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 _GNU_SOURCE
  21 #define _LGPL_SOURCE
  22 #include <common/common.h>
  23 #include <common/index/index.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 = 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 = 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_fd = NULL;
 120         } else {
 121                 int read_fd;
 122
 123                 read_fd = index_open(vstream->path_name, vstream->channel_name,
 124                                 stream->tracefile_count,
 125                                 vstream->current_tracefile_id);
 126                 if (read_fd < 0) {
 127                         goto error_unlock;
 128                 }
 129                 vstream->index_fd = stream_fd_create(read_fd);
 130                 if (!vstream->index_fd) {
 131                         if (close(read_fd)) {
 132                                 PERROR("close");
 133                         }
 134                         goto error_unlock;
 135                 }
 136         }
 137
 138         if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_fd) {
 139                 off_t lseek_ret;
 140
 141                 lseek_ret = lseek(vstream->index_fd->fd, 0, SEEK_END);
 142                 if (lseek_ret < 0) {
 143                         goto error_unlock;
 144                 }
 145         }
 146         if (stream->is_metadata) {
 147                 rcu_assign_pointer(stream->trace->viewer_metadata_stream,
 148                                 vstream);
 149         }
 150         pthread_mutex_unlock(&stream->lock);
 151
 152         /* Globally visible after the add unique. */
 153         lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
 154         lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
 155
 156         pthread_mutex_init(&vstream->reflock, NULL);
 157         urcu_ref_init(&vstream->ref);
 158
 159         return vstream;
 160
 161 error_unlock:
 162         pthread_mutex_unlock(&stream->lock);
 163 error:
 164         if (vstream) {
 165                 viewer_stream_destroy(vstream);
 166         }
 167         return NULL;
 168 }
 169
 170 static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
 171 {
 172         int ret;
 173         struct lttng_ht_iter iter;
 174
 175         iter.iter.node = &vstream->stream_n.node;
 176         ret = lttng_ht_del(viewer_streams_ht, &iter);
 177         assert(!ret);
 178 }
 179
 180 static void viewer_stream_release(struct urcu_ref *ref)
 181 {
 182         struct relay_viewer_stream *vstream = caa_container_of(ref,
 183                         struct relay_viewer_stream, ref);
 184
 185         if (vstream->stream->is_metadata) {
 186                 rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
 187         }
 188
 189         viewer_stream_unpublish(vstream);
 190
 191         if (vstream->stream_fd) {
 192                 stream_fd_put(vstream->stream_fd);
 193                 vstream->stream_fd = NULL;
 194         }
 195         if (vstream->index_fd) {
 196                 stream_fd_put(vstream->index_fd);
 197                 vstream->index_fd = NULL;
 198         }
 199         if (vstream->stream) {
 200                 stream_put(vstream->stream);
 201                 vstream->stream = NULL;
 202         }
 203         call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
 204 }
 205
 206 /* Must be called with RCU read-side lock held. */
 207 bool viewer_stream_get(struct relay_viewer_stream *vstream)
 208 {
 209         bool has_ref = false;
 210
 211         pthread_mutex_lock(&vstream->reflock);
 212         if (vstream->ref.refcount != 0) {
 213                 has_ref = true;
 214                 urcu_ref_get(&vstream->ref);
 215         }
 216         pthread_mutex_unlock(&vstream->reflock);
 217
 218         return has_ref;
 219 }
 220
 221 /*
 222  * Get viewer stream by id.
 223  *
 224  * Return viewer stream if found else NULL.
 225  */
 226 struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
 227 {
 228         struct lttng_ht_node_u64 *node;
 229         struct lttng_ht_iter iter;
 230         struct relay_viewer_stream *vstream = NULL;
 231
 232         rcu_read_lock();
 233         lttng_ht_lookup(viewer_streams_ht, &id, &iter);
 234         node = lttng_ht_iter_get_node_u64(&iter);
 235         if (!node) {
 236                 DBG("Relay viewer stream %" PRIu64 " not found", id);
 237                 goto end;
 238         }
 239         vstream = caa_container_of(node, struct relay_viewer_stream, stream_n);
 240         if (!viewer_stream_get(vstream)) {
 241                 vstream = NULL;
 242         }
 243 end:
 244         rcu_read_unlock();
 245         return vstream;
 246 }
 247
 248 void viewer_stream_put(struct relay_viewer_stream *vstream)
 249 {
 250         rcu_read_lock();
 251         pthread_mutex_lock(&vstream->reflock);
 252         urcu_ref_put(&vstream->ref, viewer_stream_release);
 253         pthread_mutex_unlock(&vstream->reflock);
 254         rcu_read_unlock();
 255 }
 256
 257 /*
 258  * Rotate a stream to the next tracefile.
 259  *
 260  * Must be called with the rstream lock held.
 261  * Returns 0 on success, 1 on EOF, a negative value on error.
 262  */
 263 int viewer_stream_rotate(struct relay_viewer_stream *vstream)
 264 {
 265         int ret;
 266         struct relay_stream *stream = vstream->stream;
 267         uint64_t new_id;
 268
 269         /* Detect the last tracefile to open. */
 270         if (stream->index_received_seqcount
 271                         == vstream->index_sent_seqcount
 272                         && stream->trace->session->connection_closed) {
 273                 ret = 1;
 274                 goto end;
 275         }
 276
 277         if (stream->tracefile_count == 0) {
 278                 /* Ignore rotation, there is none to do. */
 279                 ret = 0;
 280                 goto end;
 281         }
 282
 283         /*
 284          * Try to move to the next file.
 285          */
 286         new_id = (vstream->current_tracefile_id + 1)
 287                         % stream->tracefile_count;
 288         if (tracefile_array_seq_in_file(stream->tfa, new_id,
 289                         vstream->index_sent_seqcount)) {
 290                 vstream->current_tracefile_id = new_id;
 291         } else {
 292                 uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
 293
 294                 /*
 295                  * This can only be reached on overwrite, which implies there
 296                  * has been data written at some point, which will have set the
 297                  * tail.
 298                  */
 299                 assert(seq_tail != -1ULL);
 300                 /*
 301                  * We need to resync because we lag behind tail.
 302                  */
 303                 vstream->current_tracefile_id =
 304                         tracefile_array_get_file_index_tail(stream->tfa);
 305                 vstream->index_sent_seqcount = seq_tail;
 306         }
 307
 308         if (vstream->index_fd) {
 309                 stream_fd_put(vstream->index_fd);
 310                 vstream->index_fd = NULL;
 311         }
 312         if (vstream->stream_fd) {
 313                 stream_fd_put(vstream->stream_fd);
 314                 vstream->stream_fd = NULL;
 315         }
 316
 317         ret = index_open(vstream->path_name, vstream->channel_name,
 318                         stream->tracefile_count,
 319                         vstream->current_tracefile_id);
 320         if (ret < 0) {
 321                 goto end;
 322         }
 323         vstream->index_fd = stream_fd_create(ret);
 324         if (vstream->index_fd) {
 325                 ret = 0;
 326         } else {
 327                 if (close(ret)) {
 328                         PERROR("close");
 329                 }
 330                 ret = -1;
 331         }
 332 end:
 333         return ret;
 334 }
 335
 336 void print_viewer_streams(void)
 337 {
 338         struct lttng_ht_iter iter;
 339         struct relay_viewer_stream *vstream;
 340
 341         rcu_read_lock();
 342         cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, vstream,
 343                         stream_n.node) {
 344                 if (!viewer_stream_get(vstream)) {
 345                         continue;
 346                 }
 347                 DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64
 348                         " session %" PRIu64,
 349                         vstream,
 350                         vstream->ref.refcount,
 351                         vstream->stream->stream_handle,
 352                         vstream->stream->trace->id,
 353                         vstream->stream->trace->session->id);
 354                 viewer_stream_put(vstream);
 355         }
 356         rcu_read_unlock();
 357 }