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

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