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