manager.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 #include <assert.h>
   4 #include <errno.h>
   5 #include <string.h>
   6 #include <sys/epoll.h>
   7 #include <signal.h>
   8 #include <sys/signalfd.h>
   9 #include <sys/wait.h>
  10 #include <unistd.h>
  11 #include <sys/poll.h>
  12
  13 #include "manager.h"
  14 #include "hashmap.h"
  15 #include "macro.h"
  16 #include "strv.h"
  17 #include "log.h"
  18
  19 Manager* manager_new(void) {
  20         Manager *m;
  21         sigset_t mask;
  22         struct epoll_event ev;
  23
  24         if (!(m = new0(Manager, 1)))
  25                 return NULL;
  26
  27         m->signal_fd = m->epoll_fd = -1;
  28
  29         if (!(m->units = hashmap_new(string_hash_func, string_compare_func)))
  30                 goto fail;
  31
  32         if (!(m->jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  33                 goto fail;
  34
  35         if (!(m->transaction_jobs = hashmap_new(trivial_hash_func, trivial_compare_func)))
  36                 goto fail;
  37
  38         if (!(m->watch_pids = hashmap_new(trivial_hash_func, trivial_compare_func)))
  39                 goto fail;
  40
  41         if ((m->epoll_fd = epoll_create1(EPOLL_CLOEXEC)) < 0)
  42                 goto fail;
  43
  44         assert_se(sigemptyset(&mask) == 0);
  45         assert_se(sigaddset(&mask, SIGCHLD) == 0);
  46         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
  47
  48         if ((m->signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0)
  49                 goto fail;
  50
  51         zero(ev);
  52         ev.events = EPOLLIN;
  53         ev.data.fd = m->signal_fd;
  54
  55         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->signal_fd, &ev) < 0)
  56                 goto fail;
  57
  58         return m;
  59
  60 fail:
  61         manager_free(m);
  62         return NULL;
  63 }
  64
  65 void manager_free(Manager *m) {
  66         Unit *u;
  67         Job *j;
  68
  69         assert(m);
  70
  71         while ((j = hashmap_first(m->transaction_jobs)))
  72                 job_free(j);
  73
  74         while ((u = hashmap_first(m->units)))
  75                 unit_free(u);
  76
  77         hashmap_free(m->units);
  78         hashmap_free(m->jobs);
  79         hashmap_free(m->transaction_jobs);
  80         hashmap_free(m->watch_pids);
  81
  82         if (m->epoll_fd >= 0)
  83                 close_nointr(m->epoll_fd);
  84         if (m->signal_fd >= 0)
  85                 close_nointr(m->signal_fd);
  86
  87         free(m);
  88 }
  89
  90 static void transaction_delete_job(Manager *m, Job *j) {
  91         assert(m);
  92         assert(j);
  93
  94         /* Deletes one job from the transaction */
  95
  96         manager_transaction_unlink_job(m, j);
  97
  98         if (!j->installed)
  99                 job_free(j);
 100 }
 101
 102 static void transaction_delete_unit(Manager *m, Unit *u) {
 103         Job *j;
 104
 105         /* Deletes all jobs associated with a certain unit from the
 106          * transaction */
 107
 108         while ((j = hashmap_get(m->transaction_jobs, u)))
 109                 transaction_delete_job(m, j);
 110 }
 111
 112 static void transaction_clean_dependencies(Manager *m) {
 113         Iterator i;
 114         Job *j;
 115
 116         assert(m);
 117
 118         /* Drops all dependencies of all installed jobs */
 119
 120         HASHMAP_FOREACH(j, m->jobs, i) {
 121                 while (j->subject_list)
 122                         job_dependency_free(j->subject_list);
 123                 while (j->object_list)
 124                         job_dependency_free(j->object_list);
 125         }
 126
 127         assert(!m->transaction_anchor);
 128 }
 129
 130 static void transaction_abort(Manager *m) {
 131         Job *j;
 132
 133         assert(m);
 134
 135         while ((j = hashmap_first(m->transaction_jobs)))
 136                 if (j->installed)
 137                         transaction_delete_job(m, j);
 138                 else
 139                         job_free(j);
 140
 141         assert(hashmap_isempty(m->transaction_jobs));
 142
 143         transaction_clean_dependencies(m);
 144 }
 145
 146 static void transaction_find_jobs_that_matter_to_anchor(Manager *m, Job *j, unsigned generation) {
 147         JobDependency *l;
 148
 149         assert(m);
 150
 151         /* A recursive sweep through the graph that marks all units
 152          * that matter to the anchor job, i.e. are directly or
 153          * indirectly a dependency of the anchor job via paths that
 154          * are fully marked as mattering. */
 155
 156         if (j)
 157                 l = j->subject_list;
 158         else
 159                 l = m->transaction_anchor;
 160
 161         LIST_FOREACH(subject, l, l) {
 162
 163                 /* This link does not matter */
 164                 if (!l->matters)
 165                         continue;
 166
 167                 /* This unit has already been marked */
 168                 if (l->object->generation == generation)
 169                         continue;
 170
 171                 l->object->matters_to_anchor = true;
 172                 l->object->generation = generation;
 173
 174                 transaction_find_jobs_that_matter_to_anchor(m, l->object, generation);
 175         }
 176 }
 177
 178 static void transaction_merge_and_delete_job(Manager *m, Job *j, Job *other, JobType t) {
 179         JobDependency *l, *last;
 180
 181         assert(j);
 182         assert(other);
 183         assert(j->unit == other->unit);
 184         assert(!j->installed);
 185
 186         /* Merges 'other' into 'j' and then deletes j. */
 187
 188         j->type = t;
 189         j->state = JOB_WAITING;
 190         j->forced = j->forced || other->forced;
 191
 192         j->matters_to_anchor = j->matters_to_anchor || other->matters_to_anchor;
 193
 194         /* Patch us in as new owner of the JobDependency objects */
 195         last = NULL;
 196         LIST_FOREACH(subject, l, other->subject_list) {
 197                 assert(l->subject == other);
 198                 l->subject = j;
 199                 last = l;
 200         }
 201
 202         /* Merge both lists */
 203         if (last) {
 204                 last->subject_next = j->subject_list;
 205                 if (j->subject_list)
 206                         j->subject_list->subject_prev = last;
 207                 j->subject_list = other->subject_list;
 208         }
 209
 210         /* Patch us in as new owner of the JobDependency objects */
 211         last = NULL;
 212         LIST_FOREACH(object, l, other->object_list) {
 213                 assert(l->object == other);
 214                 l->object = j;
 215                 last = l;
 216         }
 217
 218         /* Merge both lists */
 219         if (last) {
 220                 last->object_next = j->object_list;
 221                 if (j->object_list)
 222                         j->object_list->object_prev = last;
 223                 j->object_list = other->object_list;
 224         }
 225
 226         /* Kill the other job */
 227         other->subject_list = NULL;
 228         other->object_list = NULL;
 229         transaction_delete_job(m, other);
 230 }
 231
 232 static int delete_one_unmergeable_job(Manager *m, Job *j) {
 233         Job *k;
 234
 235         assert(j);
 236
 237         /* Tries to delete one item in the linked list
 238          * j->transaction_next->transaction_next->... that conflicts
 239          * whith another one, in an attempt to make an inconsistent
 240          * transaction work. */
 241
 242         /* We rely here on the fact that if a merged with b does not
 243          * merge with c, either a or b merge with c neither */
 244         LIST_FOREACH(transaction, j, j)
 245                 LIST_FOREACH(transaction, k, j->transaction_next) {
 246                         Job *d;
 247
 248                         /* Is this one mergeable? Then skip it */
 249                         if (job_type_is_mergeable(j->type, k->type))
 250                                 continue;
 251
 252                         /* Ok, we found two that conflict, let's see if we can
 253                          * drop one of them */
 254                         if (!j->matters_to_anchor)
 255                                 d = j;
 256                         else if (!k->matters_to_anchor)
 257                                 d = k;
 258                         else
 259                                 return -ENOEXEC;
 260
 261                         /* Ok, we can drop one, so let's do so. */
 262                         log_debug("Try to fix job merging by deleting job %s/%s", unit_id(d->unit), job_type_to_string(d->type));
 263                         transaction_delete_job(m, d);
 264                         return 0;
 265                 }
 266
 267         return -EINVAL;
 268 }
 269
 270 static int transaction_merge_jobs(Manager *m) {
 271         Job *j;
 272         Iterator i;
 273         int r;
 274
 275         assert(m);
 276
 277         /* First step, check whether any of the jobs for one specific
 278          * task conflict. If so, try to drop one of them. */
 279         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 280                 JobType t;
 281                 Job *k;
 282
 283                 t = j->type;
 284                 LIST_FOREACH(transaction, k, j->transaction_next) {
 285                         if ((r = job_type_merge(&t, k->type)) >= 0)
 286                                 continue;
 287
 288                         /* OK, we could not merge all jobs for this
 289                          * action. Let's see if we can get rid of one
 290                          * of them */
 291
 292                         if ((r = delete_one_unmergeable_job(m, j)) >= 0)
 293                                 /* Ok, we managed to drop one, now
 294                                  * let's ask our callers to call us
 295                                  * again after garbage collecting */
 296                                 return -EAGAIN;
 297
 298                         /* We couldn't merge anything. Failure */
 299                         return r;
 300                 }
 301         }
 302
 303         /* Second step, merge the jobs. */
 304         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 305                 JobType t = j->type;
 306                 Job *k;
 307
 308                 /* Merge all transactions */
 309                 LIST_FOREACH(transaction, k, j->transaction_next)
 310                         assert_se(job_type_merge(&t, k->type) == 0);
 311
 312                 /* If an active job is mergeable, merge it too */
 313                 if (j->unit->meta.job)
 314                         job_type_merge(&t, j->unit->meta.job->type); /* Might fail. Which is OK */
 315
 316                 while ((k = j->transaction_next)) {
 317                         if (j->installed) {
 318                                 transaction_merge_and_delete_job(m, k, j, t);
 319                                 j = k;
 320                         } else
 321                                 transaction_merge_and_delete_job(m, j, k, t);
 322                 }
 323
 324                 assert(!j->transaction_next);
 325                 assert(!j->transaction_prev);
 326         }
 327
 328         return 0;
 329 }
 330
 331 static bool unit_matters_to_anchor(Unit *u, Job *j) {
 332         assert(u);
 333         assert(!j->transaction_prev);
 334
 335         /* Checks whether at least one of the jobs for this unit
 336          * matters to the anchor. */
 337
 338         LIST_FOREACH(transaction, j, j)
 339                 if (j->matters_to_anchor)
 340                         return true;
 341
 342         return false;
 343 }
 344
 345 static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned generation) {
 346         Iterator i;
 347         Unit *u;
 348         int r;
 349
 350         assert(m);
 351         assert(j);
 352         assert(!j->transaction_prev);
 353
 354         /* Does a recursive sweep through the ordering graph, looking
 355          * for a cycle. If we find cycle we try to break it. */
 356
 357         /* Did we find a cycle? */
 358         if (j->marker && j->generation == generation) {
 359                 Job *k;
 360
 361                 /* So, we already have been here. We have a
 362                  * cycle. Let's try to break it. We go backwards in
 363                  * our path and try to find a suitable job to
 364                  * remove. We use the marker to find our way back,
 365                  * since smart how we are we stored our way back in
 366                  * there. */
 367
 368                 for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
 369
 370                         if (!k->installed &&
 371                             !unit_matters_to_anchor(k->unit, k)) {
 372                                 /* Ok, we can drop this one, so let's
 373                                  * do so. */
 374                                 log_debug("Breaking order cycle by deleting job %s/%s", unit_id(k->unit), job_type_to_string(k->type));
 375                                 transaction_delete_unit(m, k->unit);
 376                                 return -EAGAIN;
 377                         }
 378
 379                         /* Check if this in fact was the beginning of
 380                          * the cycle */
 381                         if (k == j)
 382                                 break;
 383                 }
 384
 385                 return -ENOEXEC;
 386         }
 387
 388         /* Make the marker point to where we come from, so that we can
 389          * find our way backwards if we want to break a cycle */
 390         j->marker = from;
 391         j->generation = generation;
 392
 393         /* We assume that the the dependencies are bidirectional, and
 394          * hence can ignore UNIT_AFTER */
 395         SET_FOREACH(u, j->unit->meta.dependencies[UNIT_BEFORE], i) {
 396                 Job *o;
 397
 398                 /* Is there a job for this unit? */
 399                 if (!(o = hashmap_get(m->transaction_jobs, u)))
 400
 401                         /* Ok, there is no job for this in the
 402                          * transaction, but maybe there is already one
 403                          * running? */
 404                         if (!(o = u->meta.job))
 405                                 continue;
 406
 407                 if ((r = transaction_verify_order_one(m, o, j, generation)) < 0)
 408                         return r;
 409         }
 410
 411         return 0;
 412 }
 413
 414 static int transaction_verify_order(Manager *m, unsigned *generation) {
 415         Job *j;
 416         int r;
 417         Iterator i;
 418
 419         assert(m);
 420         assert(generation);
 421
 422         /* Check if the ordering graph is cyclic. If it is, try to fix
 423          * that up by dropping one of the jobs. */
 424
 425         HASHMAP_FOREACH(j, m->transaction_jobs, i)
 426                 if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
 427                         return r;
 428
 429         return 0;
 430 }
 431
 432 static void transaction_collect_garbage(Manager *m) {
 433         bool again;
 434
 435         assert(m);
 436
 437         /* Drop jobs that are not required by any other job */
 438
 439         do {
 440                 Iterator i;
 441                 Job *j;
 442
 443                 again = false;
 444
 445                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 446                         if (j->object_list)
 447                                 continue;
 448
 449                         log_debug("Garbage collecting job %s/%s", unit_id(j->unit), job_type_to_string(j->type));
 450                         transaction_delete_job(m, j);
 451                         again = true;
 452                         break;
 453                 }
 454
 455         } while (again);
 456 }
 457
 458 static int transaction_is_destructive(Manager *m, JobMode mode) {
 459         Iterator i;
 460         Job *j;
 461
 462         assert(m);
 463
 464         /* Checks whether applying this transaction means that
 465          * existing jobs would be replaced */
 466
 467         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 468
 469                 /* Assume merged */
 470                 assert(!j->transaction_prev);
 471                 assert(!j->transaction_next);
 472
 473                 if (j->unit->meta.job &&
 474                     j->unit->meta.job != j &&
 475                     !job_type_is_superset(j->type, j->unit->meta.job->type))
 476                         return -EEXIST;
 477         }
 478
 479         return 0;
 480 }
 481
 482 static void transaction_minimize_impact(Manager *m) {
 483         bool again;
 484         assert(m);
 485
 486         /* Drops all unnecessary jobs that reverse already active jobs
 487          * or that stop a running service. */
 488
 489         do {
 490                 Job *j;
 491                 Iterator i;
 492
 493                 again = false;
 494
 495                 HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 496                         LIST_FOREACH(transaction, j, j) {
 497
 498                                 /* If it matters, we shouldn't drop it */
 499                                 if (j->matters_to_anchor)
 500                                         continue;
 501
 502                                 /* Would this stop a running service?
 503                                  * Would this change an existing job?
 504                                  * If so, let's drop this entry */
 505                                 if ((j->type != JOB_STOP || UNIT_IS_INACTIVE_OR_DEACTIVATING(unit_active_state(j->unit))) &&
 506                                     (!j->unit->meta.job  || job_type_is_conflicting(j->type, j->unit->meta.job->state)))
 507                                         continue;
 508
 509                                 /* Ok, let's get rid of this */
 510                                 log_debug("Deleting %s/%s to minimize impact", unit_id(j->unit), job_type_to_string(j->type));
 511                                 transaction_delete_job(m, j);
 512                                 again = true;
 513                                 break;
 514                         }
 515
 516                         if (again)
 517                                 break;
 518                 }
 519
 520         } while (again);
 521 }
 522
 523 static int transaction_apply(Manager *m, JobMode mode) {
 524         Iterator i;
 525         Job *j;
 526         int r;
 527
 528         /* Moves the transaction jobs to the set of active jobs */
 529
 530         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 531                 /* Assume merged */
 532                 assert(!j->transaction_prev);
 533                 assert(!j->transaction_next);
 534
 535                 if (j->installed)
 536                         continue;
 537
 538                 if ((r = hashmap_put(m->jobs, UINT32_TO_PTR(j->id), j)) < 0)
 539                         goto rollback;
 540         }
 541
 542         while ((j = hashmap_steal_first(m->transaction_jobs))) {
 543                 if (j->installed)
 544                         continue;
 545
 546                 if (j->unit->meta.job)
 547                         job_free(j->unit->meta.job);
 548
 549                 j->unit->meta.job = j;
 550                 j->installed = true;
 551
 552                 /* We're fully installed. Now let's free data we don't
 553                  * need anymore. */
 554
 555                 assert(!j->transaction_next);
 556                 assert(!j->transaction_prev);
 557
 558         }
 559
 560         /* As last step, kill all remaining job dependencies. */
 561         transaction_clean_dependencies(m);
 562
 563         return 0;
 564
 565 rollback:
 566
 567         HASHMAP_FOREACH(j, m->transaction_jobs, i) {
 568                 if (j->installed)
 569                         continue;
 570
 571                 hashmap_remove(m->jobs, UINT32_TO_PTR(j->id));
 572         }
 573
 574         return r;
 575 }
 576
 577 static int transaction_activate(Manager *m, JobMode mode) {
 578         int r;
 579         unsigned generation = 1;
 580
 581         assert(m);
 582
 583         /* This applies the changes recorded in transaction_jobs to
 584          * the actual list of jobs, if possible. */
 585
 586         /* First step: figure out which jobs matter */
 587         transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
 588
 589         /* Second step: Try not to stop any running services if
 590          * we don't have to. Don't try to reverse running
 591          * jobs if we don't have to. */
 592         transaction_minimize_impact(m);
 593
 594         for (;;) {
 595                 /* Third step: Let's remove unneeded jobs that might
 596                  * be lurking. */
 597                 transaction_collect_garbage(m);
 598
 599                 /* Fourth step: verify order makes sense and correct
 600                  * cycles if necessary and possible */
 601                 if ((r = transaction_verify_order(m, &generation)) >= 0)
 602                         break;
 603
 604                 if (r != -EAGAIN)
 605                         goto rollback;
 606
 607                 /* Let's see if the resulting transaction ordering
 608                  * graph is still cyclic... */
 609         }
 610
 611         for (;;) {
 612                 /* Fifth step: let's drop unmergeable entries if
 613                  * necessary and possible, merge entries we can
 614                  * merge */
 615                 if ((r = transaction_merge_jobs(m)) >= 0)
 616                         break;
 617
 618                 if (r != -EAGAIN)
 619                         goto rollback;
 620
 621                 /* Sixth step: an entry got dropped, let's garbage
 622                  * collect its dependencies. */
 623                 transaction_collect_garbage(m);
 624
 625                 /* Let's see if the resulting transaction still has
 626                  * unmergeable entries ... */
 627         }
 628
 629         /* Seventh step: check whether we can actually apply this */
 630         if (mode == JOB_FAIL)
 631                 if ((r = transaction_is_destructive(m, mode)) < 0)
 632                         goto rollback;
 633
 634         /* Eights step: apply changes */
 635         if ((r = transaction_apply(m, mode)) < 0)
 636                 goto rollback;
 637
 638         assert(hashmap_isempty(m->transaction_jobs));
 639         assert(!m->transaction_anchor);
 640
 641         return 0;
 642
 643 rollback:
 644         transaction_abort(m);
 645         return r;
 646 }
 647
 648 static Job* transaction_add_one_job(Manager *m, JobType type, Unit *unit, bool force, bool *is_new) {
 649         Job *j, *f;
 650         int r;
 651
 652         assert(m);
 653         assert(unit);
 654
 655         /* Looks for an axisting prospective job and returns that. If
 656          * it doesn't exist it is created and added to the prospective
 657          * jobs list. */
 658
 659         f = hashmap_get(m->transaction_jobs, unit);
 660
 661         LIST_FOREACH(transaction, j, f) {
 662                 assert(j->unit == unit);
 663
 664                 if (j->type == type) {
 665                         if (is_new)
 666                                 *is_new = false;
 667                         return j;
 668                 }
 669         }
 670
 671         if (unit->meta.job && unit->meta.job->type == type)
 672                 j = unit->meta.job;
 673         else if (!(j = job_new(m, type, unit)))
 674                 return NULL;
 675
 676         j->generation = 0;
 677         j->marker = NULL;
 678         j->matters_to_anchor = false;
 679         j->forced = force;
 680
 681         LIST_PREPEND(Job, transaction, f, j);
 682
 683         if ((r = hashmap_replace(m->transaction_jobs, unit, f)) < 0) {
 684                 job_free(j);
 685                 return NULL;
 686         }
 687
 688         if (is_new)
 689                 *is_new = true;
 690
 691         return j;
 692 }
 693
 694 void manager_transaction_unlink_job(Manager *m, Job *j) {
 695         assert(m);
 696         assert(j);
 697
 698         if (j->transaction_prev)
 699                 j->transaction_prev->transaction_next = j->transaction_next;
 700         else if (j->transaction_next)
 701                 hashmap_replace(m->transaction_jobs, j->unit, j->transaction_next);
 702         else
 703                 hashmap_remove_value(m->transaction_jobs, j->unit, j);
 704
 705         if (j->transaction_next)
 706                 j->transaction_next->transaction_prev = j->transaction_prev;
 707
 708         j->transaction_prev = j->transaction_next = NULL;
 709
 710         while (j->subject_list)
 711                 job_dependency_free(j->subject_list);
 712
 713         while (j->object_list) {
 714                 Job *other = j->object_list->matters ? j->object_list->subject : NULL;
 715
 716                 job_dependency_free(j->object_list);
 717
 718                 if (other) {
 719                         log_debug("Deleting job %s/%s as dependency of job %s/%s",
 720                                   unit_id(other->unit), job_type_to_string(other->type),
 721                                   unit_id(j->unit), job_type_to_string(j->type));
 722                         transaction_delete_job(m, other);
 723                 }
 724         }
 725 }
 726
 727 static int transaction_add_job_and_dependencies(Manager *m, JobType type, Unit *unit, Job *by, bool matters, bool force, Job **_ret) {
 728         Job *ret;
 729         Iterator i;
 730         Unit *dep;
 731         int r;
 732         bool is_new;
 733
 734         assert(m);
 735         assert(type < _JOB_TYPE_MAX);
 736         assert(unit);
 737
 738         if (unit->meta.load_state != UNIT_LOADED)
 739                 return -EINVAL;
 740
 741         if (!unit_job_is_applicable(unit, type))
 742                 return -EBADR;
 743
 744         /* First add the job. */
 745         if (!(ret = transaction_add_one_job(m, type, unit, force, &is_new)))
 746                 return -ENOMEM;
 747
 748         /* Then, add a link to the job. */
 749         if (!job_dependency_new(by, ret, matters))
 750                 return -ENOMEM;
 751
 752         if (is_new) {
 753                 /* Finally, recursively add in all dependencies. */
 754                 if (type == JOB_START || type == JOB_RELOAD_OR_START) {
 755                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRES], i)
 756                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 757                                         goto fail;
 758                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUIRES], i)
 759                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 760                                         goto fail;
 761                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_WANTS], i)
 762                                 if ((r = transaction_add_job_and_dependencies(m, JOB_START, dep, ret, false, force, NULL)) < 0 && r != -EBADR)
 763                                         goto fail;
 764                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUISITE], i)
 765                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 766                                         goto fail;
 767                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_SOFT_REQUISITE], i)
 768                                 if ((r = transaction_add_job_and_dependencies(m, JOB_VERIFY_ACTIVE, dep, ret, !force, force, NULL)) < 0 && r != -EBADR)
 769                                         goto fail;
 770                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_CONFLICTS], i)
 771                                 if ((r = transaction_add_job_and_dependencies(m, JOB_STOP, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 772                                         goto fail;
 773
 774                 } else if (type == JOB_STOP || type == JOB_RESTART || type == JOB_TRY_RESTART) {
 775
 776                         SET_FOREACH(dep, ret->unit->meta.dependencies[UNIT_REQUIRED_BY], i)
 777                                 if ((r = transaction_add_job_and_dependencies(m, type, dep, ret, true, force, NULL)) < 0 && r != -EBADR)
 778                                         goto fail;
 779                 }
 780
 781                 /* JOB_VERIFY_STARTED, JOB_RELOAD require no dependency handling */
 782         }
 783
 784         return 0;
 785
 786 fail:
 787         return r;
 788 }
 789
 790 int manager_add_job(Manager *m, JobType type, Unit *unit, JobMode mode, bool force, Job **_ret) {
 791         int r;
 792         Job *ret;
 793
 794         assert(m);
 795         assert(type < _JOB_TYPE_MAX);
 796         assert(unit);
 797         assert(mode < _JOB_MODE_MAX);
 798
 799         if ((r = transaction_add_job_and_dependencies(m, type, unit, NULL, true, force, &ret))) {
 800                 transaction_abort(m);
 801                 return r;
 802         }
 803
 804         if ((r = transaction_activate(m, mode)) < 0)
 805                 return r;
 806
 807         if (_ret)
 808                 *_ret = ret;
 809
 810         return 0;
 811 }
 812
 813 Job *manager_get_job(Manager *m, uint32_t id) {
 814         assert(m);
 815
 816         return hashmap_get(m->jobs, UINT32_TO_PTR(id));
 817 }
 818
 819 Unit *manager_get_unit(Manager *m, const char *name) {
 820         assert(m);
 821         assert(name);
 822
 823         return hashmap_get(m->units, name);
 824 }
 825
 826 static void dispatch_load_queue(Manager *m) {
 827         Meta *meta;
 828
 829         assert(m);
 830
 831         /* Make sure we are not run recursively */
 832         if (m->dispatching_load_queue)
 833                 return;
 834
 835         m->dispatching_load_queue = true;
 836
 837         /* Dispatches the load queue. Takes a unit from the queue and
 838          * tries to load its data until the queue is empty */
 839
 840         while ((meta = m->load_queue)) {
 841                 assert(meta->in_load_queue);
 842
 843                 unit_load(UNIT(meta));
 844         }
 845
 846         m->dispatching_load_queue = false;
 847 }
 848
 849 int manager_load_unit(Manager *m, const char *path, Unit **_ret) {
 850         Unit *ret;
 851         int r;
 852         const char *name;
 853
 854         assert(m);
 855         assert(path);
 856         assert(_ret);
 857
 858         /* This will load the service information files, but not actually
 859          * start any services or anything. */
 860
 861         name = file_name_from_path(path);
 862
 863         if ((ret = manager_get_unit(m, name))) {
 864                 *_ret = ret;
 865                 return 0;
 866         }
 867
 868         if (!(ret = unit_new(m)))
 869                 return -ENOMEM;
 870
 871         if (is_path(path)) {
 872                 if (!(ret->meta.load_path = strdup(path))) {
 873                         unit_free(ret);
 874                         return -ENOMEM;
 875                 }
 876         }
 877
 878         if ((r = unit_add_name(ret, name)) < 0) {
 879                 unit_free(ret);
 880                 return r;
 881         }
 882
 883         unit_add_to_load_queue(ret);
 884         dispatch_load_queue(m);
 885
 886         *_ret = ret;
 887         return 0;
 888 }
 889
 890 void manager_dump_jobs(Manager *s, FILE *f, const char *prefix) {
 891         Iterator i;
 892         Job *j;
 893
 894         assert(s);
 895         assert(f);
 896
 897         HASHMAP_FOREACH(j, s->jobs, i)
 898                 job_dump(j, f, prefix);
 899 }
 900
 901 void manager_dump_units(Manager *s, FILE *f, const char *prefix) {
 902         Iterator i;
 903         Unit *u;
 904         const char *t;
 905
 906         assert(s);
 907         assert(f);
 908
 909         HASHMAP_FOREACH_KEY(u, t, s->units, i)
 910                 if (unit_id(u) == t)
 911                         unit_dump(u, f, prefix);
 912 }
 913
 914 void manager_clear_jobs(Manager *m) {
 915         Job *j;
 916
 917         assert(m);
 918
 919         transaction_abort(m);
 920
 921         while ((j = hashmap_first(m->jobs)))
 922                 job_free(j);
 923 }
 924
 925 void manager_dispatch_run_queue(Manager *m) {
 926         Job *j;
 927
 928         if (m->dispatching_run_queue)
 929                 return;
 930
 931         m->dispatching_run_queue = true;
 932
 933         while ((j = m->run_queue)) {
 934                 assert(j->installed);
 935                 assert(j->in_run_queue);
 936
 937                 job_run_and_invalidate(j);
 938         }
 939
 940         m->dispatching_run_queue = false;
 941 }
 942
 943 static int manager_dispatch_sigchld(Manager *m) {
 944         assert(m);
 945
 946         for (;;) {
 947                 siginfo_t si;
 948                 Unit *u;
 949
 950                 zero(si);
 951                 if (waitid(P_ALL, 0, &si, WNOHANG) < 0)
 952                         return -errno;
 953
 954                 if (si.si_pid == 0)
 955                         break;
 956
 957                 if (si.si_code != CLD_EXITED && si.si_code != CLD_KILLED && si.si_code != CLD_DUMPED)
 958                         continue;
 959
 960                 if (!(u = hashmap_remove(m->watch_pids, UINT32_TO_PTR(si.si_pid))))
 961                         continue;
 962
 963                 UNIT_VTABLE(u)->sigchld_event(u, si.si_pid, si.si_code, si.si_status);
 964         }
 965
 966         return 0;
 967 }
 968
 969 static int manager_process_signal_fd(Manager *m) {
 970         ssize_t n;
 971         struct signalfd_siginfo sfsi;
 972         bool sigchld = false;
 973
 974         assert(m);
 975
 976         for (;;) {
 977                 if ((n = read(m->signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
 978
 979                         if (n >= 0)
 980                                 return -EIO;
 981
 982                         if (errno == EAGAIN)
 983                                 return 0;
 984
 985                         return -errno;
 986                 }
 987
 988                 if (sfsi.ssi_signo == SIGCHLD)
 989                         sigchld = true;
 990         }
 991
 992         if (sigchld)
 993                 return manager_dispatch_sigchld(m);
 994
 995         return 0;
 996 }
 997
 998 static int process_event(Manager *m, struct epoll_event *ev) {
 999         int r;
1000
1001         assert(m);
1002         assert(ev);
1003
1004         switch (ev->data.u32) {
1005
1006                 case MANAGER_SIGNAL:
1007                         assert(ev->data.fd == m->signal_fd);
1008
1009                         /* An incoming signal? */
1010                         if (ev->events != POLLIN)
1011                                 return -EINVAL;
1012
1013                         if ((r = manager_process_signal_fd(m)) < 0)
1014                                 return -r;
1015
1016                         break;
1017
1018                 case MANAGER_FD: {
1019                         Unit *u;
1020
1021                         /* Some fd event, to be dispatched to the units */
1022                         assert_se(u = ev->data.ptr);
1023                         UNIT_VTABLE(u)->fd_event(u, ev->data.fd, ev->events);
1024                         break;
1025                 }
1026
1027                 case MANAGER_TIMER: {
1028                         Unit *u;
1029                         uint64_t v;
1030                         ssize_t k;
1031
1032                         /* Some timer event, to be dispatched to the units */
1033                         if ((k = read(ev->data.fd, &v, sizeof(v))) != sizeof(v)) {
1034
1035                                 if (k < 0 && (errno == EINTR || errno == EAGAIN))
1036                                         break;
1037
1038                                 return k < 0 ? -errno : -EIO;
1039                         }
1040
1041                         assert_se(u = ev->data.ptr);
1042                         UNIT_VTABLE(u)->timer_event(u, ev->data.fd, v);
1043                         break;
1044                 }
1045
1046                 default:
1047                         assert_not_reached("Unknown epoll event type.");
1048         }
1049
1050         return 0;
1051 }
1052
1053 int manager_loop(Manager *m) {
1054         int r;
1055
1056         assert(m);
1057
1058         for (;;) {
1059                 struct epoll_event events[32];
1060                 int n, i;
1061
1062                 manager_dispatch_run_queue(m);
1063
1064                 if ((n = epoll_wait(m->epoll_fd, events, ELEMENTSOF(events), -1)) < 0) {
1065
1066                         if (errno == -EINTR)
1067                                 continue;
1068
1069                         return -errno;
1070                 }
1071
1072                 for (i = 0; i < n; i++)
1073                         if ((r = process_event(m, events + i)) < 0)
1074                                 return r;
1075         }
1076 }