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 wait_fd_is_copy;
  82         int cpucount;
  83 };
  84
  85 /* Forward declaration for UST. */
  86 struct lttng_ust_lib_ring_buffer;
  87
  88 /*
  89  * Internal representation of the streams, sessiond_key is used to identify
  90  * uniquely a stream.
  91  */
  92 struct lttng_consumer_stream {
  93         struct lttng_ht_node_ulong node;
  94         struct lttng_consumer_channel *chan;    /* associated channel */
  95         /*
  96          * key is the key used by the session daemon to refer to the
  97          * object in the consumer daemon.
  98          */
  99         int key;
 100         int shm_fd;
 101         int wait_fd;
 102         int out_fd; /* output file to write the data */
 103         off_t out_fd_offset; /* write position in the output file descriptor */
 104         char path_name[PATH_MAX]; /* tracefile name */
 105         enum lttng_consumer_stream_state state;
 106         size_t shm_len;
 107         void *mmap_base;
 108         size_t mmap_len;
 109         enum lttng_event_output output; /* splice or mmap */
 110         int shm_fd_is_copy;
 111         int wait_fd_is_copy;
 112         /* For UST */
 113         struct lttng_ust_lib_ring_buffer *buf;
 114         int cpu;
 115         int hangup_flush_done;
 116         /* UID/GID of the user owning the session to which stream belongs */
 117         uid_t uid;
 118         gid_t gid;
 119 };
 120
 121 /*
 122  * UST consumer local data to the program. One or more instance per
 123  * process.
 124  */
 125 struct lttng_consumer_local_data {
 126         /* function to call when data is available on a buffer */
 127         int (*on_buffer_ready)(struct lttng_consumer_stream *stream,
 128                         struct lttng_consumer_local_data *ctx);
 129         /*
 130          * function to call when we receive a new channel, it receives a
 131          * newly allocated channel, depending on the return code of this
 132          * function, the new channel will be handled by the application
 133          * or the library.
 134          *
 135          * Returns:
 136          *    > 0 (success, FD is kept by application)
 137          *   == 0 (success, FD is left to library)
 138          *    < 0 (error)
 139          */
 140         int (*on_recv_channel)(struct lttng_consumer_channel *channel);
 141         /*
 142          * function to call when we receive a new stream, it receives a
 143          * newly allocated stream, depending on the return code of this
 144          * function, the new stream will be handled by the application
 145          * or the library.
 146          *
 147          * Returns:
 148          *    > 0 (success, FD is kept by application)
 149          *   == 0 (success, FD is left to library)
 150          *    < 0 (error)
 151          */
 152         int (*on_recv_stream)(struct lttng_consumer_stream *stream);
 153         /*
 154          * function to call when a stream is getting updated by the session
 155          * daemon, this function receives the sessiond key and the new
 156          * state, depending on the return code of this function the
 157          * update of state for the stream is handled by the application
 158          * or the library.
 159          *
 160          * Returns:
 161          *    > 0 (success, FD is kept by application)
 162          *   == 0 (success, FD is left to library)
 163          *    < 0 (error)
 164          */
 165         int (*on_update_stream)(int sessiond_key, uint32_t state);
 166         /* socket to communicate errors with sessiond */
 167         int consumer_error_socket;
 168         /* socket to exchange commands with sessiond */
 169         char *consumer_command_sock_path;
 170         /* communication with splice */
 171         int consumer_thread_pipe[2];
 172         /* pipe to wake the poll thread when necessary */
 173         int consumer_poll_pipe[2];
 174         /* to let the signal handler wake up the fd receiver thread */
 175         int consumer_should_quit[2];
 176 };
 177
 178 /*
 179  * Library-level data. One instance per process.
 180  */
 181 struct lttng_consumer_global_data {
 182
 183         /*
 184          * At this time, this lock is used to ensure coherence between the count
 185          * and number of element in the hash table. It's also a protection for
 186          * concurrent read/write between threads.
 187          *
 188          * XXX: We need to see if this lock is still needed with the lockless RCU
 189          * hash tables.
 190          */
 191         pthread_mutex_t lock;
 192
 193         /*
 194          * Number of streams in the hash table. Protected by consumer_data.lock.
 195          */
 196         int stream_count;
 197         /*
 198          * Hash tables of streams and channels. Protected by consumer_data.lock.
 199          */
 200         struct lttng_ht *stream_ht;
 201         struct lttng_ht *channel_ht;
 202         /*
 203          * Flag specifying if the local array of FDs needs update in the
 204          * poll function. Protected by consumer_data.lock.
 205          */
 206         unsigned int need_update;
 207         enum lttng_consumer_type type;
 208 };
 209
 210 /*
 211  * Init consumer data structures.
 212  */
 213 extern void lttng_consumer_init(void);
 214
 215 /*
 216  * Set the error socket for communication with a session daemon.
 217  */
 218 extern void lttng_consumer_set_error_sock(
 219                 struct lttng_consumer_local_data *ctx, int sock);
 220
 221 /*
 222  * Set the command socket path for communication with a session daemon.
 223  */
 224 extern void lttng_consumer_set_command_sock_path(
 225                 struct lttng_consumer_local_data *ctx, char *sock);
 226
 227 /*
 228  * Send return code to session daemon.
 229  *
 230  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 231  * on error.
 232  */
 233 extern int lttng_consumer_send_error(
 234                 struct lttng_consumer_local_data *ctx, int cmd);
 235
 236 /*
 237  * Called from signal handler to ensure a clean exit.
 238  */
 239 extern void lttng_consumer_should_exit(
 240                 struct lttng_consumer_local_data *ctx);
 241
 242 /*
 243  * Cleanup the daemon's socket on exit.
 244  */
 245 extern void lttng_consumer_cleanup(void);
 246
 247 /*
 248  * Flush pending writes to trace output disk file.
 249  */
 250 extern void lttng_consumer_sync_trace_file(
 251                 struct lttng_consumer_stream *stream, off_t orig_offset);
 252
 253 /*
 254  * Poll on the should_quit pipe and the command socket return -1 on error and
 255  * should exit, 0 if data is available on the command socket
 256  */
 257 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 258
 259 extern int consumer_update_poll_array(
 260                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 261                 struct lttng_consumer_stream **local_consumer_streams);
 262
 263 extern struct lttng_consumer_stream *consumer_allocate_stream(
 264                 int channel_key, int stream_key,
 265                 int shm_fd, int wait_fd,
 266                 enum lttng_consumer_stream_state state,
 267                 uint64_t mmap_len,
 268                 enum lttng_event_output output,
 269                 const char *path_name,
 270                 uid_t uid,
 271                 gid_t gid);
 272 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 273 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 274 extern void consumer_change_stream_state(int stream_key,
 275                 enum lttng_consumer_stream_state state);
 276 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 277 extern struct lttng_consumer_channel *consumer_allocate_channel(
 278                 int channel_key,
 279                 int shm_fd, int wait_fd,
 280                 uint64_t mmap_len,
 281                 uint64_t max_sb_size);
 282 int consumer_add_channel(struct lttng_consumer_channel *channel);
 283
 284 extern struct lttng_consumer_local_data *lttng_consumer_create(
 285                 enum lttng_consumer_type type,
 286                 int (*buffer_ready)(struct lttng_consumer_stream *stream,
 287                         struct lttng_consumer_local_data *ctx),
 288                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 289                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 290                 int (*update_stream)(int sessiond_key, uint32_t state));
 291 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 292 extern int lttng_consumer_on_read_subbuffer_mmap(
 293                 struct lttng_consumer_local_data *ctx,
 294                 struct lttng_consumer_stream *stream, unsigned long len);
 295 extern int lttng_consumer_on_read_subbuffer_splice(
 296                 struct lttng_consumer_local_data *ctx,
 297                 struct lttng_consumer_stream *stream, unsigned long len);
 298 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 299                 struct lttng_consumer_stream *stream);
 300 extern int lttng_consumer_get_produced_snapshot(
 301                 struct lttng_consumer_local_data *ctx,
 302                 struct lttng_consumer_stream *stream,
 303                 unsigned long *pos);
 304 extern void *lttng_consumer_thread_poll_fds(void *data);
 305 extern void *lttng_consumer_thread_receive_fds(void *data);
 306 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 307                 int sock, struct pollfd *consumer_sockpoll);
 308
 309 int lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 310                 struct lttng_consumer_local_data *ctx);
 311 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
 312
 313 #endif /* _LTTNG_CONSUMER_H */