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 data_read;
 118         int hangup_flush_done;
 119         /* UID/GID of the user owning the session to which stream belongs */
 120         uid_t uid;
 121         gid_t gid;
 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         /*
 130          * Function to call when data is available on a buffer.
 131          * Returns the number of bytes read, or negative error value.
 132          */
 133         ssize_t (*on_buffer_ready)(struct lttng_consumer_stream *stream,
 134                         struct lttng_consumer_local_data *ctx);
 135         /*
 136          * function to call when we receive a new channel, it receives a
 137          * newly allocated channel, depending on the return code of this
 138          * function, the new channel will be handled by the application
 139          * or the library.
 140          *
 141          * Returns:
 142          *    > 0 (success, FD is kept by application)
 143          *   == 0 (success, FD is left to library)
 144          *    < 0 (error)
 145          */
 146         int (*on_recv_channel)(struct lttng_consumer_channel *channel);
 147         /*
 148          * function to call when we receive a new stream, it receives a
 149          * newly allocated stream, depending on the return code of this
 150          * function, the new stream will be handled by the application
 151          * or the library.
 152          *
 153          * Returns:
 154          *    > 0 (success, FD is kept by application)
 155          *   == 0 (success, FD is left to library)
 156          *    < 0 (error)
 157          */
 158         int (*on_recv_stream)(struct lttng_consumer_stream *stream);
 159         /*
 160          * function to call when a stream is getting updated by the session
 161          * daemon, this function receives the sessiond key and the new
 162          * state, depending on the return code of this function the
 163          * update of state for the stream is handled by the application
 164          * or the library.
 165          *
 166          * Returns:
 167          *    > 0 (success, FD is kept by application)
 168          *   == 0 (success, FD is left to library)
 169          *    < 0 (error)
 170          */
 171         int (*on_update_stream)(int sessiond_key, uint32_t state);
 172         /* socket to communicate errors with sessiond */
 173         int consumer_error_socket;
 174         /* socket to exchange commands with sessiond */
 175         char *consumer_command_sock_path;
 176         /* communication with splice */
 177         int consumer_thread_pipe[2];
 178         /* pipe to wake the poll thread when necessary */
 179         int consumer_poll_pipe[2];
 180         /* to let the signal handler wake up the fd receiver thread */
 181         int consumer_should_quit[2];
 182 };
 183
 184 /*
 185  * Library-level data. One instance per process.
 186  */
 187 struct lttng_consumer_global_data {
 188
 189         /*
 190          * At this time, this lock is used to ensure coherence between the count
 191          * and number of element in the hash table. It's also a protection for
 192          * concurrent read/write between threads.
 193          *
 194          * XXX: We need to see if this lock is still needed with the lockless RCU
 195          * hash tables.
 196          */
 197         pthread_mutex_t lock;
 198
 199         /*
 200          * Number of streams in the hash table. Protected by consumer_data.lock.
 201          */
 202         int stream_count;
 203         /*
 204          * Hash tables of streams and channels. Protected by consumer_data.lock.
 205          */
 206         struct lttng_ht *stream_ht;
 207         struct lttng_ht *channel_ht;
 208         /*
 209          * Flag specifying if the local array of FDs needs update in the
 210          * poll function. Protected by consumer_data.lock.
 211          */
 212         unsigned int need_update;
 213         enum lttng_consumer_type type;
 214 };
 215
 216 /*
 217  * Init consumer data structures.
 218  */
 219 extern void lttng_consumer_init(void);
 220
 221 /*
 222  * Set the error socket for communication with a session daemon.
 223  */
 224 extern void lttng_consumer_set_error_sock(
 225                 struct lttng_consumer_local_data *ctx, int sock);
 226
 227 /*
 228  * Set the command socket path for communication with a session daemon.
 229  */
 230 extern void lttng_consumer_set_command_sock_path(
 231                 struct lttng_consumer_local_data *ctx, char *sock);
 232
 233 /*
 234  * Send return code to session daemon.
 235  *
 236  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 237  * on error.
 238  */
 239 extern int lttng_consumer_send_error(
 240                 struct lttng_consumer_local_data *ctx, int cmd);
 241
 242 /*
 243  * Called from signal handler to ensure a clean exit.
 244  */
 245 extern void lttng_consumer_should_exit(
 246                 struct lttng_consumer_local_data *ctx);
 247
 248 /*
 249  * Cleanup the daemon's socket on exit.
 250  */
 251 extern void lttng_consumer_cleanup(void);
 252
 253 /*
 254  * Flush pending writes to trace output disk file.
 255  */
 256 extern void lttng_consumer_sync_trace_file(
 257                 struct lttng_consumer_stream *stream, off_t orig_offset);
 258
 259 /*
 260  * Poll on the should_quit pipe and the command socket return -1 on error and
 261  * should exit, 0 if data is available on the command socket
 262  */
 263 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 264
 265 extern int consumer_update_poll_array(
 266                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 267                 struct lttng_consumer_stream **local_consumer_streams);
 268
 269 extern struct lttng_consumer_stream *consumer_allocate_stream(
 270                 int channel_key, int stream_key,
 271                 int shm_fd, int wait_fd,
 272                 enum lttng_consumer_stream_state state,
 273                 uint64_t mmap_len,
 274                 enum lttng_event_output output,
 275                 const char *path_name,
 276                 uid_t uid,
 277                 gid_t gid);
 278 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 279 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 280 extern void consumer_change_stream_state(int stream_key,
 281                 enum lttng_consumer_stream_state state);
 282 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 283 extern struct lttng_consumer_channel *consumer_allocate_channel(
 284                 int channel_key,
 285                 int shm_fd, int wait_fd,
 286                 uint64_t mmap_len,
 287                 uint64_t max_sb_size);
 288 int consumer_add_channel(struct lttng_consumer_channel *channel);
 289
 290 extern struct lttng_consumer_local_data *lttng_consumer_create(
 291                 enum lttng_consumer_type type,
 292                 ssize_t (*buffer_ready)(struct lttng_consumer_stream *stream,
 293                         struct lttng_consumer_local_data *ctx),
 294                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 295                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 296                 int (*update_stream)(int sessiond_key, uint32_t state));
 297 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 298 extern ssize_t lttng_consumer_on_read_subbuffer_mmap(
 299                 struct lttng_consumer_local_data *ctx,
 300                 struct lttng_consumer_stream *stream, unsigned long len);
 301 extern ssize_t lttng_consumer_on_read_subbuffer_splice(
 302                 struct lttng_consumer_local_data *ctx,
 303                 struct lttng_consumer_stream *stream, unsigned long len);
 304 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 305                 struct lttng_consumer_stream *stream);
 306 extern int lttng_consumer_get_produced_snapshot(
 307                 struct lttng_consumer_local_data *ctx,
 308                 struct lttng_consumer_stream *stream,
 309                 unsigned long *pos);
 310 extern void *lttng_consumer_thread_poll_fds(void *data);
 311 extern void *lttng_consumer_thread_receive_fds(void *data);
 312 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 313                 int sock, struct pollfd *consumer_sockpoll);
 314
 315 ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 316                 struct lttng_consumer_local_data *ctx);
 317 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
 318
 319 #endif /* _LTTNG_CONSUMER_H */