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