metadata data is sent
174 * over that socket, at least two sendmsg() are needed (header + data)
175 * creating a race for packets to overlap between threads using it.
176 */
00e2e675 177 pthread_mutex_t ctrl_sock_mutex;
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178
179 /* Control socket. Command and metadata are passed over it */
00e2e675 180 struct lttcomm_sock control_sock;
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181
182 /*
183 * We don't need a mutex at this point since we only splice or write single
184 * large chunk of data with a header appended at the begining. Moreover,
185 * this socket is for now only used in a single thread.
186 */
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187 struct lttcomm_sock data_sock;
188 struct lttng_ht_node_ulong node;
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189};
190
191/*
192 * UST consumer local data to the program. One or more instance per
193 * process.
194 */
195struct lttng_consumer_local_data {
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196 /*
197 * Function to call when data is available on a buffer.
198 * Returns the number of bytes read, or negative error value.
199 */
200 ssize_t (*on_buffer_ready)(struct lttng_consumer_stream *stream,
d41f73b7 201 struct lttng_consumer_local_data *ctx);
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202 /*
203 * function to call when we receive a new channel, it receives a
204 * newly allocated channel, depending on the return code of this
205 * function, the new channel will be handled by the application
206 * or the library.
207 *
208 * Returns:
209 * > 0 (success, FD is kept by application)
210 * == 0 (success, FD is left to library)
211 * < 0 (error)
212 */
213 int (*on_recv_channel)(struct lttng_consumer_channel *channel);
214 /*
215 * function to call when we receive a new stream, it receives a
216 * newly allocated stream, depending on the return code of this
217 * function, the new stream will be handled by the application
218 * or the library.
219 *
220 * Returns:
221 * > 0 (success, FD is kept by application)
222 * == 0 (success, FD is left to library)
223 * < 0 (error)
224 */
225 int (*on_recv_stream)(struct lttng_consumer_stream *stream);
226 /*
227 * function to call when a stream is getting updated by the session
228 * daemon, this function receives the sessiond key and the new
229 * state, depending on the return code of this function the
230 * update of state for the stream is handled by the application
231 * or the library.
232 *
233 * Returns:
234 * > 0 (success, FD is kept by application)
235 * == 0 (success, FD is left to library)
236 * < 0 (error)
237 */
238 int (*on_update_stream)(int sessiond_key, uint32_t state);
239 /* socket to communicate errors with sessiond */
240 int consumer_error_socket;
241 /* socket to exchange commands with sessiond */
242 char *consumer_command_sock_path;
243 /* communication with splice */
244 int consumer_thread_pipe[2];
fb3a43a9 245 int consumer_splice_metadata_pipe[2];
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246 /* Data stream poll thread pipe. To transfer data stream to the thread */
247 int consumer_data_pipe[2];
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248 /* to let the signal handler wake up the fd receiver thread */
249 int consumer_should_quit[2];
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250 /* Metadata poll thread pipe. Transfer metadata stream to it */
251 int consumer_metadata_pipe[2];
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252};
253
254/*
255 * Library-level data. One instance per process.
256 */
257struct lttng_consumer_global_data {
258 /*
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259 * At this time, this lock is used to ensure coherence between the count
260 * and number of element in the hash table. It's also a protection for
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261 * concurrent read/write between threads.
262 *
263 * XXX: We need to see if this lock is still needed with the lockless RCU
264 * hash tables.
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265 */
266 pthread_mutex_t lock;
e4421fec 267
3bd1e081 268 /*
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269 * Number of streams in the data stream hash table declared outside.
270 * Protected by consumer_data.lock.
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271 */
272 int stream_count;
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273
274 /* Channel hash table protected by consumer_data.lock. */
e4421fec 275 struct lttng_ht *channel_ht;
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276 /*
277 * Flag specifying if the local array of FDs needs update in the
278 * poll function. Protected by consumer_data.lock.
279 */
280 unsigned int need_update;
281 enum lttng_consumer_type type;
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282
283 /*
284 * Relayd socket(s) hashtable indexed by network sequence number. Each
285 * stream has an index which associate the right relayd socket to use.
286 */
287 struct lttng_ht *relayd_ht;
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288
289 /*
290 * This hash table contains all streams (metadata and data) indexed by
291 * session id. In other words, the ht is indexed by session id and each
292 * bucket contains the list of associated streams.
293 *
294 * This HT uses the "node_session_id" of the consumer stream.
295 */
296 struct lttng_ht *stream_list_ht;
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297};
298
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299/* Defined in consumer.c and coupled with explanations */
300extern struct lttng_ht *metadata_ht;
301extern struct lttng_ht *data_ht;
302
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303/*
304 * Init consumer data structures.
305 */
306extern void lttng_consumer_init(void);
307
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308/*
309 * Set the error socket for communication with a session daemon.
310 */
311extern void lttng_consumer_set_error_sock(
312 struct lttng_consumer_local_data *ctx, int sock);
313
314/*
315 * Set the command socket path for communication with a session daemon.
316 */
317extern void lttng_consumer_set_command_sock_path(
318 struct lttng_consumer_local_data *ctx, char *sock);
319
320/*
321 * Send return code to session daemon.
322 *
323 * Returns the return code of sendmsg : the number of bytes transmitted or -1
324 * on error.
325 */
326extern int lttng_consumer_send_error(
327 struct lttng_consumer_local_data *ctx, int cmd);
328
329/*
330 * Called from signal handler to ensure a clean exit.
331 */
332extern void lttng_consumer_should_exit(
333 struct lttng_consumer_local_data *ctx);
334
335/*
336 * Cleanup the daemon's socket on exit.
337 */
338extern void lttng_consumer_cleanup(void);
339
340/*
341 * Flush pending writes to trace output disk file.
342 */
343extern void lttng_consumer_sync_trace_file(
344 struct lttng_consumer_stream *stream, off_t orig_offset);
345
346/*
347 * Poll on the should_quit pipe and the command socket return -1 on error and
348 * should exit, 0 if data is available on the command socket
349 */
350extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
351
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352extern struct lttng_consumer_stream *consumer_allocate_stream(
353 int channel_key, int stream_key,
354 int shm_fd, int wait_fd,
355 enum lttng_consumer_stream_state state,
356 uint64_t mmap_len,
357 enum lttng_event_output output,
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358 const char *path_name,
359 uid_t uid,
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360 gid_t gid,
361 int net_index,
c80048c6 362 int metadata_flag,
53632229 363 uint64_t session_id,
c80048c6 364 int *alloc_ret);
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365extern void consumer_del_stream(struct lttng_consumer_stream *stream,
366 struct lttng_ht *ht);
367extern void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
368 struct lttng_ht *ht);
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369extern void consumer_del_channel(struct lttng_consumer_channel *channel);
370extern struct lttng_consumer_channel *consumer_allocate_channel(
371 int channel_key,
372 int shm_fd, int wait_fd,
373 uint64_t mmap_len,
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374 uint64_t max_sb_size,
375 unsigned int nb_init_streams);
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376int consumer_add_channel(struct lttng_consumer_channel *channel);
377
00e2e675 378/* lttng-relayd consumer command */
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379struct consumer_relayd_sock_pair *consumer_allocate_relayd_sock_pair(
380 int net_seq_idx);
381struct consumer_relayd_sock_pair *consumer_find_relayd(int key);
382int consumer_handle_stream_before_relayd(struct lttng_consumer_stream *stream,
383 size_t data_size);
c869f647 384void consumer_steal_stream_key(int key, struct lttng_ht *ht);
00e2e675 385
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386extern struct lttng_consumer_local_data *lttng_consumer_create(
387 enum lttng_consumer_type type,
4078b776 388 ssize_t (*buffer_ready)(struct lttng_consumer_stream *stream,
d41f73b7 389 struct lttng_consumer_local_data *ctx),
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390 int (*recv_channel)(struct lttng_consumer_channel *channel),
391 int (*recv_stream)(struct lttng_consumer_stream *stream),
392 int (*update_stream)(int sessiond_key, uint32_t state));
393extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
4078b776 394extern ssize_t lttng_consumer_on_read_subbuffer_mmap(
3bd1e081 395 struct lttng_consumer_local_data *ctx,
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396 struct lttng_consumer_stream *stream, unsigned long len,
397 unsigned long padding);
4078b776 398extern ssize_t lttng_consumer_on_read_subbuffer_splice(
3bd1e081 399 struct lttng_consumer_local_data *ctx,
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400 struct lttng_consumer_stream *stream, unsigned long len,
401 unsigned long padding);
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402extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
403 struct lttng_consumer_stream *stream);
404extern int lttng_consumer_get_produced_snapshot(
405 struct lttng_consumer_local_data *ctx,
406 struct lttng_consumer_stream *stream,
407 unsigned long *pos);
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408extern void *consumer_thread_metadata_poll(void *data);
409extern void *consumer_thread_data_poll(void *data);
410extern void *consumer_thread_sessiond_poll(void *data);
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411extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
412 int sock, struct pollfd *consumer_sockpoll);
413
4078b776 414ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
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415 struct lttng_consumer_local_data *ctx);
416int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
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417int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
418 struct lttng_consumer_local_data *ctx, int sock,
419 struct pollfd *consumer_sockpoll, struct lttcomm_sock *relayd_sock);
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420void consumer_flag_relayd_for_destroy(
421 struct consumer_relayd_sock_pair *relayd);
ca22feea 422int consumer_data_available(uint64_t id);
d41f73b7 423
f02e1e8a 424#endif /* LIB_CONSUMER_H */
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