src/plugins/ctf/lttng-live/lttng-live.c

   1 /*
   2  * lttng-live.c
   3  *
   4  * Babeltrace CTF LTTng-live Client Component
   5  *
   6  * Copyright 2019 Francis Deslauriers <francis.deslauriers@efficios.com>
   7  * Copyright 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   8  * Copyright 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * Author: Jérémie Galarneau <jeremie.galarneau@efficios.com>
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this software and associated documentation files (the "Software"), to deal
  14  * in the Software without restriction, including without limitation the rights
  15  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  16  * copies of the Software, and to permit persons to whom the Software is
  17  * furnished to do so, subject to the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  27  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  28  * SOFTWARE.
  29  */
  30
  31 #define BT_COMP_LOG_SELF_COMP self_comp
  32 #define BT_LOG_OUTPUT_LEVEL log_level
  33 #define BT_LOG_TAG "PLUGIN/SRC.CTF.LTTNG-LIVE"
  34 #include "logging/comp-logging.h"
  35
  36 #include <inttypes.h>
  37 #include <stdbool.h>
  38 #include <unistd.h>
  39
  40 #include <glib.h>
  41
  42 #include "common/assert.h"
  43 #include <babeltrace2/babeltrace.h>
  44 #include "compat/compiler.h"
  45 #include <babeltrace2/types.h>
  46
  47 #include "plugins/common/muxing/muxing.h"
  48 #include "plugins/common/param-validation/param-validation.h"
  49
  50 #include "data-stream.h"
  51 #include "metadata.h"
  52 #include "lttng-live.h"
  53
  54 #define MAX_QUERY_SIZE                      (256*1024)
  55 #define URL_PARAM                           "url"
  56 #define INPUTS_PARAM                        "inputs"
  57 #define SESS_NOT_FOUND_ACTION_PARAM         "session-not-found-action"
  58 #define SESS_NOT_FOUND_ACTION_CONTINUE_STR  "continue"
  59 #define SESS_NOT_FOUND_ACTION_FAIL_STR      "fail"
  60 #define SESS_NOT_FOUND_ACTION_END_STR       "end"
  61
  62 #define print_dbg(fmt, ...)     BT_COMP_LOGD(fmt, ## __VA_ARGS__)
  63
  64 static
  65 const char *lttng_live_iterator_status_string(
  66                 enum lttng_live_iterator_status status)
  67 {
  68         switch (status) {
  69         case LTTNG_LIVE_ITERATOR_STATUS_CONTINUE:
  70                 return "LTTNG_LIVE_ITERATOR_STATUS_CONTINUE";
  71         case LTTNG_LIVE_ITERATOR_STATUS_AGAIN:
  72                 return "LTTNG_LIVE_ITERATOR_STATUS_AGAIN";
  73         case LTTNG_LIVE_ITERATOR_STATUS_END:
  74                 return "LTTNG_LIVE_ITERATOR_STATUS_END";
  75         case LTTNG_LIVE_ITERATOR_STATUS_OK:
  76                 return "LTTNG_LIVE_ITERATOR_STATUS_OK";
  77         case LTTNG_LIVE_ITERATOR_STATUS_INVAL:
  78                 return "LTTNG_LIVE_ITERATOR_STATUS_INVAL";
  79         case LTTNG_LIVE_ITERATOR_STATUS_ERROR:
  80                 return "LTTNG_LIVE_ITERATOR_STATUS_ERROR";
  81         case LTTNG_LIVE_ITERATOR_STATUS_NOMEM:
  82                 return "LTTNG_LIVE_ITERATOR_STATUS_NOMEM";
  83         case LTTNG_LIVE_ITERATOR_STATUS_UNSUPPORTED:
  84                 return "LTTNG_LIVE_ITERATOR_STATUS_UNSUPPORTED";
  85         default:
  86                 bt_common_abort();
  87         }
  88 }
  89
  90 static
  91 const char *lttng_live_stream_state_string(enum lttng_live_stream_state state)
  92 {
  93         switch (state) {
  94         case LTTNG_LIVE_STREAM_ACTIVE_NO_DATA:
  95                 return "ACTIVE_NO_DATA";
  96         case LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA:
  97                 return "QUIESCENT_NO_DATA";
  98         case LTTNG_LIVE_STREAM_QUIESCENT:
  99                 return "QUIESCENT";
 100         case LTTNG_LIVE_STREAM_ACTIVE_DATA:
 101                 return "ACTIVE_DATA";
 102         case LTTNG_LIVE_STREAM_EOF:
 103                 return "EOF";
 104         default:
 105                 return "ERROR";
 106         }
 107 }
 108
 109 #define LTTNG_LIVE_LOGD_STREAM_ITER(live_stream_iter) \
 110         do { \
 111                 BT_COMP_LOGD("Live stream iterator state=%s, last-inact-ts=%" PRId64  \
 112                         ", curr-inact-ts %" PRId64, \
 113                         lttng_live_stream_state_string(live_stream_iter->state), \
 114                         live_stream_iter->last_inactivity_ts, \
 115                         live_stream_iter->current_inactivity_ts); \
 116         } while (0);
 117
 118 BT_HIDDEN
 119 bool lttng_live_graph_is_canceled(struct lttng_live_msg_iter *msg_iter)
 120 {
 121         bool ret;
 122
 123         if (!msg_iter) {
 124                 ret = false;
 125                 goto end;
 126         }
 127
 128         ret = bt_self_message_iterator_is_interrupted(
 129                 msg_iter->self_msg_iter);
 130
 131 end:
 132         return ret;
 133 }
 134
 135 static
 136 struct lttng_live_trace *lttng_live_find_trace(struct lttng_live_session *session,
 137                 uint64_t trace_id)
 138 {
 139         uint64_t trace_idx;
 140         struct lttng_live_trace *ret_trace = NULL;
 141
 142         for (trace_idx = 0; trace_idx < session->traces->len; trace_idx++) {
 143                 struct lttng_live_trace *trace =
 144                         g_ptr_array_index(session->traces, trace_idx);
 145                 if (trace->id == trace_id) {
 146                         ret_trace = trace;
 147                         goto end;
 148                 }
 149         }
 150
 151 end:
 152         return ret_trace;
 153 }
 154
 155 static
 156 void lttng_live_destroy_trace(struct lttng_live_trace *trace)
 157 {
 158         bt_logging_level log_level = trace->log_level;
 159         bt_self_component *self_comp = trace->self_comp;
 160
 161         BT_COMP_LOGD("Destroying live trace: trace-id=%"PRIu64, trace->id);
 162
 163         BT_ASSERT(trace->stream_iterators);
 164         g_ptr_array_free(trace->stream_iterators, TRUE);
 165
 166         BT_TRACE_PUT_REF_AND_RESET(trace->trace);
 167         BT_TRACE_CLASS_PUT_REF_AND_RESET(trace->trace_class);
 168
 169         lttng_live_metadata_fini(trace);
 170         g_free(trace);
 171 }
 172
 173 static
 174 struct lttng_live_trace *lttng_live_create_trace(struct lttng_live_session *session,
 175                 uint64_t trace_id)
 176 {
 177         struct lttng_live_trace *trace = NULL;
 178         bt_logging_level log_level = session->log_level;
 179         bt_self_component *self_comp = session->self_comp;
 180
 181         BT_COMP_LOGD("Creating live trace: "
 182                 "session-id=%"PRIu64", trace-id=%"PRIu64,
 183                 session->id, trace_id);
 184         trace = g_new0(struct lttng_live_trace, 1);
 185         if (!trace) {
 186                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 187                         "Failed to allocate live trace");
 188                 goto error;
 189         }
 190         trace->log_level = session->log_level;
 191         trace->self_comp = session->self_comp;
 192         trace->session = session;
 193         trace->id = trace_id;
 194         trace->trace_class = NULL;
 195         trace->trace = NULL;
 196         trace->stream_iterators = g_ptr_array_new_with_free_func(
 197                 (GDestroyNotify) lttng_live_stream_iterator_destroy);
 198         BT_ASSERT(trace->stream_iterators);
 199         trace->metadata_stream_state = LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED;
 200         g_ptr_array_add(session->traces, trace);
 201
 202         goto end;
 203 error:
 204         g_free(trace);
 205         trace = NULL;
 206 end:
 207         return trace;
 208 }
 209
 210 BT_HIDDEN
 211 struct lttng_live_trace *lttng_live_borrow_trace(
 212                 struct lttng_live_session *session, uint64_t trace_id)
 213 {
 214         struct lttng_live_trace *trace;
 215
 216         trace = lttng_live_find_trace(session, trace_id);
 217         if (trace) {
 218                 goto end;
 219         }
 220
 221         /* The session is the owner of the newly created trace. */
 222         trace = lttng_live_create_trace(session, trace_id);
 223
 224 end:
 225         return trace;
 226 }
 227
 228 BT_HIDDEN
 229 int lttng_live_add_session(struct lttng_live_msg_iter *lttng_live_msg_iter,
 230                 uint64_t session_id, const char *hostname,
 231                 const char *session_name)
 232 {
 233         int ret = 0;
 234         struct lttng_live_session *session;
 235         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 236         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 237
 238         BT_COMP_LOGD("Adding live session: "
 239                 "session-id=%" PRIu64 ", hostname=\"%s\" session-name=\"%s\"",
 240                 session_id, hostname, session_name);
 241
 242         session = g_new0(struct lttng_live_session, 1);
 243         if (!session) {
 244                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 245                         "Failed to allocate live session");
 246                 goto error;
 247         }
 248
 249         session->log_level = lttng_live_msg_iter->log_level;
 250         session->self_comp = lttng_live_msg_iter->self_comp;
 251         session->id = session_id;
 252         session->traces = g_ptr_array_new_with_free_func(
 253                 (GDestroyNotify) lttng_live_destroy_trace);
 254         BT_ASSERT(session->traces);
 255         session->lttng_live_msg_iter = lttng_live_msg_iter;
 256         session->new_streams_needed = true;
 257         session->hostname = g_string_new(hostname);
 258         BT_ASSERT(session->hostname);
 259
 260         session->session_name = g_string_new(session_name);
 261         BT_ASSERT(session->session_name);
 262
 263         g_ptr_array_add(lttng_live_msg_iter->sessions, session);
 264         goto end;
 265 error:
 266         g_free(session);
 267         ret = -1;
 268 end:
 269         return ret;
 270 }
 271
 272 static
 273 void lttng_live_destroy_session(struct lttng_live_session *session)
 274 {
 275         bt_logging_level log_level;
 276         bt_self_component *self_comp;
 277
 278         if (!session) {
 279                 goto end;
 280         }
 281
 282         log_level = session->log_level;
 283         self_comp = session->self_comp;
 284         BT_COMP_LOGD("Destroying live session: "
 285                 "session-id=%"PRIu64", session-name=\"%s\"",
 286                 session->id, session->session_name->str);
 287         if (session->id != -1ULL) {
 288                 if (lttng_live_detach_session(session)) {
 289                         if (!lttng_live_graph_is_canceled(
 290                                         session->lttng_live_msg_iter)) {
 291                                 /* Old relayd cannot detach sessions. */
 292                                 BT_COMP_LOGD("Unable to detach lttng live session %" PRIu64,
 293                                         session->id);
 294                         }
 295                 }
 296                 session->id = -1ULL;
 297         }
 298
 299         if (session->traces) {
 300                 g_ptr_array_free(session->traces, TRUE);
 301         }
 302
 303         if (session->hostname) {
 304                 g_string_free(session->hostname, TRUE);
 305         }
 306         if (session->session_name) {
 307                 g_string_free(session->session_name, TRUE);
 308         }
 309         g_free(session);
 310
 311 end:
 312         return;
 313 }
 314
 315 static
 316 void lttng_live_msg_iter_destroy(struct lttng_live_msg_iter *lttng_live_msg_iter)
 317 {
 318         if (!lttng_live_msg_iter) {
 319                 goto end;
 320         }
 321
 322         if (lttng_live_msg_iter->sessions) {
 323                 g_ptr_array_free(lttng_live_msg_iter->sessions, TRUE);
 324         }
 325
 326         if (lttng_live_msg_iter->viewer_connection) {
 327                 live_viewer_connection_destroy(lttng_live_msg_iter->viewer_connection);
 328         }
 329         BT_ASSERT(lttng_live_msg_iter->lttng_live_comp);
 330         BT_ASSERT(lttng_live_msg_iter->lttng_live_comp->has_msg_iter);
 331
 332         /* All stream iterators must be destroyed at this point. */
 333         BT_ASSERT(lttng_live_msg_iter->active_stream_iter == 0);
 334         lttng_live_msg_iter->lttng_live_comp->has_msg_iter = false;
 335
 336         g_free(lttng_live_msg_iter);
 337
 338 end:
 339         return;
 340 }
 341
 342 BT_HIDDEN
 343 void lttng_live_msg_iter_finalize(bt_self_message_iterator *self_msg_iter)
 344 {
 345         struct lttng_live_msg_iter *lttng_live_msg_iter;
 346
 347         BT_ASSERT(self_msg_iter);
 348
 349         lttng_live_msg_iter = bt_self_message_iterator_get_data(self_msg_iter);
 350         BT_ASSERT(lttng_live_msg_iter);
 351         lttng_live_msg_iter_destroy(lttng_live_msg_iter);
 352 }
 353
 354 static
 355 enum lttng_live_iterator_status lttng_live_iterator_next_check_stream_state(
 356                 struct lttng_live_stream_iterator *lttng_live_stream)
 357 {
 358         bt_logging_level log_level = lttng_live_stream->log_level;
 359         bt_self_component *self_comp = lttng_live_stream->self_comp;
 360
 361         switch (lttng_live_stream->state) {
 362         case LTTNG_LIVE_STREAM_QUIESCENT:
 363         case LTTNG_LIVE_STREAM_ACTIVE_DATA:
 364                 break;
 365         case LTTNG_LIVE_STREAM_ACTIVE_NO_DATA:
 366                 /* Invalid state. */
 367                 BT_COMP_LOGF("Unexpected stream state \"ACTIVE_NO_DATA\"");
 368                 bt_common_abort();
 369         case LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA:
 370                 /* Invalid state. */
 371                 BT_COMP_LOGF("Unexpected stream state \"QUIESCENT_NO_DATA\"");
 372                 bt_common_abort();
 373         case LTTNG_LIVE_STREAM_EOF:
 374                 break;
 375         }
 376         return LTTNG_LIVE_ITERATOR_STATUS_OK;
 377 }
 378
 379 /*
 380  * For active no data stream, fetch next data. It can be either:
 381  * - quiescent: need to put it in the prio heap at quiescent end
 382  *   timestamp,
 383  * - have data: need to wire up first event into the prio heap,
 384  * - have no data on this stream at this point: need to retry (AGAIN) or
 385  *   return EOF.
 386  */
 387 static
 388 enum lttng_live_iterator_status lttng_live_iterator_next_handle_one_no_data_stream(
 389                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 390                 struct lttng_live_stream_iterator *lttng_live_stream)
 391 {
 392         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 393         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 394         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 395         enum lttng_live_stream_state orig_state = lttng_live_stream->state;
 396         struct packet_index index;
 397
 398         if (lttng_live_stream->trace->metadata_stream_state ==
 399                         LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED) {
 400                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 401                 goto end;
 402         }
 403         if (lttng_live_stream->trace->session->new_streams_needed) {
 404                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 405                 goto end;
 406         }
 407         if (lttng_live_stream->state != LTTNG_LIVE_STREAM_ACTIVE_NO_DATA &&
 408                         lttng_live_stream->state != LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA) {
 409                 goto end;
 410         }
 411         ret = lttng_live_get_next_index(lttng_live_msg_iter, lttng_live_stream,
 412                 &index);
 413         if (ret != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 414                 goto end;
 415         }
 416         BT_ASSERT_DBG(lttng_live_stream->state != LTTNG_LIVE_STREAM_EOF);
 417         if (lttng_live_stream->state == LTTNG_LIVE_STREAM_QUIESCENT) {
 418                 uint64_t last_inact_ts = lttng_live_stream->last_inactivity_ts,
 419                          curr_inact_ts = lttng_live_stream->current_inactivity_ts;
 420
 421                 if (orig_state == LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA &&
 422                                 last_inact_ts == curr_inact_ts) {
 423                         ret = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
 424                         LTTNG_LIVE_LOGD_STREAM_ITER(lttng_live_stream);
 425                 } else {
 426                         ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 427                 }
 428                 goto end;
 429         }
 430         lttng_live_stream->base_offset = index.offset;
 431         lttng_live_stream->offset = index.offset;
 432         lttng_live_stream->len = index.packet_size / CHAR_BIT;
 433 end:
 434         if (ret == LTTNG_LIVE_ITERATOR_STATUS_OK) {
 435                 ret = lttng_live_iterator_next_check_stream_state(lttng_live_stream);
 436         }
 437         return ret;
 438 }
 439
 440 /*
 441  * Creation of the message requires the ctf trace class to be created
 442  * beforehand, but the live protocol gives us all streams (including metadata)
 443  * at once. So we split it in three steps: getting streams, getting metadata
 444  * (which creates the ctf trace class), and then creating the per-stream
 445  * messages.
 446  */
 447 static
 448 enum lttng_live_iterator_status lttng_live_get_session(
 449                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 450                 struct lttng_live_session *session)
 451 {
 452         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 453         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 454         enum lttng_live_iterator_status status;
 455         uint64_t trace_idx;
 456
 457         BT_COMP_LOGD("Updating all streams for session: "
 458                 "session-id=%"PRIu64", session-name=\"%s\"",
 459                 session->id, session->session_name->str);
 460
 461         if (!session->attached) {
 462                 enum lttng_live_viewer_status attach_status =
 463                         lttng_live_attach_session(session,
 464                                 lttng_live_msg_iter->self_msg_iter);
 465                 if (attach_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
 466                         if (lttng_live_graph_is_canceled(lttng_live_msg_iter)) {
 467                                 /*
 468                                  * Clear any causes appended in
 469                                  * `lttng_live_attach_session()` as we want to
 470                                  * return gracefully since the graph was
 471                                  * cancelled.
 472                                  */
 473                                 bt_current_thread_clear_error();
 474                                 status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
 475                         } else {
 476                                 status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 477                                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 478                                         "Error attaching to LTTng live session");
 479                         }
 480                         goto end;
 481                 }
 482         }
 483
 484         status = lttng_live_get_new_streams(session,
 485                 lttng_live_msg_iter->self_msg_iter);
 486         if (status != LTTNG_LIVE_ITERATOR_STATUS_OK &&
 487                         status != LTTNG_LIVE_ITERATOR_STATUS_END) {
 488                 goto end;
 489         }
 490         trace_idx = 0;
 491         while (trace_idx < session->traces->len) {
 492                 struct lttng_live_trace *trace =
 493                         g_ptr_array_index(session->traces, trace_idx);
 494
 495                 status = lttng_live_metadata_update(trace);
 496                 switch (status) {
 497                 case LTTNG_LIVE_ITERATOR_STATUS_END:
 498                 case LTTNG_LIVE_ITERATOR_STATUS_OK:
 499                         trace_idx++;
 500                         break;
 501                 case LTTNG_LIVE_ITERATOR_STATUS_CONTINUE:
 502                 case LTTNG_LIVE_ITERATOR_STATUS_AGAIN:
 503                         goto end;
 504                 default:
 505                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 506                                 "Error updating trace metadata: "
 507                                 "stream-iter-status=%s, trace-id=%"PRIu64,
 508                                 lttng_live_iterator_status_string(status),
 509                                 trace->id);
 510                         goto end;
 511                 }
 512         }
 513         status = lttng_live_lazy_msg_init(session,
 514                 lttng_live_msg_iter->self_msg_iter);
 515
 516 end:
 517         return status;
 518 }
 519
 520 BT_HIDDEN
 521 void lttng_live_need_new_streams(struct lttng_live_msg_iter *lttng_live_msg_iter)
 522 {
 523         uint64_t session_idx;
 524
 525         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 526                         session_idx++) {
 527                 struct lttng_live_session *session =
 528                         g_ptr_array_index(lttng_live_msg_iter->sessions, session_idx);
 529                 session->new_streams_needed = true;
 530         }
 531 }
 532
 533 static
 534 void lttng_live_force_new_streams_and_metadata(struct lttng_live_msg_iter *lttng_live_msg_iter)
 535 {
 536         uint64_t session_idx, trace_idx;
 537
 538         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 539                         session_idx++) {
 540                 struct lttng_live_session *session =
 541                         g_ptr_array_index(lttng_live_msg_iter->sessions, session_idx);
 542                 session->new_streams_needed = true;
 543                 for (trace_idx = 0; trace_idx < session->traces->len;
 544                                 trace_idx++) {
 545                         struct lttng_live_trace *trace =
 546                                 g_ptr_array_index(session->traces, trace_idx);
 547
 548                         BT_ASSERT(trace->metadata_stream_state !=
 549                                 LTTNG_LIVE_METADATA_STREAM_STATE_CLOSED);
 550
 551                         trace->metadata_stream_state = LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED;
 552                 }
 553         }
 554 }
 555
 556 static
 557 enum lttng_live_iterator_status
 558 lttng_live_iterator_handle_new_streams_and_metadata(
 559                 struct lttng_live_msg_iter *lttng_live_msg_iter)
 560 {
 561         enum lttng_live_iterator_status status;
 562         enum lttng_live_viewer_status viewer_status;
 563         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 564         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 565         uint64_t session_idx = 0, nr_sessions_opened = 0;
 566         struct lttng_live_session *session;
 567         enum session_not_found_action sess_not_found_act =
 568                 lttng_live_msg_iter->lttng_live_comp->params.sess_not_found_act;
 569
 570         BT_COMP_LOGD("Update data and metadata of all sessions"
 571                 "live-msg-iter-addr=%p", lttng_live_msg_iter);
 572         /*
 573          * In a remotely distant future, we could add a "new
 574          * session" flag to the protocol, which would tell us that we
 575          * need to query for new sessions even though we have sessions
 576          * currently ongoing.
 577          */
 578         if (lttng_live_msg_iter->sessions->len == 0) {
 579                 if (sess_not_found_act != SESSION_NOT_FOUND_ACTION_CONTINUE) {
 580                         BT_COMP_LOGD("No session found. Exiting in accordance with the `session-not-found-action` parameter");
 581                         status = LTTNG_LIVE_ITERATOR_STATUS_END;
 582                         goto end;
 583                 } else {
 584                         BT_COMP_LOGD("No session found. Try creating a new one in accordance with the `session-not-found-action` parameter");
 585                         /*
 586                          * Retry to create a viewer session for the requested
 587                          * session name.
 588                          */
 589                         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
 590                         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
 591                                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
 592                                         status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 593                                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 594                                                 "Error creating LTTng live viewer session");
 595                                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
 596                                         status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
 597                                 } else {
 598                                         bt_common_abort();
 599                                 }
 600                                 goto end;
 601                         }
 602                 }
 603         }
 604
 605         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 606                         session_idx++) {
 607                 session = g_ptr_array_index(lttng_live_msg_iter->sessions,
 608                                 session_idx);
 609                 status = lttng_live_get_session(lttng_live_msg_iter, session);
 610                 switch (status) {
 611                 case LTTNG_LIVE_ITERATOR_STATUS_OK:
 612                         break;
 613                 case LTTNG_LIVE_ITERATOR_STATUS_END:
 614                         status = LTTNG_LIVE_ITERATOR_STATUS_OK;
 615                         break;
 616                 default:
 617                         goto end;
 618                 }
 619                 if (!session->closed) {
 620                         nr_sessions_opened++;
 621                 }
 622         }
 623
 624         if (sess_not_found_act != SESSION_NOT_FOUND_ACTION_CONTINUE &&
 625                         nr_sessions_opened == 0) {
 626                 status = LTTNG_LIVE_ITERATOR_STATUS_END;
 627         } else {
 628                 status = LTTNG_LIVE_ITERATOR_STATUS_OK;
 629         }
 630
 631 end:
 632         return status;
 633 }
 634
 635 static
 636 enum lttng_live_iterator_status emit_inactivity_message(
 637                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 638                 struct lttng_live_stream_iterator *stream_iter,
 639                 bt_message **message, uint64_t timestamp)
 640 {
 641         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 642         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 643         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 644         bt_message *msg = NULL;
 645
 646         BT_ASSERT(stream_iter->trace->clock_class);
 647
 648         msg = bt_message_message_iterator_inactivity_create(
 649                 lttng_live_msg_iter->self_msg_iter,
 650                 stream_iter->trace->clock_class, timestamp);
 651         if (!msg) {
 652                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 653                         "Error emitting message iterator inactivity message");
 654                 goto error;
 655         }
 656
 657         *message = msg;
 658 end:
 659         return ret;
 660
 661 error:
 662         ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 663         bt_message_put_ref(msg);
 664         goto end;
 665 }
 666
 667 static
 668 enum lttng_live_iterator_status lttng_live_iterator_next_handle_one_quiescent_stream(
 669                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 670                 struct lttng_live_stream_iterator *lttng_live_stream,
 671                 bt_message **message)
 672 {
 673         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 674
 675         if (lttng_live_stream->state != LTTNG_LIVE_STREAM_QUIESCENT) {
 676                 return LTTNG_LIVE_ITERATOR_STATUS_OK;
 677         }
 678
 679         if (lttng_live_stream->current_inactivity_ts ==
 680                         lttng_live_stream->last_inactivity_ts) {
 681                 lttng_live_stream->state = LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA;
 682                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 683                 goto end;
 684         }
 685
 686         ret = emit_inactivity_message(lttng_live_msg_iter, lttng_live_stream,
 687                 message, lttng_live_stream->current_inactivity_ts);
 688
 689         lttng_live_stream->last_inactivity_ts =
 690                 lttng_live_stream->current_inactivity_ts;
 691 end:
 692         return ret;
 693 }
 694
 695 static
 696 int live_get_msg_ts_ns(struct lttng_live_stream_iterator *stream_iter,
 697                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 698                 const bt_message *msg, int64_t last_msg_ts_ns,
 699                 int64_t *ts_ns)
 700 {
 701         const bt_clock_class *clock_class = NULL;
 702         const bt_clock_snapshot *clock_snapshot = NULL;
 703         int ret = 0;
 704         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 705         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 706
 707         BT_ASSERT_DBG(msg);
 708         BT_ASSERT_DBG(ts_ns);
 709
 710         BT_COMP_LOGD("Getting message's timestamp: iter-data-addr=%p, msg-addr=%p, "
 711                 "last-msg-ts=%" PRId64, lttng_live_msg_iter, msg,
 712                 last_msg_ts_ns);
 713
 714         switch (bt_message_get_type(msg)) {
 715         case BT_MESSAGE_TYPE_EVENT:
 716                 clock_class = bt_message_event_borrow_stream_class_default_clock_class_const(
 717                                 msg);
 718                 BT_ASSERT_DBG(clock_class);
 719
 720                 clock_snapshot = bt_message_event_borrow_default_clock_snapshot_const(
 721                         msg);
 722                 break;
 723         case BT_MESSAGE_TYPE_PACKET_BEGINNING:
 724                 clock_class = bt_message_packet_beginning_borrow_stream_class_default_clock_class_const(
 725                         msg);
 726                 BT_ASSERT(clock_class);
 727
 728                 clock_snapshot = bt_message_packet_beginning_borrow_default_clock_snapshot_const(
 729                         msg);
 730                 break;
 731         case BT_MESSAGE_TYPE_PACKET_END:
 732                 clock_class = bt_message_packet_end_borrow_stream_class_default_clock_class_const(
 733                         msg);
 734                 BT_ASSERT(clock_class);
 735
 736                 clock_snapshot = bt_message_packet_end_borrow_default_clock_snapshot_const(
 737                         msg);
 738                 break;
 739         case BT_MESSAGE_TYPE_DISCARDED_EVENTS:
 740                 clock_class = bt_message_discarded_events_borrow_stream_class_default_clock_class_const(
 741                         msg);
 742                 BT_ASSERT(clock_class);
 743
 744                 clock_snapshot = bt_message_discarded_events_borrow_beginning_default_clock_snapshot_const(
 745                         msg);
 746                 break;
 747         case BT_MESSAGE_TYPE_DISCARDED_PACKETS:
 748                 clock_class = bt_message_discarded_packets_borrow_stream_class_default_clock_class_const(
 749                         msg);
 750                 BT_ASSERT(clock_class);
 751
 752                 clock_snapshot = bt_message_discarded_packets_borrow_beginning_default_clock_snapshot_const(
 753                         msg);
 754                 break;
 755         case BT_MESSAGE_TYPE_MESSAGE_ITERATOR_INACTIVITY:
 756                 clock_snapshot = bt_message_message_iterator_inactivity_borrow_default_clock_snapshot_const(
 757                         msg);
 758                 break;
 759         default:
 760                 /* All the other messages have a higher priority */
 761                 BT_COMP_LOGD_STR("Message has no timestamp: using the last message timestamp.");
 762                 *ts_ns = last_msg_ts_ns;
 763                 goto end;
 764         }
 765
 766         clock_class = bt_clock_snapshot_borrow_clock_class_const(clock_snapshot);
 767         BT_ASSERT_DBG(clock_class);
 768
 769         ret = bt_clock_snapshot_get_ns_from_origin(clock_snapshot, ts_ns);
 770         if (ret) {
 771                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 772                         "Cannot get nanoseconds from Epoch of clock snapshot: "
 773                         "clock-snapshot-addr=%p", clock_snapshot);
 774                 goto error;
 775         }
 776
 777         goto end;
 778
 779 error:
 780         ret = -1;
 781
 782 end:
 783         if (ret == 0) {
 784                 BT_COMP_LOGD("Found message's timestamp: "
 785                         "iter-data-addr=%p, msg-addr=%p, "
 786                         "last-msg-ts=%" PRId64 ", ts=%" PRId64,
 787                         lttng_live_msg_iter, msg, last_msg_ts_ns, *ts_ns);
 788         }
 789
 790         return ret;
 791 }
 792
 793 static
 794 enum lttng_live_iterator_status lttng_live_iterator_next_handle_one_active_data_stream(
 795                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 796                 struct lttng_live_stream_iterator *lttng_live_stream,
 797                 bt_message **message)
 798 {
 799         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 800         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 801         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 802         enum ctf_msg_iter_status status;
 803         uint64_t session_idx, trace_idx;
 804
 805         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 806                         session_idx++) {
 807                 struct lttng_live_session *session =
 808                         g_ptr_array_index(lttng_live_msg_iter->sessions, session_idx);
 809
 810                 if (session->new_streams_needed) {
 811                         ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 812                         goto end;
 813                 }
 814                 for (trace_idx = 0; trace_idx < session->traces->len;
 815                                 trace_idx++) {
 816                         struct lttng_live_trace *trace =
 817                                 g_ptr_array_index(session->traces, trace_idx);
 818                         if (trace->metadata_stream_state == LTTNG_LIVE_METADATA_STREAM_STATE_NEEDED) {
 819                                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 820                                 goto end;
 821                         }
 822                 }
 823         }
 824
 825         if (lttng_live_stream->state != LTTNG_LIVE_STREAM_ACTIVE_DATA) {
 826                 ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 827                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 828                         "Invalid state of live stream iterator"
 829                         "stream-iter-status=%s",
 830                         lttng_live_stream_state_string(lttng_live_stream->state));
 831                 goto end;
 832         }
 833
 834         status = ctf_msg_iter_get_next_message(
 835                 lttng_live_stream->msg_iter, message);
 836         switch (status) {
 837         case CTF_MSG_ITER_STATUS_EOF:
 838                 ret = LTTNG_LIVE_ITERATOR_STATUS_END;
 839                 break;
 840         case CTF_MSG_ITER_STATUS_OK:
 841                 ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 842                 break;
 843         case CTF_MSG_ITER_STATUS_AGAIN:
 844                 /*
 845                  * Continue immediately (end of packet). The next
 846                  * get_index may return AGAIN to delay the following
 847                  * attempt.
 848                  */
 849                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 850                 break;
 851         case CTF_MSG_ITER_STATUS_INVAL:
 852                 /* No argument provided by the user, so don't return INVAL. */
 853         case CTF_MSG_ITER_STATUS_ERROR:
 854         default:
 855                 ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 856                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 857                         "CTF message iterator failed to get next message: "
 858                         "msg-iter=%p, msg-iter-status=%s",
 859                         lttng_live_stream->msg_iter,
 860                         ctf_msg_iter_status_string(status));
 861                 break;
 862         }
 863
 864 end:
 865         return ret;
 866 }
 867
 868 static
 869 enum lttng_live_iterator_status lttng_live_iterator_close_stream(
 870                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 871                 struct lttng_live_stream_iterator *stream_iter,
 872                 bt_message **curr_msg)
 873 {
 874         enum lttng_live_iterator_status live_status =
 875                 LTTNG_LIVE_ITERATOR_STATUS_OK;
 876         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 877         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 878         /*
 879          * The viewer has hung up on us so we are closing the stream. The
 880          * `ctf_msg_iter` should simply realize that it needs to close the
 881          * stream properly by emitting the necessary stream end message.
 882          */
 883         enum ctf_msg_iter_status status = ctf_msg_iter_get_next_message(
 884                 stream_iter->msg_iter, curr_msg);
 885
 886         if (status == CTF_MSG_ITER_STATUS_ERROR) {
 887                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 888                         "Error getting the next message from CTF message iterator");
 889                 live_status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 890                 goto end;
 891         }
 892
 893         BT_ASSERT(status == CTF_MSG_ITER_STATUS_OK);
 894
 895 end:
 896         return live_status;
 897 }
 898
 899 /*
 900  * helper function:
 901  *            handle_no_data_streams()
 902  *              retry:
 903  *                - for each ACTIVE_NO_DATA stream:
 904  *                  - query relayd for stream data, or quiescence info.
 905  *                    - if need metadata, get metadata, goto retry.
 906  *                    - if new stream, get new stream as ACTIVE_NO_DATA, goto retry
 907  *                  - if quiescent, move to QUIESCENT streams
 908  *                  - if fetched data, move to ACTIVE_DATA streams
 909  *                (at this point each stream either has data, or is quiescent)
 910  *
 911  *
 912  * iterator_next:
 913  *            handle_new_streams_and_metadata()
 914  *                  - query relayd for known streams, add them as ACTIVE_NO_DATA
 915  *                  - query relayd for metadata
 916  *
 917  *            call handle_active_no_data_streams()
 918  *
 919  *            handle_quiescent_streams()
 920  *                - if at least one stream is ACTIVE_DATA:
 921  *                  - peek stream event with lowest timestamp -> next_ts
 922  *                  - for each quiescent stream
 923  *                    - if next_ts >= quiescent end
 924  *                      - set state to ACTIVE_NO_DATA
 925  *                - else
 926  *                  - for each quiescent stream
 927  *                      - set state to ACTIVE_NO_DATA
 928  *
 929  *            call handle_active_no_data_streams()
 930  *
 931  *            handle_active_data_streams()
 932  *                - if at least one stream is ACTIVE_DATA:
 933  *                    - get stream event with lowest timestamp from heap
 934  *                    - make that stream event the current message.
 935  *                    - move this stream heap position to its next event
 936  *                      - if we need to fetch data from relayd, move
 937  *                        stream to ACTIVE_NO_DATA.
 938  *                    - return OK
 939  *                - return AGAIN
 940  *
 941  * end criterion: ctrl-c on client. If relayd exits or the session
 942  * closes on the relay daemon side, we keep on waiting for streams.
 943  * Eventually handle --end timestamp (also an end criterion).
 944  *
 945  * When disconnected from relayd: try to re-connect endlessly.
 946  */
 947 static
 948 enum lttng_live_iterator_status lttng_live_iterator_next_msg_on_stream(
 949                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 950                 struct lttng_live_stream_iterator *stream_iter,
 951                 bt_message **curr_msg)
 952 {
 953         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 954         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 955         enum lttng_live_iterator_status live_status;
 956
 957         BT_COMP_LOGD("Finding the next message for stream iterator: "
 958                 "stream-name=\"%s\"", stream_iter->name->str);
 959
 960         if (stream_iter->has_stream_hung_up) {
 961                 /*
 962                  * The stream has hung up and the stream was properly closed
 963                  * during the last call to the current function. Return _END
 964                  * status now so that this stream iterator is removed for the
 965                  * stream iterator list.
 966                  */
 967                 live_status = LTTNG_LIVE_ITERATOR_STATUS_END;
 968                 goto end;
 969         }
 970
 971 retry:
 972         LTTNG_LIVE_LOGD_STREAM_ITER(stream_iter);
 973         live_status = lttng_live_iterator_handle_new_streams_and_metadata(
 974                 lttng_live_msg_iter);
 975         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 976                 goto end;
 977         }
 978         live_status = lttng_live_iterator_next_handle_one_no_data_stream(
 979                 lttng_live_msg_iter, stream_iter);
 980
 981         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 982                 if (live_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
 983                         /*
 984                          * We overwrite `live_status` since `curr_msg` is
 985                          * likely set to a valid message in this function.
 986                          */
 987                         live_status = lttng_live_iterator_close_stream(
 988                                 lttng_live_msg_iter, stream_iter, curr_msg);
 989                 }
 990                 goto end;
 991         }
 992         live_status = lttng_live_iterator_next_handle_one_quiescent_stream(
 993                 lttng_live_msg_iter, stream_iter, curr_msg);
 994         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 995                 BT_ASSERT(!*curr_msg);
 996                 goto end;
 997         }
 998         if (*curr_msg) {
 999                 goto end;
1000         }
1001         live_status = lttng_live_iterator_next_handle_one_active_data_stream(
1002                 lttng_live_msg_iter, stream_iter, curr_msg);
1003         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1004                 BT_ASSERT(!*curr_msg);
1005         }
1006
1007 end:
1008         if (live_status == LTTNG_LIVE_ITERATOR_STATUS_CONTINUE) {
1009                 goto retry;
1010         }
1011
1012         return live_status;
1013 }
1014
1015 static
1016 enum lttng_live_iterator_status next_stream_iterator_for_trace(
1017                 struct lttng_live_msg_iter *lttng_live_msg_iter,
1018                 struct lttng_live_trace *live_trace,
1019                 struct lttng_live_stream_iterator **youngest_trace_stream_iter)
1020 {
1021         struct lttng_live_stream_iterator *youngest_candidate_stream_iter = NULL;
1022         bt_logging_level log_level = lttng_live_msg_iter->log_level;
1023         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
1024         enum lttng_live_iterator_status stream_iter_status;;
1025         int64_t youngest_candidate_msg_ts = INT64_MAX;
1026         uint64_t stream_iter_idx;
1027
1028         BT_ASSERT_DBG(live_trace);
1029         BT_ASSERT_DBG(live_trace->stream_iterators);
1030
1031         BT_COMP_LOGD("Finding the next stream iterator for trace: "
1032                 "trace-id=%"PRIu64, live_trace->id);
1033         /*
1034          * Update the current message of every stream iterators of this trace.
1035          * The current msg of every stream must have a timestamp equal or
1036          * larger than the last message returned by this iterator. We must
1037          * ensure monotonicity.
1038          */
1039         stream_iter_idx = 0;
1040         while (stream_iter_idx < live_trace->stream_iterators->len) {
1041                 bool stream_iter_is_ended = false;
1042                 struct lttng_live_stream_iterator *stream_iter =
1043                         g_ptr_array_index(live_trace->stream_iterators,
1044                                 stream_iter_idx);
1045
1046                 /*
1047                  * Find if there is are now current message for this stream
1048                  * iterator get it.
1049                  */
1050                 while (!stream_iter->current_msg) {
1051                         bt_message *msg = NULL;
1052                         int64_t curr_msg_ts_ns = INT64_MAX;
1053                         stream_iter_status = lttng_live_iterator_next_msg_on_stream(
1054                                 lttng_live_msg_iter, stream_iter, &msg);
1055
1056                         BT_COMP_LOGD("live stream iterator returned status :%s",
1057                                 lttng_live_iterator_status_string(stream_iter_status));
1058                         if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1059                                 stream_iter_is_ended = true;
1060                                 break;
1061                         }
1062
1063                         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1064                                 goto end;
1065                         }
1066
1067                         BT_ASSERT_DBG(msg);
1068
1069                         /*
1070                          * Get the timestamp in nanoseconds from origin of this
1071                          * messsage.
1072                          */
1073                         live_get_msg_ts_ns(stream_iter, lttng_live_msg_iter,
1074                                 msg, lttng_live_msg_iter->last_msg_ts_ns,
1075                                 &curr_msg_ts_ns);
1076
1077                         /*
1078                          * Check if the message of the current live stream
1079                          * iterator occured at the exact same time or after the
1080                          * last message returned by this component's message
1081                          * iterator. If not, we return an error.
1082                          */
1083                         if (curr_msg_ts_ns >= lttng_live_msg_iter->last_msg_ts_ns) {
1084                                 stream_iter->current_msg = msg;
1085                                 stream_iter->current_msg_ts_ns = curr_msg_ts_ns;
1086                         } else {
1087                                 /*
1088                                  * We received a message in the past. To ensure
1089                                  * monotonicity, we can't send it forward.
1090                                  */
1091                                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1092                                         "Message's timestamp is less than "
1093                                         "lttng-live's message iterator's last "
1094                                         "returned timestamp: "
1095                                         "lttng-live-msg-iter-addr=%p, ts=%" PRId64 ", "
1096                                         "last-msg-ts=%" PRId64,
1097                                         lttng_live_msg_iter, curr_msg_ts_ns,
1098                                         lttng_live_msg_iter->last_msg_ts_ns);
1099                                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
1100                                 goto end;
1101                         }
1102                 }
1103
1104                 BT_ASSERT_DBG(stream_iter != youngest_candidate_stream_iter);
1105
1106                 if (!stream_iter_is_ended) {
1107                         if (G_UNLIKELY(youngest_candidate_stream_iter == NULL) ||
1108                                         stream_iter->current_msg_ts_ns < youngest_candidate_msg_ts) {
1109                                 /*
1110                                  * Update the current best candidate message
1111                                  * for the stream iterator of this live trace
1112                                  * to be forwarded downstream.
1113                                  */
1114                                 youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1115                                 youngest_candidate_stream_iter = stream_iter;
1116                         } else if (stream_iter->current_msg_ts_ns == youngest_candidate_msg_ts) {
1117                                 /*
1118                                  * Order the messages in an arbitrary but
1119                                  * deterministic way.
1120                                  */
1121                                 BT_ASSERT_DBG(stream_iter != youngest_candidate_stream_iter);
1122                                 int ret = common_muxing_compare_messages(
1123                                         stream_iter->current_msg,
1124                                         youngest_candidate_stream_iter->current_msg);
1125                                 if (ret < 0) {
1126                                         /*
1127                                          * The `youngest_candidate_stream_iter->current_msg`
1128                                          * should go first. Update the next
1129                                          * iterator and the current timestamp.
1130                                          */
1131                                         youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1132                                         youngest_candidate_stream_iter = stream_iter;
1133                                 } else if (ret == 0) {
1134                                         /*
1135                                          * Unable to pick which one should go
1136                                          * first.
1137                                          */
1138                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1139                                                 "stream-iter-addr=%p"
1140                                                 "stream-iter-addr=%p",
1141                                                 stream_iter,
1142                                                 youngest_candidate_stream_iter);
1143                                 }
1144                         }
1145
1146                         stream_iter_idx++;
1147                 } else {
1148                         /*
1149                          * The live stream iterator has ended. That
1150                          * iterator is removed from the array, but
1151                          * there is no need to increment
1152                          * stream_iter_idx as
1153                          * g_ptr_array_remove_index_fast replaces the
1154                          * removed element with the array's last
1155                          * element.
1156                          */
1157                         g_ptr_array_remove_index_fast(
1158                                 live_trace->stream_iterators,
1159                                 stream_iter_idx);
1160                 }
1161         }
1162
1163         if (youngest_candidate_stream_iter) {
1164                 *youngest_trace_stream_iter = youngest_candidate_stream_iter;
1165                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1166         } else {
1167                 /*
1168                  * The only case where we don't have a candidate for this trace
1169                  * is if we reached the end of all the iterators.
1170                  */
1171                 BT_ASSERT(live_trace->stream_iterators->len == 0);
1172                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_END;
1173         }
1174
1175 end:
1176         return stream_iter_status;
1177 }
1178
1179 static
1180 enum lttng_live_iterator_status next_stream_iterator_for_session(
1181                 struct lttng_live_msg_iter *lttng_live_msg_iter,
1182                 struct lttng_live_session *session,
1183                 struct lttng_live_stream_iterator **youngest_session_stream_iter)
1184 {
1185         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
1186         bt_logging_level log_level = lttng_live_msg_iter->log_level;
1187         enum lttng_live_iterator_status stream_iter_status;
1188         uint64_t trace_idx = 0;
1189         int64_t youngest_candidate_msg_ts = INT64_MAX;
1190         struct lttng_live_stream_iterator *youngest_candidate_stream_iter = NULL;
1191
1192         BT_COMP_LOGD("Finding the next stream iterator for session: "
1193                 "session-id=%"PRIu64, session->id);
1194         /*
1195          * Make sure we are attached to the session and look for new streams
1196          * and metadata.
1197          */
1198         stream_iter_status = lttng_live_get_session(lttng_live_msg_iter, session);
1199         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK &&
1200                         stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_CONTINUE &&
1201                         stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_END) {
1202                 goto end;
1203         }
1204
1205         BT_ASSERT_DBG(session->traces);
1206
1207         while (trace_idx < session->traces->len) {
1208                 bool trace_is_ended = false;
1209                 struct lttng_live_stream_iterator *stream_iter;
1210                 struct lttng_live_trace *trace =
1211                         g_ptr_array_index(session->traces, trace_idx);
1212
1213                 stream_iter_status = next_stream_iterator_for_trace(
1214                         lttng_live_msg_iter, trace, &stream_iter);
1215                 if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1216                         /*
1217                          * All the live stream iterators for this trace are
1218                          * ENDed. Remove the trace from this session.
1219                          */
1220                         trace_is_ended = true;
1221                 } else if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1222                         goto end;
1223                 }
1224
1225                 if (!trace_is_ended) {
1226                         BT_ASSERT_DBG(stream_iter);
1227
1228                         if (G_UNLIKELY(youngest_candidate_stream_iter == NULL) ||
1229                                         stream_iter->current_msg_ts_ns < youngest_candidate_msg_ts) {
1230                                 youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1231                                 youngest_candidate_stream_iter = stream_iter;
1232                         } else if (stream_iter->current_msg_ts_ns == youngest_candidate_msg_ts) {
1233                                 /*
1234                                  * Order the messages in an arbitrary but
1235                                  * deterministic way.
1236                                  */
1237                                 int ret = common_muxing_compare_messages(
1238                                         stream_iter->current_msg,
1239                                         youngest_candidate_stream_iter->current_msg);
1240                                 if (ret < 0) {
1241                                         /*
1242                                          * The `youngest_candidate_stream_iter->current_msg`
1243                                          * should go first. Update the next iterator
1244                                          * and the current timestamp.
1245                                          */
1246                                         youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1247                                         youngest_candidate_stream_iter = stream_iter;
1248                                 } else if (ret == 0) {
1249                                         /* Unable to pick which one should go first. */
1250                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1251                                                 "stream-iter-addr=%p" "stream-iter-addr=%p",
1252                                                 stream_iter, youngest_candidate_stream_iter);
1253                                 }
1254                         }
1255                         trace_idx++;
1256                 } else {
1257                         /*
1258                          * trace_idx is not incremented since
1259                          * g_ptr_array_remove_index_fast replaces the
1260                          * element at trace_idx with the array's last element.
1261                          */
1262                         g_ptr_array_remove_index_fast(session->traces,
1263                                 trace_idx);
1264                 }
1265         }
1266         if (youngest_candidate_stream_iter) {
1267                 *youngest_session_stream_iter = youngest_candidate_stream_iter;
1268                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1269         } else {
1270                 /*
1271                  * The only cases where we don't have a candidate for this
1272                  * trace is:
1273                  *  1. if we reached the end of all the iterators of all the
1274                  *  traces of this session,
1275                  *  2. if we never had live stream iterator in the first place.
1276                  *
1277                  * In either cases, we return END.
1278                  */
1279                 BT_ASSERT(session->traces->len == 0);
1280                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_END;
1281         }
1282 end:
1283         return stream_iter_status;
1284 }
1285
1286 static inline
1287 void put_messages(bt_message_array_const msgs, uint64_t count)
1288 {
1289         uint64_t i;
1290
1291         for (i = 0; i < count; i++) {
1292                 BT_MESSAGE_PUT_REF_AND_RESET(msgs[i]);
1293         }
1294 }
1295
1296 BT_HIDDEN
1297 bt_component_class_message_iterator_next_method_status lttng_live_msg_iter_next(
1298                 bt_self_message_iterator *self_msg_it,
1299                 bt_message_array_const msgs, uint64_t capacity,
1300                 uint64_t *count)
1301 {
1302         bt_component_class_message_iterator_next_method_status status;
1303         enum lttng_live_viewer_status viewer_status;
1304         struct lttng_live_msg_iter *lttng_live_msg_iter =
1305                 bt_self_message_iterator_get_data(self_msg_it);
1306         struct lttng_live_component *lttng_live =
1307                 lttng_live_msg_iter->lttng_live_comp;
1308         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
1309         bt_logging_level log_level = lttng_live_msg_iter->log_level;
1310         enum lttng_live_iterator_status stream_iter_status;
1311         uint64_t session_idx;
1312
1313         *count = 0;
1314
1315         BT_ASSERT_DBG(lttng_live_msg_iter);
1316
1317         if (G_UNLIKELY(lttng_live_msg_iter->was_interrupted)) {
1318                 /*
1319                  * The iterator was interrupted in a previous call to the
1320                  * `_next()` method. We currently do not support generating
1321                  * messages after such event. The babeltrace2 CLI should never
1322                  * be running the graph after being interrupted. So this check
1323                  * is to prevent other graph users from using this live
1324                  * iterator in an messed up internal state.
1325                  */
1326                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1327                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1328                         "Message iterator was interrupted during a previous call to the `next()` and currently does not support continuing after such event.");
1329                 goto end;
1330         }
1331
1332         /*
1333          * Clear all the invalid message reference that might be left over in
1334          * the output array.
1335          */
1336         memset(msgs, 0, capacity * sizeof(*msgs));
1337
1338         /*
1339          * If no session are exposed on the relay found at the url provided by
1340          * the user, session count will be 0. In this case, we return status
1341          * end to return gracefully.
1342          */
1343         if (lttng_live_msg_iter->sessions->len == 0) {
1344                 if (lttng_live->params.sess_not_found_act !=
1345                                 SESSION_NOT_FOUND_ACTION_CONTINUE) {
1346                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_END;
1347                         goto end;
1348                 } else {
1349                         /*
1350                          * The are no more active session for this session
1351                          * name. Retry to create a viewer session for the
1352                          * requested session name.
1353                          */
1354                         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
1355                         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1356                                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1357                                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1358                                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1359                                                 "Error creating LTTng live viewer session");
1360                                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1361                                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_AGAIN;
1362                                 } else {
1363                                         bt_common_abort();
1364                                 }
1365                                 goto end;
1366                         }
1367                 }
1368         }
1369
1370         if (lttng_live_msg_iter->active_stream_iter == 0) {
1371                 lttng_live_force_new_streams_and_metadata(lttng_live_msg_iter);
1372         }
1373
1374         /*
1375          * Here the muxing of message is done.
1376          *
1377          * We need to iterate over all the streams of all the traces of all the
1378          * viewer sessions in order to get the message with the smallest
1379          * timestamp. In this case, a session is a viewer session and there is
1380          * one viewer session per consumer daemon. (UST 32bit, UST 64bit and/or
1381          * kernel). Each viewer session can have multiple traces, for example,
1382          * 64bit UST viewer sessions could have multiple per-pid traces.
1383          *
1384          * We iterate over the streams of each traces to update and see what is
1385          * their next message's timestamp. From those timestamps, we select the
1386          * message with the smallest timestamp as the best candidate message
1387          * for that trace and do the same thing across all the sessions.
1388          *
1389          * We then compare the timestamp of best candidate message of all the
1390          * sessions to pick the message with the smallest timestamp and we
1391          * return it.
1392          */
1393         while (*count < capacity) {
1394                 struct lttng_live_stream_iterator *youngest_stream_iter = NULL,
1395                           *candidate_stream_iter = NULL;
1396                 int64_t youngest_msg_ts_ns = INT64_MAX;
1397
1398                 BT_ASSERT_DBG(lttng_live_msg_iter->sessions);
1399                 session_idx = 0;
1400                 while (session_idx < lttng_live_msg_iter->sessions->len) {
1401                         struct lttng_live_session *session =
1402                                 g_ptr_array_index(lttng_live_msg_iter->sessions,
1403                                         session_idx);
1404
1405                         /* Find the best candidate message to send downstream. */
1406                         stream_iter_status = next_stream_iterator_for_session(
1407                                 lttng_live_msg_iter, session,
1408                                 &candidate_stream_iter);
1409
1410                         /* If we receive an END status, it means that either:
1411                          * - Those traces never had active streams (UST with no
1412                          *   data produced yet),
1413                          * - All live stream iterators have ENDed.*/
1414                         if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1415                                 if (session->closed && session->traces->len == 0) {
1416                                         /*
1417                                          * Remove the session from the list.
1418                                          * session_idx is not modified since
1419                                          * g_ptr_array_remove_index_fast
1420                                          * replaces the the removed element with
1421                                          * the array's last element.
1422                                          */
1423                                         g_ptr_array_remove_index_fast(
1424                                                 lttng_live_msg_iter->sessions,
1425                                                 session_idx);
1426                                 } else {
1427                                         session_idx++;
1428                                 }
1429                                 continue;
1430                         }
1431
1432                         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1433                                 goto return_status;
1434                         }
1435
1436                         if (G_UNLIKELY(youngest_stream_iter == NULL) ||
1437                                         candidate_stream_iter->current_msg_ts_ns < youngest_msg_ts_ns) {
1438                                 youngest_msg_ts_ns = candidate_stream_iter->current_msg_ts_ns;
1439                                 youngest_stream_iter = candidate_stream_iter;
1440                         } else if (candidate_stream_iter->current_msg_ts_ns == youngest_msg_ts_ns) {
1441                                 /*
1442                                  * The currently selected message to be sent
1443                                  * downstream next has the exact same timestamp
1444                                  * that of the current candidate message. We
1445                                  * must break the tie in a predictable manner.
1446                                  */
1447                                 BT_COMP_LOGD_STR("Two of the next message candidates have the same timestamps, pick one deterministically.");
1448                                 /*
1449                                  * Order the messages in an arbitrary but
1450                                  * deterministic way.
1451                                  */
1452                                 int ret = common_muxing_compare_messages(
1453                                         candidate_stream_iter->current_msg,
1454                                         youngest_stream_iter->current_msg);
1455                                 if (ret < 0) {
1456                                         /*
1457                                          * The `candidate_stream_iter->current_msg`
1458                                          * should go first. Update the next
1459                                          * iterator and the current timestamp.
1460                                          */
1461                                         youngest_msg_ts_ns = candidate_stream_iter->current_msg_ts_ns;
1462                                         youngest_stream_iter = candidate_stream_iter;
1463                                 } else if (ret == 0) {
1464                                         /* Unable to pick which one should go first. */
1465                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1466                                                 "next-stream-iter-addr=%p" "candidate-stream-iter-addr=%p",
1467                                                 youngest_stream_iter, candidate_stream_iter);
1468                                 }
1469                         }
1470
1471                         session_idx++;
1472                 }
1473
1474                 if (!youngest_stream_iter) {
1475                         stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
1476                         goto return_status;
1477                 }
1478
1479                 BT_ASSERT_DBG(youngest_stream_iter->current_msg);
1480                 /* Ensure monotonicity. */
1481                 BT_ASSERT_DBG(lttng_live_msg_iter->last_msg_ts_ns <=
1482                         youngest_stream_iter->current_msg_ts_ns);
1483
1484                 /*
1485                  * Insert the next message to the message batch. This will set
1486                  * stream iterator current messsage to NULL so that next time
1487                  * we fetch the next message of that stream iterator
1488                  */
1489                 BT_MESSAGE_MOVE_REF(msgs[*count], youngest_stream_iter->current_msg);
1490                 (*count)++;
1491
1492                 /* Update the last timestamp in nanoseconds sent downstream. */
1493                 lttng_live_msg_iter->last_msg_ts_ns = youngest_msg_ts_ns;
1494                 youngest_stream_iter->current_msg_ts_ns = INT64_MAX;
1495
1496                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1497         }
1498
1499 return_status:
1500         switch (stream_iter_status) {
1501         case LTTNG_LIVE_ITERATOR_STATUS_OK:
1502         case LTTNG_LIVE_ITERATOR_STATUS_AGAIN:
1503                 /*
1504                  * If we gathered messages, return _OK even if the graph was
1505                  * interrupted. This allows for the components downstream to at
1506                  * least get the thoses messages. If the graph was indeed
1507                  * interrupted there should not be another _next() call as the
1508                  * application will tear down the graph. This component class
1509                  * doesn't support restarting after an interruption.
1510                  */
1511                 if (*count > 0) {
1512                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_OK;
1513                 } else {
1514                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_AGAIN;
1515                 }
1516                 break;
1517         case LTTNG_LIVE_ITERATOR_STATUS_END:
1518                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_END;
1519                 break;
1520         case LTTNG_LIVE_ITERATOR_STATUS_NOMEM:
1521                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1522                         "Memory error preparing the next batch of messages: "
1523                         "live-iter-status=%s",
1524                         lttng_live_iterator_status_string(stream_iter_status));
1525                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_MEMORY_ERROR;
1526                 break;
1527         case LTTNG_LIVE_ITERATOR_STATUS_ERROR:
1528         case LTTNG_LIVE_ITERATOR_STATUS_INVAL:
1529         case LTTNG_LIVE_ITERATOR_STATUS_UNSUPPORTED:
1530                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1531                         "Error preparing the next batch of messages: "
1532                         "live-iter-status=%s",
1533                         lttng_live_iterator_status_string(stream_iter_status));
1534
1535                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1536                 /* Put all existing messages on error. */
1537                 put_messages(msgs, *count);
1538                 break;
1539         default:
1540                 bt_common_abort();
1541         }
1542
1543 end:
1544         return status;
1545 }
1546
1547 static
1548 struct lttng_live_msg_iter *lttng_live_msg_iter_create(
1549                 struct lttng_live_component *lttng_live_comp,
1550                 bt_self_message_iterator *self_msg_it)
1551 {
1552         bt_self_component *self_comp = lttng_live_comp->self_comp;
1553         bt_logging_level log_level = lttng_live_comp->log_level;
1554
1555         struct lttng_live_msg_iter *lttng_live_msg_iter =
1556                 g_new0(struct lttng_live_msg_iter, 1);
1557         if (!lttng_live_msg_iter) {
1558                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1559                         "Failed to allocate lttng_live_msg_iter");
1560                 goto end;
1561         }
1562
1563         lttng_live_msg_iter->log_level = lttng_live_comp->log_level;
1564         lttng_live_msg_iter->self_comp = lttng_live_comp->self_comp;
1565         lttng_live_msg_iter->lttng_live_comp = lttng_live_comp;
1566         lttng_live_msg_iter->self_msg_iter = self_msg_it;
1567
1568         lttng_live_msg_iter->active_stream_iter = 0;
1569         lttng_live_msg_iter->last_msg_ts_ns = INT64_MIN;
1570         lttng_live_msg_iter->was_interrupted = false;
1571
1572         lttng_live_msg_iter->sessions = g_ptr_array_new_with_free_func(
1573                 (GDestroyNotify) lttng_live_destroy_session);
1574         BT_ASSERT(lttng_live_msg_iter->sessions);
1575
1576 end:
1577         return lttng_live_msg_iter;
1578
1579 }
1580
1581 BT_HIDDEN
1582 bt_component_class_message_iterator_initialize_method_status lttng_live_msg_iter_init(
1583                 bt_self_message_iterator *self_msg_it,
1584                 bt_self_message_iterator_configuration *config,
1585                 bt_self_component_source *self_comp_src,
1586                 bt_self_component_port_output *self_port)
1587 {
1588         bt_component_class_message_iterator_initialize_method_status status;
1589         bt_self_component *self_comp =
1590                 bt_self_component_source_as_self_component(self_comp_src);
1591         struct lttng_live_component *lttng_live;
1592         struct lttng_live_msg_iter *lttng_live_msg_iter;
1593         enum lttng_live_viewer_status viewer_status;
1594         bt_logging_level log_level;
1595
1596         BT_ASSERT(self_msg_it);
1597
1598         lttng_live = bt_self_component_get_data(self_comp);
1599         log_level = lttng_live->log_level;
1600         self_comp = lttng_live->self_comp;
1601
1602
1603         /* There can be only one downstream iterator at the same time. */
1604         BT_ASSERT(!lttng_live->has_msg_iter);
1605         lttng_live->has_msg_iter = true;
1606
1607         lttng_live_msg_iter = lttng_live_msg_iter_create(lttng_live,
1608                 self_msg_it);
1609         if (!lttng_live_msg_iter) {
1610                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1611                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1612                         "Failed to create lttng_live_msg_iter");
1613                 goto error;
1614         }
1615
1616          viewer_status = live_viewer_connection_create(self_comp, NULL,
1617                 log_level, lttng_live->params.url->str, false,
1618                 lttng_live_msg_iter, &lttng_live_msg_iter->viewer_connection);
1619         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1620                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1621                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1622                                 "Failed to create viewer connection");
1623                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1624                         /*
1625                          * Interruption in the _iter_init() method is not
1626                          * supported. Return an error.
1627                          */
1628                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1629                                 "Interrupted while creating viewer connection");
1630                 }
1631                 goto error;
1632         }
1633
1634         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
1635         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1636                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1637                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1638                                 "Failed to create viewer session");
1639                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1640                         /*
1641                          * Interruption in the _iter_init() method is not
1642                          * supported. Return an error.
1643                          */
1644                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1645                                 "Interrupted when creating viewer session");
1646                 }
1647                 goto error;
1648         }
1649
1650         if (lttng_live_msg_iter->sessions->len == 0) {
1651                 switch (lttng_live->params.sess_not_found_act) {
1652                 case SESSION_NOT_FOUND_ACTION_CONTINUE:
1653                         BT_COMP_LOGI("Unable to connect to the requested live viewer session. Keep trying to connect because of "
1654                                 "%s=\"%s\" component parameter: url=\"%s\"",
1655                                 SESS_NOT_FOUND_ACTION_PARAM,
1656                                 SESS_NOT_FOUND_ACTION_CONTINUE_STR,
1657                                 lttng_live->params.url->str);
1658                         break;
1659                 case SESSION_NOT_FOUND_ACTION_FAIL:
1660                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1661                                 "Unable to connect to the requested live viewer session. Fail the message iterator initialization because of %s=\"%s\" "
1662                                 "component parameter: url =\"%s\"",
1663                                 SESS_NOT_FOUND_ACTION_PARAM,
1664                                 SESS_NOT_FOUND_ACTION_FAIL_STR,
1665                                 lttng_live->params.url->str);
1666                         goto error;
1667                 case SESSION_NOT_FOUND_ACTION_END:
1668                         BT_COMP_LOGI("Unable to connect to the requested live viewer session. End gracefully at the first _next() "
1669                                 "call because of %s=\"%s\" component parameter: "
1670                                 "url=\"%s\"", SESS_NOT_FOUND_ACTION_PARAM,
1671                                 SESS_NOT_FOUND_ACTION_END_STR,
1672                                 lttng_live->params.url->str);
1673                         break;
1674                 default:
1675                         bt_common_abort();
1676                 }
1677         }
1678
1679         bt_self_message_iterator_set_data(self_msg_it, lttng_live_msg_iter);
1680         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_OK;
1681         goto end;
1682
1683 error:
1684         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_ERROR;
1685         lttng_live_msg_iter_destroy(lttng_live_msg_iter);
1686 end:
1687         return status;
1688 }
1689
1690 static struct bt_param_validation_map_value_entry_descr list_sessions_params[] = {
1691         { URL_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_MANDATORY, { .type = BT_VALUE_TYPE_STRING } },
1692         BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_END
1693 };
1694
1695 static
1696 bt_component_class_query_method_status lttng_live_query_list_sessions(
1697                 const bt_value *params, const bt_value **result,
1698                 bt_self_component_class *self_comp_class,
1699                 bt_logging_level log_level)
1700 {
1701         bt_component_class_query_method_status status;
1702         const bt_value *url_value = NULL;
1703         const char *url;
1704         struct live_viewer_connection *viewer_connection = NULL;
1705         enum lttng_live_viewer_status viewer_status;
1706         enum bt_param_validation_status validation_status;
1707         gchar *validate_error = NULL;
1708
1709         validation_status = bt_param_validation_validate(params,
1710                 list_sessions_params, &validate_error);
1711         if (validation_status == BT_PARAM_VALIDATION_STATUS_MEMORY_ERROR) {
1712                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
1713                 goto error;
1714         } else if (validation_status == BT_PARAM_VALIDATION_STATUS_VALIDATION_ERROR) {
1715                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1716                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class, "%s",
1717                         validate_error);
1718                 goto error;
1719         }
1720
1721         url_value = bt_value_map_borrow_entry_value_const(params, URL_PARAM);
1722         url = bt_value_string_get(url_value);
1723
1724         viewer_status = live_viewer_connection_create(NULL, self_comp_class,
1725                 log_level, url, true, NULL, &viewer_connection);
1726         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1727                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1728                         BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1729                                 "Failed to create viewer connection");
1730                         status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1731                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1732                         status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_AGAIN;
1733                 } else {
1734                         bt_common_abort();
1735                 }
1736                 goto error;
1737         }
1738
1739         status = live_viewer_connection_list_sessions(viewer_connection,
1740                 result);
1741         if (status != BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK) {
1742                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1743                         "Failed to list viewer sessions");
1744                 goto error;
1745         }
1746
1747         goto end;
1748
1749 error:
1750         BT_VALUE_PUT_REF_AND_RESET(*result);
1751
1752         if (status >= 0) {
1753                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1754         }
1755
1756 end:
1757         if (viewer_connection) {
1758                 live_viewer_connection_destroy(viewer_connection);
1759         }
1760
1761         g_free(validate_error);
1762
1763         return status;
1764 }
1765
1766 static
1767 bt_component_class_query_method_status lttng_live_query_support_info(
1768                 const bt_value *params, const bt_value **result,
1769                 bt_self_component_class *self_comp_class,
1770                 bt_logging_level log_level)
1771 {
1772         bt_component_class_query_method_status status =
1773                 BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
1774         const bt_value *input_type_value;
1775         const bt_value *input_value;
1776         double weight = 0;
1777         struct bt_common_lttng_live_url_parts parts = { 0 };
1778
1779         /* Used by the logging macros */
1780         __attribute__((unused)) bt_self_component *self_comp = NULL;
1781
1782         *result = NULL;
1783         input_type_value = bt_value_map_borrow_entry_value_const(params,
1784                 "type");
1785         if (!input_type_value) {
1786                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1787                         "Missing expected `type` parameter.");
1788                 goto error;
1789         }
1790
1791         if (!bt_value_is_string(input_type_value)) {
1792                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1793                         "`type` parameter is not a string value.");
1794                 goto error;
1795         }
1796
1797         if (strcmp(bt_value_string_get(input_type_value), "string") != 0) {
1798                 /* We don't handle file system paths */
1799                 goto create_result;
1800         }
1801
1802         input_value = bt_value_map_borrow_entry_value_const(params, "input");
1803         if (!input_value) {
1804                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1805                         "Missing expected `input` parameter.");
1806                 goto error;
1807         }
1808
1809         if (!bt_value_is_string(input_value)) {
1810                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1811                         "`input` parameter is not a string value.");
1812                 goto error;
1813         }
1814
1815         parts = bt_common_parse_lttng_live_url(bt_value_string_get(input_value),
1816                 NULL, 0);
1817         if (parts.session_name) {
1818                 /*
1819                  * Looks pretty much like an LTTng live URL: we got the
1820                  * session name part, which forms a complete URL.
1821                  */
1822                 weight = .75;
1823         }
1824
1825 create_result:
1826         *result = bt_value_real_create_init(weight);
1827         if (!*result) {
1828                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
1829                 goto error;
1830         }
1831
1832         goto end;
1833
1834 error:
1835         if (status >= 0) {
1836                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1837         }
1838
1839         BT_ASSERT(!*result);
1840
1841 end:
1842         bt_common_destroy_lttng_live_url_parts(&parts);
1843         return status;
1844 }
1845
1846 BT_HIDDEN
1847 bt_component_class_query_method_status lttng_live_query(
1848                 bt_self_component_class_source *comp_class,
1849                 bt_private_query_executor *priv_query_exec,
1850                 const char *object, const bt_value *params,
1851                 __attribute__((unused)) void *method_data,
1852                 const bt_value **result)
1853 {
1854         bt_component_class_query_method_status status =
1855                 BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
1856         bt_self_component *self_comp = NULL;
1857         bt_self_component_class *self_comp_class =
1858                 bt_self_component_class_source_as_self_component_class(comp_class);
1859         bt_logging_level log_level = bt_query_executor_get_logging_level(
1860                 bt_private_query_executor_as_query_executor_const(
1861                         priv_query_exec));
1862
1863         if (strcmp(object, "sessions") == 0) {
1864                 status = lttng_live_query_list_sessions(params, result,
1865                         self_comp_class, log_level);
1866         } else if (strcmp(object, "babeltrace.support-info") == 0) {
1867                 status = lttng_live_query_support_info(params, result,
1868                         self_comp_class, log_level);
1869         } else {
1870                 BT_COMP_LOGI("Unknown query object `%s`", object);
1871                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_UNKNOWN_OBJECT;
1872                 goto end;
1873         }
1874
1875 end:
1876         return status;
1877 }
1878
1879 static
1880 void lttng_live_component_destroy_data(struct lttng_live_component *lttng_live)
1881 {
1882         if (!lttng_live) {
1883                 return;
1884         }
1885         if (lttng_live->params.url) {
1886                 g_string_free(lttng_live->params.url, TRUE);
1887         }
1888         g_free(lttng_live);
1889 }
1890
1891 BT_HIDDEN
1892 void lttng_live_component_finalize(bt_self_component_source *component)
1893 {
1894         void *data = bt_self_component_get_data(
1895                 bt_self_component_source_as_self_component(component));
1896
1897         if (!data) {
1898                 return;
1899         }
1900         lttng_live_component_destroy_data(data);
1901 }
1902
1903 static
1904 enum session_not_found_action parse_session_not_found_action_param(
1905         const bt_value *no_session_param)
1906 {
1907         enum session_not_found_action action;
1908         const char *no_session_act_str = bt_value_string_get(no_session_param);
1909
1910         if (strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_CONTINUE_STR) == 0) {
1911                 action = SESSION_NOT_FOUND_ACTION_CONTINUE;
1912         } else if (strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_FAIL_STR) == 0) {
1913                 action = SESSION_NOT_FOUND_ACTION_FAIL;
1914         } else {
1915                 BT_ASSERT(strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_END_STR) == 0);
1916                 action = SESSION_NOT_FOUND_ACTION_END;
1917         }
1918
1919         return action;
1920 }
1921
1922 static struct bt_param_validation_value_descr inputs_elem_descr = {
1923         .type = BT_VALUE_TYPE_STRING,
1924 };
1925
1926 static const char *sess_not_found_action_choices[] = {
1927         SESS_NOT_FOUND_ACTION_CONTINUE_STR,
1928         SESS_NOT_FOUND_ACTION_FAIL_STR,
1929         SESS_NOT_FOUND_ACTION_END_STR,
1930 };
1931
1932 static struct bt_param_validation_map_value_entry_descr params_descr[] = {
1933         { INPUTS_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_MANDATORY, { BT_VALUE_TYPE_ARRAY, .array = {
1934                 .min_length = 1,
1935                 .max_length = 1,
1936                 .element_type = &inputs_elem_descr,
1937         } } },
1938         { SESS_NOT_FOUND_ACTION_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_OPTIONAL, { BT_VALUE_TYPE_STRING, .string = {
1939                 .choices = sess_not_found_action_choices,
1940         } } },
1941         BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_END
1942 };
1943
1944 static
1945 bt_component_class_initialize_method_status lttng_live_component_create(
1946                 const bt_value *params,
1947                 bt_logging_level log_level,
1948                 bt_self_component *self_comp,
1949                 struct lttng_live_component **component)
1950 {
1951         struct lttng_live_component *lttng_live = NULL;
1952         const bt_value *inputs_value;
1953         const bt_value *url_value;
1954         const bt_value *value;
1955         const char *url;
1956         enum bt_param_validation_status validation_status;
1957         gchar *validation_error = NULL;
1958         bt_component_class_initialize_method_status status;
1959
1960         validation_status = bt_param_validation_validate(params, params_descr,
1961                 &validation_error);
1962         if (validation_status == BT_PARAM_VALIDATION_STATUS_MEMORY_ERROR) {
1963                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1964                 goto error;
1965         } else if (validation_status == BT_PARAM_VALIDATION_STATUS_VALIDATION_ERROR) {
1966                 BT_COMP_LOGE_APPEND_CAUSE(self_comp, "%s", validation_error);
1967                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
1968                 goto error;
1969         }
1970
1971         lttng_live = g_new0(struct lttng_live_component, 1);
1972         if (!lttng_live) {
1973                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1974                 goto end;
1975         }
1976         lttng_live->log_level = log_level;
1977         lttng_live->self_comp = self_comp;
1978         lttng_live->max_query_size = MAX_QUERY_SIZE;
1979         lttng_live->has_msg_iter = false;
1980
1981         inputs_value =
1982                 bt_value_map_borrow_entry_value_const(params, INPUTS_PARAM);
1983         url_value =
1984                 bt_value_array_borrow_element_by_index_const(inputs_value, 0);
1985         url = bt_value_string_get(url_value);
1986
1987         lttng_live->params.url = g_string_new(url);
1988         if (!lttng_live->params.url) {
1989                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1990                 goto error;
1991         }
1992
1993         value = bt_value_map_borrow_entry_value_const(params,
1994                 SESS_NOT_FOUND_ACTION_PARAM);
1995         if (value) {
1996                 lttng_live->params.sess_not_found_act =
1997                         parse_session_not_found_action_param(value);
1998         } else {
1999                 BT_COMP_LOGI("Optional `%s` parameter is missing: "
2000                         "defaulting to `%s`.",
2001                         SESS_NOT_FOUND_ACTION_PARAM,
2002                         SESS_NOT_FOUND_ACTION_CONTINUE_STR);
2003                 lttng_live->params.sess_not_found_act =
2004                         SESSION_NOT_FOUND_ACTION_CONTINUE;
2005         }
2006
2007         status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_OK;
2008         goto end;
2009
2010 error:
2011         lttng_live_component_destroy_data(lttng_live);
2012         lttng_live = NULL;
2013 end:
2014         g_free(validation_error);
2015
2016         *component = lttng_live;
2017         return status;
2018 }
2019
2020 BT_HIDDEN
2021 bt_component_class_initialize_method_status lttng_live_component_init(
2022                 bt_self_component_source *self_comp_src,
2023                 bt_self_component_source_configuration *config,
2024                 const bt_value *params,
2025                 __attribute__((unused)) void *init_method_data)
2026 {
2027         struct lttng_live_component *lttng_live;
2028         bt_component_class_initialize_method_status ret;
2029         bt_self_component *self_comp =
2030                 bt_self_component_source_as_self_component(self_comp_src);
2031         bt_logging_level log_level = bt_component_get_logging_level(
2032                 bt_self_component_as_component(self_comp));
2033         bt_self_component_add_port_status add_port_status;
2034
2035         ret = lttng_live_component_create(params, log_level, self_comp, &lttng_live);
2036         if (ret != BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_OK) {
2037                 goto error;
2038         }
2039
2040         add_port_status = bt_self_component_source_add_output_port(
2041                 self_comp_src, "out", NULL, NULL);
2042         if (add_port_status != BT_SELF_COMPONENT_ADD_PORT_STATUS_OK) {
2043                 ret = (int) add_port_status;
2044                 goto end;
2045         }
2046
2047         bt_self_component_set_data(self_comp, lttng_live);
2048         goto end;
2049
2050 error:
2051         lttng_live_component_destroy_data(lttng_live);
2052         lttng_live = NULL;
2053 end:
2054         return ret;
2055 }