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 <urcu/list.h>
  26 #include <lttng/lttng.h>
  27
  28 /*
  29  * When the receiving thread dies, we need to have a way to make the polling
  30  * thread exit eventually. If all FDs hang up (normal case when the
  31  * ltt-sessiond stops), we can exit cleanly, but if there is a problem and for
  32  * whatever reason some FDs remain open, the consumer should still exit
  33  * eventually.
  34  *
  35  * If the timeout is reached, it means that during this period no events
  36  * occurred on the FDs so we need to force an exit. This case should not happen
  37  * but it is a safety to ensure we won't block the consumer indefinitely.
  38  *
  39  * The value of 2 seconds is an arbitrary choice.
  40  */
  41 #define LTTNG_CONSUMER_POLL_TIMEOUT 2000
  42
  43 /* Commands for consumer */
  44 enum lttng_consumer_command {
  45         LTTNG_CONSUMER_ADD_CHANNEL,
  46         LTTNG_CONSUMER_ADD_STREAM,
  47         /* pause, delete, active depending on fd state */
  48         LTTNG_CONSUMER_UPDATE_STREAM,
  49         /* inform the consumer to quit when all fd has hang up */
  50         LTTNG_CONSUMER_STOP,
  51 };
  52
  53 /* State of each fd in consumer */
  54 enum lttng_consumer_stream_state {
  55         LTTNG_CONSUMER_ACTIVE_STREAM,
  56         LTTNG_CONSUMER_PAUSE_STREAM,
  57         LTTNG_CONSUMER_DELETE_STREAM,
  58 };
  59
  60 struct lttng_consumer_channel_list {
  61         struct cds_list_head head;
  62 };
  63
  64 struct lttng_consumer_stream_list {
  65         struct cds_list_head head;
  66 };
  67
  68 enum lttng_consumer_type {
  69         LTTNG_CONSUMER_UNKNOWN = 0,
  70         LTTNG_CONSUMER_KERNEL,
  71         LTTNG_CONSUMER_UST,
  72 };
  73
  74 struct lttng_consumer_channel {
  75         struct cds_list_head list;
  76         int key;
  77         uint64_t max_sb_size; /* the subbuffer size for this channel */
  78         int refcount; /* Number of streams referencing this channel */
  79         /* For UST */
  80         int shm_fd;
  81         int wait_fd;
  82         void *mmap_base;
  83         size_t mmap_len;
  84         struct shm_handle *handle;
  85         int nr_streams;
  86 };
  87
  88 /* Forward declaration for UST. */
  89 struct lib_ring_buffer;
  90
  91 /*
  92  * Internal representation of the streams, sessiond_key is used to identify
  93  * uniquely a stream.
  94  */
  95 struct lttng_consumer_stream {
  96         struct cds_list_head list;
  97         struct lttng_consumer_channel *chan;    /* associated channel */
  98         /*
  99          * key is the key used by the session daemon to refer to the
 100          * object in the consumer daemon.
 101          */
 102         int key;
 103         int shm_fd;
 104         int wait_fd;
 105         int out_fd; /* output file to write the data */
 106         off_t out_fd_offset; /* write position in the output file descriptor */
 107         char path_name[PATH_MAX]; /* tracefile name */
 108         enum lttng_consumer_stream_state state;
 109         size_t shm_len;
 110         void *mmap_base;
 111         size_t mmap_len;
 112         enum lttng_event_output output; /* splice or mmap */
 113         /* For UST */
 114         struct lib_ring_buffer *buf;
 115         int cpu;
 116 };
 117
 118 /*
 119  * UST consumer local data to the program. One or more instance per
 120  * process.
 121  */
 122 struct lttng_consumer_local_data {
 123         /* function to call when data is available on a buffer */
 124         int (*on_buffer_ready)(struct lttng_consumer_stream *stream);
 125         /*
 126          * function to call when we receive a new channel, it receives a
 127          * newly allocated channel, depending on the return code of this
 128          * function, the new channel will be handled by the application
 129          * or the library.
 130          *
 131          * Returns:
 132          *    > 0 (success, FD is kept by application)
 133          *   == 0 (success, FD is left to library)
 134          *    < 0 (error)
 135          */
 136         int (*on_recv_channel)(struct lttng_consumer_channel *channel);
 137         /*
 138          * function to call when we receive a new stream, it receives a
 139          * newly allocated stream, depending on the return code of this
 140          * function, the new stream will be handled by the application
 141          * or the library.
 142          *
 143          * Returns:
 144          *    > 0 (success, FD is kept by application)
 145          *   == 0 (success, FD is left to library)
 146          *    < 0 (error)
 147          */
 148         int (*on_recv_stream)(struct lttng_consumer_stream *stream);
 149         /*
 150          * function to call when a stream is getting updated by the session
 151          * daemon, this function receives the sessiond key and the new
 152          * state, depending on the return code of this function the
 153          * update of state for the stream is handled by the application
 154          * or the library.
 155          *
 156          * Returns:
 157          *    > 0 (success, FD is kept by application)
 158          *   == 0 (success, FD is left to library)
 159          *    < 0 (error)
 160          */
 161         int (*on_update_stream)(int sessiond_key, uint32_t state);
 162         /* socket to communicate errors with sessiond */
 163         int consumer_error_socket;
 164         /* socket to exchange commands with sessiond */
 165         char *consumer_command_sock_path;
 166         /* communication with splice */
 167         int consumer_thread_pipe[2];
 168         /* pipe to wake the poll thread when necessary */
 169         int consumer_poll_pipe[2];
 170         /* to let the signal handler wake up the fd receiver thread */
 171         int consumer_should_quit[2];
 172 };
 173
 174 /*
 175  * Library-level data. One instance per process.
 176  */
 177 struct lttng_consumer_global_data {
 178         /*
 179          * consumer_data.lock protects consumer_data.fd_list,
 180          * consumer_data.stream_count, and consumer_data.need_update. It
 181          * ensures the count matches the number of items in the fd_list.
 182          * It ensures the list updates *always* trigger an fd_array
 183          * update (therefore need to make list update vs
 184          * consumer_data.need_update flag update atomic, and also flag
 185          * read, fd array and flag clear atomic).
 186          */
 187         pthread_mutex_t lock;
 188         /*
 189          * Number of streams in the list below. Protected by
 190          * consumer_data.lock.
 191          */
 192         int stream_count;
 193         /*
 194          * Lists of streams and channels. Protected by consumer_data.lock.
 195          */
 196         struct lttng_consumer_stream_list stream_list;
 197         struct lttng_consumer_channel_list channel_list;
 198         /*
 199          * Flag specifying if the local array of FDs needs update in the
 200          * poll function. Protected by consumer_data.lock.
 201          */
 202         unsigned int need_update;
 203         enum lttng_consumer_type type;
 204 };
 205
 206 /*
 207  * Set the error socket for communication with a session daemon.
 208  */
 209 extern void lttng_consumer_set_error_sock(
 210                 struct lttng_consumer_local_data *ctx, int sock);
 211
 212 /*
 213  * Set the command socket path for communication with a session daemon.
 214  */
 215 extern void lttng_consumer_set_command_sock_path(
 216                 struct lttng_consumer_local_data *ctx, char *sock);
 217
 218 /*
 219  * Send return code to session daemon.
 220  *
 221  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 222  * on error.
 223  */
 224 extern int lttng_consumer_send_error(
 225                 struct lttng_consumer_local_data *ctx, int cmd);
 226
 227 /*
 228  * Called from signal handler to ensure a clean exit.
 229  */
 230 extern void lttng_consumer_should_exit(
 231                 struct lttng_consumer_local_data *ctx);
 232
 233 /*
 234  * Cleanup the daemon's socket on exit.
 235  */
 236 extern void lttng_consumer_cleanup(void);
 237
 238 /*
 239  * Flush pending writes to trace output disk file.
 240  */
 241 extern void lttng_consumer_sync_trace_file(
 242                 struct lttng_consumer_stream *stream, off_t orig_offset);
 243
 244 /*
 245  * Poll on the should_quit pipe and the command socket return -1 on error and
 246  * should exit, 0 if data is available on the command socket
 247  */
 248 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 249
 250 extern int consumer_update_poll_array(
 251                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 252                 struct lttng_consumer_stream **local_consumer_streams);
 253
 254 extern struct lttng_consumer_stream *consumer_allocate_stream(
 255                 int channel_key, int stream_key,
 256                 int shm_fd, int wait_fd,
 257                 enum lttng_consumer_stream_state state,
 258                 uint64_t mmap_len,
 259                 enum lttng_event_output output,
 260                 const char *path_name);
 261 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 262 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 263 extern void consumer_change_stream_state(int stream_key,
 264                 enum lttng_consumer_stream_state state);
 265 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 266 extern struct lttng_consumer_channel *consumer_allocate_channel(
 267                 int channel_key,
 268                 int shm_fd, int wait_fd,
 269                 uint64_t mmap_len,
 270                 uint64_t max_sb_size);
 271 int consumer_add_channel(struct lttng_consumer_channel *channel);
 272
 273 extern struct lttng_consumer_local_data *lttng_consumer_create(
 274                 enum lttng_consumer_type type,
 275                 int (*buffer_ready)(struct lttng_consumer_stream *stream),
 276                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 277                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 278                 int (*update_stream)(int sessiond_key, uint32_t state));
 279 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 280 extern int lttng_consumer_on_read_subbuffer_mmap(
 281                 struct lttng_consumer_local_data *ctx,
 282                 struct lttng_consumer_stream *stream, unsigned long len);
 283 extern int lttng_consumer_on_read_subbuffer_splice(
 284                 struct lttng_consumer_local_data *ctx,
 285                 struct lttng_consumer_stream *stream, unsigned long len);
 286 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 287                 struct lttng_consumer_stream *stream);
 288 extern int lttng_consumer_get_produced_snapshot(
 289                 struct lttng_consumer_local_data *ctx,
 290                 struct lttng_consumer_stream *stream,
 291                 unsigned long *pos);
 292 extern void *lttng_consumer_thread_poll_fds(void *data);
 293 extern void *lttng_consumer_thread_receive_fds(void *data);
 294 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 295                 int sock, struct pollfd *consumer_sockpoll);
 296
 297 #endif /* _LTTNG_CONSUMER_H */