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  * lttng-sessiond stops), we can exit cleanly, but if there is a problem and
  32  * for 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 lttng_ust_shm_handle *handle;
  85         int nr_streams;
  86         int shm_fd_is_copy;
  87         int wait_fd_is_copy;
  88         int cpucount;
  89 };
  90
  91 /* Forward declaration for UST. */
  92 struct lttng_ust_lib_ring_buffer;
  93
  94 /*
  95  * Internal representation of the streams, sessiond_key is used to identify
  96  * uniquely a stream.
  97  */
  98 struct lttng_consumer_stream {
  99         struct cds_list_head list;
 100         struct lttng_consumer_channel *chan;    /* associated channel */
 101         /*
 102          * key is the key used by the session daemon to refer to the
 103          * object in the consumer daemon.
 104          */
 105         int key;
 106         int shm_fd;
 107         int wait_fd;
 108         int out_fd; /* output file to write the data */
 109         off_t out_fd_offset; /* write position in the output file descriptor */
 110         char path_name[PATH_MAX]; /* tracefile name */
 111         enum lttng_consumer_stream_state state;
 112         size_t shm_len;
 113         void *mmap_base;
 114         size_t mmap_len;
 115         enum lttng_event_output output; /* splice or mmap */
 116         int shm_fd_is_copy;
 117         int wait_fd_is_copy;
 118         /* For UST */
 119         struct lttng_ust_lib_ring_buffer *buf;
 120         int cpu;
 121 };
 122
 123 /*
 124  * UST consumer local data to the program. One or more instance per
 125  * process.
 126  */
 127 struct lttng_consumer_local_data {
 128         /* function to call when data is available on a buffer */
 129         int (*on_buffer_ready)(struct lttng_consumer_stream *stream,
 130                         struct lttng_consumer_local_data *ctx);
 131         /*
 132          * function to call when we receive a new channel, it receives a
 133          * newly allocated channel, depending on the return code of this
 134          * function, the new channel will be handled by the application
 135          * or the library.
 136          *
 137          * Returns:
 138          *    > 0 (success, FD is kept by application)
 139          *   == 0 (success, FD is left to library)
 140          *    < 0 (error)
 141          */
 142         int (*on_recv_channel)(struct lttng_consumer_channel *channel);
 143         /*
 144          * function to call when we receive a new stream, it receives a
 145          * newly allocated stream, depending on the return code of this
 146          * function, the new stream will be handled by the application
 147          * or the library.
 148          *
 149          * Returns:
 150          *    > 0 (success, FD is kept by application)
 151          *   == 0 (success, FD is left to library)
 152          *    < 0 (error)
 153          */
 154         int (*on_recv_stream)(struct lttng_consumer_stream *stream);
 155         /*
 156          * function to call when a stream is getting updated by the session
 157          * daemon, this function receives the sessiond key and the new
 158          * state, depending on the return code of this function the
 159          * update of state for the stream is handled by the application
 160          * or the library.
 161          *
 162          * Returns:
 163          *    > 0 (success, FD is kept by application)
 164          *   == 0 (success, FD is left to library)
 165          *    < 0 (error)
 166          */
 167         int (*on_update_stream)(int sessiond_key, uint32_t state);
 168         /* socket to communicate errors with sessiond */
 169         int consumer_error_socket;
 170         /* socket to exchange commands with sessiond */
 171         char *consumer_command_sock_path;
 172         /* communication with splice */
 173         int consumer_thread_pipe[2];
 174         /* pipe to wake the poll thread when necessary */
 175         int consumer_poll_pipe[2];
 176         /* to let the signal handler wake up the fd receiver thread */
 177         int consumer_should_quit[2];
 178 };
 179
 180 /*
 181  * Library-level data. One instance per process.
 182  */
 183 struct lttng_consumer_global_data {
 184         /*
 185          * consumer_data.lock protects consumer_data.fd_list,
 186          * consumer_data.stream_count, and consumer_data.need_update. It
 187          * ensures the count matches the number of items in the fd_list.
 188          * It ensures the list updates *always* trigger an fd_array
 189          * update (therefore need to make list update vs
 190          * consumer_data.need_update flag update atomic, and also flag
 191          * read, fd array and flag clear atomic).
 192          */
 193         pthread_mutex_t lock;
 194         /*
 195          * Number of streams in the list below. Protected by
 196          * consumer_data.lock.
 197          */
 198         int stream_count;
 199         /*
 200          * Lists of streams and channels. Protected by consumer_data.lock.
 201          */
 202         struct lttng_consumer_stream_list stream_list;
 203         struct lttng_consumer_channel_list channel_list;
 204         /*
 205          * Flag specifying if the local array of FDs needs update in the
 206          * poll function. Protected by consumer_data.lock.
 207          */
 208         unsigned int need_update;
 209         enum lttng_consumer_type type;
 210 };
 211
 212 /*
 213  * Set the error socket for communication with a session daemon.
 214  */
 215 extern void lttng_consumer_set_error_sock(
 216                 struct lttng_consumer_local_data *ctx, int sock);
 217
 218 /*
 219  * Set the command socket path for communication with a session daemon.
 220  */
 221 extern void lttng_consumer_set_command_sock_path(
 222                 struct lttng_consumer_local_data *ctx, char *sock);
 223
 224 /*
 225  * Send return code to session daemon.
 226  *
 227  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 228  * on error.
 229  */
 230 extern int lttng_consumer_send_error(
 231                 struct lttng_consumer_local_data *ctx, int cmd);
 232
 233 /*
 234  * Called from signal handler to ensure a clean exit.
 235  */
 236 extern void lttng_consumer_should_exit(
 237                 struct lttng_consumer_local_data *ctx);
 238
 239 /*
 240  * Cleanup the daemon's socket on exit.
 241  */
 242 extern void lttng_consumer_cleanup(void);
 243
 244 /*
 245  * Flush pending writes to trace output disk file.
 246  */
 247 extern void lttng_consumer_sync_trace_file(
 248                 struct lttng_consumer_stream *stream, off_t orig_offset);
 249
 250 /*
 251  * Poll on the should_quit pipe and the command socket return -1 on error and
 252  * should exit, 0 if data is available on the command socket
 253  */
 254 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 255
 256 extern int consumer_update_poll_array(
 257                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 258                 struct lttng_consumer_stream **local_consumer_streams);
 259
 260 extern struct lttng_consumer_stream *consumer_allocate_stream(
 261                 int channel_key, int stream_key,
 262                 int shm_fd, int wait_fd,
 263                 enum lttng_consumer_stream_state state,
 264                 uint64_t mmap_len,
 265                 enum lttng_event_output output,
 266                 const char *path_name);
 267 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 268 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 269 extern void consumer_change_stream_state(int stream_key,
 270                 enum lttng_consumer_stream_state state);
 271 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 272 extern struct lttng_consumer_channel *consumer_allocate_channel(
 273                 int channel_key,
 274                 int shm_fd, int wait_fd,
 275                 uint64_t mmap_len,
 276                 uint64_t max_sb_size);
 277 int consumer_add_channel(struct lttng_consumer_channel *channel);
 278
 279 extern struct lttng_consumer_local_data *lttng_consumer_create(
 280                 enum lttng_consumer_type type,
 281                 int (*buffer_ready)(struct lttng_consumer_stream *stream,
 282                         struct lttng_consumer_local_data *ctx),
 283                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 284                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 285                 int (*update_stream)(int sessiond_key, uint32_t state));
 286 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 287 extern int lttng_consumer_on_read_subbuffer_mmap(
 288                 struct lttng_consumer_local_data *ctx,
 289                 struct lttng_consumer_stream *stream, unsigned long len);
 290 extern int lttng_consumer_on_read_subbuffer_splice(
 291                 struct lttng_consumer_local_data *ctx,
 292                 struct lttng_consumer_stream *stream, unsigned long len);
 293 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 294                 struct lttng_consumer_stream *stream);
 295 extern int lttng_consumer_get_produced_snapshot(
 296                 struct lttng_consumer_local_data *ctx,
 297                 struct lttng_consumer_stream *stream,
 298                 unsigned long *pos);
 299 extern void *lttng_consumer_thread_poll_fds(void *data);
 300 extern void *lttng_consumer_thread_receive_fds(void *data);
 301 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 302                 int sock, struct pollfd *consumer_sockpoll);
 303
 304 int lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 305                 struct lttng_consumer_local_data *ctx);
 306 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
 307
 308 #endif /* _LTTNG_CONSUMER_H */