src/bin/lttng-sessiond/jul.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <assert.h>
  20 #include <urcu/uatomic.h>
  21
  22 #include <common/common.h>
  23 #include <common/sessiond-comm/jul.h>
  24
  25 #include "jul.h"
  26 #include "ust-app.h"
  27 #include "utils.h"
  28
  29 /*
  30  * URCU intermediate call to complete destroy a JUL event.
  31  */
  32 static void destroy_event_jul_rcu(struct rcu_head *head)
  33 {
  34         struct lttng_ht_node_str *node =
  35                 caa_container_of(head, struct lttng_ht_node_str, head);
  36         struct jul_event *event =
  37                 caa_container_of(node, struct jul_event, node);
  38
  39         free(event);
  40 }
  41
  42 /*
  43  * URCU intermediate call to complete destroy a JUL event.
  44  */
  45 static void destroy_app_jul_rcu(struct rcu_head *head)
  46 {
  47         struct lttng_ht_node_ulong *node =
  48                 caa_container_of(head, struct lttng_ht_node_ulong, head);
  49         struct jul_app *app =
  50                 caa_container_of(node, struct jul_app, node);
  51
  52         free(app);
  53 }
  54
  55 /*
  56  * Communication with Java agent call. Send the message header to the given
  57  * socket all in big endian.
  58  *
  59  * Return 0 on success or else a negative errno message of sendmsg() op.
  60  */
  61 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
  62                 uint32_t cmd, uint32_t cmd_version)
  63 {
  64         int ret;
  65         ssize_t size;
  66         struct lttcomm_jul_hdr msg;
  67
  68         assert(sock);
  69
  70         msg.data_size = htobe64(data_size);
  71         msg.cmd = htobe32(cmd);
  72         msg.cmd_version = htobe32(cmd_version);
  73
  74         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
  75         if (size < sizeof(msg)) {
  76                 ret = -errno;
  77                 goto error;
  78         }
  79         ret = 0;
  80
  81 error:
  82         return ret;
  83 }
  84
  85 /*
  86  * Communication call with the Java agent. Send the payload to the given
  87  * socket. The header MUST be sent prior to this call.
  88  *
  89  * Return 0 on success or else a negative errno value of sendmsg() op.
  90  */
  91 static int send_payload(struct lttcomm_sock *sock, void *data,
  92                 size_t size)
  93 {
  94         int ret;
  95         ssize_t len;
  96
  97         assert(sock);
  98         assert(data);
  99
 100         len = sock->ops->sendmsg(sock, data, size, 0);
 101         if (len < size) {
 102                 ret = -errno;
 103                 goto error;
 104         }
 105         ret = 0;
 106
 107 error:
 108         return ret;
 109 }
 110
 111 /*
 112  * Communication call with the Java agent. Receive reply from the agent using
 113  * the given socket.
 114  *
 115  * Return 0 on success or else a negative errno value from recvmsg() op.
 116  */
 117 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 118 {
 119         int ret;
 120         ssize_t len;
 121
 122         assert(sock);
 123         assert(buf);
 124
 125         len = sock->ops->recvmsg(sock, buf, size, 0);
 126         if (len < size) {
 127                 ret = -errno;
 128                 goto error;
 129         }
 130         ret = 0;
 131
 132 error:
 133         return ret;
 134 }
 135
 136
 137 /*
 138  * Internal call to list events on a given app. Populate events.
 139  *
 140  * Return number of element in the list or else a negative LTTNG_ERR* code.
 141  */
 142 static ssize_t list_events(struct jul_app *app, struct lttng_event **events)
 143 {
 144         int ret, i, len = 0, offset = 0;
 145         uint32_t nb_event;
 146         size_t data_size;
 147         struct lttng_event *tmp_events = NULL;
 148         struct lttcomm_jul_list_reply *reply = NULL;
 149         struct lttcomm_jul_list_reply_hdr reply_hdr;
 150
 151         assert(app);
 152         assert(app->sock);
 153         assert(events);
 154
 155         DBG2("JUL listing events for app pid: %d and socket %d", app->pid,
 156                         app->sock->fd);
 157
 158         ret = send_header(app->sock, 0, JUL_CMD_LIST, 0);
 159         if (ret < 0) {
 160                 goto error_io;
 161         }
 162
 163         /* Get list header so we know how much we'll receive. */
 164         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 165         if (ret < 0) {
 166                 goto error_io;
 167         }
 168
 169         switch (be32toh(reply_hdr.ret_code)) {
 170         case JUL_RET_CODE_SUCCESS:
 171                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 172                 break;
 173         default:
 174                 ERR("Java agent returned an unknown code: %" PRIu32,
 175                                 be32toh(reply_hdr.ret_code));
 176                 ret = LTTNG_ERR_FATAL;
 177                 goto error;
 178         }
 179
 180         reply = zmalloc(data_size);
 181         if (!reply) {
 182                 ret = LTTNG_ERR_NOMEM;
 183                 goto error;
 184         }
 185
 186         /* Get the list with the appropriate data size. */
 187         ret = recv_reply(app->sock, reply, data_size);
 188         if (ret < 0) {
 189                 goto error_io;
 190         }
 191
 192         nb_event = be32toh(reply->nb_event);
 193         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 194         if (!tmp_events) {
 195                 ret = LTTNG_ERR_NOMEM;
 196                 goto error;
 197         }
 198
 199         for (i = 0; i < nb_event; i++) {
 200                 offset += len;
 201                 strncpy(tmp_events[i].name, reply->payload + offset,
 202                                 sizeof(tmp_events[i].name));
 203                 tmp_events[i].pid = app->pid;
 204                 tmp_events[i].enabled = -1;
 205                 len = strlen(reply->payload + offset) + 1;
 206         }
 207
 208         *events = tmp_events;
 209
 210         free(reply);
 211         return nb_event;
 212
 213 error_io:
 214         ret = LTTNG_ERR_UST_LIST_FAIL;
 215 error:
 216         free(reply);
 217         free(tmp_events);
 218         return -ret;
 219
 220 }
 221
 222 /*
 223  * Internal enable JUL event call on a JUL application. This function
 224  * communicates with the Java agent to enable a given event (Logger name).
 225  *
 226  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 227  */
 228 static int enable_event(struct jul_app *app, struct jul_event *event)
 229 {
 230         int ret;
 231         uint64_t data_size;
 232         struct lttcomm_jul_enable msg;
 233         struct lttcomm_jul_generic_reply reply;
 234
 235         assert(app);
 236         assert(app->sock);
 237         assert(event);
 238
 239         DBG2("JUL enabling event %s for app pid: %d and socket %d", event->name,
 240                         app->pid, app->sock->fd);
 241
 242         data_size = sizeof(msg);
 243
 244         ret = send_header(app->sock, data_size, JUL_CMD_ENABLE, 0);
 245         if (ret < 0) {
 246                 goto error_io;
 247         }
 248
 249         strncpy(msg.name, event->name, sizeof(msg.name));
 250         ret = send_payload(app->sock, &msg, sizeof(msg));
 251         if (ret < 0) {
 252                 goto error_io;
 253         }
 254
 255         ret = recv_reply(app->sock, &reply, sizeof(reply));
 256         if (ret < 0) {
 257                 goto error_io;
 258         }
 259
 260         switch (be32toh(reply.ret_code)) {
 261         case JUL_RET_CODE_SUCCESS:
 262                 break;
 263         case JUL_RET_CODE_UNKNOWN_NAME:
 264                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 265                 goto error;
 266         default:
 267                 ERR("Java agent returned an unknown code: %" PRIu32,
 268                                 be32toh(reply.ret_code));
 269                 ret = LTTNG_ERR_FATAL;
 270                 goto error;
 271         }
 272
 273         return LTTNG_OK;
 274
 275 error_io:
 276         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 277 error:
 278         return ret;
 279 }
 280
 281 /*
 282  * Internal disable JUL event call on a JUL application. This function
 283  * communicates with the Java agent to disable a given event (Logger name).
 284  *
 285  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 286  */
 287 static int disable_event(struct jul_app *app, struct jul_event *event)
 288 {
 289         int ret;
 290         uint64_t data_size;
 291         struct lttcomm_jul_disable msg;
 292         struct lttcomm_jul_generic_reply reply;
 293
 294         assert(app);
 295         assert(app->sock);
 296         assert(event);
 297
 298         DBG2("JUL disabling event %s for app pid: %d and socket %d", event->name,
 299                         app->pid, app->sock->fd);
 300
 301         data_size = sizeof(msg);
 302
 303         ret = send_header(app->sock, data_size, JUL_CMD_DISABLE, 0);
 304         if (ret < 0) {
 305                 goto error_io;
 306         }
 307
 308         strncpy(msg.name, event->name, sizeof(msg.name));
 309         ret = send_payload(app->sock, &msg, sizeof(msg));
 310         if (ret < 0) {
 311                 goto error_io;
 312         }
 313
 314         ret = recv_reply(app->sock, &reply, sizeof(reply));
 315         if (ret < 0) {
 316                 goto error_io;
 317         }
 318
 319         switch (be32toh(reply.ret_code)) {
 320                 case JUL_RET_CODE_SUCCESS:
 321                         break;
 322                 case JUL_RET_CODE_UNKNOWN_NAME:
 323                         ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 324                         goto error;
 325                 default:
 326                         ERR("Java agent returned an unknown code: %" PRIu32,
 327                                         be32toh(reply.ret_code));
 328                         ret = LTTNG_ERR_FATAL;
 329                         goto error;
 330         }
 331
 332         return LTTNG_OK;
 333
 334 error_io:
 335         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 336 error:
 337         return ret;
 338 }
 339
 340 /*
 341  * Enable JUL event on every JUL applications registered with the session
 342  * daemon.
 343  *
 344  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 345  */
 346 int jul_enable_event(struct jul_event *event)
 347 {
 348         int ret;
 349         struct jul_app *app;
 350         struct lttng_ht_iter iter;
 351
 352         assert(event);
 353
 354         rcu_read_lock();
 355
 356         cds_lfht_for_each_entry(jul_apps_ht_by_sock->ht, &iter.iter, app,
 357                         node.node) {
 358                 /* Enable event on JUL application through TCP socket. */
 359                 ret = enable_event(app, event);
 360                 if (ret != LTTNG_OK) {
 361                         goto error;
 362                 }
 363         }
 364
 365         event->enabled = 1;
 366         ret = LTTNG_OK;
 367
 368 error:
 369         rcu_read_unlock();
 370         return ret;
 371 }
 372
 373 /*
 374  * Disable JUL event on every JUL applications registered with the session
 375  * daemon.
 376  *
 377  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 378  */
 379 int jul_disable_event(struct jul_event *event)
 380 {
 381         int ret;
 382         struct jul_app *app;
 383         struct lttng_ht_iter iter;
 384
 385         assert(event);
 386
 387         rcu_read_lock();
 388
 389         cds_lfht_for_each_entry(jul_apps_ht_by_sock->ht, &iter.iter, app,
 390                         node.node) {
 391                 /* Enable event on JUL application through TCP socket. */
 392                 ret = disable_event(app, event);
 393                 if (ret != LTTNG_OK) {
 394                         goto error;
 395                 }
 396         }
 397
 398         event->enabled = 0;
 399         ret = LTTNG_OK;
 400
 401 error:
 402         rcu_read_unlock();
 403         return ret;
 404 }
 405
 406 /*
 407  * Ask every java agent for the list of possible event (logger name). Events is
 408  * allocated with the events of every JUL application.
 409  *
 410  * Return the number of events or else a negative value.
 411  */
 412 int jul_list_events(struct lttng_event **events)
 413 {
 414         int ret;
 415         size_t nbmem, count = 0;
 416         struct jul_app *app;
 417         struct lttng_event *tmp_events;
 418         struct lttng_ht_iter iter;
 419
 420         assert(events);
 421
 422         nbmem = UST_APP_EVENT_LIST_SIZE;
 423         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 424         if (!tmp_events) {
 425                 PERROR("zmalloc jul list events");
 426                 ret = -ENOMEM;
 427                 goto error;
 428         }
 429
 430         rcu_read_lock();
 431         cds_lfht_for_each_entry(jul_apps_ht_by_sock->ht, &iter.iter, app,
 432                         node.node) {
 433                 ssize_t nb_ev;
 434                 struct lttng_event *jul_events;
 435
 436                 nb_ev = list_events(app, &jul_events);
 437                 if (nb_ev < 0) {
 438                         ret = nb_ev;
 439                         rcu_read_unlock();
 440                         goto error;
 441                 }
 442
 443                 if (count >= nbmem) {
 444                         /* In case the realloc fails, we free the memory */
 445                         void *ptr;
 446
 447                         DBG2("Reallocating JUL event list from %zu to %zu entries", nbmem,
 448                                         2 * nbmem);
 449                         nbmem *= 2;
 450                         ptr = realloc(tmp_events, nbmem * sizeof(*tmp_events));
 451                         if (!ptr) {
 452                                 PERROR("realloc JUL events");
 453                                 free(tmp_events);
 454                                 ret = -ENOMEM;
 455                                 rcu_read_unlock();
 456                                 goto error;
 457                         }
 458                         tmp_events = ptr;
 459                 }
 460                 memcpy(tmp_events + (count * sizeof(*tmp_events)), jul_events,
 461                                 nb_ev * sizeof(*tmp_events));
 462                 free(jul_events);
 463                 count += nb_ev;
 464         }
 465         rcu_read_unlock();
 466
 467         ret = count;
 468         *events = tmp_events;
 469
 470 error:
 471         return ret;
 472 }
 473
 474 /*
 475  * Create a JUL app object using the given PID.
 476  *
 477  * Return newly allocated object or else NULL on error.
 478  */
 479 struct jul_app *jul_create_app(pid_t pid, struct lttcomm_sock *sock)
 480 {
 481         struct jul_app *app;
 482
 483         assert(sock);
 484
 485         app = zmalloc(sizeof(*app));
 486         if (!app) {
 487                 PERROR("zmalloc JUL create");
 488                 goto error;
 489         }
 490
 491         app->pid = pid;
 492         app->sock = sock;
 493         /* Flag it invalid until assignation. */
 494         app->ust_app_sock = -1;
 495         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 496
 497 error:
 498         return app;
 499 }
 500
 501 /*
 502  * Lookup JUL app by socket in the global hash table.
 503  *
 504  * RCU read side lock MUST be acquired.
 505  *
 506  * Return object if found else NULL.
 507  */
 508 struct jul_app *jul_find_app_by_sock(int sock)
 509 {
 510         struct lttng_ht_node_ulong *node;
 511         struct lttng_ht_iter iter;
 512         struct jul_app *app;
 513
 514         assert(sock >= 0);
 515
 516         lttng_ht_lookup(jul_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 517         node = lttng_ht_iter_get_node_ulong(&iter);
 518         if (node == NULL) {
 519                 goto error;
 520         }
 521         app = caa_container_of(node, struct jul_app, node);
 522
 523         DBG3("JUL app pid %d found by sock %d.", app->pid, sock);
 524         return app;
 525
 526 error:
 527         DBG3("JUL app NOT found by sock %d.", sock);
 528         return NULL;
 529 }
 530
 531 /*
 532  * Add JUL application object to a given hash table.
 533  */
 534 void jul_add_app(struct jul_app *app)
 535 {
 536         assert(app);
 537
 538         DBG3("JUL adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 539
 540         rcu_read_lock();
 541         lttng_ht_add_unique_ulong(jul_apps_ht_by_sock, &app->node);
 542         rcu_read_unlock();
 543 }
 544
 545 /*
 546  * Attach a given JUL application to an UST app object. This is done by copying
 547  * the socket fd value into the ust app obj. atomically.
 548  */
 549 void jul_attach_app(struct jul_app *japp)
 550 {
 551         struct ust_app *uapp;
 552
 553         assert(japp);
 554
 555         rcu_read_lock();
 556         uapp = ust_app_find_by_pid(japp->pid);
 557         if (!uapp) {
 558                 goto end;
 559         }
 560
 561         uatomic_set(&uapp->jul_app_sock, japp->sock->fd);
 562
 563         DBG3("JUL app pid: %d, sock: %d attached to UST app.", japp->pid,
 564                         japp->sock->fd);
 565
 566 end:
 567         rcu_read_unlock();
 568         return;
 569 }
 570
 571 /*
 572  * Remove JUL app. reference from an UST app object and set it to NULL.
 573  */
 574 void jul_detach_app(struct jul_app *japp)
 575 {
 576         struct ust_app *uapp;
 577
 578         assert(japp);
 579
 580         rcu_read_lock();
 581
 582         if (japp->ust_app_sock < 0) {
 583                 goto end;
 584         }
 585
 586         uapp = ust_app_find_by_sock(japp->ust_app_sock);
 587         if (!uapp) {
 588                 goto end;
 589         }
 590
 591         uapp->jul_app_sock = -1;
 592
 593 end:
 594         rcu_read_unlock();
 595         return;
 596 }
 597
 598 /*
 599  * Delete JUL application from the global hash table.
 600  */
 601 void jul_delete_app(struct jul_app *app)
 602 {
 603         int ret;
 604         struct lttng_ht_iter iter;
 605
 606         assert(app);
 607
 608         DBG3("JUL deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 609
 610         iter.iter.node = &app->node.node;
 611         rcu_read_lock();
 612         ret = lttng_ht_del(jul_apps_ht_by_sock, &iter);
 613         rcu_read_unlock();
 614         assert(!ret);
 615 }
 616
 617 /*
 618  * Destroy a JUL application object by detaching it from its corresponding UST
 619  * app if one, closing the socket and freeing the memory.
 620  */
 621 void jul_destroy_app(struct jul_app *app)
 622 {
 623         assert(app);
 624
 625         if (app->sock) {
 626                 app->sock->ops->close(app->sock);
 627                 lttcomm_destroy_sock(app->sock);
 628         }
 629
 630         call_rcu(&app->node.head, destroy_app_jul_rcu);
 631 }
 632
 633 /*
 634  * Initialize an already allocated JUL domain object.
 635  *
 636  * Return 0 on success or else a negative errno value.
 637  */
 638 int jul_init_domain(struct jul_domain *dom)
 639 {
 640         int ret;
 641
 642         assert(dom);
 643
 644         dom->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 645         if (!dom->events) {
 646                 ret = -ENOMEM;
 647                 goto error;
 648         }
 649
 650         return 0;
 651
 652 error:
 653         return ret;
 654 }
 655
 656 /*
 657  * Create a newly allocated JUL event data structure. If name is valid, it's
 658  * copied into the created event.
 659  *
 660  * Return a new object else NULL on error.
 661  */
 662 struct jul_event *jul_create_event(const char *name)
 663 {
 664         struct jul_event *event;
 665
 666         DBG3("JUL create new event with name %s", name);
 667
 668         event = zmalloc(sizeof(*event));
 669         if (!event) {
 670                 goto error;
 671         }
 672
 673         if (name) {
 674                 strncpy(event->name, name, sizeof(event->name));
 675                 event->name[sizeof(event->name) - 1] = '\0';
 676                 lttng_ht_node_init_str(&event->node, event->name);
 677         }
 678
 679 error:
 680         return event;
 681 }
 682
 683 /*
 684  * Unique add of a JUL event to a given domain.
 685  */
 686 void jul_add_event(struct jul_event *event, struct jul_domain *dom)
 687 {
 688         assert(event);
 689         assert(dom);
 690         assert(dom->events);
 691
 692         DBG3("JUL adding event %s to domain", event->name);
 693
 694         rcu_read_lock();
 695         lttng_ht_add_unique_str(dom->events, &event->node);
 696         rcu_read_unlock();
 697         dom->being_used = 1;
 698 }
 699
 700 /*
 701  * Find a JUL event in the given domain using name.
 702  *
 703  * RCU read side lock MUST be acquired.
 704  *
 705  * Return object if found else NULL.
 706  */
 707 struct jul_event *jul_find_by_name(const char *name, struct jul_domain *dom)
 708 {
 709         struct lttng_ht_node_str *node;
 710         struct lttng_ht_iter iter;
 711
 712         assert(name);
 713         assert(dom);
 714         assert(dom->events);
 715
 716         lttng_ht_lookup(dom->events, (void *)name, &iter);
 717         node = lttng_ht_iter_get_node_str(&iter);
 718         if (node == NULL) {
 719                 goto error;
 720         }
 721
 722         DBG3("JUL found by name %s in domain.", name);
 723         return caa_container_of(node, struct jul_event, node);
 724
 725 error:
 726         DBG3("JUL NOT found by name %s in domain.", name);
 727         return NULL;
 728 }
 729
 730 /*
 731  * Delete JUL event from given domain. Events hash table MUST be initialized.
 732  */
 733 void jul_delete_event(struct jul_event *event, struct jul_domain *dom)
 734 {
 735         int ret;
 736         struct lttng_ht_iter iter;
 737
 738         assert(event);
 739         assert(dom);
 740         assert(dom->events);
 741
 742         DBG3("JUL deleting event %s from domain", event->name);
 743
 744         iter.iter.node = &event->node.node;
 745         rcu_read_lock();
 746         ret = lttng_ht_del(dom->events, &iter);
 747         rcu_read_unlock();
 748         assert(!ret);
 749 }
 750
 751 /*
 752  * Free given JUl event. After this call, the pointer is not usable anymore.
 753  */
 754 void jul_destroy_event(struct jul_event *event)
 755 {
 756         assert(event);
 757
 758         free(event);
 759 }
 760
 761 /*
 762  * Destroy a JUL domain completely. Note that the given pointer is NOT freed
 763  * thus a reference can be passed to this function.
 764  */
 765 void jul_destroy_domain(struct jul_domain *dom)
 766 {
 767         struct lttng_ht_node_str *node;
 768         struct lttng_ht_iter iter;
 769
 770         assert(dom);
 771
 772         DBG3("JUL destroy domain");
 773
 774         /*
 775          * Just ignore if no events hash table exists. This is possible if for
 776          * instance a JUL domain object was allocated but not initialized.
 777          */
 778         if (!dom->events) {
 779                 return;
 780         }
 781
 782         rcu_read_lock();
 783         cds_lfht_for_each_entry(dom->events->ht, &iter.iter, node, node) {
 784                 int ret;
 785
 786                 ret = lttng_ht_del(dom->events, &iter);
 787                 assert(!ret);
 788                 call_rcu(&node->head, destroy_event_jul_rcu);
 789         }
 790         rcu_read_unlock();
 791
 792         lttng_ht_destroy(dom->events);
 793 }
 794
 795 /*
 796  * Initialize JUL subsystem.
 797  */
 798 int jul_init(void)
 799 {
 800         jul_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
 801         if (!jul_apps_ht_by_sock) {
 802                 return -1;
 803         }
 804
 805         return 0;
 806 }
 807
 808 /*
 809  * Update a JUL application (given socket) using the given domain.
 810  *
 811  * Note that this function is most likely to be used with a tracing session
 812  * thus the caller should make sure to hold the appropriate lock(s).
 813  */
 814 void jul_update(struct jul_domain *domain, int sock)
 815 {
 816         int ret;
 817         struct jul_app *app;
 818         struct jul_event *event;
 819         struct lttng_ht_iter iter;
 820
 821         assert(domain);
 822         assert(sock >= 0);
 823
 824         DBG("JUL updating app socket %d", sock);
 825
 826         rcu_read_lock();
 827         cds_lfht_for_each_entry(domain->events->ht, &iter.iter, event, node.node) {
 828                 /* Skip event if disabled. */
 829                 if (!event->enabled) {
 830                         continue;
 831                 }
 832
 833                 app = jul_find_app_by_sock(sock);
 834                 /*
 835                  * We are in the registration path thus if the application is gone,
 836                  * there is a serious code flow error.
 837                  */
 838                 assert(app);
 839
 840                 ret = enable_event(app, event);
 841                 if (ret != LTTNG_OK) {
 842                         DBG2("JUL update unable to enable event %s on app pid: %d sock %d",
 843                                         event->name, app->pid, app->sock->fd);
 844                         /* Let's try the others here and don't assume the app is dead. */
 845                         continue;
 846                 }
 847         }
 848         rcu_read_unlock();
 849 }