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, struct ctf_trace *ctf_trace)
  45 {
  46         struct relay_viewer_stream *vstream;
  47
  48         assert(stream);
  49         assert(ctf_trace);
  50
  51         vstream = zmalloc(sizeof(*vstream));
  52         if (!vstream) {
  53                 PERROR("relay viewer stream zmalloc");
  54                 goto error;
  55         }
  56
  57         vstream->session_id = stream->session_id;
  58         vstream->stream_handle = stream->stream_handle;
  59         vstream->path_name = strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
  60         vstream->channel_name = strndup(stream->channel_name,
  61                         LTTNG_VIEWER_NAME_MAX);
  62         vstream->tracefile_count = stream->tracefile_count;
  63         vstream->metadata_flag = stream->metadata_flag;
  64         vstream->tracefile_count_last = -1ULL;
  65
  66         switch (seek_t) {
  67         case VIEWER_SEEK_BEGINNING:
  68                 vstream->tracefile_count_current = stream->oldest_tracefile_id;
  69                 break;
  70         case VIEWER_SEEK_LAST:
  71                 vstream->tracefile_count_current = stream->tracefile_count_current;
  72                 break;
  73         default:
  74                 assert(0);
  75                 goto error;
  76         }
  77
  78         if (vstream->metadata_flag) {
  79                 ctf_trace->viewer_metadata_stream = vstream;
  80         }
  81
  82         /* Globally visible after the add unique. */
  83         lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
  84         lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
  85
  86         vstream->index_read_fd = -1;
  87         vstream->read_fd = -1;
  88
  89         /*
  90          * This is to avoid a race between the initialization of this object and
  91          * the close of the given stream. If the stream is unable to find this
  92          * viewer stream when closing, this copy will at least take the latest
  93          * value. We also need that for the seek_last.
  94          */
  95         vstream->total_index_received = stream->total_index_received;
  96
  97         /*
  98          * If we never received an index for the current stream, delay the opening
  99          * of the index, otherwise open it right now.
 100          */
 101         if (vstream->tracefile_count_current == stream->tracefile_count_current
 102                         && vstream->total_index_received == 0) {
 103                 vstream->index_read_fd = -1;
 104         } else {
 105                 int read_fd;
 106
 107                 read_fd = index_open(vstream->path_name, vstream->channel_name,
 108                                 vstream->tracefile_count, vstream->tracefile_count_current);
 109                 if (read_fd < 0) {
 110                         goto error;
 111                 }
 112                 vstream->index_read_fd = read_fd;
 113         }
 114
 115         if (seek_t == VIEWER_SEEK_LAST && vstream->index_read_fd >= 0) {
 116                 off_t lseek_ret;
 117
 118                 lseek_ret = lseek(vstream->index_read_fd,
 119                                 vstream->total_index_received * sizeof(struct ctf_packet_index),
 120                                 SEEK_CUR);
 121                 if (lseek_ret < 0) {
 122                         goto error;
 123                 }
 124                 vstream->last_sent_index = vstream->total_index_received;
 125         }
 126
 127         return vstream;
 128
 129 error:
 130         if (vstream) {
 131                 free_stream(vstream);
 132         }
 133         return NULL;
 134 }
 135
 136 void viewer_stream_delete(struct relay_viewer_stream *stream)
 137 {
 138         int ret;
 139         struct lttng_ht_iter iter;
 140
 141         iter.iter.node = &stream->stream_n.node;
 142         ret = lttng_ht_del(viewer_streams_ht, &iter);
 143         assert(!ret);
 144 }
 145
 146 void viewer_stream_destroy(struct ctf_trace *ctf_trace,
 147                 struct relay_viewer_stream *stream)
 148 {
 149         int ret;
 150
 151         assert(stream);
 152
 153         if (ctf_trace) {
 154                 ctf_trace_put_ref(ctf_trace);
 155         }
 156
 157         if (stream->read_fd >= 0) {
 158                 ret = close(stream->read_fd);
 159                 if (ret < 0) {
 160                         PERROR("close read_fd");
 161                 }
 162         }
 163         if (stream->index_read_fd >= 0) {
 164                 ret = close(stream->index_read_fd);
 165                 if (ret < 0) {
 166                         PERROR("close index_read_fd");
 167                 }
 168         }
 169
 170         call_rcu(&stream->rcu_node, deferred_free_viewer_stream);
 171 }
 172
 173 /*
 174  * Find viewer stream by id. RCU read side lock MUST be acquired.
 175  *
 176  * Return stream if found else NULL.
 177  */
 178 struct relay_viewer_stream *viewer_stream_find_by_id(uint64_t id)
 179 {
 180         struct lttng_ht_node_u64 *node;
 181         struct lttng_ht_iter iter;
 182         struct relay_viewer_stream *stream = NULL;
 183
 184         lttng_ht_lookup(viewer_streams_ht, &id, &iter);
 185         node = lttng_ht_iter_get_node_u64(&iter);
 186         if (!node) {
 187                 DBG("Relay viewer stream %" PRIu64 " not found", id);
 188                 goto end;
 189         }
 190         stream = caa_container_of(node, struct relay_viewer_stream, stream_n);
 191
 192 end:
 193         return stream;
 194 }
 195
 196 /*
 197  * Rotate a stream to the next tracefile.
 198  *
 199  * Returns 0 on success, 1 on EOF, a negative value on error.
 200  */
 201 int viewer_stream_rotate(struct relay_viewer_stream *vstream,
 202                 struct relay_stream *stream)
 203 {
 204         int ret;
 205         uint64_t tracefile_id;
 206
 207         assert(vstream);
 208         assert(stream);
 209
 210         if (vstream->tracefile_count == 0) {
 211                 /* Ignore rotation, there is none to do. */
 212                 ret = 0;
 213                 goto end;
 214         }
 215
 216         tracefile_id = (vstream->tracefile_count_current + 1) %
 217                 vstream->tracefile_count;
 218
 219         /* Detect the last tracefile to open. */
 220         if (vstream->tracefile_count_last != -1ULL &&
 221                         vstream->tracefile_count_last ==
 222                         vstream->tracefile_count_current) {
 223                 ret = 1;
 224                 goto end;
 225         }
 226
 227         /*
 228          * Lock to execute rotation in order to avoid races between a modification
 229          * on the index values.
 230          */
 231         pthread_mutex_lock(&stream->viewer_stream_rotation_lock);
 232
 233         /*
 234          * The writer and the reader are not working in the same tracefile, we can
 235          * read up to EOF, we don't care about the total_index_received.
 236          */
 237         if (stream->close_flag || (stream->tracefile_count_current != tracefile_id)) {
 238                 vstream->close_write_flag = 1;
 239         } else {
 240                 /*
 241                  * We are opening a file that is still open in write, make sure we
 242                  * limit our reading to the number of indexes received.
 243                  */
 244                 vstream->close_write_flag = 0;
 245                 if (stream->close_flag) {
 246                         vstream->total_index_received = stream->total_index_received;
 247                 }
 248         }
 249         vstream->tracefile_count_current = tracefile_id;
 250
 251         ret = close(vstream->index_read_fd);
 252         if (ret < 0) {
 253                 PERROR("close index file %d", vstream->index_read_fd);
 254         }
 255         vstream->index_read_fd = -1;
 256
 257         ret = close(vstream->read_fd);
 258         if (ret < 0) {
 259                 PERROR("close tracefile %d", vstream->read_fd);
 260         }
 261         vstream->read_fd = -1;
 262
 263         pthread_mutex_lock(&vstream->overwrite_lock);
 264         vstream->abort_flag = 0;
 265         pthread_mutex_unlock(&vstream->overwrite_lock);
 266
 267         pthread_mutex_unlock(&stream->viewer_stream_rotation_lock);
 268
 269         ret = index_open(vstream->path_name, vstream->channel_name,
 270                         vstream->tracefile_count, vstream->tracefile_count_current);
 271         if (ret < 0) {
 272                 goto error;
 273         }
 274         vstream->index_read_fd = ret;
 275
 276         ret = 0;
 277
 278 end:
 279 error:
 280         return ret;
 281 }