1 /* 2 * work_thread.c - threads implementation for blocking worker child. 3 */ 4 #include <config.h> 5 #include "ntp_workimpl.h" 6 7 #ifdef WORK_THREAD 8 9 #include <stdio.h> 10 #include <ctype.h> 11 #include <signal.h> 12 #ifndef SYS_WINNT 13 #include <pthread.h> 14 #endif 15 16 #include "ntp_stdlib.h" 17 #include "ntp_malloc.h" 18 #include "ntp_syslog.h" 19 #include "ntpd.h" 20 #include "ntp_io.h" 21 #include "ntp_assert.h" 22 #include "ntp_unixtime.h" 23 #include "timespecops.h" 24 #include "ntp_worker.h" 25 26 #define CHILD_EXIT_REQ ((blocking_pipe_header *)(intptr_t)-1) 27 #define CHILD_GONE_RESP CHILD_EXIT_REQ 28 /* Queue size increments: 29 * The request queue grows a bit faster than the response queue -- the 30 * daemon can push requests and pull results faster on avarage than the 31 * worker can process requests and push results... If this really pays 32 * off is debatable. 33 */ 34 #define WORKITEMS_ALLOC_INC 16 35 #define RESPONSES_ALLOC_INC 4 36 37 /* Fiddle with min/max stack sizes. 64kB minimum seems to work, so we 38 * set the maximum to 256kB. If the minimum goes below the 39 * system-defined minimum stack size, we have to adjust accordingly. 40 */ 41 #ifndef THREAD_MINSTACKSIZE 42 # define THREAD_MINSTACKSIZE (64U * 1024) 43 #endif 44 45 #ifndef THREAD_MAXSTACKSIZE 46 # define THREAD_MAXSTACKSIZE (256U * 1024) 47 #endif 48 49 /* need a good integer to store a pointer... */ 50 #ifndef UINTPTR_T 51 # if defined(UINTPTR_MAX) 52 # define UINTPTR_T uintptr_t 53 # elif defined(UINT_PTR) 54 # define UINTPTR_T UINT_PTR 55 # else 56 # define UINTPTR_T size_t 57 # endif 58 #endif 59 60 61 #ifdef SYS_WINNT 62 63 # define thread_exit(c) _endthreadex(c) 64 # define tickle_sem(sh) ReleaseSemaphore((sh->shnd), 1, NULL) 65 u_int WINAPI blocking_thread(void *); 66 static BOOL same_os_sema(const sem_ref obj, void * osobj); 67 68 #else 69 70 # define thread_exit(c) pthread_exit((void*)(UINTPTR_T)(c)) 71 # define tickle_sem sem_post 72 void * blocking_thread(void *); 73 static void block_thread_signals(sigset_t *); 74 75 #endif 76 77 #ifdef WORK_PIPE 78 addremove_io_fd_func addremove_io_fd; 79 #else 80 addremove_io_semaphore_func addremove_io_semaphore; 81 #endif 82 83 static void start_blocking_thread(blocking_child *); 84 static void start_blocking_thread_internal(blocking_child *); 85 static void prepare_child_sems(blocking_child *); 86 static int wait_for_sem(sem_ref, struct timespec *); 87 static int ensure_workitems_empty_slot(blocking_child *); 88 static int ensure_workresp_empty_slot(blocking_child *); 89 static int queue_req_pointer(blocking_child *, blocking_pipe_header *); 90 static void cleanup_after_child(blocking_child *); 91 92 static sema_type worker_mmutex; 93 static sem_ref worker_memlock; 94 95 /* -------------------------------------------------------------------- 96 * locking the global worker state table (and other global stuff) 97 */ 98 void 99 worker_global_lock( 100 int inOrOut) 101 { 102 if (worker_memlock) { 103 if (inOrOut) 104 wait_for_sem(worker_memlock, NULL); 105 else 106 tickle_sem(worker_memlock); 107 } 108 } 109 110 /* -------------------------------------------------------------------- 111 * implementation isolation wrapper 112 */ 113 void 114 exit_worker( 115 int exitcode 116 ) 117 { 118 thread_exit(exitcode); /* see #define thread_exit */ 119 } 120 121 /* -------------------------------------------------------------------- 122 * sleep for a given time or until the wakup semaphore is tickled. 123 */ 124 int 125 worker_sleep( 126 blocking_child * c, 127 time_t seconds 128 ) 129 { 130 struct timespec until; 131 int rc; 132 133 # ifdef HAVE_CLOCK_GETTIME 134 if (0 != clock_gettime(CLOCK_REALTIME, &until)) { 135 msyslog(LOG_ERR, "worker_sleep: clock_gettime() failed: %m"); 136 return -1; 137 } 138 # else 139 if (0 != getclock(TIMEOFDAY, &until)) { 140 msyslog(LOG_ERR, "worker_sleep: getclock() failed: %m"); 141 return -1; 142 } 143 # endif 144 until.tv_sec += seconds; 145 rc = wait_for_sem(c->wake_scheduled_sleep, &until); 146 if (0 == rc) 147 return -1; 148 if (-1 == rc && ETIMEDOUT == errno) 149 return 0; 150 msyslog(LOG_ERR, "worker_sleep: sem_timedwait: %m"); 151 return -1; 152 } 153 154 155 /* -------------------------------------------------------------------- 156 * Wake up a worker that takes a nap. 157 */ 158 void 159 interrupt_worker_sleep(void) 160 { 161 u_int idx; 162 blocking_child * c; 163 164 for (idx = 0; idx < blocking_children_alloc; idx++) { 165 c = blocking_children[idx]; 166 if (NULL == c || NULL == c->wake_scheduled_sleep) 167 continue; 168 tickle_sem(c->wake_scheduled_sleep); 169 } 170 } 171 172 /* -------------------------------------------------------------------- 173 * Make sure there is an empty slot at the head of the request 174 * queue. Tell if the queue is currently empty. 175 */ 176 static int 177 ensure_workitems_empty_slot( 178 blocking_child *c 179 ) 180 { 181 /* 182 ** !!! PRECONDITION: caller holds access lock! 183 ** 184 ** This simply tries to increase the size of the buffer if it 185 ** becomes full. The resize operation does *not* maintain the 186 ** order of requests, but that should be irrelevant since the 187 ** processing is considered asynchronous anyway. 188 ** 189 ** Return if the buffer is currently empty. 190 */ 191 192 static const size_t each = 193 sizeof(blocking_children[0]->workitems[0]); 194 195 size_t new_alloc; 196 size_t slots_used; 197 size_t sidx; 198 199 slots_used = c->head_workitem - c->tail_workitem; 200 if (slots_used >= c->workitems_alloc) { 201 new_alloc = c->workitems_alloc + WORKITEMS_ALLOC_INC; 202 c->workitems = erealloc(c->workitems, new_alloc * each); 203 for (sidx = c->workitems_alloc; sidx < new_alloc; ++sidx) 204 c->workitems[sidx] = NULL; 205 c->tail_workitem = 0; 206 c->head_workitem = c->workitems_alloc; 207 c->workitems_alloc = new_alloc; 208 } 209 INSIST(NULL == c->workitems[c->head_workitem % c->workitems_alloc]); 210 return (0 == slots_used); 211 } 212 213 /* -------------------------------------------------------------------- 214 * Make sure there is an empty slot at the head of the response 215 * queue. Tell if the queue is currently empty. 216 */ 217 static int 218 ensure_workresp_empty_slot( 219 blocking_child *c 220 ) 221 { 222 /* 223 ** !!! PRECONDITION: caller holds access lock! 224 ** 225 ** Works like the companion function above. 226 */ 227 228 static const size_t each = 229 sizeof(blocking_children[0]->responses[0]); 230 231 size_t new_alloc; 232 size_t slots_used; 233 size_t sidx; 234 235 slots_used = c->head_response - c->tail_response; 236 if (slots_used >= c->responses_alloc) { 237 new_alloc = c->responses_alloc + RESPONSES_ALLOC_INC; 238 c->responses = erealloc(c->responses, new_alloc * each); 239 for (sidx = c->responses_alloc; sidx < new_alloc; ++sidx) 240 c->responses[sidx] = NULL; 241 c->tail_response = 0; 242 c->head_response = c->responses_alloc; 243 c->responses_alloc = new_alloc; 244 } 245 INSIST(NULL == c->responses[c->head_response % c->responses_alloc]); 246 return (0 == slots_used); 247 } 248 249 250 /* -------------------------------------------------------------------- 251 * queue_req_pointer() - append a work item or idle exit request to 252 * blocking_workitems[]. Employ proper locking. 253 */ 254 static int 255 queue_req_pointer( 256 blocking_child * c, 257 blocking_pipe_header * hdr 258 ) 259 { 260 size_t qhead; 261 262 /* >>>> ACCESS LOCKING STARTS >>>> */ 263 wait_for_sem(c->accesslock, NULL); 264 ensure_workitems_empty_slot(c); 265 qhead = c->head_workitem; 266 c->workitems[qhead % c->workitems_alloc] = hdr; 267 c->head_workitem = 1 + qhead; 268 tickle_sem(c->accesslock); 269 /* <<<< ACCESS LOCKING ENDS <<<< */ 270 271 /* queue consumer wake-up notification */ 272 tickle_sem(c->workitems_pending); 273 274 return 0; 275 } 276 277 /* -------------------------------------------------------------------- 278 * API function to make sure a worker is running, a proper private copy 279 * of the data is made, the data eneterd into the queue and the worker 280 * is signalled. 281 */ 282 int 283 send_blocking_req_internal( 284 blocking_child * c, 285 blocking_pipe_header * hdr, 286 void * data 287 ) 288 { 289 blocking_pipe_header * threadcopy; 290 size_t payload_octets; 291 292 REQUIRE(hdr != NULL); 293 REQUIRE(data != NULL); 294 DEBUG_REQUIRE(BLOCKING_REQ_MAGIC == hdr->magic_sig); 295 296 if (hdr->octets <= sizeof(*hdr)) 297 return 1; /* failure */ 298 payload_octets = hdr->octets - sizeof(*hdr); 299 300 if (NULL == c->thread_ref) 301 start_blocking_thread(c); 302 threadcopy = emalloc(hdr->octets); 303 memcpy(threadcopy, hdr, sizeof(*hdr)); 304 memcpy((char *)threadcopy + sizeof(*hdr), data, payload_octets); 305 306 return queue_req_pointer(c, threadcopy); 307 } 308 309 /* -------------------------------------------------------------------- 310 * Wait for the 'incoming queue no longer empty' signal, lock the shared 311 * structure and dequeue an item. 312 */ 313 blocking_pipe_header * 314 receive_blocking_req_internal( 315 blocking_child * c 316 ) 317 { 318 blocking_pipe_header * req; 319 size_t qhead, qtail; 320 321 req = NULL; 322 do { 323 /* wait for tickle from the producer side */ 324 wait_for_sem(c->workitems_pending, NULL); 325 326 /* >>>> ACCESS LOCKING STARTS >>>> */ 327 wait_for_sem(c->accesslock, NULL); 328 qhead = c->head_workitem; 329 do { 330 qtail = c->tail_workitem; 331 if (qhead == qtail) 332 break; 333 c->tail_workitem = qtail + 1; 334 qtail %= c->workitems_alloc; 335 req = c->workitems[qtail]; 336 c->workitems[qtail] = NULL; 337 } while (NULL == req); 338 tickle_sem(c->accesslock); 339 /* <<<< ACCESS LOCKING ENDS <<<< */ 340 341 } while (NULL == req); 342 343 INSIST(NULL != req); 344 if (CHILD_EXIT_REQ == req) { /* idled out */ 345 send_blocking_resp_internal(c, CHILD_GONE_RESP); 346 req = NULL; 347 } 348 349 return req; 350 } 351 352 /* -------------------------------------------------------------------- 353 * Push a response into the return queue and eventually tickle the 354 * receiver. 355 */ 356 int 357 send_blocking_resp_internal( 358 blocking_child * c, 359 blocking_pipe_header * resp 360 ) 361 { 362 size_t qhead; 363 int empty; 364 365 /* >>>> ACCESS LOCKING STARTS >>>> */ 366 wait_for_sem(c->accesslock, NULL); 367 empty = ensure_workresp_empty_slot(c); 368 qhead = c->head_response; 369 c->responses[qhead % c->responses_alloc] = resp; 370 c->head_response = 1 + qhead; 371 tickle_sem(c->accesslock); 372 /* <<<< ACCESS LOCKING ENDS <<<< */ 373 374 /* queue consumer wake-up notification */ 375 if (empty) 376 { 377 # ifdef WORK_PIPE 378 if (1 != write(c->resp_write_pipe, "", 1)) 379 msyslog(LOG_WARNING, "async resolver: blocking_get%sinfo" 380 " failed to notify main thread!", 381 (BLOCKING_GETNAMEINFO == resp->rtype) 382 ? "name" 383 : "addr" 384 ); 385 # else 386 tickle_sem(c->responses_pending); 387 # endif 388 } 389 return 0; 390 } 391 392 393 #ifndef WORK_PIPE 394 395 /* -------------------------------------------------------------------- 396 * Check if a (Windows-)handle to a semaphore is actually the same we 397 * are using inside the sema wrapper. 398 */ 399 static BOOL 400 same_os_sema( 401 const sem_ref obj, 402 void* osh 403 ) 404 { 405 return obj && osh && (obj->shnd == (HANDLE)osh); 406 } 407 408 /* -------------------------------------------------------------------- 409 * Find the shared context that associates to an OS handle and make sure 410 * the data is dequeued and processed. 411 */ 412 void 413 handle_blocking_resp_sem( 414 void * context 415 ) 416 { 417 blocking_child * c; 418 u_int idx; 419 420 c = NULL; 421 for (idx = 0; idx < blocking_children_alloc; idx++) { 422 c = blocking_children[idx]; 423 if (c != NULL && 424 c->thread_ref != NULL && 425 same_os_sema(c->responses_pending, context)) 426 break; 427 } 428 if (idx < blocking_children_alloc) 429 process_blocking_resp(c); 430 } 431 #endif /* !WORK_PIPE */ 432 433 /* -------------------------------------------------------------------- 434 * Fetch the next response from the return queue. In case of signalling 435 * via pipe, make sure the pipe is flushed, too. 436 */ 437 blocking_pipe_header * 438 receive_blocking_resp_internal( 439 blocking_child * c 440 ) 441 { 442 blocking_pipe_header * removed; 443 size_t qhead, qtail, slot; 444 445 #ifdef WORK_PIPE 446 int rc; 447 char scratch[32]; 448 449 do 450 rc = read(c->resp_read_pipe, scratch, sizeof(scratch)); 451 while (-1 == rc && EINTR == errno); 452 #endif 453 454 /* >>>> ACCESS LOCKING STARTS >>>> */ 455 wait_for_sem(c->accesslock, NULL); 456 qhead = c->head_response; 457 qtail = c->tail_response; 458 for (removed = NULL; !removed && (qhead != qtail); ++qtail) { 459 slot = qtail % c->responses_alloc; 460 removed = c->responses[slot]; 461 c->responses[slot] = NULL; 462 } 463 c->tail_response = qtail; 464 tickle_sem(c->accesslock); 465 /* <<<< ACCESS LOCKING ENDS <<<< */ 466 467 if (NULL != removed) { 468 DEBUG_ENSURE(CHILD_GONE_RESP == removed || 469 BLOCKING_RESP_MAGIC == removed->magic_sig); 470 } 471 if (CHILD_GONE_RESP == removed) { 472 cleanup_after_child(c); 473 removed = NULL; 474 } 475 476 return removed; 477 } 478 479 /* -------------------------------------------------------------------- 480 * Light up a new worker. 481 */ 482 static void 483 start_blocking_thread( 484 blocking_child * c 485 ) 486 { 487 488 DEBUG_INSIST(!c->reusable); 489 490 prepare_child_sems(c); 491 start_blocking_thread_internal(c); 492 } 493 494 /* -------------------------------------------------------------------- 495 * Create a worker thread. There are several differences between POSIX 496 * and Windows, of course -- most notably the Windows thread is a 497 * detached thread, and we keep the handle around until we want to get 498 * rid of the thread. The notification scheme also differs: Windows 499 * makes use of semaphores in both directions, POSIX uses a pipe for 500 * integration with 'select()' or alike. 501 */ 502 static void 503 start_blocking_thread_internal( 504 blocking_child * c 505 ) 506 #ifdef SYS_WINNT 507 { 508 BOOL resumed; 509 510 c->thread_ref = NULL; 511 (*addremove_io_semaphore)(c->responses_pending->shnd, FALSE); 512 c->thr_table[0].thnd = 513 (HANDLE)_beginthreadex( 514 NULL, 515 0, 516 &blocking_thread, 517 c, 518 CREATE_SUSPENDED, 519 NULL); 520 521 if (NULL == c->thr_table[0].thnd) { 522 msyslog(LOG_ERR, "start blocking thread failed: %m"); 523 exit(-1); 524 } 525 /* remember the thread priority is only within the process class */ 526 if (!SetThreadPriority(c->thr_table[0].thnd, 527 THREAD_PRIORITY_BELOW_NORMAL)) { 528 msyslog(LOG_ERR, "Error lowering blocking thread priority: %m"); 529 } 530 if (NULL != pSetThreadDescription) { 531 (*pSetThreadDescription)(c->thr_table[0].thnd, L"ntp_worker"); 532 } 533 resumed = ResumeThread(c->thr_table[0].thnd); 534 DEBUG_INSIST(resumed); 535 c->thread_ref = &c->thr_table[0]; 536 } 537 #else /* pthreads start_blocking_thread_internal() follows */ 538 { 539 # ifdef NEED_PTHREAD_INIT 540 static int pthread_init_called; 541 # endif 542 pthread_attr_t thr_attr; 543 int rc; 544 int pipe_ends[2]; /* read then write */ 545 int is_pipe; 546 int flags; 547 size_t ostacksize; 548 size_t nstacksize; 549 sigset_t saved_sig_mask; 550 551 c->thread_ref = NULL; 552 553 # ifdef NEED_PTHREAD_INIT 554 /* 555 * from lib/isc/unix/app.c: 556 * BSDI 3.1 seg faults in pthread_sigmask() if we don't do this. 557 */ 558 if (!pthread_init_called) { 559 pthread_init(); 560 pthread_init_called = TRUE; 561 } 562 # endif 563 564 rc = pipe_socketpair(&pipe_ends[0], &is_pipe); 565 if (0 != rc) { 566 msyslog(LOG_ERR, "start_blocking_thread: pipe_socketpair() %m"); 567 exit(1); 568 } 569 c->resp_read_pipe = move_fd(pipe_ends[0]); 570 c->resp_write_pipe = move_fd(pipe_ends[1]); 571 c->ispipe = is_pipe; 572 flags = fcntl(c->resp_read_pipe, F_GETFL, 0); 573 if (-1 == flags) { 574 msyslog(LOG_ERR, "start_blocking_thread: fcntl(F_GETFL) %m"); 575 exit(1); 576 } 577 rc = fcntl(c->resp_read_pipe, F_SETFL, O_NONBLOCK | flags); 578 if (-1 == rc) { 579 msyslog(LOG_ERR, 580 "start_blocking_thread: fcntl(F_SETFL, O_NONBLOCK) %m"); 581 exit(1); 582 } 583 (*addremove_io_fd)(c->resp_read_pipe, c->ispipe, FALSE); 584 pthread_attr_init(&thr_attr); 585 pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED); 586 #if defined(HAVE_PTHREAD_ATTR_GETSTACKSIZE) && \ 587 defined(HAVE_PTHREAD_ATTR_SETSTACKSIZE) 588 rc = pthread_attr_getstacksize(&thr_attr, &ostacksize); 589 if (0 != rc) { 590 msyslog(LOG_ERR, 591 "start_blocking_thread: pthread_attr_getstacksize() -> %s", 592 strerror(rc)); 593 } else { 594 nstacksize = ostacksize; 595 /* order is important here: first clamp on upper limit, 596 * and the PTHREAD min stack size is ultimate override! 597 */ 598 if (nstacksize > THREAD_MAXSTACKSIZE) 599 nstacksize = THREAD_MAXSTACKSIZE; 600 # ifdef PTHREAD_STACK_MAX 601 if (nstacksize > PTHREAD_STACK_MAX) 602 nstacksize = PTHREAD_STACK_MAX; 603 # endif 604 605 /* now clamp on lower stack limit. */ 606 if (nstacksize < THREAD_MINSTACKSIZE) 607 nstacksize = THREAD_MINSTACKSIZE; 608 # ifdef PTHREAD_STACK_MIN 609 if (nstacksize < PTHREAD_STACK_MIN) 610 nstacksize = PTHREAD_STACK_MIN; 611 # endif 612 613 if (nstacksize != ostacksize) 614 rc = pthread_attr_setstacksize(&thr_attr, nstacksize); 615 if (0 != rc) 616 msyslog(LOG_ERR, 617 "start_blocking_thread: pthread_attr_setstacksize(0x%lx -> 0x%lx) -> %s", 618 (u_long)ostacksize, (u_long)nstacksize, 619 strerror(rc)); 620 } 621 #else 622 UNUSED_ARG(nstacksize); 623 UNUSED_ARG(ostacksize); 624 #endif 625 #if defined(PTHREAD_SCOPE_SYSTEM) && defined(NEED_PTHREAD_SCOPE_SYSTEM) 626 pthread_attr_setscope(&thr_attr, PTHREAD_SCOPE_SYSTEM); 627 #endif 628 c->thread_ref = emalloc_zero(sizeof(*c->thread_ref)); 629 block_thread_signals(&saved_sig_mask); 630 rc = pthread_create(&c->thr_table[0], &thr_attr, 631 &blocking_thread, c); 632 pthread_sigmask(SIG_SETMASK, &saved_sig_mask, NULL); 633 pthread_attr_destroy(&thr_attr); 634 if (0 != rc) { 635 msyslog(LOG_ERR, "start_blocking_thread: pthread_create() -> %s", 636 strerror(rc)); 637 exit(1); 638 } 639 c->thread_ref = &c->thr_table[0]; 640 } 641 #endif 642 643 /* -------------------------------------------------------------------- 644 * block_thread_signals() 645 * 646 * Temporarily block signals used by ntpd main thread, so that signal 647 * mask inherited by child threads leaves them blocked. Returns prior 648 * active signal mask via pmask, to be restored by the main thread 649 * after pthread_create(). 650 */ 651 #ifndef SYS_WINNT 652 void 653 block_thread_signals( 654 sigset_t * pmask 655 ) 656 { 657 sigset_t block; 658 659 sigemptyset(&block); 660 # ifdef HAVE_SIGNALED_IO 661 # ifdef SIGIO 662 sigaddset(&block, SIGIO); 663 # endif 664 # ifdef SIGPOLL 665 sigaddset(&block, SIGPOLL); 666 # endif 667 # endif /* HAVE_SIGNALED_IO */ 668 sigaddset(&block, SIGALRM); 669 sigaddset(&block, MOREDEBUGSIG); 670 sigaddset(&block, LESSDEBUGSIG); 671 # ifdef SIGDIE1 672 sigaddset(&block, SIGDIE1); 673 # endif 674 # ifdef SIGDIE2 675 sigaddset(&block, SIGDIE2); 676 # endif 677 # ifdef SIGDIE3 678 sigaddset(&block, SIGDIE3); 679 # endif 680 # ifdef SIGDIE4 681 sigaddset(&block, SIGDIE4); 682 # endif 683 # ifdef SIGBUS 684 sigaddset(&block, SIGBUS); 685 # endif 686 sigemptyset(pmask); 687 pthread_sigmask(SIG_BLOCK, &block, pmask); 688 } 689 #endif /* !SYS_WINNT */ 690 691 692 /* -------------------------------------------------------------------- 693 * Create & destroy semaphores. This is sufficiently different between 694 * POSIX and Windows to warrant wrapper functions and close enough to 695 * use the concept of synchronization via semaphore for all platforms. 696 */ 697 static sem_ref 698 create_sema( 699 sema_type* semptr, 700 u_int inival, 701 u_int maxval) 702 { 703 #ifdef SYS_WINNT 704 705 long svini, svmax; 706 if (NULL != semptr) { 707 svini = (inival < LONG_MAX) 708 ? (long)inival : LONG_MAX; 709 svmax = (maxval < LONG_MAX && maxval > 0) 710 ? (long)maxval : LONG_MAX; 711 semptr->shnd = CreateSemaphore(NULL, svini, svmax, NULL); 712 if (NULL == semptr->shnd) 713 semptr = NULL; 714 } 715 716 #else 717 718 (void)maxval; 719 if (semptr && sem_init(semptr, FALSE, inival)) 720 semptr = NULL; 721 722 #endif 723 724 return semptr; 725 } 726 727 /* ------------------------------------------------------------------ */ 728 static sem_ref 729 delete_sema( 730 sem_ref obj) 731 { 732 733 # ifdef SYS_WINNT 734 735 if (obj) { 736 if (obj->shnd) 737 CloseHandle(obj->shnd); 738 obj->shnd = NULL; 739 } 740 741 # else 742 743 if (obj) 744 sem_destroy(obj); 745 746 # endif 747 748 return NULL; 749 } 750 751 /* -------------------------------------------------------------------- 752 * prepare_child_sems() 753 * 754 * create sync & access semaphores 755 * 756 * All semaphores are cleared, only the access semaphore has 1 unit. 757 * Childs wait on 'workitems_pending', then grabs 'sema_access' 758 * and dequeues jobs. When done, 'sema_access' is given one unit back. 759 * 760 * The producer grabs 'sema_access', manages the queue, restores 761 * 'sema_access' and puts one unit into 'workitems_pending'. 762 * 763 * The story goes the same for the response queue. 764 */ 765 static void 766 prepare_child_sems( 767 blocking_child *c 768 ) 769 { 770 if (NULL == worker_memlock) 771 worker_memlock = create_sema(&worker_mmutex, 1, 1); 772 773 c->accesslock = create_sema(&c->sem_table[0], 1, 1); 774 c->workitems_pending = create_sema(&c->sem_table[1], 0, 0); 775 c->wake_scheduled_sleep = create_sema(&c->sem_table[2], 0, 1); 776 # ifndef WORK_PIPE 777 c->responses_pending = create_sema(&c->sem_table[3], 0, 0); 778 # endif 779 } 780 781 /* -------------------------------------------------------------------- 782 * wait for semaphore. Where the wait can be interrupted, it will 783 * internally resume -- When this function returns, there is either no 784 * semaphore at all, a timeout occurred, or the caller could 785 * successfully take a token from the semaphore. 786 * 787 * For untimed wait, not checking the result of this function at all is 788 * definitely an option. 789 */ 790 static int 791 wait_for_sem( 792 sem_ref sem, 793 struct timespec * timeout /* wall-clock */ 794 ) 795 #ifdef SYS_WINNT 796 { 797 struct timespec now; 798 struct timespec delta; 799 DWORD msec; 800 DWORD rc; 801 802 if (!(sem && sem->shnd)) { 803 errno = EINVAL; 804 return -1; 805 } 806 807 if (NULL == timeout) { 808 msec = INFINITE; 809 } else { 810 getclock(TIMEOFDAY, &now); 811 delta = sub_tspec(*timeout, now); 812 if (delta.tv_sec < 0) { 813 msec = 0; 814 } else if ((delta.tv_sec + 1) >= (MAXDWORD / 1000)) { 815 msec = INFINITE; 816 } else { 817 msec = 1000 * (DWORD)delta.tv_sec; 818 msec += delta.tv_nsec / (1000 * 1000); 819 } 820 } 821 rc = WaitForSingleObject(sem->shnd, msec); 822 if (WAIT_OBJECT_0 == rc) 823 return 0; 824 if (WAIT_TIMEOUT == rc) { 825 errno = ETIMEDOUT; 826 return -1; 827 } 828 msyslog(LOG_ERR, "WaitForSingleObject unexpected 0x%x", rc); 829 errno = EFAULT; 830 return -1; 831 } 832 #else /* pthreads wait_for_sem() follows */ 833 { 834 int rc = -1; 835 836 if (sem) do { 837 if (NULL == timeout) 838 rc = sem_wait(sem); 839 else 840 rc = sem_timedwait(sem, timeout); 841 } while (rc == -1 && errno == EINTR); 842 else 843 errno = EINVAL; 844 845 return rc; 846 } 847 #endif 848 849 /* -------------------------------------------------------------------- 850 * blocking_thread - thread functions have WINAPI (aka 'stdcall') 851 * calling conventions under Windows and POSIX-defined signature 852 * otherwise. 853 */ 854 #ifdef SYS_WINNT 855 u_int WINAPI 856 #else 857 void * 858 #endif 859 blocking_thread( 860 void * ThreadArg 861 ) 862 { 863 blocking_child *c; 864 865 c = ThreadArg; 866 exit_worker(blocking_child_common(c)); 867 868 /* NOTREACHED */ 869 return 0; 870 } 871 872 /* -------------------------------------------------------------------- 873 * req_child_exit() runs in the parent. 874 * 875 * This function is called from from the idle timer, too, and possibly 876 * without a thread being there any longer. Since we have folded up our 877 * tent in that case and all the semaphores are already gone, we simply 878 * ignore this request in this case. 879 * 880 * Since the existence of the semaphores is controlled exclusively by 881 * the parent, there's no risk of data race here. 882 */ 883 int 884 req_child_exit( 885 blocking_child *c 886 ) 887 { 888 return (c->accesslock) 889 ? queue_req_pointer(c, CHILD_EXIT_REQ) 890 : 0; 891 } 892 893 /* -------------------------------------------------------------------- 894 * cleanup_after_child() runs in parent. 895 */ 896 static void 897 cleanup_after_child( 898 blocking_child * c 899 ) 900 { 901 DEBUG_INSIST(!c->reusable); 902 903 # ifdef SYS_WINNT 904 /* The thread was not created in detached state, so we better 905 * clean up. 906 */ 907 if (c->thread_ref && c->thread_ref->thnd) { 908 WaitForSingleObject(c->thread_ref->thnd, INFINITE); 909 INSIST(CloseHandle(c->thread_ref->thnd)); 910 c->thread_ref->thnd = NULL; 911 } 912 # endif 913 c->thread_ref = NULL; 914 915 /* remove semaphores and (if signalling vi IO) pipes */ 916 917 c->accesslock = delete_sema(c->accesslock); 918 c->workitems_pending = delete_sema(c->workitems_pending); 919 c->wake_scheduled_sleep = delete_sema(c->wake_scheduled_sleep); 920 921 # ifdef WORK_PIPE 922 DEBUG_INSIST(-1 != c->resp_read_pipe); 923 DEBUG_INSIST(-1 != c->resp_write_pipe); 924 (*addremove_io_fd)(c->resp_read_pipe, c->ispipe, TRUE); 925 close(c->resp_write_pipe); 926 close(c->resp_read_pipe); 927 c->resp_write_pipe = -1; 928 c->resp_read_pipe = -1; 929 # else 930 DEBUG_INSIST(NULL != c->responses_pending); 931 (*addremove_io_semaphore)(c->responses_pending->shnd, TRUE); 932 c->responses_pending = delete_sema(c->responses_pending); 933 # endif 934 935 /* Is it necessary to check if there are pending requests and 936 * responses? If so, and if there are, what to do with them? 937 */ 938 939 /* re-init buffer index sequencers */ 940 c->head_workitem = 0; 941 c->tail_workitem = 0; 942 c->head_response = 0; 943 c->tail_response = 0; 944 945 c->reusable = TRUE; 946 } 947 948 949 #else /* !WORK_THREAD follows */ 950 char work_thread_nonempty_compilation_unit; 951 #endif 952