Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
branch: trunk
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 1697 lines (1522 sloc) 44.746 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696
/**********************************************************************

cont.c -

$Author$
created at: Thu May 23 09:03:43 2007

Copyright (C) 2007 Koichi Sasada

**********************************************************************/

#include "ruby/ruby.h"
#include "internal.h"
#include "vm_core.h"
#include "gc.h"
#include "eval_intern.h"

/* FIBER_USE_NATIVE enables Fiber performance improvement using system
* dependent method such as make/setcontext on POSIX system or
* CreateFiber() API on Windows.
* This hack make Fiber context switch faster (x2 or more).
* However, it decrease maximum number of Fiber. For example, on the
* 32bit POSIX OS, ten or twenty thousands Fiber can be created.
*
* Details is reported in the paper "A Fast Fiber Implementation for Ruby 1.9"
* in Proc. of 51th Programming Symposium, pp.21--28 (2010) (in Japanese).
*/

#if !defined(FIBER_USE_NATIVE)
# if defined(HAVE_GETCONTEXT) && defined(HAVE_SETCONTEXT)
# if 0
# elif defined(__NetBSD__)
/* On our experience, NetBSD doesn't support using setcontext() and pthread
* simultaneously. This is because pthread_self(), TLS and other information
* are represented by stack pointer (higher bits of stack pointer).
* TODO: check such constraint on configure.
*/
# define FIBER_USE_NATIVE 0
# elif defined(__sun)
/* On Solaris because resuming any Fiber caused SEGV, for some reason.
*/
# define FIBER_USE_NATIVE 0
# elif defined(__ia64)
/* At least, Linux/ia64's getcontext(3) doesn't save register window.
*/
# define FIBER_USE_NATIVE 0
# elif defined(__GNU__)
/* GNU/Hurd doesn't fully support getcontext, setcontext, makecontext
* and swapcontext functions. Disabling their usage till support is
* implemented. More info at
* http://darnassus.sceen.net/~hurd-web/open_issues/glibc/#getcontext
*/
# define FIBER_USE_NATIVE 0
# else
# define FIBER_USE_NATIVE 1
# endif
# elif defined(_WIN32)
# if _WIN32_WINNT >= 0x0400
/* only when _WIN32_WINNT >= 0x0400 on Windows because Fiber APIs are
* supported only such building (and running) environments.
* [ruby-dev:41192]
*/
# define FIBER_USE_NATIVE 1
# endif
# endif
#endif
#if !defined(FIBER_USE_NATIVE)
#define FIBER_USE_NATIVE 0
#endif

#if FIBER_USE_NATIVE
#ifndef _WIN32
#include <unistd.h>
#include <sys/mman.h>
#include <ucontext.h>
#endif
#define RB_PAGE_SIZE (pagesize)
#define RB_PAGE_MASK (~(RB_PAGE_SIZE - 1))
static long pagesize;
#endif /*FIBER_USE_NATIVE*/

#define CAPTURE_JUST_VALID_VM_STACK 1

enum context_type {
    CONTINUATION_CONTEXT = 0,
    FIBER_CONTEXT = 1,
    ROOT_FIBER_CONTEXT = 2
};

typedef struct rb_context_struct {
    enum context_type type;
    VALUE self;
    int argc;
    VALUE value;
    VALUE *vm_stack;
#ifdef CAPTURE_JUST_VALID_VM_STACK
    size_t vm_stack_slen; /* length of stack (head of th->stack) */
    size_t vm_stack_clen; /* length of control frames (tail of th->stack) */
#endif
    struct {
VALUE *stack;
VALUE *stack_src;
size_t stack_size;
#ifdef __ia64
VALUE *register_stack;
VALUE *register_stack_src;
int register_stack_size;
#endif
    } machine;
    rb_thread_t saved_thread;
    rb_jmpbuf_t jmpbuf;
    rb_ensure_entry_t *ensure_array;
    rb_ensure_list_t *ensure_list;
} rb_context_t;

enum fiber_status {
    CREATED,
    RUNNING,
    TERMINATED
};

#if FIBER_USE_NATIVE && !defined(_WIN32)
#define MAX_MACHINE_STACK_CACHE 10
static int machine_stack_cache_index = 0;
typedef struct machine_stack_cache_struct {
    void *ptr;
    size_t size;
} machine_stack_cache_t;
static machine_stack_cache_t machine_stack_cache[MAX_MACHINE_STACK_CACHE];
static machine_stack_cache_t terminated_machine_stack;
#endif

typedef struct rb_fiber_struct {
    rb_context_t cont;
    VALUE prev;
    enum fiber_status status;
    struct rb_fiber_struct *prev_fiber;
    struct rb_fiber_struct *next_fiber;
    /* If a fiber invokes "transfer",
* then this fiber can't "resume" any more after that.
* You shouldn't mix "transfer" and "resume".
*/
    int transfered;

#if FIBER_USE_NATIVE
#ifdef _WIN32
    void *fib_handle;
#else
    ucontext_t context;
#endif
#endif
} rb_fiber_t;

static const rb_data_type_t cont_data_type, fiber_data_type;
static VALUE rb_cContinuation;
static VALUE rb_cFiber;
static VALUE rb_eFiberError;

#define GetContPtr(obj, ptr) \
TypedData_Get_Struct((obj), rb_context_t, &cont_data_type, (ptr))

#define GetFiberPtr(obj, ptr) do {\
TypedData_Get_Struct((obj), rb_fiber_t, &fiber_data_type, (ptr)); \
if (!(ptr)) rb_raise(rb_eFiberError, "uninitialized fiber"); \
} while (0)

NOINLINE(static VALUE cont_capture(volatile int *stat));

#define THREAD_MUST_BE_RUNNING(th) do { \
if (!(th)->tag) rb_raise(rb_eThreadError, "not running thread"); \
} while (0)

static void
cont_mark(void *ptr)
{
    RUBY_MARK_ENTER("cont");
    if (ptr) {
rb_context_t *cont = ptr;
rb_gc_mark(cont->value);
rb_thread_mark(&cont->saved_thread);
rb_gc_mark(cont->saved_thread.self);

if (cont->vm_stack) {
#ifdef CAPTURE_JUST_VALID_VM_STACK
rb_gc_mark_locations(cont->vm_stack,
cont->vm_stack + cont->vm_stack_slen + cont->vm_stack_clen);
#else
rb_gc_mark_localtion(cont->vm_stack,
cont->vm_stack, cont->saved_thread.stack_size);
#endif
}

if (cont->machine.stack) {
if (cont->type == CONTINUATION_CONTEXT) {
/* cont */
rb_gc_mark_locations(cont->machine.stack,
cont->machine.stack + cont->machine.stack_size);
            }
            else {
/* fiber */
rb_thread_t *th;
                rb_fiber_t *fib = (rb_fiber_t*)cont;
GetThreadPtr(cont->saved_thread.self, th);
if ((th->fiber != cont->self) && fib->status == RUNNING) {
rb_gc_mark_locations(cont->machine.stack,
cont->machine.stack + cont->machine.stack_size);
}
}
}
#ifdef __ia64
if (cont->machine.register_stack) {
rb_gc_mark_locations(cont->machine.register_stack,
cont->machine.register_stack + cont->machine.register_stack_size);
}
#endif
    }
    RUBY_MARK_LEAVE("cont");
}

static void
cont_free(void *ptr)
{
    RUBY_FREE_ENTER("cont");
    if (ptr) {
rb_context_t *cont = ptr;
RUBY_FREE_UNLESS_NULL(cont->saved_thread.stack); fflush(stdout);
#if FIBER_USE_NATIVE
if (cont->type == CONTINUATION_CONTEXT) {
/* cont */
ruby_xfree(cont->ensure_array);
RUBY_FREE_UNLESS_NULL(cont->machine.stack);
}
else {
/* fiber */
#ifdef _WIN32
if (GET_THREAD()->fiber != cont->self && cont->type != ROOT_FIBER_CONTEXT) {
/* don't delete root fiber handle */
rb_fiber_t *fib = (rb_fiber_t*)cont;
if (fib->fib_handle) {
DeleteFiber(fib->fib_handle);
}
}
#else /* not WIN32 */
if (GET_THREAD()->fiber != cont->self) {
                rb_fiber_t *fib = (rb_fiber_t*)cont;
                if (fib->context.uc_stack.ss_sp) {
                    if (cont->type == ROOT_FIBER_CONTEXT) {
rb_bug("Illegal root fiber parameter");
                    }
munmap((void*)fib->context.uc_stack.ss_sp, fib->context.uc_stack.ss_size);
}
}
            else {
/* It may reached here when finalize */
/* TODO examine whether it is a bug */
                /* rb_bug("cont_free: release self"); */
            }
#endif
}
#else /* not FIBER_USE_NATIVE */
ruby_xfree(cont->ensure_array);
RUBY_FREE_UNLESS_NULL(cont->machine.stack);
#endif
#ifdef __ia64
RUBY_FREE_UNLESS_NULL(cont->machine.register_stack);
#endif
RUBY_FREE_UNLESS_NULL(cont->vm_stack);

/* free rb_cont_t or rb_fiber_t */
ruby_xfree(ptr);
    }
    RUBY_FREE_LEAVE("cont");
}

static size_t
cont_memsize(const void *ptr)
{
    const rb_context_t *cont = ptr;
    size_t size = 0;
    if (cont) {
size = sizeof(*cont);
if (cont->vm_stack) {
#ifdef CAPTURE_JUST_VALID_VM_STACK
size_t n = (cont->vm_stack_slen + cont->vm_stack_clen);
#else
size_t n = cont->saved_thread.stack_size;
#endif
size += n * sizeof(*cont->vm_stack);
}

if (cont->machine.stack) {
size += cont->machine.stack_size * sizeof(*cont->machine.stack);
}
#ifdef __ia64
if (cont->machine.register_stack) {
size += cont->machine.register_stack_size * sizeof(*cont->machine.register_stack);
}
#endif
    }
    return size;
}

static void
fiber_mark(void *ptr)
{
    RUBY_MARK_ENTER("cont");
    if (ptr) {
rb_fiber_t *fib = ptr;
rb_gc_mark(fib->prev);
cont_mark(&fib->cont);
    }
    RUBY_MARK_LEAVE("cont");
}

static void
fiber_link_join(rb_fiber_t *fib)
{
    VALUE current_fibval = rb_fiber_current();
    rb_fiber_t *current_fib;
    GetFiberPtr(current_fibval, current_fib);

    /* join fiber link */
    fib->next_fiber = current_fib->next_fiber;
    fib->prev_fiber = current_fib;
    current_fib->next_fiber->prev_fiber = fib;
    current_fib->next_fiber = fib;
}

static void
fiber_link_remove(rb_fiber_t *fib)
{
    fib->prev_fiber->next_fiber = fib->next_fiber;
    fib->next_fiber->prev_fiber = fib->prev_fiber;
}

static void
fiber_free(void *ptr)
{
    RUBY_FREE_ENTER("fiber");
    if (ptr) {
rb_fiber_t *fib = ptr;
if (fib->cont.type != ROOT_FIBER_CONTEXT &&
fib->cont.saved_thread.local_storage) {
st_free_table(fib->cont.saved_thread.local_storage);
}
fiber_link_remove(fib);

cont_free(&fib->cont);
    }
    RUBY_FREE_LEAVE("fiber");
}

static size_t
fiber_memsize(const void *ptr)
{
    const rb_fiber_t *fib = ptr;
    size_t size = 0;
    if (ptr) {
size = sizeof(*fib);
if (fib->cont.type != ROOT_FIBER_CONTEXT &&
fib->cont.saved_thread.local_storage != NULL) {
size += st_memsize(fib->cont.saved_thread.local_storage);
}
size += cont_memsize(&fib->cont);
    }
    return size;
}

VALUE
rb_obj_is_fiber(VALUE obj)
{
    if (rb_typeddata_is_kind_of(obj, &fiber_data_type)) {
return Qtrue;
    }
    else {
return Qfalse;
    }
}

static void
cont_save_machine_stack(rb_thread_t *th, rb_context_t *cont)
{
    size_t size;

    SET_MACHINE_STACK_END(&th->machine.stack_end);
#ifdef __ia64
    th->machine.register_stack_end = rb_ia64_bsp();
#endif

    if (th->machine.stack_start > th->machine.stack_end) {
size = cont->machine.stack_size = th->machine.stack_start - th->machine.stack_end;
cont->machine.stack_src = th->machine.stack_end;
    }
    else {
size = cont->machine.stack_size = th->machine.stack_end - th->machine.stack_start;
cont->machine.stack_src = th->machine.stack_start;
    }

    if (cont->machine.stack) {
REALLOC_N(cont->machine.stack, VALUE, size);
    }
    else {
cont->machine.stack = ALLOC_N(VALUE, size);
    }

    FLUSH_REGISTER_WINDOWS;
    MEMCPY(cont->machine.stack, cont->machine.stack_src, VALUE, size);

#ifdef __ia64
    rb_ia64_flushrs();
    size = cont->machine.register_stack_size = th->machine.register_stack_end - th->machine.register_stack_start;
    cont->machine.register_stack_src = th->machine.register_stack_start;
    if (cont->machine.register_stack) {
REALLOC_N(cont->machine.register_stack, VALUE, size);
    }
    else {
cont->machine.register_stack = ALLOC_N(VALUE, size);
    }

    MEMCPY(cont->machine.register_stack, cont->machine.register_stack_src, VALUE, size);
#endif
}

static const rb_data_type_t cont_data_type = {
    "continuation",
    {cont_mark, cont_free, cont_memsize,},
    NULL, NULL, RUBY_TYPED_FREE_IMMEDIATELY
};

static void
cont_save_thread(rb_context_t *cont, rb_thread_t *th)
{
    /* save thread context */
    cont->saved_thread = *th;
    /* saved_thread->machine.stack_(start|end) should be NULL */
    /* because it may happen GC afterward */
    cont->saved_thread.machine.stack_start = 0;
    cont->saved_thread.machine.stack_end = 0;
#ifdef __ia64
    cont->saved_thread.machine.register_stack_start = 0;
    cont->saved_thread.machine.register_stack_end = 0;
#endif
}

static void
cont_init(rb_context_t *cont, rb_thread_t *th)
{
    /* save thread context */
    cont_save_thread(cont, th);
    cont->saved_thread.local_storage = 0;
}

static rb_context_t *
cont_new(VALUE klass)
{
    rb_context_t *cont;
    volatile VALUE contval;
    rb_thread_t *th = GET_THREAD();

    THREAD_MUST_BE_RUNNING(th);
    contval = TypedData_Make_Struct(klass, rb_context_t, &cont_data_type, cont);
    cont->self = contval;
    cont_init(cont, th);
    return cont;
}

static VALUE
cont_capture(volatile int *stat)
{
    rb_context_t *cont;
    rb_thread_t *th = GET_THREAD(), *sth;
    volatile VALUE contval;

    THREAD_MUST_BE_RUNNING(th);
    rb_vm_stack_to_heap(th);
    cont = cont_new(rb_cContinuation);
    contval = cont->self;
    sth = &cont->saved_thread;

#ifdef CAPTURE_JUST_VALID_VM_STACK
    cont->vm_stack_slen = th->cfp->sp + th->mark_stack_len - th->stack;
    cont->vm_stack_clen = th->stack + th->stack_size - (VALUE*)th->cfp;
    cont->vm_stack = ALLOC_N(VALUE, cont->vm_stack_slen + cont->vm_stack_clen);
    MEMCPY(cont->vm_stack, th->stack, VALUE, cont->vm_stack_slen);
    MEMCPY(cont->vm_stack + cont->vm_stack_slen, (VALUE*)th->cfp, VALUE, cont->vm_stack_clen);
#else
    cont->vm_stack = ALLOC_N(VALUE, th->stack_size);
    MEMCPY(cont->vm_stack, th->stack, VALUE, th->stack_size);
#endif
    sth->stack = 0;

    cont_save_machine_stack(th, cont);

    /* backup ensure_list to array for search in another context */
    {
rb_ensure_list_t *p;
int size = 0;
rb_ensure_entry_t *entry;
for (p=th->ensure_list; p; p=p->next)
size++;
entry = cont->ensure_array = ALLOC_N(rb_ensure_entry_t,size+1);
for (p=th->ensure_list; p; p=p->next) {
if (!p->entry.marker)
p->entry.marker = rb_ary_tmp_new(0); /* dummy object */
*entry++ = p->entry;
}
entry->marker = 0;
    }

    if (ruby_setjmp(cont->jmpbuf)) {
volatile VALUE value;

VAR_INITIALIZED(cont);
value = cont->value;
if (cont->argc == -1) rb_exc_raise(value);
cont->value = Qnil;
*stat = 1;
return value;
    }
    else {
*stat = 0;
return contval;
    }
}

static void
cont_restore_thread(rb_context_t *cont)
{
    rb_thread_t *th = GET_THREAD(), *sth = &cont->saved_thread;

    /* restore thread context */
    if (cont->type == CONTINUATION_CONTEXT) {
/* continuation */
VALUE fib;

th->fiber = sth->fiber;
fib = th->fiber ? th->fiber : th->root_fiber;

if (fib) {
rb_fiber_t *fcont;
GetFiberPtr(fib, fcont);
th->stack_size = fcont->cont.saved_thread.stack_size;
th->stack = fcont->cont.saved_thread.stack;
}
#ifdef CAPTURE_JUST_VALID_VM_STACK
MEMCPY(th->stack, cont->vm_stack, VALUE, cont->vm_stack_slen);
MEMCPY(th->stack + sth->stack_size - cont->vm_stack_clen,
cont->vm_stack + cont->vm_stack_slen, VALUE, cont->vm_stack_clen);
#else
MEMCPY(th->stack, cont->vm_stack, VALUE, sth->stack_size);
#endif
    }
    else {
/* fiber */
th->stack = sth->stack;
th->stack_size = sth->stack_size;
th->local_storage = sth->local_storage;
th->fiber = cont->self;
    }

    th->cfp = sth->cfp;
    th->safe_level = sth->safe_level;
    th->raised_flag = sth->raised_flag;
    th->state = sth->state;
    th->status = sth->status;
    th->tag = sth->tag;
    th->protect_tag = sth->protect_tag;
    th->errinfo = sth->errinfo;
    th->first_proc = sth->first_proc;
    th->root_lep = sth->root_lep;
    th->root_svar = sth->root_svar;
    th->ensure_list = sth->ensure_list;

}

#if FIBER_USE_NATIVE
#ifdef _WIN32
static void
fiber_set_stack_location(void)
{
    rb_thread_t *th = GET_THREAD();
    VALUE *ptr;

    SET_MACHINE_STACK_END(&ptr);
    th->machine.stack_start = (void*)(((VALUE)ptr & RB_PAGE_MASK) + STACK_UPPER((void *)&ptr, 0, RB_PAGE_SIZE));
}

static VOID CALLBACK
fiber_entry(void *arg)
{
    fiber_set_stack_location();
    rb_fiber_start();
}
#else /* _WIN32 */

/*
* FreeBSD require a first (i.e. addr) argument of mmap(2) is not NULL
* if MAP_STACK is passed.
* http://www.FreeBSD.org/cgi/query-pr.cgi?pr=158755
*/
#if defined(MAP_STACK) && !defined(__FreeBSD__) && !defined(__FreeBSD_kernel__)
#define FIBER_STACK_FLAGS (MAP_PRIVATE | MAP_ANON | MAP_STACK)
#else
#define FIBER_STACK_FLAGS (MAP_PRIVATE | MAP_ANON)
#endif

static char*
fiber_machine_stack_alloc(size_t size)
{
    char *ptr;

    if (machine_stack_cache_index > 0) {
if (machine_stack_cache[machine_stack_cache_index - 1].size == (size / sizeof(VALUE))) {
ptr = machine_stack_cache[machine_stack_cache_index - 1].ptr;
machine_stack_cache_index--;
machine_stack_cache[machine_stack_cache_index].ptr = NULL;
machine_stack_cache[machine_stack_cache_index].size = 0;
}
else{
            /* TODO handle multiple machine stack size */
rb_bug("machine_stack_cache size is not canonicalized");
}
    }
    else {
void *page;
STACK_GROW_DIR_DETECTION;

errno = 0;
ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, FIBER_STACK_FLAGS, -1, 0);
if (ptr == MAP_FAILED) {
rb_raise(rb_eFiberError, "can't alloc machine stack to fiber: %s", strerror(errno));
}

/* guard page setup */
page = ptr + STACK_DIR_UPPER(size - RB_PAGE_SIZE, 0);
if (mprotect(page, RB_PAGE_SIZE, PROT_NONE) < 0) {
rb_raise(rb_eFiberError, "mprotect failed");
}
    }

    return ptr;
}
#endif

static void
fiber_initialize_machine_stack_context(rb_fiber_t *fib, size_t size)
{
    rb_thread_t *sth = &fib->cont.saved_thread;

#ifdef _WIN32
    fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
    if (!fib->fib_handle) {
/* try to release unnecessary fibers & retry to create */
rb_gc();
fib->fib_handle = CreateFiberEx(size - 1, size, 0, fiber_entry, NULL);
if (!fib->fib_handle) {
rb_raise(rb_eFiberError, "can't create fiber");
}
    }
    sth->machine.stack_maxsize = size;
#else /* not WIN32 */
    ucontext_t *context = &fib->context;
    char *ptr;
    STACK_GROW_DIR_DETECTION;

    getcontext(context);
    ptr = fiber_machine_stack_alloc(size);
    context->uc_link = NULL;
    context->uc_stack.ss_sp = ptr;
    context->uc_stack.ss_size = size;
    makecontext(context, rb_fiber_start, 0);
    sth->machine.stack_start = (VALUE*)(ptr + STACK_DIR_UPPER(0, size));
    sth->machine.stack_maxsize = size - RB_PAGE_SIZE;
#endif
#ifdef __ia64
    sth->machine.register_stack_maxsize = sth->machine.stack_maxsize;
#endif
}

NOINLINE(static void fiber_setcontext(rb_fiber_t *newfib, rb_fiber_t *oldfib));

static void
fiber_setcontext(rb_fiber_t *newfib, rb_fiber_t *oldfib)
{
    rb_thread_t *th = GET_THREAD(), *sth = &newfib->cont.saved_thread;

    if (newfib->status != RUNNING) {
fiber_initialize_machine_stack_context(newfib, th->vm->default_params.fiber_machine_stack_size);
    }

    /* restore thread context */
    cont_restore_thread(&newfib->cont);
    th->machine.stack_maxsize = sth->machine.stack_maxsize;
    if (sth->machine.stack_end && (newfib != oldfib)) {
rb_bug("fiber_setcontext: sth->machine.stack_end has non zero value");
    }

    /* save oldfib's machine stack */
    if (oldfib->status != TERMINATED) {
STACK_GROW_DIR_DETECTION;
SET_MACHINE_STACK_END(&th->machine.stack_end);
if (STACK_DIR_UPPER(0, 1)) {
oldfib->cont.machine.stack_size = th->machine.stack_start - th->machine.stack_end;
oldfib->cont.machine.stack = th->machine.stack_end;
}
else {
oldfib->cont.machine.stack_size = th->machine.stack_end - th->machine.stack_start;
oldfib->cont.machine.stack = th->machine.stack_start;
}
    }
    /* exchange machine_stack_start between oldfib and newfib */
    oldfib->cont.saved_thread.machine.stack_start = th->machine.stack_start;
    th->machine.stack_start = sth->machine.stack_start;
    /* oldfib->machine.stack_end should be NULL */
    oldfib->cont.saved_thread.machine.stack_end = 0;
#ifndef _WIN32
    if (!newfib->context.uc_stack.ss_sp && th->root_fiber != newfib->cont.self) {
rb_bug("non_root_fiber->context.uc_stac.ss_sp should not be NULL");
    }
#endif

    /* swap machine context */
#ifdef _WIN32
    SwitchToFiber(newfib->fib_handle);
#else
    swapcontext(&oldfib->context, &newfib->context);
#endif
}
#endif

NOINLINE(NORETURN(static void cont_restore_1(rb_context_t *)));

static void
cont_restore_1(rb_context_t *cont)
{
    cont_restore_thread(cont);

    /* restore machine stack */
#ifdef _M_AMD64
    {
/* workaround for x64 SEH */
jmp_buf buf;
setjmp(buf);
((_JUMP_BUFFER*)(&cont->jmpbuf))->Frame =
((_JUMP_BUFFER*)(&buf))->Frame;
    }
#endif
    if (cont->machine.stack_src) {
FLUSH_REGISTER_WINDOWS;
MEMCPY(cont->machine.stack_src, cont->machine.stack,
VALUE, cont->machine.stack_size);
    }

#ifdef __ia64
    if (cont->machine.register_stack_src) {
MEMCPY(cont->machine.register_stack_src, cont->machine.register_stack,
VALUE, cont->machine.register_stack_size);
    }
#endif

    ruby_longjmp(cont->jmpbuf, 1);
}

NORETURN(NOINLINE(static void cont_restore_0(rb_context_t *, VALUE *)));

#ifdef __ia64
#define C(a) rse_##a##0, rse_##a##1, rse_##a##2, rse_##a##3, rse_##a##4
#define E(a) rse_##a##0= rse_##a##1= rse_##a##2= rse_##a##3= rse_##a##4
static volatile int C(a), C(b), C(c), C(d), C(e);
static volatile int C(f), C(g), C(h), C(i), C(j);
static volatile int C(k), C(l), C(m), C(n), C(o);
static volatile int C(p), C(q), C(r), C(s), C(t);
#if 0
{/* the above lines make cc-mode.el confused so much */}
#endif
int rb_dummy_false = 0;
NORETURN(NOINLINE(static void register_stack_extend(rb_context_t *, VALUE *, VALUE *)));
static void
register_stack_extend(rb_context_t *cont, VALUE *vp, VALUE *curr_bsp)
{
    if (rb_dummy_false) {
        /* use registers as much as possible */
        E(a) = E(b) = E(c) = E(d) = E(e) =
        E(f) = E(g) = E(h) = E(i) = E(j) =
        E(k) = E(l) = E(m) = E(n) = E(o) =
        E(p) = E(q) = E(r) = E(s) = E(t) = 0;
        E(a) = E(b) = E(c) = E(d) = E(e) =
        E(f) = E(g) = E(h) = E(i) = E(j) =
        E(k) = E(l) = E(m) = E(n) = E(o) =
        E(p) = E(q) = E(r) = E(s) = E(t) = 0;
    }
    if (curr_bsp < cont->machine.register_stack_src+cont->machine.register_stack_size) {
        register_stack_extend(cont, vp, (VALUE*)rb_ia64_bsp());
    }
    cont_restore_0(cont, vp);
}
#undef C
#undef E
#endif

static void
cont_restore_0(rb_context_t *cont, VALUE *addr_in_prev_frame)
{
    if (cont->machine.stack_src) {
#ifdef HAVE_ALLOCA
#define STACK_PAD_SIZE 1
#else
#define STACK_PAD_SIZE 1024
#endif
VALUE space[STACK_PAD_SIZE];

#if !STACK_GROW_DIRECTION
if (addr_in_prev_frame > &space[0]) {
/* Stack grows downward */
#endif
#if STACK_GROW_DIRECTION <= 0
volatile VALUE *const end = cont->machine.stack_src;
if (&space[0] > end) {
# ifdef HAVE_ALLOCA
volatile VALUE *sp = ALLOCA_N(VALUE, &space[0] - end);
space[0] = *sp;
# else
cont_restore_0(cont, &space[0]);
# endif
}
#endif
#if !STACK_GROW_DIRECTION
}
else {
/* Stack grows upward */
#endif
#if STACK_GROW_DIRECTION >= 0
volatile VALUE *const end = cont->machine.stack_src + cont->machine.stack_size;
if (&space[STACK_PAD_SIZE] < end) {
# ifdef HAVE_ALLOCA
volatile VALUE *sp = ALLOCA_N(VALUE, end - &space[STACK_PAD_SIZE]);
space[0] = *sp;
# else
cont_restore_0(cont, &space[STACK_PAD_SIZE-1]);
# endif
}
#endif
#if !STACK_GROW_DIRECTION
}
#endif
    }
    cont_restore_1(cont);
}
#ifdef __ia64
#define cont_restore_0(cont, vp) register_stack_extend((cont), (vp), (VALUE*)rb_ia64_bsp())
#endif

/*
* Document-class: Continuation
*
* Continuation objects are generated by Kernel#callcc,
* after having +require+d <i>continuation</i>. They hold
* a return address and execution context, allowing a nonlocal return
* to the end of the <code>callcc</code> block from anywhere within a
* program. Continuations are somewhat analogous to a structured
* version of C's <code>setjmp/longjmp</code> (although they contain
* more state, so you might consider them closer to threads).
*
* For instance:
*
* require "continuation"
* arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
* callcc{|cc| $cc = cc}
* puts(message = arr.shift)
* $cc.call unless message =~ /Max/
*
* <em>produces:</em>
*
* Freddie
* Herbie
* Ron
* Max
*
* This (somewhat contrived) example allows the inner loop to abandon
* processing early:
*
* require "continuation"
* callcc {|cont|
* for i in 0..4
* print "\n#{i}: "
* for j in i*5...(i+1)*5
* cont.call() if j == 17
* printf "%3d", j
* end
* end
* }
* puts
*
* <em>produces:</em>
*
* 0: 0 1 2 3 4
* 1: 5 6 7 8 9
* 2: 10 11 12 13 14
* 3: 15 16
*/

/*
* call-seq:
* callcc {|cont| block } -> obj
*
* Generates a Continuation object, which it passes to
* the associated block. You need to <code>require
* 'continuation'</code> before using this method. Performing a
* <em>cont</em><code>.call</code> will cause the #callcc
* to return (as will falling through the end of the block). The
* value returned by the #callcc is the value of the
* block, or the value passed to <em>cont</em><code>.call</code>. See
* class Continuation for more details. Also see
* Kernel#throw for an alternative mechanism for
* unwinding a call stack.
*/

static VALUE
rb_callcc(VALUE self)
{
    volatile int called;
    volatile VALUE val = cont_capture(&called);

    if (called) {
return val;
    }
    else {
return rb_yield(val);
    }
}

static VALUE
make_passing_arg(int argc, VALUE *argv)
{
    switch (argc) {
      case 0:
return Qnil;
      case 1:
return argv[0];
      default:
return rb_ary_new4(argc, argv);
    }
}

/* CAUTION!! : Currently, error in rollback_func is not supported */
/* same as rb_protect if set rollback_func to NULL */
void
ruby_register_rollback_func_for_ensure(VALUE (*ensure_func)(ANYARGS), VALUE (*rollback_func)(ANYARGS))
{
    st_table **table_p = &GET_VM()->ensure_rollback_table;
    if (UNLIKELY(*table_p == NULL)) {
*table_p = st_init_numtable();
    }
    st_insert(*table_p, (st_data_t)ensure_func, (st_data_t)rollback_func);
}

static inline VALUE
lookup_rollback_func(VALUE (*ensure_func)(ANYARGS))
{
    st_table *table = GET_VM()->ensure_rollback_table;
    st_data_t val;
    if (table && st_lookup(table, (st_data_t)ensure_func, &val))
return (VALUE) val;
    return Qundef;
}


static inline void
rollback_ensure_stack(VALUE self,rb_ensure_list_t *current,rb_ensure_entry_t *target)
{
    rb_ensure_list_t *p;
    rb_ensure_entry_t *entry;
    size_t i;
    size_t cur_size;
    size_t target_size;
    size_t base_point;
    VALUE (*func)(ANYARGS);

    cur_size = 0;
    for (p=current; p; p=p->next)
cur_size++;
    target_size = 0;
    for (entry=target; entry->marker; entry++)
target_size++;

    /* search common stack point */
    p = current;
    base_point = cur_size;
    while (base_point) {
if (target_size >= base_point &&
p->entry.marker == target[target_size - base_point].marker)
break;
base_point --;
p = p->next;
    }

    /* rollback function check */
    for (i=0; i < target_size - base_point; i++) {
if (!lookup_rollback_func(target[i].e_proc)) {
rb_raise(rb_eRuntimeError, "continuation called from out of critical rb_ensure scope");
}
    }
    /* pop ensure stack */
    while (cur_size > base_point) {
/* escape from ensure block */
(*current->entry.e_proc)(current->entry.data2);
current = current->next;
cur_size--;
    }
    /* push ensure stack */
    while (i--) {
func = (VALUE (*)(ANYARGS)) lookup_rollback_func(target[i].e_proc);
if ((VALUE)func != Qundef) {
(*func)(target[i].data2);
}
    }
}

/*
* call-seq:
* cont.call(args, ...)
* cont[args, ...]
*
* Invokes the continuation. The program continues from the end of the
* <code>callcc</code> block. If no arguments are given, the original
* <code>callcc</code> returns <code>nil</code>. If one argument is
* given, <code>callcc</code> returns it. Otherwise, an array
* containing <i>args</i> is returned.
*
* callcc {|cont| cont.call } #=> nil
* callcc {|cont| cont.call 1 } #=> 1
* callcc {|cont| cont.call 1, 2, 3 } #=> [1, 2, 3]
*/

static VALUE
rb_cont_call(int argc, VALUE *argv, VALUE contval)
{
    rb_context_t *cont;
    rb_thread_t *th = GET_THREAD();
    GetContPtr(contval, cont);

    if (cont->saved_thread.self != th->self) {
rb_raise(rb_eRuntimeError, "continuation called across threads");
    }
    if (cont->saved_thread.protect_tag != th->protect_tag) {
rb_raise(rb_eRuntimeError, "continuation called across stack rewinding barrier");
    }
    if (cont->saved_thread.fiber) {
rb_fiber_t *fcont;
GetFiberPtr(cont->saved_thread.fiber, fcont);

if (th->fiber != cont->saved_thread.fiber) {
rb_raise(rb_eRuntimeError, "continuation called across fiber");
}
    }
    rollback_ensure_stack(contval, th->ensure_list, cont->ensure_array);

    cont->argc = argc;
    cont->value = make_passing_arg(argc, argv);

    /* restore `tracing' context. see [Feature #4347] */
    th->trace_arg = cont->saved_thread.trace_arg;

    cont_restore_0(cont, &contval);
    return Qnil; /* unreachable */
}

/*********/
/* fiber */
/*********/

/*
* Document-class: Fiber
*
* Fibers are primitives for implementing light weight cooperative
* concurrency in Ruby. Basically they are a means of creating code blocks
* that can be paused and resumed, much like threads. The main difference
* is that they are never preempted and that the scheduling must be done by
* the programmer and not the VM.
*
* As opposed to other stackless light weight concurrency models, each fiber
* comes with a small 4KB stack. This enables the fiber to be paused from deeply
* nested function calls within the fiber block.
*
* When a fiber is created it will not run automatically. Rather it must be
* be explicitly asked to run using the <code>Fiber#resume</code> method.
* The code running inside the fiber can give up control by calling
* <code>Fiber.yield</code> in which case it yields control back to caller
* (the caller of the <code>Fiber#resume</code>).
*
* Upon yielding or termination the Fiber returns the value of the last
* executed expression
*
* For instance:
*
* fiber = Fiber.new do
* Fiber.yield 1
* 2
* end
*
* puts fiber.resume
* puts fiber.resume
* puts fiber.resume
*
* <em>produces</em>
*
* 1
* 2
* FiberError: dead fiber called
*
* The <code>Fiber#resume</code> method accepts an arbitrary number of
* parameters, if it is the first call to <code>resume</code> then they
* will be passed as block arguments. Otherwise they will be the return
* value of the call to <code>Fiber.yield</code>
*
* Example:
*
* fiber = Fiber.new do |first|
* second = Fiber.yield first + 2
* end
*
* puts fiber.resume 10
* puts fiber.resume 14
* puts fiber.resume 18
*
* <em>produces</em>
*
* 12
* 14
* FiberError: dead fiber called
*
*/

static const rb_data_type_t fiber_data_type = {
    "fiber",
    {fiber_mark, fiber_free, fiber_memsize,},
    NULL, NULL, RUBY_TYPED_FREE_IMMEDIATELY
};

static VALUE
fiber_alloc(VALUE klass)
{
    return TypedData_Wrap_Struct(klass, &fiber_data_type, 0);
}

static rb_fiber_t*
fiber_t_alloc(VALUE fibval)
{
    rb_fiber_t *fib;
    rb_thread_t *th = GET_THREAD();

    if (DATA_PTR(fibval) != 0) {
rb_raise(rb_eRuntimeError, "cannot initialize twice");
    }

    THREAD_MUST_BE_RUNNING(th);
    fib = ALLOC(rb_fiber_t);
    memset(fib, 0, sizeof(rb_fiber_t));
    fib->cont.self = fibval;
    fib->cont.type = FIBER_CONTEXT;
    cont_init(&fib->cont, th);
    fib->prev = Qnil;
    fib->status = CREATED;

    DATA_PTR(fibval) = fib;

    return fib;
}

static VALUE
fiber_init(VALUE fibval, VALUE proc)
{
    rb_fiber_t *fib = fiber_t_alloc(fibval);
    rb_context_t *cont = &fib->cont;
    rb_thread_t *th = &cont->saved_thread;

    /* initialize cont */
    cont->vm_stack = 0;

    th->stack = 0;
    th->stack_size = 0;

    fiber_link_join(fib);

    th->stack_size = th->vm->default_params.fiber_vm_stack_size / sizeof(VALUE);
    th->stack = ALLOC_N(VALUE, th->stack_size);

    th->cfp = (void *)(th->stack + th->stack_size);
    th->cfp--;
    th->cfp->pc = 0;
    th->cfp->sp = th->stack + 1;
#if VM_DEBUG_BP_CHECK
    th->cfp->bp_check = 0;
#endif
    th->cfp->ep = th->stack;
    *th->cfp->ep = VM_ENVVAL_BLOCK_PTR(0);
    th->cfp->self = Qnil;
    th->cfp->klass = Qnil;
    th->cfp->flag = 0;
    th->cfp->iseq = 0;
    th->cfp->proc = 0;
    th->cfp->block_iseq = 0;
    th->cfp->me = 0;
    th->tag = 0;
    th->local_storage = st_init_numtable();

    th->first_proc = proc;

#if !FIBER_USE_NATIVE
    MEMCPY(&cont->jmpbuf, &th->root_jmpbuf, rb_jmpbuf_t, 1);
#endif

    return fibval;
}

/* :nodoc: */
static VALUE
rb_fiber_init(VALUE fibval)
{
    return fiber_init(fibval, rb_block_proc());
}

VALUE
rb_fiber_new(VALUE (*func)(ANYARGS), VALUE obj)
{
    return fiber_init(fiber_alloc(rb_cFiber), rb_proc_new(func, obj));
}

static VALUE
return_fiber(void)
{
    rb_fiber_t *fib;
    VALUE curr = rb_fiber_current();
    VALUE prev;
    GetFiberPtr(curr, fib);

    prev = fib->prev;
    if (NIL_P(prev)) {
const VALUE root_fiber = GET_THREAD()->root_fiber;

if (root_fiber == curr) {
rb_raise(rb_eFiberError, "can't yield from root fiber");
}
return root_fiber;
    }
    else {
fib->prev = Qnil;
return prev;
    }
}

VALUE rb_fiber_transfer(VALUE fib, int argc, VALUE *argv);

static void
rb_fiber_terminate(rb_fiber_t *fib)
{
    VALUE value = fib->cont.value;
    fib->status = TERMINATED;
#if FIBER_USE_NATIVE && !defined(_WIN32)
    /* Ruby must not switch to other thread until storing terminated_machine_stack */
    terminated_machine_stack.ptr = fib->context.uc_stack.ss_sp;
    terminated_machine_stack.size = fib->context.uc_stack.ss_size / sizeof(VALUE);
    fib->context.uc_stack.ss_sp = NULL;
    fib->cont.machine.stack = NULL;
    fib->cont.machine.stack_size = 0;
#endif
    rb_fiber_transfer(return_fiber(), 1, &value);
}

void
rb_fiber_start(void)
{
    rb_thread_t *th = GET_THREAD();
    rb_fiber_t *fib;
    rb_proc_t *proc;
    int state;

    GetFiberPtr(th->fiber, fib);

    TH_PUSH_TAG(th);
    if ((state = EXEC_TAG()) == 0) {
rb_context_t *cont = &VAR_FROM_MEMORY(fib)->cont;
int argc;
const VALUE *argv, args = cont->value;
GetProcPtr(cont->saved_thread.first_proc, proc);
argv = (argc = cont->argc) > 1 ? RARRAY_CONST_PTR(args) : &args;
cont->value = Qnil;
th->errinfo = Qnil;
th->root_lep = rb_vm_ep_local_ep(proc->block.ep);
th->root_svar = Qnil;

fib->status = RUNNING;
cont->value = rb_vm_invoke_proc(th, proc, argc, argv, 0);
    }
    TH_POP_TAG();

    if (state) {
if (state == TAG_RAISE || state == TAG_FATAL) {
rb_threadptr_pending_interrupt_enque(th, th->errinfo);
}
else {
VALUE err = rb_vm_make_jump_tag_but_local_jump(state, th->errinfo);
if (!NIL_P(err))
rb_threadptr_pending_interrupt_enque(th, err);
}
RUBY_VM_SET_INTERRUPT(th);
    }

    rb_fiber_terminate(fib);
    rb_bug("rb_fiber_start: unreachable");
}

static rb_fiber_t *
root_fiber_alloc(rb_thread_t *th)
{
    rb_fiber_t *fib;
    /* no need to allocate vm stack */
    fib = fiber_t_alloc(fiber_alloc(rb_cFiber));
    fib->cont.type = ROOT_FIBER_CONTEXT;
#if FIBER_USE_NATIVE
#ifdef _WIN32
    fib->fib_handle = ConvertThreadToFiber(0);
#endif
#endif
    fib->status = RUNNING;
    fib->prev_fiber = fib->next_fiber = fib;

    return fib;
}

VALUE
rb_fiber_current(void)
{
    rb_thread_t *th = GET_THREAD();
    if (th->fiber == 0) {
/* save root */
rb_fiber_t *fib = root_fiber_alloc(th);
th->root_fiber = th->fiber = fib->cont.self;
    }
    return th->fiber;
}

static VALUE
fiber_store(rb_fiber_t *next_fib)
{
    rb_thread_t *th = GET_THREAD();
    rb_fiber_t *fib;

    if (th->fiber) {
GetFiberPtr(th->fiber, fib);
cont_save_thread(&fib->cont, th);
    }
    else {
/* create current fiber */
fib = root_fiber_alloc(th);
th->root_fiber = th->fiber = fib->cont.self;
    }

#if !FIBER_USE_NATIVE
    cont_save_machine_stack(th, &fib->cont);
#endif

    if (FIBER_USE_NATIVE || ruby_setjmp(fib->cont.jmpbuf)) {
#if FIBER_USE_NATIVE
fiber_setcontext(next_fib, fib);
#ifndef _WIN32
if (terminated_machine_stack.ptr) {
if (machine_stack_cache_index < MAX_MACHINE_STACK_CACHE) {
machine_stack_cache[machine_stack_cache_index].ptr = terminated_machine_stack.ptr;
machine_stack_cache[machine_stack_cache_index].size = terminated_machine_stack.size;
machine_stack_cache_index++;
}
else {
if (terminated_machine_stack.ptr != fib->cont.machine.stack) {
munmap((void*)terminated_machine_stack.ptr, terminated_machine_stack.size * sizeof(VALUE));
}
else {
rb_bug("terminated fiber resumed");
}
}
terminated_machine_stack.ptr = NULL;
terminated_machine_stack.size = 0;
}
#endif
#endif
/* restored */
GetFiberPtr(th->fiber, fib);
if (fib->cont.argc == -1) rb_exc_raise(fib->cont.value);
return fib->cont.value;
    }
#if !FIBER_USE_NATIVE
    else {
return Qundef;
    }
#endif
}

static inline VALUE
fiber_switch(VALUE fibval, int argc, VALUE *argv, int is_resume)
{
    VALUE value;
    rb_fiber_t *fib;
    rb_context_t *cont;
    rb_thread_t *th = GET_THREAD();

    GetFiberPtr(fibval, fib);
    cont = &fib->cont;

    if (th->fiber == fibval) {
/* ignore fiber context switch
* because destination fiber is same as current fiber
*/
return make_passing_arg(argc, argv);
    }

    if (cont->saved_thread.self != th->self) {
rb_raise(rb_eFiberError, "fiber called across threads");
    }
    else if (cont->saved_thread.protect_tag != th->protect_tag) {
rb_raise(rb_eFiberError, "fiber called across stack rewinding barrier");
    }
    else if (fib->status == TERMINATED) {
value = rb_exc_new2(rb_eFiberError, "dead fiber called");
if (th->fiber != fibval) {
GetFiberPtr(th->fiber, fib);
if (fib->status != TERMINATED) rb_exc_raise(value);
fibval = th->root_fiber;
}
else {
fibval = fib->prev;
if (NIL_P(fibval)) fibval = th->root_fiber;
}
GetFiberPtr(fibval, fib);
cont = &fib->cont;
cont->argc = -1;
cont->value = value;
#if FIBER_USE_NATIVE
{
VALUE oldfibval;
rb_fiber_t *oldfib;
oldfibval = rb_fiber_current();
GetFiberPtr(oldfibval, oldfib);
fiber_setcontext(fib, oldfib);
}
#else
cont_restore_0(cont, &value);
#endif
    }

    if (is_resume) {
fib->prev = rb_fiber_current();
    }
    else {
/* restore `tracing' context. see [Feature #4347] */
th->trace_arg = cont->saved_thread.trace_arg;
    }

    cont->argc = argc;
    cont->value = make_passing_arg(argc, argv);

    value = fiber_store(fib);
#if !FIBER_USE_NATIVE
    if (value == Qundef) {
cont_restore_0(cont, &value);
rb_bug("rb_fiber_resume: unreachable");
    }
#endif
    RUBY_VM_CHECK_INTS(th);

    return value;
}

VALUE
rb_fiber_transfer(VALUE fib, int argc, VALUE *argv)
{
    return fiber_switch(fib, argc, argv, 0);
}

VALUE
rb_fiber_resume(VALUE fibval, int argc, VALUE *argv)
{
    rb_fiber_t *fib;
    GetFiberPtr(fibval, fib);

    if (fib->prev != Qnil || fib->cont.type == ROOT_FIBER_CONTEXT) {
rb_raise(rb_eFiberError, "double resume");
    }
    if (fib->transfered != 0) {
rb_raise(rb_eFiberError, "cannot resume transferred Fiber");
    }

    return fiber_switch(fibval, argc, argv, 1);
}

VALUE
rb_fiber_yield(int argc, VALUE *argv)
{
    return rb_fiber_transfer(return_fiber(), argc, argv);
}

void
rb_fiber_reset_root_local_storage(VALUE thval)
{
    rb_thread_t *th;
    rb_fiber_t *fib;

    GetThreadPtr(thval, th);
    if (th->root_fiber && th->root_fiber != th->fiber) {
GetFiberPtr(th->root_fiber, fib);
th->local_storage = fib->cont.saved_thread.local_storage;
    }
}

/*
* call-seq:
* fiber.alive? -> true or false
*
* Returns true if the fiber can still be resumed (or transferred
* to). After finishing execution of the fiber block this method will
* always return false. You need to <code>require 'fiber'</code>
* before using this method.
*/
VALUE
rb_fiber_alive_p(VALUE fibval)
{
    rb_fiber_t *fib;
    GetFiberPtr(fibval, fib);
    return fib->status != TERMINATED ? Qtrue : Qfalse;
}

/*
* call-seq:
* fiber.resume(args, ...) -> obj
*
* Resumes the fiber from the point at which the last <code>Fiber.yield</code>
* was called, or starts running it if it is the first call to
* <code>resume</code>. Arguments passed to resume will be the value of
* the <code>Fiber.yield</code> expression or will be passed as block
* parameters to the fiber's block if this is the first <code>resume</code>.
*
* Alternatively, when resume is called it evaluates to the arguments passed
* to the next <code>Fiber.yield</code> statement inside the fiber's block
* or to the block value if it runs to completion without any
* <code>Fiber.yield</code>
*/
static VALUE
rb_fiber_m_resume(int argc, VALUE *argv, VALUE fib)
{
    return rb_fiber_resume(fib, argc, argv);
}

/*
* call-seq:
* fiber.transfer(args, ...) -> obj
*
* Transfer control to another fiber, resuming it from where it last
* stopped or starting it if it was not resumed before. The calling
* fiber will be suspended much like in a call to
* <code>Fiber.yield</code>. You need to <code>require 'fiber'</code>
* before using this method.
*
* The fiber which receives the transfer call is treats it much like
* a resume call. Arguments passed to transfer are treated like those
* passed to resume.
*
* You cannot resume a fiber that transferred control to another one.
* This will cause a double resume error. You need to transfer control
* back to this fiber before it can yield and resume.
*
* Example:
*
* fiber1 = Fiber.new do
* puts "In Fiber 1"
* Fiber.yield
* end
*
* fiber2 = Fiber.new do
* puts "In Fiber 2"
* fiber1.transfer
* puts "Never see this message"
* end
*
* fiber3 = Fiber.new do
* puts "In Fiber 3"
* end
*
* fiber2.resume
* fiber3.resume
*
* <em>produces</em>
*
* In fiber 2
* In fiber 1
* In fiber 3
*
*/
static VALUE
rb_fiber_m_transfer(int argc, VALUE *argv, VALUE fibval)
{
    rb_fiber_t *fib;
    GetFiberPtr(fibval, fib);
    fib->transfered = 1;
    return rb_fiber_transfer(fibval, argc, argv);
}

/*
* call-seq:
* Fiber.yield(args, ...) -> obj
*
* Yields control back to the context that resumed the fiber, passing
* along any arguments that were passed to it. The fiber will resume
* processing at this point when <code>resume</code> is called next.
* Any arguments passed to the next <code>resume</code> will be the
* value that this <code>Fiber.yield</code> expression evaluates to.
*/
static VALUE
rb_fiber_s_yield(int argc, VALUE *argv, VALUE klass)
{
    return rb_fiber_yield(argc, argv);
}

/*
* call-seq:
* Fiber.current() -> fiber
*
* Returns the current fiber. You need to <code>require 'fiber'</code>
* before using this method. If you are not running in the context of
* a fiber this method will return the root fiber.
*/
static VALUE
rb_fiber_s_current(VALUE klass)
{
    return rb_fiber_current();
}



/*
* Document-class: FiberError
*
* Raised when an invalid operation is attempted on a Fiber, in
* particular when attempting to call/resume a dead fiber,
* attempting to yield from the root fiber, or calling a fiber across
* threads.
*
* fiber = Fiber.new{}
* fiber.resume #=> nil
* fiber.resume #=> FiberError: dead fiber called
*/

void
Init_Cont(void)
{
#if FIBER_USE_NATIVE
    rb_thread_t *th = GET_THREAD();

#ifdef _WIN32
    SYSTEM_INFO info;
    GetSystemInfo(&info);
    pagesize = info.dwPageSize;
#else /* not WIN32 */
    pagesize = sysconf(_SC_PAGESIZE);
#endif
    SET_MACHINE_STACK_END(&th->machine.stack_end);
#endif

    rb_cFiber = rb_define_class("Fiber", rb_cObject);
    rb_define_alloc_func(rb_cFiber, fiber_alloc);
    rb_eFiberError = rb_define_class("FiberError", rb_eStandardError);
    rb_define_singleton_method(rb_cFiber, "yield", rb_fiber_s_yield, -1);
    rb_define_method(rb_cFiber, "initialize", rb_fiber_init, 0);
    rb_define_method(rb_cFiber, "resume", rb_fiber_m_resume, -1);
}

RUBY_SYMBOL_EXPORT_BEGIN

void
ruby_Init_Continuation_body(void)
{
    rb_cContinuation = rb_define_class("Continuation", rb_cObject);
    rb_undef_alloc_func(rb_cContinuation);
    rb_undef_method(CLASS_OF(rb_cContinuation), "new");
    rb_define_method(rb_cContinuation, "call", rb_cont_call, -1);
    rb_define_method(rb_cContinuation, "[]", rb_cont_call, -1);
    rb_define_global_function("callcc", rb_callcc, 0);
}

void
ruby_Init_Fiber_as_Coroutine(void)
{
    rb_define_method(rb_cFiber, "transfer", rb_fiber_m_transfer, -1);
    rb_define_method(rb_cFiber, "alive?", rb_fiber_alive_p, 0);
    rb_define_singleton_method(rb_cFiber, "current", rb_fiber_s_current, 0);
}

RUBY_SYMBOL_EXPORT_END
Something went wrong with that request. Please try again.