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

   1 /*
   2  * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
   3  * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
   4  * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-only
   7  *
   8  */
   9
  10 #define _LGPL_SOURCE
  11 #include "lttng-relayd.hpp"
  12 #include "viewer-stream.hpp"
  13
  14 #include <common/common.hpp>
  15 #include <common/compat/string.hpp>
  16 #include <common/index/index.hpp>
  17 #include <common/utils.hpp>
  18
  19 #include <algorithm>
  20 #include <fcntl.h>
  21 #include <sys/stat.h>
  22 #include <sys/types.h>
  23
  24 static void viewer_stream_release_composite_objects(struct relay_viewer_stream *vstream)
  25 {
  26         if (vstream->stream_file.handle) {
  27                 fs_handle_close(vstream->stream_file.handle);
  28                 vstream->stream_file.handle = nullptr;
  29         }
  30         if (vstream->index_file) {
  31                 lttng_index_file_put(vstream->index_file);
  32                 vstream->index_file = nullptr;
  33         }
  34         if (vstream->stream) {
  35                 stream_put(vstream->stream);
  36                 vstream->stream = nullptr;
  37         }
  38         lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
  39         vstream->stream_file.trace_chunk = nullptr;
  40 }
  41
  42 static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
  43 {
  44         free(vstream->path_name);
  45         free(vstream->channel_name);
  46         free(vstream);
  47 }
  48
  49 static void viewer_stream_destroy_rcu(struct rcu_head *head)
  50 {
  51         struct relay_viewer_stream *vstream =
  52                 lttng::utils::container_of(head, &relay_viewer_stream::rcu_node);
  53
  54         viewer_stream_destroy(vstream);
  55 }
  56
  57 /* Relay stream's lock must be held by the caller. */
  58 struct relay_viewer_stream *viewer_stream_create(struct relay_stream *stream,
  59                                                  struct lttng_trace_chunk *trace_chunk,
  60                                                  enum lttng_viewer_seek seek_t)
  61 {
  62         struct relay_viewer_stream *vstream = nullptr;
  63
  64         ASSERT_LOCKED(stream->lock);
  65
  66         vstream = zmalloc<relay_viewer_stream>();
  67         if (!vstream) {
  68                 PERROR("relay viewer stream zmalloc");
  69                 goto error;
  70         }
  71
  72         if (trace_chunk) {
  73                 const bool acquired_reference = lttng_trace_chunk_get(trace_chunk);
  74
  75                 LTTNG_ASSERT(acquired_reference);
  76         }
  77
  78         vstream->stream_file.trace_chunk = trace_chunk;
  79         vstream->path_name = lttng_strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
  80         if (vstream->path_name == nullptr) {
  81                 PERROR("relay viewer path_name alloc");
  82                 goto error;
  83         }
  84         vstream->channel_name = lttng_strndup(stream->channel_name, LTTNG_VIEWER_NAME_MAX);
  85         if (vstream->channel_name == nullptr) {
  86                 PERROR("relay viewer channel_name alloc");
  87                 goto error;
  88         }
  89
  90         if (!stream_get(stream)) {
  91                 ERR("Cannot get stream");
  92                 goto error;
  93         }
  94         vstream->stream = stream;
  95
  96         if (stream->is_metadata && stream->trace->viewer_metadata_stream) {
  97                 ERR("Cannot attach viewer metadata stream to trace (busy).");
  98                 goto error;
  99         }
 100
 101         switch (seek_t) {
 102         case LTTNG_VIEWER_SEEK_BEGINNING:
 103         {
 104                 uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
 105
 106                 if (seq_tail == -1ULL) {
 107                         /*
 108                          * Tail may not be initialized yet. Nonetheless, we know
 109                          * we want to send the first index once it becomes
 110                          * available.
 111                          */
 112                         seq_tail = 0;
 113                 }
 114                 vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
 115                 vstream->index_sent_seqcount = seq_tail;
 116                 break;
 117         }
 118         case LTTNG_VIEWER_SEEK_LAST:
 119                 vstream->current_tracefile_id =
 120                         tracefile_array_get_read_file_index_head(stream->tfa);
 121                 /*
 122                  * We seek at the very end of each stream, awaiting for
 123                  * a future packet to eventually come in.
 124                  *
 125                  * We don't need to check the head position for -1ULL since the
 126                  * increment will set it to 0.
 127                  */
 128                 vstream->index_sent_seqcount = tracefile_array_get_seq_head(stream->tfa) + 1;
 129                 break;
 130         default:
 131                 goto error;
 132         }
 133
 134         /*
 135          * If we never received an index for the current stream, delay
 136          * the opening of the index, otherwise open it right now.
 137          */
 138         if (stream->index_file == nullptr) {
 139                 vstream->index_file = nullptr;
 140         } else if (vstream->stream_file.trace_chunk) {
 141                 const uint32_t connection_major = stream->trace->session->major;
 142                 const uint32_t connection_minor = stream->trace->session->minor;
 143                 enum lttng_trace_chunk_status chunk_status;
 144
 145                 chunk_status = lttng_index_file_create_from_trace_chunk_read_only(
 146                         vstream->stream_file.trace_chunk,
 147                         stream->path_name,
 148                         stream->channel_name,
 149                         stream->tracefile_size,
 150                         vstream->current_tracefile_id,
 151                         lttng_to_index_major(connection_major, connection_minor),
 152                         lttng_to_index_minor(connection_major, connection_minor),
 153                         true,
 154                         &vstream->index_file);
 155                 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 156                         if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NO_FILE) {
 157                                 vstream->index_file = nullptr;
 158                         } else {
 159                                 goto error;
 160                         }
 161                 }
 162         }
 163
 164         /*
 165          * If we never received a data file for the current stream, delay the
 166          * opening, otherwise open it right now.
 167          */
 168         if (stream->file && vstream->stream_file.trace_chunk) {
 169                 int ret;
 170                 char file_path[LTTNG_PATH_MAX];
 171                 enum lttng_trace_chunk_status status;
 172
 173                 ret = utils_stream_file_path(stream->path_name,
 174                                              stream->channel_name,
 175                                              stream->tracefile_size,
 176                                              vstream->current_tracefile_id,
 177                                              nullptr,
 178                                              file_path,
 179                                              sizeof(file_path));
 180                 if (ret < 0) {
 181                         goto error;
 182                 }
 183
 184                 status = lttng_trace_chunk_open_fs_handle(vstream->stream_file.trace_chunk,
 185                                                           file_path,
 186                                                           O_RDONLY,
 187                                                           0,
 188                                                           &vstream->stream_file.handle,
 189                                                           true);
 190                 if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 191                         goto error;
 192                 }
 193         }
 194
 195         if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_file) {
 196                 off_t lseek_ret;
 197
 198                 lseek_ret = fs_handle_seek(vstream->index_file->file, 0, SEEK_END);
 199                 if (lseek_ret < 0) {
 200                         goto error;
 201                 }
 202         }
 203         if (stream->is_metadata) {
 204                 rcu_assign_pointer(stream->trace->viewer_metadata_stream, vstream);
 205         }
 206
 207         vstream->last_seen_rotation_count = stream->completed_rotation_count;
 208
 209         /* Globally visible after the add unique. */
 210         lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
 211         urcu_ref_init(&vstream->ref);
 212         lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
 213
 214         return vstream;
 215
 216 error:
 217         if (vstream) {
 218                 /* Not using `put` since vstream is assumed to be published. */
 219                 viewer_stream_release_composite_objects(vstream);
 220                 viewer_stream_destroy(vstream);
 221         }
 222         return nullptr;
 223 }
 224
 225 static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
 226 {
 227         int ret;
 228         struct lttng_ht_iter iter;
 229
 230         iter.iter.node = &vstream->stream_n.node;
 231         ret = lttng_ht_del(viewer_streams_ht, &iter);
 232         LTTNG_ASSERT(!ret);
 233 }
 234
 235 static void viewer_stream_release(struct urcu_ref *ref)
 236 {
 237         struct relay_viewer_stream *vstream =
 238                 caa_container_of(ref, struct relay_viewer_stream, ref);
 239
 240         if (vstream->stream->is_metadata) {
 241                 rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
 242         }
 243         viewer_stream_unpublish(vstream);
 244         viewer_stream_release_composite_objects(vstream);
 245         call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
 246 }
 247
 248 /* Must be called with RCU read-side lock held. */
 249 bool viewer_stream_get(struct relay_viewer_stream *vstream)
 250 {
 251         return urcu_ref_get_unless_zero(&vstream->ref);
 252 }
 253
 254 /*
 255  * Get viewer stream by id.
 256  *
 257  * Return viewer stream if found else NULL.
 258  */
 259 struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
 260 {
 261         struct lttng_ht_node_u64 *node;
 262         struct lttng_ht_iter iter;
 263         struct relay_viewer_stream *vstream = nullptr;
 264
 265         rcu_read_lock();
 266         lttng_ht_lookup(viewer_streams_ht, &id, &iter);
 267         node = lttng_ht_iter_get_node_u64(&iter);
 268         if (!node) {
 269                 DBG("Relay viewer stream %" PRIu64 " not found", id);
 270                 goto end;
 271         }
 272         vstream = lttng::utils::container_of(node, &relay_viewer_stream::stream_n);
 273         if (!viewer_stream_get(vstream)) {
 274                 vstream = nullptr;
 275         }
 276 end:
 277         rcu_read_unlock();
 278         return vstream;
 279 }
 280
 281 void viewer_stream_put(struct relay_viewer_stream *vstream)
 282 {
 283         rcu_read_lock();
 284         urcu_ref_put(&vstream->ref, viewer_stream_release);
 285         rcu_read_unlock();
 286 }
 287
 288 void viewer_stream_close_files(struct relay_viewer_stream *vstream)
 289 {
 290         if (vstream->index_file) {
 291                 lttng_index_file_put(vstream->index_file);
 292                 vstream->index_file = nullptr;
 293         }
 294         if (vstream->stream_file.handle) {
 295                 fs_handle_close(vstream->stream_file.handle);
 296                 vstream->stream_file.handle = nullptr;
 297         }
 298 }
 299
 300 void viewer_stream_sync_tracefile_array_tail(struct relay_viewer_stream *vstream)
 301 {
 302         const struct relay_stream *stream = vstream->stream;
 303         uint64_t seq_tail;
 304
 305         vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
 306         seq_tail = tracefile_array_get_seq_tail(stream->tfa);
 307         if (seq_tail == -1ULL) {
 308                 seq_tail = 0;
 309         }
 310
 311         /*
 312          * Move the index sent seqcount forward if it was lagging behind
 313          * the new tail of the tracefile array. If the current
 314          * index_sent_seqcount is already further than the tracefile
 315          * array tail position, keep its current position.
 316          */
 317         vstream->index_sent_seqcount = std::max(seq_tail, vstream->index_sent_seqcount);
 318 }
 319
 320 /*
 321  * Rotate a stream to the next tracefile.
 322  *
 323  * Must be called with the rstream lock held.
 324  * Returns 0 on success, 1 on EOF.
 325  */
 326 int viewer_stream_rotate(struct relay_viewer_stream *vstream)
 327 {
 328         int ret;
 329         uint64_t new_id;
 330         const struct relay_stream *stream = vstream->stream;
 331
 332         /* Detect the last tracefile to open. */
 333         if (stream->index_received_seqcount == vstream->index_sent_seqcount &&
 334             stream->trace->session->connection_closed) {
 335                 ret = 1;
 336                 goto end;
 337         }
 338
 339         if (stream->tracefile_count == 0) {
 340                 /* Ignore rotation, there is none to do. */
 341                 ret = 0;
 342                 goto end;
 343         }
 344
 345         /*
 346          * Try to move to the next file.
 347          */
 348         new_id = (vstream->current_tracefile_id + 1) % stream->tracefile_count;
 349         if (tracefile_array_seq_in_file(stream->tfa, new_id, vstream->index_sent_seqcount)) {
 350                 vstream->current_tracefile_id = new_id;
 351         } else {
 352                 uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
 353
 354                 /*
 355                  * This can only be reached on overwrite, which implies there
 356                  * has been data written at some point, which will have set the
 357                  * tail.
 358                  */
 359                 LTTNG_ASSERT(seq_tail != -1ULL);
 360                 /*
 361                  * We need to resync because we lag behind tail.
 362                  */
 363                 vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
 364                 vstream->index_sent_seqcount = seq_tail;
 365         }
 366         viewer_stream_close_files(vstream);
 367         ret = 0;
 368 end:
 369         return ret;
 370 }
 371
 372 void print_viewer_streams()
 373 {
 374         struct lttng_ht_iter iter;
 375         struct relay_viewer_stream *vstream;
 376
 377         if (!viewer_streams_ht) {
 378                 return;
 379         }
 380
 381         rcu_read_lock();
 382         cds_lfht_for_each_entry (viewer_streams_ht->ht, &iter.iter, vstream, stream_n.node) {
 383                 if (!viewer_stream_get(vstream)) {
 384                         continue;
 385                 }
 386                 DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64 " session %" PRIu64,
 387                     vstream,
 388                     vstream->ref.refcount,
 389                     vstream->stream->stream_handle,
 390                     vstream->stream->trace->id,
 391                     vstream->stream->trace->session->id);
 392                 viewer_stream_put(vstream);
 393         }
 394         rcu_read_unlock();
 395 }