src/common/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
  29 #include <common/hashtable/hashtable.h>
  30 #include <common/compat/fcntl.h>
  31
  32 /*
  33  * When the receiving thread dies, we need to have a way to make the polling
  34  * thread exit eventually. If all FDs hang up (normal case when the
  35  * lttng-sessiond stops), we can exit cleanly, but if there is a problem and
  36  * for whatever reason some FDs remain open, the consumer should still exit
  37  * eventually.
  38  *
  39  * If the timeout is reached, it means that during this period no events
  40  * occurred on the FDs so we need to force an exit. This case should not happen
  41  * but it is a safety to ensure we won't block the consumer indefinitely.
  42  *
  43  * The value of 2 seconds is an arbitrary choice.
  44  */
  45 #define LTTNG_CONSUMER_POLL_TIMEOUT 2000
  46
  47 /* Commands for consumer */
  48 enum lttng_consumer_command {
  49         LTTNG_CONSUMER_ADD_CHANNEL,
  50         LTTNG_CONSUMER_ADD_STREAM,
  51         /* pause, delete, active depending on fd state */
  52         LTTNG_CONSUMER_UPDATE_STREAM,
  53         /* inform the consumer to quit when all fd has hang up */
  54         LTTNG_CONSUMER_STOP,
  55 };
  56
  57 /* State of each fd in consumer */
  58 enum lttng_consumer_stream_state {
  59         LTTNG_CONSUMER_ACTIVE_STREAM,
  60         LTTNG_CONSUMER_PAUSE_STREAM,
  61         LTTNG_CONSUMER_DELETE_STREAM,
  62 };
  63
  64 enum lttng_consumer_type {
  65         LTTNG_CONSUMER_UNKNOWN = 0,
  66         LTTNG_CONSUMER_KERNEL,
  67         LTTNG_CONSUMER64_UST,
  68         LTTNG_CONSUMER32_UST,
  69 };
  70
  71 struct lttng_consumer_channel {
  72         struct lttng_ht_node_ulong node;
  73         int key;
  74         uint64_t max_sb_size; /* the subbuffer size for this channel */
  75         int refcount; /* Number of streams referencing this channel */
  76         /* For UST */
  77         int shm_fd;
  78         int wait_fd;
  79         void *mmap_base;
  80         size_t mmap_len;
  81         struct lttng_ust_shm_handle *handle;
  82         int nr_streams;
  83         int wait_fd_is_copy;
  84         int cpucount;
  85 };
  86
  87 /* Forward declaration for UST. */
  88 struct lttng_ust_lib_ring_buffer;
  89
  90 /*
  91  * Internal representation of the streams, sessiond_key is used to identify
  92  * uniquely a stream.
  93  */
  94 struct lttng_consumer_stream {
  95         struct lttng_ht_node_ulong node;
  96         struct lttng_consumer_channel *chan;    /* associated channel */
  97         /*
  98          * key is the key used by the session daemon to refer to the
  99          * object in the consumer daemon.
 100          */
 101         int key;
 102         int shm_fd;
 103         int wait_fd;
 104         int out_fd; /* output file to write the data */
 105         off_t out_fd_offset; /* write position in the output file descriptor */
 106         char path_name[PATH_MAX]; /* tracefile name */
 107         enum lttng_consumer_stream_state state;
 108         size_t shm_len;
 109         void *mmap_base;
 110         size_t mmap_len;
 111         enum lttng_event_output output; /* splice or mmap */
 112         int shm_fd_is_copy;
 113         int wait_fd_is_copy;
 114         /* For UST */
 115         struct lttng_ust_lib_ring_buffer *buf;
 116         int cpu;
 117         int hangup_flush_done;
 118         /* UID/GID of the user owning the session to which stream belongs */
 119         uid_t uid;
 120         gid_t gid;
 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         /*
 186          * At this time, this lock is used to ensure coherence between the count
 187          * and number of element in the hash table. It's also a protection for
 188          * concurrent read/write between threads.
 189          *
 190          * XXX: We need to see if this lock is still needed with the lockless RCU
 191          * hash tables.
 192          */
 193         pthread_mutex_t lock;
 194
 195         /*
 196          * Number of streams in the hash table. Protected by consumer_data.lock.
 197          */
 198         int stream_count;
 199         /*
 200          * Hash tables of streams and channels. Protected by consumer_data.lock.
 201          */
 202         struct lttng_ht *stream_ht;
 203         struct lttng_ht *channel_ht;
 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  * Init consumer data structures.
 214  */
 215 extern void lttng_consumer_init(void);
 216
 217 /*
 218  * Set the error socket for communication with a session daemon.
 219  */
 220 extern void lttng_consumer_set_error_sock(
 221                 struct lttng_consumer_local_data *ctx, int sock);
 222
 223 /*
 224  * Set the command socket path for communication with a session daemon.
 225  */
 226 extern void lttng_consumer_set_command_sock_path(
 227                 struct lttng_consumer_local_data *ctx, char *sock);
 228
 229 /*
 230  * Send return code to session daemon.
 231  *
 232  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 233  * on error.
 234  */
 235 extern int lttng_consumer_send_error(
 236                 struct lttng_consumer_local_data *ctx, int cmd);
 237
 238 /*
 239  * Called from signal handler to ensure a clean exit.
 240  */
 241 extern void lttng_consumer_should_exit(
 242                 struct lttng_consumer_local_data *ctx);
 243
 244 /*
 245  * Cleanup the daemon's socket on exit.
 246  */
 247 extern void lttng_consumer_cleanup(void);
 248
 249 /*
 250  * Flush pending writes to trace output disk file.
 251  */
 252 extern void lttng_consumer_sync_trace_file(
 253                 struct lttng_consumer_stream *stream, off_t orig_offset);
 254
 255 /*
 256  * Poll on the should_quit pipe and the command socket return -1 on error and
 257  * should exit, 0 if data is available on the command socket
 258  */
 259 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 260
 261 extern int consumer_update_poll_array(
 262                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 263                 struct lttng_consumer_stream **local_consumer_streams);
 264
 265 extern struct lttng_consumer_stream *consumer_allocate_stream(
 266                 int channel_key, int stream_key,
 267                 int shm_fd, int wait_fd,
 268                 enum lttng_consumer_stream_state state,
 269                 uint64_t mmap_len,
 270                 enum lttng_event_output output,
 271                 const char *path_name,
 272                 uid_t uid,
 273                 gid_t gid);
 274 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 275 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 276 extern void consumer_change_stream_state(int stream_key,
 277                 enum lttng_consumer_stream_state state);
 278 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 279 extern struct lttng_consumer_channel *consumer_allocate_channel(
 280                 int channel_key,
 281                 int shm_fd, int wait_fd,
 282                 uint64_t mmap_len,
 283                 uint64_t max_sb_size);
 284 int consumer_add_channel(struct lttng_consumer_channel *channel);
 285
 286 extern struct lttng_consumer_local_data *lttng_consumer_create(
 287                 enum lttng_consumer_type type,
 288                 int (*buffer_ready)(struct lttng_consumer_stream *stream,
 289                         struct lttng_consumer_local_data *ctx),
 290                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 291                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 292                 int (*update_stream)(int sessiond_key, uint32_t state));
 293 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 294 extern int lttng_consumer_on_read_subbuffer_mmap(
 295                 struct lttng_consumer_local_data *ctx,
 296                 struct lttng_consumer_stream *stream, unsigned long len);
 297 extern int lttng_consumer_on_read_subbuffer_splice(
 298                 struct lttng_consumer_local_data *ctx,
 299                 struct lttng_consumer_stream *stream, unsigned long len);
 300 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 301                 struct lttng_consumer_stream *stream);
 302 extern int lttng_consumer_get_produced_snapshot(
 303                 struct lttng_consumer_local_data *ctx,
 304                 struct lttng_consumer_stream *stream,
 305                 unsigned long *pos);
 306 extern void *lttng_consumer_thread_poll_fds(void *data);
 307 extern void *lttng_consumer_thread_receive_fds(void *data);
 308 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 309                 int sock, struct pollfd *consumer_sockpoll);
 310
 311 int lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 312                 struct lttng_consumer_local_data *ctx);
 313 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
 314
 315 #endif /* _LTTNG_CONSUMER_H */