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_viewer_status attach_status =
 451                         lttng_live_attach_session(session,
 452                                 lttng_live_msg_iter->self_msg_iter);
 453                 if (attach_status != LTTNG_LIVE_VIEWER_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 status;
 550         enum lttng_live_viewer_status viewer_status;
 551         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 552         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 553         uint64_t session_idx = 0, nr_sessions_opened = 0;
 554         struct lttng_live_session *session;
 555         enum session_not_found_action sess_not_found_act =
 556                 lttng_live_msg_iter->lttng_live_comp->params.sess_not_found_act;
 557
 558         /*
 559          * In a remotely distant future, we could add a "new
 560          * session" flag to the protocol, which would tell us that we
 561          * need to query for new sessions even though we have sessions
 562          * currently ongoing.
 563          */
 564         if (lttng_live_msg_iter->sessions->len == 0) {
 565                 if (sess_not_found_act != SESSION_NOT_FOUND_ACTION_CONTINUE) {
 566                         status = LTTNG_LIVE_ITERATOR_STATUS_END;
 567                         goto end;
 568                 } else {
 569                         /*
 570                          * Retry to create a viewer session for the requested
 571                          * session name.
 572                          */
 573                         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
 574                         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
 575                                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
 576                                         status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 577                                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 578                                                 "Error creating LTTng live viewer session");
 579                                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
 580                                         status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
 581                                 } else {
 582                                         bt_common_abort();
 583                                 }
 584                                 goto end;
 585                         }
 586                 }
 587         }
 588
 589         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 590                         session_idx++) {
 591                 session = g_ptr_array_index(lttng_live_msg_iter->sessions,
 592                                 session_idx);
 593                 status = lttng_live_get_session(lttng_live_msg_iter, session);
 594                 switch (status) {
 595                 case LTTNG_LIVE_ITERATOR_STATUS_OK:
 596                         break;
 597                 case LTTNG_LIVE_ITERATOR_STATUS_END:
 598                         status = LTTNG_LIVE_ITERATOR_STATUS_OK;
 599                         break;
 600                 default:
 601                         goto end;
 602                 }
 603                 if (!session->closed) {
 604                         nr_sessions_opened++;
 605                 }
 606         }
 607
 608         if (sess_not_found_act != SESSION_NOT_FOUND_ACTION_CONTINUE &&
 609                         nr_sessions_opened == 0) {
 610                 status = LTTNG_LIVE_ITERATOR_STATUS_END;
 611         } else {
 612                 status = LTTNG_LIVE_ITERATOR_STATUS_OK;
 613         }
 614
 615 end:
 616         return status;
 617 }
 618
 619 static
 620 enum lttng_live_iterator_status emit_inactivity_message(
 621                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 622                 struct lttng_live_stream_iterator *stream_iter,
 623                 bt_message **message, uint64_t timestamp)
 624 {
 625         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 626         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 627         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 628         bt_message *msg = NULL;
 629
 630         BT_ASSERT(stream_iter->trace->clock_class);
 631
 632         msg = bt_message_message_iterator_inactivity_create(
 633                 lttng_live_msg_iter->self_msg_iter,
 634                 stream_iter->trace->clock_class, timestamp);
 635         if (!msg) {
 636                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 637                         "Error emitting message iterator inactivity message");
 638                 goto error;
 639         }
 640
 641         *message = msg;
 642 end:
 643         return ret;
 644
 645 error:
 646         ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 647         bt_message_put_ref(msg);
 648         goto end;
 649 }
 650
 651 static
 652 enum lttng_live_iterator_status lttng_live_iterator_next_handle_one_quiescent_stream(
 653                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 654                 struct lttng_live_stream_iterator *lttng_live_stream,
 655                 bt_message **message)
 656 {
 657         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 658
 659         if (lttng_live_stream->state != LTTNG_LIVE_STREAM_QUIESCENT) {
 660                 return LTTNG_LIVE_ITERATOR_STATUS_OK;
 661         }
 662
 663         if (lttng_live_stream->current_inactivity_ts ==
 664                         lttng_live_stream->last_inactivity_ts) {
 665                 lttng_live_stream->state = LTTNG_LIVE_STREAM_QUIESCENT_NO_DATA;
 666                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 667                 goto end;
 668         }
 669
 670         ret = emit_inactivity_message(lttng_live_msg_iter, lttng_live_stream,
 671                 message, lttng_live_stream->current_inactivity_ts);
 672
 673         lttng_live_stream->last_inactivity_ts =
 674                 lttng_live_stream->current_inactivity_ts;
 675 end:
 676         return ret;
 677 }
 678
 679 static
 680 int live_get_msg_ts_ns(struct lttng_live_stream_iterator *stream_iter,
 681                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 682                 const bt_message *msg, int64_t last_msg_ts_ns,
 683                 int64_t *ts_ns)
 684 {
 685         const bt_clock_class *clock_class = NULL;
 686         const bt_clock_snapshot *clock_snapshot = NULL;
 687         int ret = 0;
 688         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 689         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 690
 691         BT_ASSERT_DBG(msg);
 692         BT_ASSERT_DBG(ts_ns);
 693
 694         BT_COMP_LOGD("Getting message's timestamp: iter-data-addr=%p, msg-addr=%p, "
 695                 "last-msg-ts=%" PRId64, lttng_live_msg_iter, msg,
 696                 last_msg_ts_ns);
 697
 698         switch (bt_message_get_type(msg)) {
 699         case BT_MESSAGE_TYPE_EVENT:
 700                 clock_class = bt_message_event_borrow_stream_class_default_clock_class_const(
 701                                 msg);
 702                 BT_ASSERT_DBG(clock_class);
 703
 704                 clock_snapshot = bt_message_event_borrow_default_clock_snapshot_const(
 705                         msg);
 706                 break;
 707         case BT_MESSAGE_TYPE_PACKET_BEGINNING:
 708                 clock_class = bt_message_packet_beginning_borrow_stream_class_default_clock_class_const(
 709                         msg);
 710                 BT_ASSERT(clock_class);
 711
 712                 clock_snapshot = bt_message_packet_beginning_borrow_default_clock_snapshot_const(
 713                         msg);
 714                 break;
 715         case BT_MESSAGE_TYPE_PACKET_END:
 716                 clock_class = bt_message_packet_end_borrow_stream_class_default_clock_class_const(
 717                         msg);
 718                 BT_ASSERT(clock_class);
 719
 720                 clock_snapshot = bt_message_packet_end_borrow_default_clock_snapshot_const(
 721                         msg);
 722                 break;
 723         case BT_MESSAGE_TYPE_DISCARDED_EVENTS:
 724                 clock_class = bt_message_discarded_events_borrow_stream_class_default_clock_class_const(
 725                         msg);
 726                 BT_ASSERT(clock_class);
 727
 728                 clock_snapshot = bt_message_discarded_events_borrow_beginning_default_clock_snapshot_const(
 729                         msg);
 730                 break;
 731         case BT_MESSAGE_TYPE_DISCARDED_PACKETS:
 732                 clock_class = bt_message_discarded_packets_borrow_stream_class_default_clock_class_const(
 733                         msg);
 734                 BT_ASSERT(clock_class);
 735
 736                 clock_snapshot = bt_message_discarded_packets_borrow_beginning_default_clock_snapshot_const(
 737                         msg);
 738                 break;
 739         case BT_MESSAGE_TYPE_MESSAGE_ITERATOR_INACTIVITY:
 740                 clock_snapshot = bt_message_message_iterator_inactivity_borrow_default_clock_snapshot_const(
 741                         msg);
 742                 break;
 743         default:
 744                 /* All the other messages have a higher priority */
 745                 BT_COMP_LOGD_STR("Message has no timestamp: using the last message timestamp.");
 746                 *ts_ns = last_msg_ts_ns;
 747                 goto end;
 748         }
 749
 750         clock_class = bt_clock_snapshot_borrow_clock_class_const(clock_snapshot);
 751         BT_ASSERT_DBG(clock_class);
 752
 753         ret = bt_clock_snapshot_get_ns_from_origin(clock_snapshot, ts_ns);
 754         if (ret) {
 755                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 756                         "Cannot get nanoseconds from Epoch of clock snapshot: "
 757                         "clock-snapshot-addr=%p", clock_snapshot);
 758                 goto error;
 759         }
 760
 761         goto end;
 762
 763 error:
 764         ret = -1;
 765
 766 end:
 767         if (ret == 0) {
 768                 BT_COMP_LOGD("Found message's timestamp: "
 769                         "iter-data-addr=%p, msg-addr=%p, "
 770                         "last-msg-ts=%" PRId64 ", ts=%" PRId64,
 771                         lttng_live_msg_iter, msg, last_msg_ts_ns, *ts_ns);
 772         }
 773
 774         return ret;
 775 }
 776
 777 static
 778 enum lttng_live_iterator_status lttng_live_iterator_next_handle_one_active_data_stream(
 779                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 780                 struct lttng_live_stream_iterator *lttng_live_stream,
 781                 bt_message **message)
 782 {
 783         enum lttng_live_iterator_status ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 784         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 785         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 786         enum ctf_msg_iter_status status;
 787         uint64_t session_idx, trace_idx;
 788
 789         for (session_idx = 0; session_idx < lttng_live_msg_iter->sessions->len;
 790                         session_idx++) {
 791                 struct lttng_live_session *session =
 792                         g_ptr_array_index(lttng_live_msg_iter->sessions, session_idx);
 793
 794                 if (session->new_streams_needed) {
 795                         ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 796                         goto end;
 797                 }
 798                 for (trace_idx = 0; trace_idx < session->traces->len;
 799                                 trace_idx++) {
 800                         struct lttng_live_trace *trace =
 801                                 g_ptr_array_index(session->traces, trace_idx);
 802                         if (trace->new_metadata_needed) {
 803                                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 804                                 goto end;
 805                         }
 806                 }
 807         }
 808
 809         if (lttng_live_stream->state != LTTNG_LIVE_STREAM_ACTIVE_DATA) {
 810                 ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 811                 goto end;
 812         }
 813
 814         status = ctf_msg_iter_get_next_message(
 815                 lttng_live_stream->msg_iter, message);
 816         switch (status) {
 817         case CTF_MSG_ITER_STATUS_EOF:
 818                 ret = LTTNG_LIVE_ITERATOR_STATUS_END;
 819                 break;
 820         case CTF_MSG_ITER_STATUS_OK:
 821                 ret = LTTNG_LIVE_ITERATOR_STATUS_OK;
 822                 break;
 823         case CTF_MSG_ITER_STATUS_AGAIN:
 824                 /*
 825                  * Continue immediately (end of packet). The next
 826                  * get_index may return AGAIN to delay the following
 827                  * attempt.
 828                  */
 829                 ret = LTTNG_LIVE_ITERATOR_STATUS_CONTINUE;
 830                 break;
 831         case CTF_MSG_ITER_STATUS_INVAL:
 832                 /* No argument provided by the user, so don't return INVAL. */
 833         case CTF_MSG_ITER_STATUS_ERROR:
 834         default:
 835                 ret = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 836                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 837                         "CTF message iterator return an error or failed: "
 838                         "msg_iter=%p", lttng_live_stream->msg_iter);
 839                 break;
 840         }
 841
 842 end:
 843         return ret;
 844 }
 845
 846 static
 847 enum lttng_live_iterator_status lttng_live_iterator_close_stream(
 848                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 849                 struct lttng_live_stream_iterator *stream_iter,
 850                 bt_message **curr_msg)
 851 {
 852         enum lttng_live_iterator_status live_status =
 853                 LTTNG_LIVE_ITERATOR_STATUS_OK;
 854         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 855         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 856         /*
 857          * The viewer has hung up on us so we are closing the stream. The
 858          * `ctf_msg_iter` should simply realize that it needs to close the
 859          * stream properly by emitting the necessary stream end message.
 860          */
 861         enum ctf_msg_iter_status status = ctf_msg_iter_get_next_message(
 862                 stream_iter->msg_iter, curr_msg);
 863
 864         if (status == CTF_MSG_ITER_STATUS_ERROR) {
 865                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
 866                         "Error getting the next message from CTF message iterator");
 867                 live_status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
 868                 goto end;
 869         }
 870
 871         BT_ASSERT(status == CTF_MSG_ITER_STATUS_OK);
 872
 873 end:
 874         return live_status;
 875 }
 876
 877 /*
 878  * helper function:
 879  *            handle_no_data_streams()
 880  *              retry:
 881  *                - for each ACTIVE_NO_DATA stream:
 882  *                  - query relayd for stream data, or quiescence info.
 883  *                    - if need metadata, get metadata, goto retry.
 884  *                    - if new stream, get new stream as ACTIVE_NO_DATA, goto retry
 885  *                  - if quiescent, move to QUIESCENT streams
 886  *                  - if fetched data, move to ACTIVE_DATA streams
 887  *                (at this point each stream either has data, or is quiescent)
 888  *
 889  *
 890  * iterator_next:
 891  *            handle_new_streams_and_metadata()
 892  *                  - query relayd for known streams, add them as ACTIVE_NO_DATA
 893  *                  - query relayd for metadata
 894  *
 895  *            call handle_active_no_data_streams()
 896  *
 897  *            handle_quiescent_streams()
 898  *                - if at least one stream is ACTIVE_DATA:
 899  *                  - peek stream event with lowest timestamp -> next_ts
 900  *                  - for each quiescent stream
 901  *                    - if next_ts >= quiescent end
 902  *                      - set state to ACTIVE_NO_DATA
 903  *                - else
 904  *                  - for each quiescent stream
 905  *                      - set state to ACTIVE_NO_DATA
 906  *
 907  *            call handle_active_no_data_streams()
 908  *
 909  *            handle_active_data_streams()
 910  *                - if at least one stream is ACTIVE_DATA:
 911  *                    - get stream event with lowest timestamp from heap
 912  *                    - make that stream event the current message.
 913  *                    - move this stream heap position to its next event
 914  *                      - if we need to fetch data from relayd, move
 915  *                        stream to ACTIVE_NO_DATA.
 916  *                    - return OK
 917  *                - return AGAIN
 918  *
 919  * end criterion: ctrl-c on client. If relayd exits or the session
 920  * closes on the relay daemon side, we keep on waiting for streams.
 921  * Eventually handle --end timestamp (also an end criterion).
 922  *
 923  * When disconnected from relayd: try to re-connect endlessly.
 924  */
 925 static
 926 enum lttng_live_iterator_status lttng_live_iterator_next_msg_on_stream(
 927                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 928                 struct lttng_live_stream_iterator *stream_iter,
 929                 bt_message **curr_msg)
 930 {
 931         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 932         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 933         enum lttng_live_iterator_status live_status;
 934
 935         if (stream_iter->has_stream_hung_up) {
 936                 /*
 937                  * The stream has hung up and the stream was properly closed
 938                  * during the last call to the current function. Return _END
 939                  * status now so that this stream iterator is removed for the
 940                  * stream iterator list.
 941                  */
 942                 live_status = LTTNG_LIVE_ITERATOR_STATUS_END;
 943                 goto end;
 944         }
 945
 946 retry:
 947         print_stream_state(stream_iter);
 948         live_status = lttng_live_iterator_handle_new_streams_and_metadata(
 949                 lttng_live_msg_iter);
 950         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 951                 goto end;
 952         }
 953         live_status = lttng_live_iterator_next_handle_one_no_data_stream(
 954                 lttng_live_msg_iter, stream_iter);
 955
 956         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 957                 if (live_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
 958                         /*
 959                          * We overwrite `live_status` since `curr_msg` is
 960                          * likely set to a valid message in this function.
 961                          */
 962                         live_status = lttng_live_iterator_close_stream(
 963                                 lttng_live_msg_iter, stream_iter, curr_msg);
 964                 }
 965                 goto end;
 966         }
 967         live_status = lttng_live_iterator_next_handle_one_quiescent_stream(
 968                 lttng_live_msg_iter, stream_iter, curr_msg);
 969         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 970                 BT_ASSERT(!*curr_msg);
 971                 goto end;
 972         }
 973         if (*curr_msg) {
 974                 goto end;
 975         }
 976         live_status = lttng_live_iterator_next_handle_one_active_data_stream(
 977                 lttng_live_msg_iter, stream_iter, curr_msg);
 978         if (live_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
 979                 BT_ASSERT(!*curr_msg);
 980         }
 981
 982 end:
 983         if (live_status == LTTNG_LIVE_ITERATOR_STATUS_CONTINUE) {
 984                 goto retry;
 985         }
 986
 987         return live_status;
 988 }
 989
 990 static
 991 enum lttng_live_iterator_status next_stream_iterator_for_trace(
 992                 struct lttng_live_msg_iter *lttng_live_msg_iter,
 993                 struct lttng_live_trace *live_trace,
 994                 struct lttng_live_stream_iterator **youngest_trace_stream_iter)
 995 {
 996         struct lttng_live_stream_iterator *youngest_candidate_stream_iter = NULL;
 997         bt_logging_level log_level = lttng_live_msg_iter->log_level;
 998         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
 999         enum lttng_live_iterator_status stream_iter_status;;
1000         int64_t youngest_candidate_msg_ts = INT64_MAX;
1001         uint64_t stream_iter_idx;
1002
1003         BT_ASSERT_DBG(live_trace);
1004         BT_ASSERT_DBG(live_trace->stream_iterators);
1005         /*
1006          * Update the current message of every stream iterators of this trace.
1007          * The current msg of every stream must have a timestamp equal or
1008          * larger than the last message returned by this iterator. We must
1009          * ensure monotonicity.
1010          */
1011         stream_iter_idx = 0;
1012         while (stream_iter_idx < live_trace->stream_iterators->len) {
1013                 bool stream_iter_is_ended = false;
1014                 struct lttng_live_stream_iterator *stream_iter =
1015                         g_ptr_array_index(live_trace->stream_iterators,
1016                                 stream_iter_idx);
1017
1018                 /*
1019                  * Find if there is are now current message for this stream
1020                  * iterator get it.
1021                  */
1022                 while (!stream_iter->current_msg) {
1023                         bt_message *msg = NULL;
1024                         int64_t curr_msg_ts_ns = INT64_MAX;
1025                         stream_iter_status = lttng_live_iterator_next_msg_on_stream(
1026                                 lttng_live_msg_iter, stream_iter, &msg);
1027
1028                         BT_COMP_LOGD("live stream iterator returned status :%s",
1029                                 print_live_iterator_status(stream_iter_status));
1030                         if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1031                                 stream_iter_is_ended = true;
1032                                 break;
1033                         }
1034
1035                         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1036                                 goto end;
1037                         }
1038
1039                         BT_ASSERT_DBG(msg);
1040
1041                         /*
1042                          * Get the timestamp in nanoseconds from origin of this
1043                          * messsage.
1044                          */
1045                         live_get_msg_ts_ns(stream_iter, lttng_live_msg_iter,
1046                                 msg, lttng_live_msg_iter->last_msg_ts_ns,
1047                                 &curr_msg_ts_ns);
1048
1049                         /*
1050                          * Check if the message of the current live stream
1051                          * iterator occured at the exact same time or after the
1052                          * last message returned by this component's message
1053                          * iterator. If not, we return an error.
1054                          */
1055                         if (curr_msg_ts_ns >= lttng_live_msg_iter->last_msg_ts_ns) {
1056                                 stream_iter->current_msg = msg;
1057                                 stream_iter->current_msg_ts_ns = curr_msg_ts_ns;
1058                         } else {
1059                                 /*
1060                                  * We received a message in the past. To ensure
1061                                  * monotonicity, we can't send it forward.
1062                                  */
1063                                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1064                                         "Message's timestamp is less than "
1065                                         "lttng-live's message iterator's last "
1066                                         "returned timestamp: "
1067                                         "lttng-live-msg-iter-addr=%p, ts=%" PRId64 ", "
1068                                         "last-msg-ts=%" PRId64,
1069                                         lttng_live_msg_iter, curr_msg_ts_ns,
1070                                         lttng_live_msg_iter->last_msg_ts_ns);
1071                                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_ERROR;
1072                                 goto end;
1073                         }
1074                 }
1075
1076                 BT_ASSERT_DBG(stream_iter != youngest_candidate_stream_iter);
1077
1078                 if (!stream_iter_is_ended) {
1079                         if (G_UNLIKELY(youngest_candidate_stream_iter == NULL) ||
1080                                         stream_iter->current_msg_ts_ns < youngest_candidate_msg_ts) {
1081                                 /*
1082                                  * Update the current best candidate message
1083                                  * for the stream iterator of this live trace
1084                                  * to be forwarded downstream.
1085                                  */
1086                                 youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1087                                 youngest_candidate_stream_iter = stream_iter;
1088                         } else if (stream_iter->current_msg_ts_ns == youngest_candidate_msg_ts) {
1089                                 /*
1090                                  * Order the messages in an arbitrary but
1091                                  * deterministic way.
1092                                  */
1093                                 BT_ASSERT_DBG(stream_iter != youngest_candidate_stream_iter);
1094                                 int ret = common_muxing_compare_messages(
1095                                         stream_iter->current_msg,
1096                                         youngest_candidate_stream_iter->current_msg);
1097                                 if (ret < 0) {
1098                                         /*
1099                                          * The `youngest_candidate_stream_iter->current_msg`
1100                                          * should go first. Update the next
1101                                          * iterator and the current timestamp.
1102                                          */
1103                                         youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1104                                         youngest_candidate_stream_iter = stream_iter;
1105                                 } else if (ret == 0) {
1106                                         /*
1107                                          * Unable to pick which one should go
1108                                          * first.
1109                                          */
1110                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1111                                                 "stream-iter-addr=%p"
1112                                                 "stream-iter-addr=%p",
1113                                                 stream_iter,
1114                                                 youngest_candidate_stream_iter);
1115                                 }
1116                         }
1117
1118                         stream_iter_idx++;
1119                 } else {
1120                         /*
1121                          * The live stream iterator has ended. That
1122                          * iterator is removed from the array, but
1123                          * there is no need to increment
1124                          * stream_iter_idx as
1125                          * g_ptr_array_remove_index_fast replaces the
1126                          * removed element with the array's last
1127                          * element.
1128                          */
1129                         g_ptr_array_remove_index_fast(
1130                                 live_trace->stream_iterators,
1131                                 stream_iter_idx);
1132                 }
1133         }
1134
1135         if (youngest_candidate_stream_iter) {
1136                 *youngest_trace_stream_iter = youngest_candidate_stream_iter;
1137                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1138         } else {
1139                 /*
1140                  * The only case where we don't have a candidate for this trace
1141                  * is if we reached the end of all the iterators.
1142                  */
1143                 BT_ASSERT(live_trace->stream_iterators->len == 0);
1144                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_END;
1145         }
1146
1147 end:
1148         return stream_iter_status;
1149 }
1150
1151 static
1152 enum lttng_live_iterator_status next_stream_iterator_for_session(
1153                 struct lttng_live_msg_iter *lttng_live_msg_iter,
1154                 struct lttng_live_session *session,
1155                 struct lttng_live_stream_iterator **youngest_session_stream_iter)
1156 {
1157         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
1158         bt_logging_level log_level = lttng_live_msg_iter->log_level;
1159         enum lttng_live_iterator_status stream_iter_status;
1160         uint64_t trace_idx = 0;
1161         int64_t youngest_candidate_msg_ts = INT64_MAX;
1162         struct lttng_live_stream_iterator *youngest_candidate_stream_iter = NULL;
1163
1164         /*
1165          * Make sure we are attached to the session and look for new streams
1166          * and metadata.
1167          */
1168         stream_iter_status = lttng_live_get_session(lttng_live_msg_iter, session);
1169         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK &&
1170                         stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_CONTINUE &&
1171                         stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_END) {
1172                 goto end;
1173         }
1174
1175         BT_ASSERT_DBG(session->traces);
1176
1177         while (trace_idx < session->traces->len) {
1178                 bool trace_is_ended = false;
1179                 struct lttng_live_stream_iterator *stream_iter;
1180                 struct lttng_live_trace *trace =
1181                         g_ptr_array_index(session->traces, trace_idx);
1182
1183                 stream_iter_status = next_stream_iterator_for_trace(
1184                         lttng_live_msg_iter, trace, &stream_iter);
1185                 if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1186                         /*
1187                          * All the live stream iterators for this trace are
1188                          * ENDed. Remove the trace from this session.
1189                          */
1190                         trace_is_ended = true;
1191                 } else if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1192                         goto end;
1193                 }
1194
1195                 if (!trace_is_ended) {
1196                         BT_ASSERT_DBG(stream_iter);
1197
1198                         if (G_UNLIKELY(youngest_candidate_stream_iter == NULL) ||
1199                                         stream_iter->current_msg_ts_ns < youngest_candidate_msg_ts) {
1200                                 youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1201                                 youngest_candidate_stream_iter = stream_iter;
1202                         } else if (stream_iter->current_msg_ts_ns == youngest_candidate_msg_ts) {
1203                                 /*
1204                                  * Order the messages in an arbitrary but
1205                                  * deterministic way.
1206                                  */
1207                                 int ret = common_muxing_compare_messages(
1208                                         stream_iter->current_msg,
1209                                         youngest_candidate_stream_iter->current_msg);
1210                                 if (ret < 0) {
1211                                         /*
1212                                          * The `youngest_candidate_stream_iter->current_msg`
1213                                          * should go first. Update the next iterator
1214                                          * and the current timestamp.
1215                                          */
1216                                         youngest_candidate_msg_ts = stream_iter->current_msg_ts_ns;
1217                                         youngest_candidate_stream_iter = stream_iter;
1218                                 } else if (ret == 0) {
1219                                         /* Unable to pick which one should go first. */
1220                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1221                                                 "stream-iter-addr=%p" "stream-iter-addr=%p",
1222                                                 stream_iter, youngest_candidate_stream_iter);
1223                                 }
1224                         }
1225                         trace_idx++;
1226                 } else {
1227                         /*
1228                          * trace_idx is not incremented since
1229                          * g_ptr_array_remove_index_fast replaces the
1230                          * element at trace_idx with the array's last element.
1231                          */
1232                         g_ptr_array_remove_index_fast(session->traces,
1233                                 trace_idx);
1234                 }
1235         }
1236         if (youngest_candidate_stream_iter) {
1237                 *youngest_session_stream_iter = youngest_candidate_stream_iter;
1238                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1239         } else {
1240                 /*
1241                  * The only cases where we don't have a candidate for this
1242                  * trace is:
1243                  *  1. if we reached the end of all the iterators of all the
1244                  *  traces of this session,
1245                  *  2. if we never had live stream iterator in the first place.
1246                  *
1247                  * In either cases, we return END.
1248                  */
1249                 BT_ASSERT(session->traces->len == 0);
1250                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_END;
1251         }
1252 end:
1253         return stream_iter_status;
1254 }
1255
1256 static inline
1257 void put_messages(bt_message_array_const msgs, uint64_t count)
1258 {
1259         uint64_t i;
1260
1261         for (i = 0; i < count; i++) {
1262                 BT_MESSAGE_PUT_REF_AND_RESET(msgs[i]);
1263         }
1264 }
1265
1266 BT_HIDDEN
1267 bt_component_class_message_iterator_next_method_status lttng_live_msg_iter_next(
1268                 bt_self_message_iterator *self_msg_it,
1269                 bt_message_array_const msgs, uint64_t capacity,
1270                 uint64_t *count)
1271 {
1272         bt_component_class_message_iterator_next_method_status status;
1273         enum lttng_live_viewer_status viewer_status;
1274         struct lttng_live_msg_iter *lttng_live_msg_iter =
1275                 bt_self_message_iterator_get_data(self_msg_it);
1276         struct lttng_live_component *lttng_live =
1277                 lttng_live_msg_iter->lttng_live_comp;
1278         bt_self_component *self_comp = lttng_live_msg_iter->self_comp;
1279         bt_logging_level log_level = lttng_live_msg_iter->log_level;
1280         enum lttng_live_iterator_status stream_iter_status;
1281         uint64_t session_idx;
1282
1283         *count = 0;
1284
1285         BT_ASSERT_DBG(lttng_live_msg_iter);
1286
1287         if (G_UNLIKELY(lttng_live_msg_iter->was_interrupted)) {
1288                 /*
1289                  * The iterator was interrupted in a previous call to the
1290                  * `_next()` method. We currently do not support generating
1291                  * messages after such event. The babeltrace2 CLI should never
1292                  * be running the graph after being interrupted. So this check
1293                  * is to prevent other graph users from using this live
1294                  * iterator in an messed up internal state.
1295                  */
1296                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1297                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1298                         "Message iterator was interrupted during a previous call to the `next()` and currently does not support continuing after such event.");
1299                 goto end;
1300         }
1301
1302         /*
1303          * Clear all the invalid message reference that might be left over in
1304          * the output array.
1305          */
1306         memset(msgs, 0, capacity * sizeof(*msgs));
1307
1308         /*
1309          * If no session are exposed on the relay found at the url provided by
1310          * the user, session count will be 0. In this case, we return status
1311          * end to return gracefully.
1312          */
1313         if (lttng_live_msg_iter->sessions->len == 0) {
1314                 if (lttng_live->params.sess_not_found_act !=
1315                                 SESSION_NOT_FOUND_ACTION_CONTINUE) {
1316                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_END;
1317                         goto end;
1318                 } else {
1319                         /*
1320                          * The are no more active session for this session
1321                          * name. Retry to create a viewer session for the
1322                          * requested session name.
1323                          */
1324                         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
1325                         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1326                                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1327                                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1328                                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1329                                                 "Error creating LTTng live viewer session");
1330                                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1331                                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_AGAIN;
1332                                 } else {
1333                                         bt_common_abort();
1334                                 }
1335                                 goto end;
1336                         }
1337                 }
1338         }
1339
1340         if (lttng_live_msg_iter->active_stream_iter == 0) {
1341                 lttng_live_force_new_streams_and_metadata(lttng_live_msg_iter);
1342         }
1343
1344         /*
1345          * Here the muxing of message is done.
1346          *
1347          * We need to iterate over all the streams of all the traces of all the
1348          * viewer sessions in order to get the message with the smallest
1349          * timestamp. In this case, a session is a viewer session and there is
1350          * one viewer session per consumer daemon. (UST 32bit, UST 64bit and/or
1351          * kernel). Each viewer session can have multiple traces, for example,
1352          * 64bit UST viewer sessions could have multiple per-pid traces.
1353          *
1354          * We iterate over the streams of each traces to update and see what is
1355          * their next message's timestamp. From those timestamps, we select the
1356          * message with the smallest timestamp as the best candidate message
1357          * for that trace and do the same thing across all the sessions.
1358          *
1359          * We then compare the timestamp of best candidate message of all the
1360          * sessions to pick the message with the smallest timestamp and we
1361          * return it.
1362          */
1363         while (*count < capacity) {
1364                 struct lttng_live_stream_iterator *youngest_stream_iter = NULL,
1365                           *candidate_stream_iter = NULL;
1366                 int64_t youngest_msg_ts_ns = INT64_MAX;
1367
1368                 BT_ASSERT_DBG(lttng_live_msg_iter->sessions);
1369                 session_idx = 0;
1370                 while (session_idx < lttng_live_msg_iter->sessions->len) {
1371                         struct lttng_live_session *session =
1372                                 g_ptr_array_index(lttng_live_msg_iter->sessions,
1373                                         session_idx);
1374
1375                         /* Find the best candidate message to send downstream. */
1376                         stream_iter_status = next_stream_iterator_for_session(
1377                                 lttng_live_msg_iter, session,
1378                                 &candidate_stream_iter);
1379
1380                         /* If we receive an END status, it means that either:
1381                          * - Those traces never had active streams (UST with no
1382                          *   data produced yet),
1383                          * - All live stream iterators have ENDed.*/
1384                         if (stream_iter_status == LTTNG_LIVE_ITERATOR_STATUS_END) {
1385                                 if (session->closed && session->traces->len == 0) {
1386                                         /*
1387                                          * Remove the session from the list.
1388                                          * session_idx is not modified since
1389                                          * g_ptr_array_remove_index_fast
1390                                          * replaces the the removed element with
1391                                          * the array's last element.
1392                                          */
1393                                         g_ptr_array_remove_index_fast(
1394                                                 lttng_live_msg_iter->sessions,
1395                                                 session_idx);
1396                                 } else {
1397                                         session_idx++;
1398                                 }
1399                                 continue;
1400                         }
1401
1402                         if (stream_iter_status != LTTNG_LIVE_ITERATOR_STATUS_OK) {
1403                                 goto return_status;
1404                         }
1405
1406                         if (G_UNLIKELY(youngest_stream_iter == NULL) ||
1407                                         candidate_stream_iter->current_msg_ts_ns < youngest_msg_ts_ns) {
1408                                 youngest_msg_ts_ns = candidate_stream_iter->current_msg_ts_ns;
1409                                 youngest_stream_iter = candidate_stream_iter;
1410                         } else if (candidate_stream_iter->current_msg_ts_ns == youngest_msg_ts_ns) {
1411                                 /*
1412                                  * The currently selected message to be sent
1413                                  * downstream next has the exact same timestamp
1414                                  * that of the current candidate message. We
1415                                  * must break the tie in a predictable manner.
1416                                  */
1417                                 BT_COMP_LOGD_STR("Two of the next message candidates have the same timestamps, pick one deterministically.");
1418                                 /*
1419                                  * Order the messages in an arbitrary but
1420                                  * deterministic way.
1421                                  */
1422                                 int ret = common_muxing_compare_messages(
1423                                         candidate_stream_iter->current_msg,
1424                                         youngest_stream_iter->current_msg);
1425                                 if (ret < 0) {
1426                                         /*
1427                                          * The `candidate_stream_iter->current_msg`
1428                                          * should go first. Update the next
1429                                          * iterator and the current timestamp.
1430                                          */
1431                                         youngest_msg_ts_ns = candidate_stream_iter->current_msg_ts_ns;
1432                                         youngest_stream_iter = candidate_stream_iter;
1433                                 } else if (ret == 0) {
1434                                         /* Unable to pick which one should go first. */
1435                                         BT_COMP_LOGW("Cannot deterministically pick next live stream message iterator because they have identical next messages: "
1436                                                 "next-stream-iter-addr=%p" "candidate-stream-iter-addr=%p",
1437                                                 youngest_stream_iter, candidate_stream_iter);
1438                                 }
1439                         }
1440
1441                         session_idx++;
1442                 }
1443
1444                 if (!youngest_stream_iter) {
1445                         stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_AGAIN;
1446                         goto return_status;
1447                 }
1448
1449                 BT_ASSERT_DBG(youngest_stream_iter->current_msg);
1450                 /* Ensure monotonicity. */
1451                 BT_ASSERT_DBG(lttng_live_msg_iter->last_msg_ts_ns <=
1452                         youngest_stream_iter->current_msg_ts_ns);
1453
1454                 /*
1455                  * Insert the next message to the message batch. This will set
1456                  * stream iterator current messsage to NULL so that next time
1457                  * we fetch the next message of that stream iterator
1458                  */
1459                 BT_MESSAGE_MOVE_REF(msgs[*count], youngest_stream_iter->current_msg);
1460                 (*count)++;
1461
1462                 /* Update the last timestamp in nanoseconds sent downstream. */
1463                 lttng_live_msg_iter->last_msg_ts_ns = youngest_msg_ts_ns;
1464                 youngest_stream_iter->current_msg_ts_ns = INT64_MAX;
1465
1466                 stream_iter_status = LTTNG_LIVE_ITERATOR_STATUS_OK;
1467         }
1468
1469 return_status:
1470         switch (stream_iter_status) {
1471         case LTTNG_LIVE_ITERATOR_STATUS_OK:
1472         case LTTNG_LIVE_ITERATOR_STATUS_AGAIN:
1473                 /*
1474                  * If we gathered messages, return _OK even if the graph was
1475                  * interrupted. This allows for the components downstream to at
1476                  * least get the thoses messages. If the graph was indeed
1477                  * interrupted there should not be another _next() call as the
1478                  * application will tear down the graph. This component class
1479                  * doesn't support restarting after an interruption.
1480                  */
1481                 if (*count > 0) {
1482                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_OK;
1483                 } else {
1484                         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_AGAIN;
1485                 }
1486                 break;
1487         case LTTNG_LIVE_ITERATOR_STATUS_END:
1488                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_END;
1489                 break;
1490         case LTTNG_LIVE_ITERATOR_STATUS_NOMEM:
1491                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_MEMORY_ERROR;
1492                 break;
1493         case LTTNG_LIVE_ITERATOR_STATUS_ERROR:
1494         case LTTNG_LIVE_ITERATOR_STATUS_INVAL:
1495         case LTTNG_LIVE_ITERATOR_STATUS_UNSUPPORTED:
1496                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_NEXT_METHOD_STATUS_ERROR;
1497                 /* Put all existing messages on error. */
1498                 put_messages(msgs, *count);
1499                 break;
1500         default:
1501                 bt_common_abort();
1502         }
1503
1504 end:
1505         return status;
1506 }
1507
1508 static
1509 struct lttng_live_msg_iter *lttng_live_msg_iter_create(
1510                 struct lttng_live_component *lttng_live_comp,
1511                 bt_self_message_iterator *self_msg_it)
1512 {
1513         bt_self_component *self_comp = lttng_live_comp->self_comp;
1514         bt_logging_level log_level = lttng_live_comp->log_level;
1515
1516         struct lttng_live_msg_iter *lttng_live_msg_iter =
1517                 g_new0(struct lttng_live_msg_iter, 1);
1518         if (!lttng_live_msg_iter) {
1519                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1520                         "Failed to allocate lttng_live_msg_iter");
1521                 goto end;
1522         }
1523
1524         lttng_live_msg_iter->log_level = lttng_live_comp->log_level;
1525         lttng_live_msg_iter->self_comp = lttng_live_comp->self_comp;
1526         lttng_live_msg_iter->lttng_live_comp = lttng_live_comp;
1527         lttng_live_msg_iter->self_msg_iter = self_msg_it;
1528
1529         lttng_live_msg_iter->active_stream_iter = 0;
1530         lttng_live_msg_iter->last_msg_ts_ns = INT64_MIN;
1531         lttng_live_msg_iter->was_interrupted = false;
1532
1533         lttng_live_msg_iter->sessions = g_ptr_array_new_with_free_func(
1534                 (GDestroyNotify) lttng_live_destroy_session);
1535         BT_ASSERT(lttng_live_msg_iter->sessions);
1536
1537 end:
1538         return lttng_live_msg_iter;
1539
1540 }
1541
1542 BT_HIDDEN
1543 bt_component_class_message_iterator_initialize_method_status lttng_live_msg_iter_init(
1544                 bt_self_message_iterator *self_msg_it,
1545                 bt_self_message_iterator_configuration *config,
1546                 bt_self_component_source *self_comp_src,
1547                 bt_self_component_port_output *self_port)
1548 {
1549         bt_component_class_message_iterator_initialize_method_status status;
1550         bt_self_component *self_comp =
1551                 bt_self_component_source_as_self_component(self_comp_src);
1552         struct lttng_live_component *lttng_live;
1553         struct lttng_live_msg_iter *lttng_live_msg_iter;
1554         enum lttng_live_viewer_status viewer_status;
1555         bt_logging_level log_level;
1556
1557         BT_ASSERT(self_msg_it);
1558
1559         lttng_live = bt_self_component_get_data(self_comp);
1560         log_level = lttng_live->log_level;
1561         self_comp = lttng_live->self_comp;
1562
1563
1564         /* There can be only one downstream iterator at the same time. */
1565         BT_ASSERT(!lttng_live->has_msg_iter);
1566         lttng_live->has_msg_iter = true;
1567
1568         lttng_live_msg_iter = lttng_live_msg_iter_create(lttng_live,
1569                 self_msg_it);
1570         if (!lttng_live_msg_iter) {
1571                 status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1572                 BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1573                         "Failed to create lttng_live_msg_iter");
1574                 goto error;
1575         }
1576
1577          viewer_status = live_viewer_connection_create(self_comp, NULL,
1578                 log_level, lttng_live->params.url->str, false,
1579                 lttng_live_msg_iter, &lttng_live_msg_iter->viewer_connection);
1580         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1581                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1582                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1583                                 "Failed to create viewer connection");
1584                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1585                         /*
1586                          * Interruption in the _iter_init() method is not
1587                          * supported. Return an error.
1588                          */
1589                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1590                                 "Interrupted while creating viewer connection");
1591                 }
1592                 goto error;
1593         }
1594
1595         viewer_status = lttng_live_create_viewer_session(lttng_live_msg_iter);
1596         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1597                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1598                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1599                                 "Failed to create viewer session");
1600                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1601                         /*
1602                          * Interruption in the _iter_init() method is not
1603                          * supported. Return an error.
1604                          */
1605                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1606                                 "Interrupted when creating viewer session");
1607                 }
1608                 goto error;
1609         }
1610
1611         if (lttng_live_msg_iter->sessions->len == 0) {
1612                 switch (lttng_live->params.sess_not_found_act) {
1613                 case SESSION_NOT_FOUND_ACTION_CONTINUE:
1614                         BT_COMP_LOGI("Unable to connect to the requested live viewer session. Keep trying to connect because of "
1615                                 "%s=\"%s\" component parameter: url=\"%s\"",
1616                                 SESS_NOT_FOUND_ACTION_PARAM,
1617                                 SESS_NOT_FOUND_ACTION_CONTINUE_STR,
1618                                 lttng_live->params.url->str);
1619                         break;
1620                 case SESSION_NOT_FOUND_ACTION_FAIL:
1621                         BT_COMP_LOGE_APPEND_CAUSE(self_comp,
1622                                 "Unable to connect to the requested live viewer session. Fail the message iterator initialization because of %s=\"%s\" "
1623                                 "component parameter: url =\"%s\"",
1624                                 SESS_NOT_FOUND_ACTION_PARAM,
1625                                 SESS_NOT_FOUND_ACTION_FAIL_STR,
1626                                 lttng_live->params.url->str);
1627                         goto error;
1628                 case SESSION_NOT_FOUND_ACTION_END:
1629                         BT_COMP_LOGI("Unable to connect to the requested live viewer session. End gracefully at the first _next() "
1630                                 "call because of %s=\"%s\" component parameter: "
1631                                 "url=\"%s\"", SESS_NOT_FOUND_ACTION_PARAM,
1632                                 SESS_NOT_FOUND_ACTION_END_STR,
1633                                 lttng_live->params.url->str);
1634                         break;
1635                 default:
1636                         bt_common_abort();
1637                 }
1638         }
1639
1640         bt_self_message_iterator_set_data(self_msg_it, lttng_live_msg_iter);
1641         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_OK;
1642         goto end;
1643
1644 error:
1645         status = BT_COMPONENT_CLASS_MESSAGE_ITERATOR_INITIALIZE_METHOD_STATUS_ERROR;
1646         lttng_live_msg_iter_destroy(lttng_live_msg_iter);
1647 end:
1648         return status;
1649 }
1650
1651 static struct bt_param_validation_map_value_entry_descr list_sessions_params[] = {
1652         { URL_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_MANDATORY, { .type = BT_VALUE_TYPE_STRING } },
1653         BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_END
1654 };
1655
1656 static
1657 bt_component_class_query_method_status lttng_live_query_list_sessions(
1658                 const bt_value *params, const bt_value **result,
1659                 bt_self_component_class *self_comp_class,
1660                 bt_logging_level log_level)
1661 {
1662         bt_component_class_query_method_status status;
1663         const bt_value *url_value = NULL;
1664         const char *url;
1665         struct live_viewer_connection *viewer_connection = NULL;
1666         enum lttng_live_viewer_status viewer_status;
1667         enum bt_param_validation_status validation_status;
1668         gchar *validate_error = NULL;
1669
1670         validation_status = bt_param_validation_validate(params,
1671                 list_sessions_params, &validate_error);
1672         if (validation_status == BT_PARAM_VALIDATION_STATUS_MEMORY_ERROR) {
1673                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
1674                 goto error;
1675         } else if (validation_status == BT_PARAM_VALIDATION_STATUS_VALIDATION_ERROR) {
1676                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1677                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class, "%s",
1678                         validate_error);
1679                 goto error;
1680         }
1681
1682         url_value = bt_value_map_borrow_entry_value_const(params, URL_PARAM);
1683         url = bt_value_string_get(url_value);
1684
1685         viewer_status = live_viewer_connection_create(NULL, self_comp_class,
1686                 log_level, url, true, NULL, &viewer_connection);
1687         if (viewer_status != LTTNG_LIVE_VIEWER_STATUS_OK) {
1688                 if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_ERROR) {
1689                         BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1690                                 "Failed to create viewer connection");
1691                         status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1692                 } else if (viewer_status == LTTNG_LIVE_VIEWER_STATUS_INTERRUPTED) {
1693                         status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_AGAIN;
1694                 } else {
1695                         bt_common_abort();
1696                 }
1697                 goto error;
1698         }
1699
1700         status = live_viewer_connection_list_sessions(viewer_connection,
1701                 result);
1702         if (status != BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK) {
1703                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1704                         "Failed to list viewer sessions");
1705                 goto error;
1706         }
1707
1708         goto end;
1709
1710 error:
1711         BT_VALUE_PUT_REF_AND_RESET(*result);
1712
1713         if (status >= 0) {
1714                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1715         }
1716
1717 end:
1718         if (viewer_connection) {
1719                 live_viewer_connection_destroy(viewer_connection);
1720         }
1721
1722         g_free(validate_error);
1723
1724         return status;
1725 }
1726
1727 static
1728 bt_component_class_query_method_status lttng_live_query_support_info(
1729                 const bt_value *params, const bt_value **result,
1730                 bt_self_component_class *self_comp_class,
1731                 bt_logging_level log_level)
1732 {
1733         bt_component_class_query_method_status status =
1734                 BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
1735         const bt_value *input_type_value;
1736         const bt_value *input_value;
1737         double weight = 0;
1738         struct bt_common_lttng_live_url_parts parts = { 0 };
1739
1740         /* Used by the logging macros */
1741         __attribute__((unused)) bt_self_component *self_comp = NULL;
1742
1743         *result = NULL;
1744         input_type_value = bt_value_map_borrow_entry_value_const(params,
1745                 "type");
1746         if (!input_type_value) {
1747                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1748                         "Missing expected `type` parameter.");
1749                 goto error;
1750         }
1751
1752         if (!bt_value_is_string(input_type_value)) {
1753                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1754                         "`type` parameter is not a string value.");
1755                 goto error;
1756         }
1757
1758         if (strcmp(bt_value_string_get(input_type_value), "string") != 0) {
1759                 /* We don't handle file system paths */
1760                 goto create_result;
1761         }
1762
1763         input_value = bt_value_map_borrow_entry_value_const(params, "input");
1764         if (!input_value) {
1765                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1766                         "Missing expected `input` parameter.");
1767                 goto error;
1768         }
1769
1770         if (!bt_value_is_string(input_value)) {
1771                 BT_COMP_CLASS_LOGE_APPEND_CAUSE(self_comp_class,
1772                         "`input` parameter is not a string value.");
1773                 goto error;
1774         }
1775
1776         parts = bt_common_parse_lttng_live_url(bt_value_string_get(input_value),
1777                 NULL, 0);
1778         if (parts.session_name) {
1779                 /*
1780                  * Looks pretty much like an LTTng live URL: we got the
1781                  * session name part, which forms a complete URL.
1782                  */
1783                 weight = .75;
1784         }
1785
1786 create_result:
1787         *result = bt_value_real_create_init(weight);
1788         if (!*result) {
1789                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_MEMORY_ERROR;
1790                 goto error;
1791         }
1792
1793         goto end;
1794
1795 error:
1796         if (status >= 0) {
1797                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_ERROR;
1798         }
1799
1800         BT_ASSERT(!*result);
1801
1802 end:
1803         bt_common_destroy_lttng_live_url_parts(&parts);
1804         return status;
1805 }
1806
1807 BT_HIDDEN
1808 bt_component_class_query_method_status lttng_live_query(
1809                 bt_self_component_class_source *comp_class,
1810                 bt_private_query_executor *priv_query_exec,
1811                 const char *object, const bt_value *params,
1812                 __attribute__((unused)) void *method_data,
1813                 const bt_value **result)
1814 {
1815         bt_component_class_query_method_status status =
1816                 BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_OK;
1817         bt_self_component *self_comp = NULL;
1818         bt_self_component_class *self_comp_class =
1819                 bt_self_component_class_source_as_self_component_class(comp_class);
1820         bt_logging_level log_level = bt_query_executor_get_logging_level(
1821                 bt_private_query_executor_as_query_executor_const(
1822                         priv_query_exec));
1823
1824         if (strcmp(object, "sessions") == 0) {
1825                 status = lttng_live_query_list_sessions(params, result,
1826                         self_comp_class, log_level);
1827         } else if (strcmp(object, "babeltrace.support-info") == 0) {
1828                 status = lttng_live_query_support_info(params, result,
1829                         self_comp_class, log_level);
1830         } else {
1831                 BT_COMP_LOGI("Unknown query object `%s`", object);
1832                 status = BT_COMPONENT_CLASS_QUERY_METHOD_STATUS_UNKNOWN_OBJECT;
1833                 goto end;
1834         }
1835
1836 end:
1837         return status;
1838 }
1839
1840 static
1841 void lttng_live_component_destroy_data(struct lttng_live_component *lttng_live)
1842 {
1843         if (!lttng_live) {
1844                 return;
1845         }
1846         if (lttng_live->params.url) {
1847                 g_string_free(lttng_live->params.url, TRUE);
1848         }
1849         g_free(lttng_live);
1850 }
1851
1852 BT_HIDDEN
1853 void lttng_live_component_finalize(bt_self_component_source *component)
1854 {
1855         void *data = bt_self_component_get_data(
1856                 bt_self_component_source_as_self_component(component));
1857
1858         if (!data) {
1859                 return;
1860         }
1861         lttng_live_component_destroy_data(data);
1862 }
1863
1864 static
1865 enum session_not_found_action parse_session_not_found_action_param(
1866         const bt_value *no_session_param)
1867 {
1868         enum session_not_found_action action;
1869         const char *no_session_act_str = bt_value_string_get(no_session_param);
1870
1871         if (strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_CONTINUE_STR) == 0) {
1872                 action = SESSION_NOT_FOUND_ACTION_CONTINUE;
1873         } else if (strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_FAIL_STR) == 0) {
1874                 action = SESSION_NOT_FOUND_ACTION_FAIL;
1875         } else {
1876                 BT_ASSERT(strcmp(no_session_act_str, SESS_NOT_FOUND_ACTION_END_STR) == 0);
1877                 action = SESSION_NOT_FOUND_ACTION_END;
1878         }
1879
1880         return action;
1881 }
1882
1883 static struct bt_param_validation_value_descr inputs_elem_descr = {
1884         .type = BT_VALUE_TYPE_STRING,
1885 };
1886
1887 static const char *sess_not_found_action_choices[] = {
1888         SESS_NOT_FOUND_ACTION_CONTINUE_STR,
1889         SESS_NOT_FOUND_ACTION_FAIL_STR,
1890         SESS_NOT_FOUND_ACTION_END_STR,
1891 };
1892
1893 static struct bt_param_validation_map_value_entry_descr params_descr[] = {
1894         { INPUTS_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_MANDATORY, { BT_VALUE_TYPE_ARRAY, .array = {
1895                 .min_length = 1,
1896                 .max_length = 1,
1897                 .element_type = &inputs_elem_descr,
1898         } } },
1899         { SESS_NOT_FOUND_ACTION_PARAM, BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_OPTIONAL, { BT_VALUE_TYPE_STRING, .string = {
1900                 .choices = sess_not_found_action_choices,
1901         } } },
1902         BT_PARAM_VALIDATION_MAP_VALUE_ENTRY_END
1903 };
1904
1905 static
1906 bt_component_class_initialize_method_status lttng_live_component_create(
1907                 const bt_value *params,
1908                 bt_logging_level log_level,
1909                 bt_self_component *self_comp,
1910                 struct lttng_live_component **component)
1911 {
1912         struct lttng_live_component *lttng_live = NULL;
1913         const bt_value *inputs_value;
1914         const bt_value *url_value;
1915         const bt_value *value;
1916         const char *url;
1917         enum bt_param_validation_status validation_status;
1918         gchar *validation_error = NULL;
1919         bt_component_class_initialize_method_status status;
1920
1921         validation_status = bt_param_validation_validate(params, params_descr,
1922                 &validation_error);
1923         if (validation_status == BT_PARAM_VALIDATION_STATUS_MEMORY_ERROR) {
1924                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1925                 goto error;
1926         } else if (validation_status == BT_PARAM_VALIDATION_STATUS_VALIDATION_ERROR) {
1927                 BT_COMP_LOGE_APPEND_CAUSE(self_comp, "%s", validation_error);
1928                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_ERROR;
1929                 goto error;
1930         }
1931
1932         lttng_live = g_new0(struct lttng_live_component, 1);
1933         if (!lttng_live) {
1934                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1935                 goto end;
1936         }
1937         lttng_live->log_level = log_level;
1938         lttng_live->self_comp = self_comp;
1939         lttng_live->max_query_size = MAX_QUERY_SIZE;
1940         lttng_live->has_msg_iter = false;
1941
1942         inputs_value =
1943                 bt_value_map_borrow_entry_value_const(params, INPUTS_PARAM);
1944         url_value =
1945                 bt_value_array_borrow_element_by_index_const(inputs_value, 0);
1946         url = bt_value_string_get(url_value);
1947
1948         lttng_live->params.url = g_string_new(url);
1949         if (!lttng_live->params.url) {
1950                 status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_MEMORY_ERROR;
1951                 goto error;
1952         }
1953
1954         value = bt_value_map_borrow_entry_value_const(params,
1955                 SESS_NOT_FOUND_ACTION_PARAM);
1956         if (value) {
1957                 lttng_live->params.sess_not_found_act =
1958                         parse_session_not_found_action_param(value);
1959         } else {
1960                 BT_COMP_LOGI("Optional `%s` parameter is missing: "
1961                         "defaulting to `%s`.",
1962                         SESS_NOT_FOUND_ACTION_PARAM,
1963                         SESS_NOT_FOUND_ACTION_CONTINUE_STR);
1964                 lttng_live->params.sess_not_found_act =
1965                         SESSION_NOT_FOUND_ACTION_CONTINUE;
1966         }
1967
1968         status = BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_OK;
1969         goto end;
1970
1971 error:
1972         lttng_live_component_destroy_data(lttng_live);
1973         lttng_live = NULL;
1974 end:
1975         g_free(validation_error);
1976
1977         *component = lttng_live;
1978         return status;
1979 }
1980
1981 BT_HIDDEN
1982 bt_component_class_initialize_method_status lttng_live_component_init(
1983                 bt_self_component_source *self_comp_src,
1984                 bt_self_component_source_configuration *config,
1985                 const bt_value *params,
1986                 __attribute__((unused)) void *init_method_data)
1987 {
1988         struct lttng_live_component *lttng_live;
1989         bt_component_class_initialize_method_status ret;
1990         bt_self_component *self_comp =
1991                 bt_self_component_source_as_self_component(self_comp_src);
1992         bt_logging_level log_level = bt_component_get_logging_level(
1993                 bt_self_component_as_component(self_comp));
1994         bt_self_component_add_port_status add_port_status;
1995
1996         ret = lttng_live_component_create(params, log_level, self_comp, &lttng_live);
1997         if (ret != BT_COMPONENT_CLASS_INITIALIZE_METHOD_STATUS_OK) {
1998                 goto error;
1999         }
2000
2001         add_port_status = bt_self_component_source_add_output_port(
2002                 self_comp_src, "out", NULL, NULL);
2003         if (add_port_status != BT_SELF_COMPONENT_ADD_PORT_STATUS_OK) {
2004                 ret = (int) add_port_status;
2005                 goto end;
2006         }
2007
2008         bt_self_component_set_data(self_comp, lttng_live);
2009         goto end;
2010
2011 error:
2012         lttng_live_component_destroy_data(lttng_live);
2013         lttng_live = NULL;
2014 end:
2015         return ret;
2016 }