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 modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #ifndef _LTTNG_CONSUMER_H
  20 #define _LTTNG_CONSUMER_H
  21
  22 #include <limits.h>
  23 #include <poll.h>
  24 #include <unistd.h>
  25
  26 #include <lttng/lttng.h>
  27
  28 #include <common/hashtable/hashtable.h>
  29 #include <common/compat/fcntl.h>
  30
  31 /*
  32  * When the receiving thread dies, we need to have a way to make the polling
  33  * thread exit eventually. If all FDs hang up (normal case when the
  34  * lttng-sessiond stops), we can exit cleanly, but if there is a problem and
  35  * for whatever reason some FDs remain open, the consumer should still exit
  36  * eventually.
  37  *
  38  * If the timeout is reached, it means that during this period no events
  39  * occurred on the FDs so we need to force an exit. This case should not happen
  40  * but it is a safety to ensure we won't block the consumer indefinitely.
  41  *
  42  * The value of 2 seconds is an arbitrary choice.
  43  */
  44 #define LTTNG_CONSUMER_POLL_TIMEOUT 2000
  45
  46 /* Commands for consumer */
  47 enum lttng_consumer_command {
  48         LTTNG_CONSUMER_ADD_CHANNEL,
  49         LTTNG_CONSUMER_ADD_STREAM,
  50         /* pause, delete, active depending on fd state */
  51         LTTNG_CONSUMER_UPDATE_STREAM,
  52         /* inform the consumer to quit when all fd has hang up */
  53         LTTNG_CONSUMER_STOP,
  54 };
  55
  56 /* State of each fd in consumer */
  57 enum lttng_consumer_stream_state {
  58         LTTNG_CONSUMER_ACTIVE_STREAM,
  59         LTTNG_CONSUMER_PAUSE_STREAM,
  60         LTTNG_CONSUMER_DELETE_STREAM,
  61 };
  62
  63 enum lttng_consumer_type {
  64         LTTNG_CONSUMER_UNKNOWN = 0,
  65         LTTNG_CONSUMER_KERNEL,
  66         LTTNG_CONSUMER64_UST,
  67         LTTNG_CONSUMER32_UST,
  68 };
  69
  70 struct lttng_consumer_channel {
  71         struct lttng_ht_node_ulong node;
  72         int key;
  73         uint64_t max_sb_size; /* the subbuffer size for this channel */
  74         int refcount; /* Number of streams referencing this channel */
  75         /* For UST */
  76         int shm_fd;
  77         int wait_fd;
  78         void *mmap_base;
  79         size_t mmap_len;
  80         struct lttng_ust_shm_handle *handle;
  81         int nr_streams;
  82         int wait_fd_is_copy;
  83         int cpucount;
  84 };
  85
  86 /* Forward declaration for UST. */
  87 struct lttng_ust_lib_ring_buffer;
  88
  89 /*
  90  * Internal representation of the streams, sessiond_key is used to identify
  91  * uniquely a stream.
  92  */
  93 struct lttng_consumer_stream {
  94         struct lttng_ht_node_ulong node;
  95         struct lttng_consumer_channel *chan;    /* associated channel */
  96         /*
  97          * key is the key used by the session daemon to refer to the
  98          * object in the consumer daemon.
  99          */
 100         int key;
 101         int shm_fd;
 102         int wait_fd;
 103         int out_fd; /* output file to write the data */
 104         off_t out_fd_offset; /* write position in the output file descriptor */
 105         char path_name[PATH_MAX]; /* tracefile name */
 106         enum lttng_consumer_stream_state state;
 107         size_t shm_len;
 108         void *mmap_base;
 109         size_t mmap_len;
 110         enum lttng_event_output output; /* splice or mmap */
 111         int shm_fd_is_copy;
 112         int wait_fd_is_copy;
 113         /* For UST */
 114         struct lttng_ust_lib_ring_buffer *buf;
 115         int cpu;
 116         int data_read;
 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         /*
 129          * Function to call when data is available on a buffer.
 130          * Returns the number of bytes read, or negative error value.
 131          */
 132         ssize_t (*on_buffer_ready)(struct lttng_consumer_stream *stream,
 133                         struct lttng_consumer_local_data *ctx);
 134         /*
 135          * function to call when we receive a new channel, it receives a
 136          * newly allocated channel, depending on the return code of this
 137          * function, the new channel will be handled by the application
 138          * or the library.
 139          *
 140          * Returns:
 141          *    > 0 (success, FD is kept by application)
 142          *   == 0 (success, FD is left to library)
 143          *    < 0 (error)
 144          */
 145         int (*on_recv_channel)(struct lttng_consumer_channel *channel);
 146         /*
 147          * function to call when we receive a new stream, it receives a
 148          * newly allocated stream, depending on the return code of this
 149          * function, the new stream will be handled by the application
 150          * or the library.
 151          *
 152          * Returns:
 153          *    > 0 (success, FD is kept by application)
 154          *   == 0 (success, FD is left to library)
 155          *    < 0 (error)
 156          */
 157         int (*on_recv_stream)(struct lttng_consumer_stream *stream);
 158         /*
 159          * function to call when a stream is getting updated by the session
 160          * daemon, this function receives the sessiond key and the new
 161          * state, depending on the return code of this function the
 162          * update of state for the stream is handled by the application
 163          * or the library.
 164          *
 165          * Returns:
 166          *    > 0 (success, FD is kept by application)
 167          *   == 0 (success, FD is left to library)
 168          *    < 0 (error)
 169          */
 170         int (*on_update_stream)(int sessiond_key, uint32_t state);
 171         /* socket to communicate errors with sessiond */
 172         int consumer_error_socket;
 173         /* socket to exchange commands with sessiond */
 174         char *consumer_command_sock_path;
 175         /* communication with splice */
 176         int consumer_thread_pipe[2];
 177         /* pipe to wake the poll thread when necessary */
 178         int consumer_poll_pipe[2];
 179         /* to let the signal handler wake up the fd receiver thread */
 180         int consumer_should_quit[2];
 181 };
 182
 183 /*
 184  * Library-level data. One instance per process.
 185  */
 186 struct lttng_consumer_global_data {
 187
 188         /*
 189          * At this time, this lock is used to ensure coherence between the count
 190          * and number of element in the hash table. It's also a protection for
 191          * concurrent read/write between threads.
 192          *
 193          * XXX: We need to see if this lock is still needed with the lockless RCU
 194          * hash tables.
 195          */
 196         pthread_mutex_t lock;
 197
 198         /*
 199          * Number of streams in the hash table. Protected by consumer_data.lock.
 200          */
 201         int stream_count;
 202         /*
 203          * Hash tables of streams and channels. Protected by consumer_data.lock.
 204          */
 205         struct lttng_ht *stream_ht;
 206         struct lttng_ht *channel_ht;
 207         /*
 208          * Flag specifying if the local array of FDs needs update in the
 209          * poll function. Protected by consumer_data.lock.
 210          */
 211         unsigned int need_update;
 212         enum lttng_consumer_type type;
 213 };
 214
 215 /*
 216  * Init consumer data structures.
 217  */
 218 extern void lttng_consumer_init(void);
 219
 220 /*
 221  * Set the error socket for communication with a session daemon.
 222  */
 223 extern void lttng_consumer_set_error_sock(
 224                 struct lttng_consumer_local_data *ctx, int sock);
 225
 226 /*
 227  * Set the command socket path for communication with a session daemon.
 228  */
 229 extern void lttng_consumer_set_command_sock_path(
 230                 struct lttng_consumer_local_data *ctx, char *sock);
 231
 232 /*
 233  * Send return code to session daemon.
 234  *
 235  * Returns the return code of sendmsg : the number of bytes transmitted or -1
 236  * on error.
 237  */
 238 extern int lttng_consumer_send_error(
 239                 struct lttng_consumer_local_data *ctx, int cmd);
 240
 241 /*
 242  * Called from signal handler to ensure a clean exit.
 243  */
 244 extern void lttng_consumer_should_exit(
 245                 struct lttng_consumer_local_data *ctx);
 246
 247 /*
 248  * Cleanup the daemon's socket on exit.
 249  */
 250 extern void lttng_consumer_cleanup(void);
 251
 252 /*
 253  * Flush pending writes to trace output disk file.
 254  */
 255 extern void lttng_consumer_sync_trace_file(
 256                 struct lttng_consumer_stream *stream, off_t orig_offset);
 257
 258 /*
 259  * Poll on the should_quit pipe and the command socket return -1 on error and
 260  * should exit, 0 if data is available on the command socket
 261  */
 262 extern int lttng_consumer_poll_socket(struct pollfd *kconsumer_sockpoll);
 263
 264 extern int consumer_update_poll_array(
 265                 struct lttng_consumer_local_data *ctx, struct pollfd **pollfd,
 266                 struct lttng_consumer_stream **local_consumer_streams);
 267
 268 extern struct lttng_consumer_stream *consumer_allocate_stream(
 269                 int channel_key, int stream_key,
 270                 int shm_fd, int wait_fd,
 271                 enum lttng_consumer_stream_state state,
 272                 uint64_t mmap_len,
 273                 enum lttng_event_output output,
 274                 const char *path_name,
 275                 uid_t uid,
 276                 gid_t gid);
 277 extern int consumer_add_stream(struct lttng_consumer_stream *stream);
 278 extern void consumer_del_stream(struct lttng_consumer_stream *stream);
 279 extern void consumer_change_stream_state(int stream_key,
 280                 enum lttng_consumer_stream_state state);
 281 extern void consumer_del_channel(struct lttng_consumer_channel *channel);
 282 extern struct lttng_consumer_channel *consumer_allocate_channel(
 283                 int channel_key,
 284                 int shm_fd, int wait_fd,
 285                 uint64_t mmap_len,
 286                 uint64_t max_sb_size);
 287 int consumer_add_channel(struct lttng_consumer_channel *channel);
 288
 289 extern struct lttng_consumer_local_data *lttng_consumer_create(
 290                 enum lttng_consumer_type type,
 291                 ssize_t (*buffer_ready)(struct lttng_consumer_stream *stream,
 292                         struct lttng_consumer_local_data *ctx),
 293                 int (*recv_channel)(struct lttng_consumer_channel *channel),
 294                 int (*recv_stream)(struct lttng_consumer_stream *stream),
 295                 int (*update_stream)(int sessiond_key, uint32_t state));
 296 extern void lttng_consumer_destroy(struct lttng_consumer_local_data *ctx);
 297 extern ssize_t lttng_consumer_on_read_subbuffer_mmap(
 298                 struct lttng_consumer_local_data *ctx,
 299                 struct lttng_consumer_stream *stream, unsigned long len);
 300 extern ssize_t lttng_consumer_on_read_subbuffer_splice(
 301                 struct lttng_consumer_local_data *ctx,
 302                 struct lttng_consumer_stream *stream, unsigned long len);
 303 extern int lttng_consumer_take_snapshot(struct lttng_consumer_local_data *ctx,
 304                 struct lttng_consumer_stream *stream);
 305 extern int lttng_consumer_get_produced_snapshot(
 306                 struct lttng_consumer_local_data *ctx,
 307                 struct lttng_consumer_stream *stream,
 308                 unsigned long *pos);
 309 extern void *lttng_consumer_thread_poll_fds(void *data);
 310 extern void *lttng_consumer_thread_receive_fds(void *data);
 311 extern int lttng_consumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 312                 int sock, struct pollfd *consumer_sockpoll);
 313
 314 ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 315                 struct lttng_consumer_local_data *ctx);
 316 int lttng_consumer_on_recv_stream(struct lttng_consumer_stream *stream);
 317
 318 #endif /* _LTTNG_CONSUMER_H */