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