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

   1 /*
   2  * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
   3  *                      David Goulet <dgoulet@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License, version 2 only, as
   7  * 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 with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <common/common.h>
  21 #include <common/index/index.h>
  22
  23 #include "lttng-relayd.h"
  24 #include "viewer-stream.h"
  25
  26 static void free_stream(struct relay_viewer_stream *stream)
  27 {
  28         assert(stream);
  29
  30         free(stream->path_name);
  31         free(stream->channel_name);
  32         free(stream);
  33 }
  34
  35 static void deferred_free_viewer_stream(struct rcu_head *head)
  36 {
  37         struct relay_viewer_stream *stream =
  38                 caa_container_of(head, struct relay_viewer_stream, rcu_node);
  39
  40         free_stream(stream);
  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         assert(stream);
  49
  50         vstream = zmalloc(sizeof(*vstream));
  51         if (!vstream) {
  52                 PERROR("relay viewer stream zmalloc");
  53                 goto error;
  54         }
  55
  56         vstream->session_id = stream->session->id;
  57         vstream->stream_handle = stream->stream_handle;
  58         vstream->path_name = strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
  59         vstream->channel_name = strndup(stream->channel_name,
  60                         LTTNG_VIEWER_NAME_MAX);
  61         vstream->tracefile_count = stream->tracefile_count;
  62         vstream->metadata_flag = stream->metadata_flag;
  63         vstream->tracefile_count_last = -1ULL;
  64
  65         switch (seek_t) {
  66         case VIEWER_SEEK_BEGINNING:
  67                 vstream->tracefile_count_current = stream->oldest_tracefile_id;
  68                 break;
  69         case VIEWER_SEEK_LAST:
  70                 vstream->tracefile_count_current = stream->tracefile_count_current;
  71                 break;
  72         default:
  73                 assert(0);
  74                 goto error;
  75         }
  76
  77         vstream->ctf_trace = stream->ctf_trace;
  78         if (vstream->metadata_flag) {
  79                 vstream->ctf_trace->viewer_metadata_stream = vstream;
  80         }
  81         uatomic_inc(&vstream->ctf_trace->refcount);
  82
  83         /* Globally visible after the add unique. */
  84         lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
  85         lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
  86
  87         vstream->index_read_fd = -1;
  88         vstream->read_fd = -1;
  89
  90         /*
  91          * This is to avoid a race between the initialization of this object and
  92          * the close of the given stream. If the stream is unable to find this
  93          * viewer stream when closing, this copy will at least take the latest
  94          * value. We also need that for the seek_last.
  95          */
  96         vstream->total_index_received = stream->total_index_received;
  97
  98         /*
  99          * If we never received an index for the current stream, delay the opening
 100          * of the index, otherwise open it right now.
 101          */
 102         if (vstream->tracefile_count_current == stream->tracefile_count_current
 103                         && vstream->total_index_received == 0) {
 104                 vstream->index_read_fd = -1;
 105         } else {
 106                 int read_fd;
 107
 108                 read_fd = index_open(vstream->path_name, vstream->channel_name,
 109                                 vstream->tracefile_count, vstream->tracefile_count_current);
 110                 if (read_fd < 0) {
 111                         goto error;
 112                 }
 113                 vstream->index_read_fd = read_fd;
 114         }
 115
 116         if (seek_t == VIEWER_SEEK_LAST && vstream->index_read_fd >= 0) {
 117                 off_t lseek_ret;
 118
 119                 lseek_ret = lseek(vstream->index_read_fd,
 120                                 vstream->total_index_received * sizeof(struct ctf_packet_index),
 121                                 SEEK_CUR);
 122                 if (lseek_ret < 0) {
 123                         goto error;
 124                 }
 125                 vstream->last_sent_index = vstream->total_index_received;
 126         }
 127
 128         return vstream;
 129
 130 error:
 131         if (vstream) {
 132                 free_stream(vstream);
 133         }
 134         return NULL;
 135 }
 136
 137 void viewer_stream_delete(struct relay_viewer_stream *stream)
 138 {
 139         int ret;
 140         struct lttng_ht_iter iter;
 141
 142         iter.iter.node = &stream->stream_n.node;
 143         ret = lttng_ht_del(viewer_streams_ht, &iter);
 144         assert(!ret);
 145 }
 146
 147 void viewer_stream_destroy(struct relay_viewer_stream *stream)
 148 {
 149         int ret;
 150         unsigned long ret_ref;
 151
 152         assert(stream);
 153         ret_ref = uatomic_add_return(&stream->ctf_trace->refcount, -1);
 154         assert(ret_ref >= 0);
 155
 156         if (stream->read_fd >= 0) {
 157                 ret = close(stream->read_fd);
 158                 if (ret < 0) {
 159                         PERROR("close read_fd");
 160                 }
 161         }
 162         if (stream->index_read_fd >= 0) {
 163                 ret = close(stream->index_read_fd);
 164                 if (ret < 0) {
 165                         PERROR("close index_read_fd");
 166                 }
 167         }
 168
 169         /*
 170          * If the only stream left in the HT is the metadata stream,
 171          * we need to remove it because we won't detect a EOF for this
 172          * stream.
 173          */
 174         if (ret_ref == 1 && stream->ctf_trace->viewer_metadata_stream) {
 175                 viewer_stream_delete(stream->ctf_trace->viewer_metadata_stream);
 176                 viewer_stream_destroy(stream->ctf_trace->viewer_metadata_stream);
 177                 stream->ctf_trace->metadata_stream = NULL;
 178                 DBG("Freeing ctf_trace %" PRIu64, stream->ctf_trace->id);
 179                 /*
 180                  * The streaming-side is already closed and we can't receive a new
 181                  * stream concurrently at this point (since the session is being
 182                  * destroyed), so when we detect the refcount equals 0, we are the
 183                  * only owners of the ctf_trace and we can free it ourself.
 184                  */
 185                 free(stream->ctf_trace);
 186         }
 187
 188         call_rcu(&stream->rcu_node, deferred_free_viewer_stream);
 189 }
 190
 191 /*
 192  * Find viewer stream by id. RCU read side lock MUST be acquired.
 193  *
 194  * Return stream if found else NULL.
 195  */
 196 struct relay_viewer_stream *viewer_stream_find_by_id(uint64_t id)
 197 {
 198         struct lttng_ht_node_u64 *node;
 199         struct lttng_ht_iter iter;
 200         struct relay_viewer_stream *stream = NULL;
 201
 202         lttng_ht_lookup(viewer_streams_ht, &id, &iter);
 203         node = lttng_ht_iter_get_node_u64(&iter);
 204         if (!node) {
 205                 DBG("Relay viewer stream %" PRIu64 " not found", id);
 206                 goto end;
 207         }
 208         stream = caa_container_of(node, struct relay_viewer_stream, stream_n);
 209
 210 end:
 211         return stream;
 212 }
 213
 214 /*
 215  * Rotate a stream to the next tracefile.
 216  *
 217  * Returns 0 on success, 1 on EOF, a negative value on error.
 218  */
 219 int viewer_stream_rotate(struct relay_viewer_stream *vstream,
 220                 struct relay_stream *stream)
 221 {
 222         int ret;
 223         uint64_t tracefile_id;
 224
 225         assert(vstream);
 226
 227         tracefile_id = (vstream->tracefile_count_current + 1) %
 228                 vstream->tracefile_count;
 229
 230         /* Detect the last tracefile to open. */
 231         if (vstream->tracefile_count_last != -1ULL &&
 232                         vstream->tracefile_count_last ==
 233                         vstream->tracefile_count_current) {
 234                 ret = 1;
 235                 goto end;
 236         }
 237
 238         /*
 239          * If the stream on the streaming side still exists, lock to execute
 240          * rotation in order to avoid races between a modification on the index
 241          * values.
 242          */
 243         if (stream) {
 244                 pthread_mutex_lock(&stream->viewer_stream_rotation_lock);
 245         }
 246
 247         /*
 248          * The writer and the reader are not working in the same tracefile, we can
 249          * read up to EOF, we don't care about the total_index_received.
 250          */
 251         if (!stream || (stream->tracefile_count_current != tracefile_id)) {
 252                 vstream->close_write_flag = 1;
 253         } else {
 254                 /*
 255                  * We are opening a file that is still open in write, make sure we
 256                  * limit our reading to the number of indexes received.
 257                  */
 258                 vstream->close_write_flag = 0;
 259                 if (stream) {
 260                         vstream->total_index_received = stream->total_index_received;
 261                 }
 262         }
 263         vstream->tracefile_count_current = tracefile_id;
 264
 265         ret = close(vstream->index_read_fd);
 266         if (ret < 0) {
 267                 PERROR("close index file %d", vstream->index_read_fd);
 268         }
 269         vstream->index_read_fd = -1;
 270
 271         ret = close(vstream->read_fd);
 272         if (ret < 0) {
 273                 PERROR("close tracefile %d", vstream->read_fd);
 274         }
 275         vstream->read_fd = -1;
 276
 277         pthread_mutex_lock(&vstream->overwrite_lock);
 278         vstream->abort_flag = 0;
 279         pthread_mutex_unlock(&vstream->overwrite_lock);
 280
 281         if (stream) {
 282                 pthread_mutex_unlock(&stream->viewer_stream_rotation_lock);
 283         }
 284
 285         ret = index_open(vstream->path_name, vstream->channel_name,
 286                         vstream->tracefile_count, vstream->tracefile_count_current);
 287         if (ret < 0) {
 288                 goto error;
 289         }
 290         vstream->index_read_fd = ret;
 291
 292         ret = 0;
 293
 294 end:
 295 error:
 296         return ret;
 297 }