src/bin/lttng-relayd/viewer-stream.c

   1 /*
   2  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *               2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License, version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #define _LGPL_SOURCE
  21 #include <common/common.h>
  22 #include <common/index/index.h>
  23 #include <common/compat/string.h>
  24
  25 #include "lttng-relayd.h"
  26 #include "viewer-stream.h"
  27
  28 static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
  29 {
  30         free(vstream->path_name);
  31         free(vstream->channel_name);
  32         free(vstream);
  33 }
  34
  35 static void viewer_stream_destroy_rcu(struct rcu_head *head)
  36 {
  37         struct relay_viewer_stream *vstream =
  38                 caa_container_of(head, struct relay_viewer_stream, rcu_node);
  39
  40         viewer_stream_destroy(vstream);
  41 }
  42
  43 struct relay_viewer_stream *viewer_stream_create(struct relay_stream *stream,
  44                 enum lttng_viewer_seek seek_t)
  45 {
  46         struct relay_viewer_stream *vstream;
  47
  48         vstream = zmalloc(sizeof(*vstream));
  49         if (!vstream) {
  50                 PERROR("relay viewer stream zmalloc");
  51                 goto error;
  52         }
  53
  54         vstream->path_name = lttng_strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
  55         if (vstream->path_name == NULL) {
  56                 PERROR("relay viewer path_name alloc");
  57                 goto error;
  58         }
  59         vstream->channel_name = lttng_strndup(stream->channel_name,
  60                         LTTNG_VIEWER_NAME_MAX);
  61         if (vstream->channel_name == NULL) {
  62                 PERROR("relay viewer channel_name alloc");
  63                 goto error;
  64         }
  65
  66         if (!stream_get(stream)) {
  67                 ERR("Cannot get stream");
  68                 goto error;
  69         }
  70         vstream->stream = stream;
  71
  72         pthread_mutex_lock(&stream->lock);
  73
  74         if (stream->is_metadata && stream->trace->viewer_metadata_stream) {
  75                 ERR("Cannot attach viewer metadata stream to trace (busy).");
  76                 goto error_unlock;
  77         }
  78
  79         switch (seek_t) {
  80         case LTTNG_VIEWER_SEEK_BEGINNING:
  81         {
  82                 uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
  83
  84                 if (seq_tail == -1ULL) {
  85                         /*
  86                          * Tail may not be initialized yet. Nonetheless, we know
  87                          * we want to send the first index once it becomes
  88                          * available.
  89                          */
  90                         seq_tail = 0;
  91                 }
  92                 vstream->current_tracefile_id =
  93                         tracefile_array_get_file_index_tail(stream->tfa);
  94                 vstream->index_sent_seqcount = seq_tail;
  95                 break;
  96         }
  97         case LTTNG_VIEWER_SEEK_LAST:
  98                 vstream->current_tracefile_id =
  99                         tracefile_array_get_file_index_head(stream->tfa);
 100                 /*
 101                  * We seek at the very end of each stream, awaiting for
 102                  * a future packet to eventually come in.
 103                  *
 104                  * We don't need to check the head position for -1ULL since the
 105                  * increment will set it to 0.
 106                  */
 107                 vstream->index_sent_seqcount =
 108                                 tracefile_array_get_seq_head(stream->tfa) + 1;
 109                 break;
 110         default:
 111                 goto error_unlock;
 112         }
 113
 114         /*
 115          * If we never received an index for the current stream, delay
 116          * the opening of the index, otherwise open it right now.
 117          */
 118         if (stream->index_received_seqcount == 0) {
 119                 vstream->index_file = NULL;
 120         } else {
 121                 vstream->index_file = lttng_index_file_open(vstream->path_name,
 122                                 vstream->channel_name,
 123                                 stream->tracefile_count,
 124                                 vstream->current_tracefile_id);
 125                 if (!vstream->index_file) {
 126                         goto error_unlock;
 127                 }
 128         }
 129
 130         if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_file) {
 131                 off_t lseek_ret;
 132
 133                 lseek_ret = lseek(vstream->index_file->fd, 0, SEEK_END);
 134                 if (lseek_ret < 0) {
 135                         goto error_unlock;
 136                 }
 137         }
 138         if (stream->is_metadata) {
 139                 rcu_assign_pointer(stream->trace->viewer_metadata_stream,
 140                                 vstream);
 141         }
 142         pthread_mutex_unlock(&stream->lock);
 143
 144         /* Globally visible after the add unique. */
 145         lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
 146         lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
 147
 148         pthread_mutex_init(&vstream->reflock, NULL);
 149         urcu_ref_init(&vstream->ref);
 150
 151         return vstream;
 152
 153 error_unlock:
 154         pthread_mutex_unlock(&stream->lock);
 155 error:
 156         if (vstream) {
 157                 viewer_stream_destroy(vstream);
 158         }
 159         return NULL;
 160 }
 161
 162 static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
 163 {
 164         int ret;
 165         struct lttng_ht_iter iter;
 166
 167         iter.iter.node = &vstream->stream_n.node;
 168         ret = lttng_ht_del(viewer_streams_ht, &iter);
 169         assert(!ret);
 170 }
 171
 172 static void viewer_stream_release(struct urcu_ref *ref)
 173 {
 174         struct relay_viewer_stream *vstream = caa_container_of(ref,
 175                         struct relay_viewer_stream, ref);
 176
 177         if (vstream->stream->is_metadata) {
 178                 rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
 179         }
 180
 181         viewer_stream_unpublish(vstream);
 182
 183         if (vstream->stream_fd) {
 184                 stream_fd_put(vstream->stream_fd);
 185                 vstream->stream_fd = NULL;
 186         }
 187         if (vstream->index_file) {
 188                 lttng_index_file_put(vstream->index_file);
 189                 vstream->index_file = NULL;
 190         }
 191         if (vstream->stream) {
 192                 stream_put(vstream->stream);
 193                 vstream->stream = NULL;
 194         }
 195         call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
 196 }
 197
 198 /* Must be called with RCU read-side lock held. */
 199 bool viewer_stream_get(struct relay_viewer_stream *vstream)
 200 {
 201         bool has_ref = false;
 202
 203         pthread_mutex_lock(&vstream->reflock);
 204         if (vstream->ref.refcount != 0) {
 205                 has_ref = true;
 206                 urcu_ref_get(&vstream->ref);
 207         }
 208         pthread_mutex_unlock(&vstream->reflock);
 209
 210         return has_ref;
 211 }
 212
 213 /*
 214  * Get viewer stream by id.
 215  *
 216  * Return viewer stream if found else NULL.
 217  */
 218 struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
 219 {
 220         struct lttng_ht_node_u64 *node;
 221         struct lttng_ht_iter iter;
 222         struct relay_viewer_stream *vstream = NULL;
 223
 224         rcu_read_lock();
 225         lttng_ht_lookup(viewer_streams_ht, &id, &iter);
 226         node = lttng_ht_iter_get_node_u64(&iter);
 227         if (!node) {
 228                 DBG("Relay viewer stream %" PRIu64 " not found", id);
 229                 goto end;
 230         }
 231         vstream = caa_container_of(node, struct relay_viewer_stream, stream_n);
 232         if (!viewer_stream_get(vstream)) {
 233                 vstream = NULL;
 234         }
 235 end:
 236         rcu_read_unlock();
 237         return vstream;
 238 }
 239
 240 void viewer_stream_put(struct relay_viewer_stream *vstream)
 241 {
 242         rcu_read_lock();
 243         pthread_mutex_lock(&vstream->reflock);
 244         urcu_ref_put(&vstream->ref, viewer_stream_release);
 245         pthread_mutex_unlock(&vstream->reflock);
 246         rcu_read_unlock();
 247 }
 248
 249 /*
 250  * Rotate a stream to the next tracefile.
 251  *
 252  * Must be called with the rstream lock held.
 253  * Returns 0 on success, 1 on EOF, a negative value on error.
 254  */
 255 int viewer_stream_rotate(struct relay_viewer_stream *vstream)
 256 {
 257         int ret;
 258         struct relay_stream *stream = vstream->stream;
 259         uint64_t new_id;
 260
 261         /* Detect the last tracefile to open. */
 262         if (stream->index_received_seqcount
 263                         == vstream->index_sent_seqcount
 264                         && stream->trace->session->connection_closed) {
 265                 ret = 1;
 266                 goto end;
 267         }
 268
 269         if (stream->tracefile_count == 0) {
 270                 /* Ignore rotation, there is none to do. */
 271                 ret = 0;
 272                 goto end;
 273         }
 274
 275         /*
 276          * Try to move to the next file.
 277          */
 278         new_id = (vstream->current_tracefile_id + 1)
 279                         % stream->tracefile_count;
 280         if (tracefile_array_seq_in_file(stream->tfa, new_id,
 281                         vstream->index_sent_seqcount)) {
 282                 vstream->current_tracefile_id = new_id;
 283         } else {
 284                 uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
 285
 286                 /*
 287                  * This can only be reached on overwrite, which implies there
 288                  * has been data written at some point, which will have set the
 289                  * tail.
 290                  */
 291                 assert(seq_tail != -1ULL);
 292                 /*
 293                  * We need to resync because we lag behind tail.
 294                  */
 295                 vstream->current_tracefile_id =
 296                         tracefile_array_get_file_index_tail(stream->tfa);
 297                 vstream->index_sent_seqcount = seq_tail;
 298         }
 299
 300         if (vstream->index_file) {
 301                 lttng_index_file_put(vstream->index_file);
 302                 vstream->index_file = NULL;
 303         }
 304         if (vstream->stream_fd) {
 305                 stream_fd_put(vstream->stream_fd);
 306                 vstream->stream_fd = NULL;
 307         }
 308
 309         vstream->index_file = lttng_index_file_open(vstream->path_name,
 310                         vstream->channel_name,
 311                         stream->tracefile_count,
 312                         vstream->current_tracefile_id);
 313         if (!vstream->index_file) {
 314                 ret = -1;
 315                 goto end;
 316         } else {
 317                 ret = 0;
 318         }
 319 end:
 320         return ret;
 321 }
 322
 323 void print_viewer_streams(void)
 324 {
 325         struct lttng_ht_iter iter;
 326         struct relay_viewer_stream *vstream;
 327
 328         if (!viewer_streams_ht) {
 329                 return;
 330         }
 331
 332         rcu_read_lock();
 333         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, vstream,
 334                         stream_n.node) {
 335                 if (!viewer_stream_get(vstream)) {
 336                         continue;
 337                 }
 338                 DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64
 339                         " session %" PRIu64,
 340                         vstream,
 341                         vstream->ref.refcount,
 342                         vstream->stream->stream_handle,
 343                         vstream->stream->trace->id,
 344                         vstream->stream->trace->session->id);
 345                 viewer_stream_put(vstream);
 346         }
 347         rcu_read_unlock();
 348 }