ext/threads/shared/shared.xs

   1 /*    shared.xs
   2  *
   3  *    Copyright (c) 2001-2002, Larry Wall
   4  *
   5  *    You may distribute under the terms of either the GNU General Public
   6  *    License or the Artistic License, as specified in the README file.
   7  *
   8  * "Hand any two wizards a piece of rope and they would instinctively pull in
   9  * opposite directions."
  10  *                         --Sourcery
  11  *
  12  * Contributed by Arthur Bergman arthur@contiller.se
  13  * pulled in the (an)other direction by Nick Ing-Simmons nick@ing-simmons.net
  14  */
  15
  16 #define PERL_NO_GET_CONTEXT
  17 #include "EXTERN.h"
  18 #include "perl.h"
  19 #include "XSUB.h"
  20
  21 #ifdef USE_ITHREADS
  22
  23 #define SHAREDSvPTR(a)      ((a)->sv)
  24
  25 /*
  26  * The shared things need an intepreter to live in ...
  27  */
  28 PerlInterpreter *PL_sharedsv_space;             /* The shared sv space */
  29 /* To access shared space we fake aTHX in this scope and thread's context */
  30
  31 /* bug #24255: we include ENTER+SAVETMPS/FREETMPS+LEAVE with
  32  * SHARED_CONTEXT/CALLER_CONTEXT macros, so that any mortals etc created
  33  * while in the shared interpreter context don't languish */
  34
  35 #define SHARED_CONTEXT \
  36     STMT_START {                                        \
  37         PERL_SET_CONTEXT((aTHX = PL_sharedsv_space));   \
  38         ENTER;                                          \
  39         SAVETMPS;                                       \
  40     } STMT_END
  41
  42 /* So we need a way to switch back to the caller's context... */
  43 /* So we declare _another_ copy of the aTHX variable ... */
  44 #define dTHXc PerlInterpreter *caller_perl = aTHX
  45
  46 /* and use it to switch back */
  47 #define CALLER_CONTEXT                                  \
  48     STMT_START {                                        \
  49         FREETMPS;                                       \
  50         LEAVE;                                          \
  51         PERL_SET_CONTEXT((aTHX = caller_perl));         \
  52     } STMT_END
  53
  54 /*
  55  * Only one thread at a time is allowed to mess with shared space.
  56  */
  57
  58 typedef struct
  59 {
  60  perl_mutex              mutex;
  61  PerlInterpreter        *owner;
  62  I32                     locks;
  63  perl_cond               cond;
  64 #ifdef DEBUG_LOCKS
  65  char *                  file;
  66  int                     line;
  67 #endif
  68 } recursive_lock_t;
  69
  70 recursive_lock_t PL_sharedsv_lock;       /* Mutex protecting the shared sv space */
  71
  72 void
  73 recursive_lock_init(pTHX_ recursive_lock_t *lock)
  74 {
  75     Zero(lock,1,recursive_lock_t);
  76     MUTEX_INIT(&lock->mutex);
  77     COND_INIT(&lock->cond);
  78 }
  79
  80 void
  81 recursive_lock_destroy(pTHX_ recursive_lock_t *lock)
  82 {
  83     MUTEX_DESTROY(&lock->mutex);
  84     COND_DESTROY(&lock->cond);
  85 }
  86
  87 void
  88 recursive_lock_release(pTHX_ recursive_lock_t *lock)
  89 {
  90     MUTEX_LOCK(&lock->mutex);
  91     if (lock->owner != aTHX) {
  92         MUTEX_UNLOCK(&lock->mutex);
  93     }
  94     else {
  95         if (--lock->locks == 0) {
  96             lock->owner = NULL;
  97             COND_SIGNAL(&lock->cond);
  98         }
  99     }
 100     MUTEX_UNLOCK(&lock->mutex);
 101 }
 102
 103 void
 104 recursive_lock_acquire(pTHX_ recursive_lock_t *lock,char *file,int line)
 105 {
 106     assert(aTHX);
 107     MUTEX_LOCK(&lock->mutex);
 108     if (lock->owner == aTHX) {
 109         lock->locks++;
 110     }
 111     else {
 112         while (lock->owner) {
 113 #ifdef DEBUG_LOCKS
 114             Perl_warn(aTHX_ " %p waiting - owned by %p %s:%d\n",
 115                       aTHX, lock->owner, lock->file, lock->line);
 116 #endif
 117             COND_WAIT(&lock->cond,&lock->mutex);
 118         }
 119         lock->locks = 1;
 120         lock->owner = aTHX;
 121 #ifdef DEBUG_LOCKS
 122         lock->file  = file;
 123         lock->line  = line;
 124 #endif
 125     }
 126     MUTEX_UNLOCK(&lock->mutex);
 127     SAVEDESTRUCTOR_X(recursive_lock_release,lock);
 128 }
 129
 130 #define ENTER_LOCK         STMT_START { \
 131                               ENTER; \
 132                               recursive_lock_acquire(aTHX_ &PL_sharedsv_lock, __FILE__, __LINE__);   \
 133                             } STMT_END
 134
 135 #define LEAVE_LOCK       LEAVE
 136
 137
 138 /* A common idiom is to acquire access and switch in ... */
 139 #define SHARED_EDIT         STMT_START {        \
 140                                 ENTER_LOCK;     \
 141                                 SHARED_CONTEXT; \
 142                             } STMT_END
 143
 144 /* then switch out and release access. */
 145 #define SHARED_RELEASE     STMT_START { \
 146                                 CALLER_CONTEXT; \
 147                                 LEAVE_LOCK;     \
 148                             } STMT_END
 149
 150
 151 /*
 152
 153   Shared SV
 154
 155   Shared SV is a structure for keeping the backend storage
 156   of shared svs.
 157
 158   Shared-ness really only needs the SV * - the rest is for locks.
 159   (Which suggests further space optimization ... )
 160
 161 */
 162
 163 typedef struct {
 164     SV                 *sv;             /* The actual SV - in shared space */
 165     recursive_lock_t    lock;
 166     perl_cond           user_cond;      /* For user-level conditions */
 167 } shared_sv;
 168
 169 /* The SV in shared-space has a back-pointer to the shared_sv
 170    struct associated with it PERL_MAGIC_ext.
 171
 172    The vtable used has just one entry - when the SV goes away
 173    we free the memory for the above.
 174
 175  */
 176
 177 int
 178 sharedsv_shared_mg_free(pTHX_ SV *sv, MAGIC *mg)
 179 {
 180     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 181     assert( aTHX == PL_sharedsv_space );
 182     if (shared) {
 183         recursive_lock_destroy(aTHX_ &shared->lock);
 184         COND_DESTROY(&shared->user_cond);
 185         PerlMemShared_free(shared);
 186         mg->mg_ptr = NULL;
 187     }
 188     return 0;
 189 }
 190
 191 MGVTBL sharedsv_shared_vtbl = {
 192  0,                             /* get */
 193  0,                             /* set */
 194  0,                             /* len */
 195  0,                             /* clear */
 196  sharedsv_shared_mg_free,       /* free */
 197  0,                             /* copy */
 198  0,                             /* dup */
 199 };
 200
 201 /* Access to shared things is heavily based on MAGIC - in mg.h/mg.c/sv.c sense */
 202
 203 /* In any thread that has access to a shared thing there is a "proxy"
 204    for it in its own space which has 'MAGIC' associated which accesses
 205    the shared thing.
 206  */
 207
 208 MGVTBL sharedsv_scalar_vtbl;    /* scalars have this vtable */
 209 MGVTBL sharedsv_array_vtbl;     /* hashes and arrays have this - like 'tie' */
 210 MGVTBL sharedsv_elem_vtbl;      /* elements of hashes and arrays have this
 211                                    _AS WELL AS_ the scalar magic */
 212
 213 /* The sharedsv_elem_vtbl associates the element with the array/hash and
 214    the sharedsv_scalar_vtbl associates it with the value
 215  */
 216
 217
 218 /* Accessor to convert threads::shared::tie objects back shared_sv * */
 219 shared_sv *
 220 SV_to_sharedsv(pTHX_ SV *sv)
 221 {
 222     shared_sv *shared = 0;
 223     if (SvROK(sv))
 224      {
 225       shared = INT2PTR(shared_sv *, SvIV(SvRV(sv)));
 226      }
 227     return shared;
 228 }
 229
 230 =for apidoc sharedsv_find
 231
 232 Given a private side SV tries to find if the SV has a shared backend,
 233 by looking for the magic.
 234
 235 =cut
 236
 237 shared_sv *
 238 Perl_sharedsv_find(pTHX_ SV *sv)
 239 {
 240     MAGIC *mg;
 241     if (SvTYPE(sv) >= SVt_PVMG) {
 242         switch(SvTYPE(sv)) {
 243         case SVt_PVAV:
 244         case SVt_PVHV:
 245             if ((mg = mg_find(sv, PERL_MAGIC_tied))
 246                 && mg->mg_virtual == &sharedsv_array_vtbl) {
 247                 return (shared_sv *) mg->mg_ptr;
 248             }
 249             break;
 250         default:
 251             /* This should work for elements as well as they
 252              * have scalar magic as well as their element magic
 253              */
 254             if ((mg = mg_find(sv, PERL_MAGIC_shared_scalar))
 255                 && mg->mg_virtual == &sharedsv_scalar_vtbl) {
 256                 return (shared_sv *) mg->mg_ptr;
 257             }
 258             break;
 259         }
 260     }
 261     /* Just for tidyness of API also handle tie objects */
 262     if (SvROK(sv) && sv_derived_from(sv, "threads::shared::tie")) {
 263         return SV_to_sharedsv(aTHX_ sv);
 264     }
 265     return NULL;
 266 }
 267
 268 /*
 269  *  Almost all the pain is in this routine.
 270  *
 271  */
 272
 273 shared_sv *
 274 Perl_sharedsv_associate(pTHX_ SV **psv, SV *ssv, shared_sv *data)
 275 {
 276     dTHXc;
 277     MAGIC *mg = 0;
 278     SV *sv    = (psv) ? *psv : Nullsv;
 279
 280     /* If we are asked for an private ops we need a thread */
 281     assert ( aTHX !=  PL_sharedsv_space );
 282
 283     /* To avoid need for recursive locks require caller to hold lock */
 284     assert ( PL_sharedsv_lock.owner == aTHX );
 285
 286     /* First try and get existing global data structure */
 287
 288     /* Try shared SV as 1st choice */
 289     if (!data && ssv && SvTYPE(ssv) >= SVt_PVMG) {
 290         if( (mg = mg_find(ssv, PERL_MAGIC_ext)) ){
 291             data = (shared_sv *) mg->mg_ptr;
 292         }
 293     }
 294
 295     /* Next see if private SV is associated with something */
 296     if (!data && sv) {
 297         data = Perl_sharedsv_find(aTHX_ sv);
 298     }
 299
 300     /* If neither of those then create a new one */
 301     if (!data) {
 302             SHARED_CONTEXT;
 303             if (!ssv) {
 304                 ssv = newSV(0);
 305                 SvREFCNT(ssv) = 0;
 306             }
 307             data = PerlMemShared_malloc(sizeof(shared_sv));
 308             Zero(data,1,shared_sv);
 309             SHAREDSvPTR(data) = ssv;
 310             /* Tag shared side SV with data pointer */
 311             sv_magicext(ssv, ssv, PERL_MAGIC_ext, &sharedsv_shared_vtbl,
 312                    (char *)data, 0);
 313             recursive_lock_init(aTHX_ &data->lock);
 314             COND_INIT(&data->user_cond);
 315             CALLER_CONTEXT;
 316     }
 317
 318     if (!ssv)
 319         ssv = SHAREDSvPTR(data);
 320     if (!SHAREDSvPTR(data))
 321         SHAREDSvPTR(data) = ssv;
 322
 323     /* If we know type upgrade shared side SV */
 324     if (sv && SvTYPE(ssv) < SvTYPE(sv)) {
 325         SHARED_CONTEXT;
 326         sv_upgrade(ssv, SvTYPE(*psv));
 327         if (SvTYPE(ssv) == SVt_PVAV)    /* #24061 */
 328             AvREAL_on(ssv);
 329         CALLER_CONTEXT;
 330     }
 331
 332     /* Now if requested allocate private SV */
 333     if (psv && !sv) {
 334         *psv = sv = newSV(0);
 335     }
 336
 337     /* Finally if private SV exists check and add magic */
 338     if (sv) {
 339         MAGIC *mg = 0;
 340         if (SvTYPE(sv) < SvTYPE(ssv)) {
 341             sv_upgrade(sv, SvTYPE(ssv));
 342         }
 343         switch(SvTYPE(sv)) {
 344         case SVt_PVAV:
 345         case SVt_PVHV:
 346             if (!(mg = mg_find(sv, PERL_MAGIC_tied))
 347                 || mg->mg_virtual != &sharedsv_array_vtbl
 348                 || (shared_sv *) mg->mg_ptr != data) {
 349                 SV *obj = newSV(0);
 350                 sv_setref_iv(obj, "threads::shared::tie",PTR2IV(data));
 351                 if (mg) {
 352                     sv_unmagic(sv, PERL_MAGIC_tied);
 353                 }
 354                 mg = sv_magicext(sv, obj, PERL_MAGIC_tied, &sharedsv_array_vtbl,
 355                                 (char *) data, 0);
 356                 mg->mg_flags |= (MGf_COPY|MGf_DUP);
 357                 SvREFCNT_inc(ssv);
 358                 SvREFCNT_dec(obj);
 359                 if(SvOBJECT(ssv)) {
 360                   STRLEN len;
 361                   char* stash_ptr = SvPV((SV*) SvSTASH(ssv), len);
 362                   HV* stash = gv_stashpvn(stash_ptr, len, TRUE);
 363                   SvOBJECT_on(sv);
 364                   SvSTASH_set(sv, (HV*)SvREFCNT_inc(stash));
 365                 }
 366             }
 367             break;
 368
 369         default:
 370             if ((SvTYPE(sv) < SVt_PVMG)
 371                 || !(mg = mg_find(sv, PERL_MAGIC_shared_scalar))
 372                 || mg->mg_virtual != &sharedsv_scalar_vtbl
 373                 || (shared_sv *) mg->mg_ptr != data) {
 374                 if (mg) {
 375                     sv_unmagic(sv, PERL_MAGIC_shared_scalar);
 376                 }
 377                 mg = sv_magicext(sv, Nullsv, PERL_MAGIC_shared_scalar,
 378                                 &sharedsv_scalar_vtbl, (char *)data, 0);
 379                 mg->mg_flags |= (MGf_COPY|MGf_DUP);
 380                 SvREFCNT_inc(ssv);
 381             }
 382             break;
 383         }
 384         assert ( Perl_sharedsv_find(aTHX_ *psv) == data );
 385     }
 386     return data;
 387 }
 388
 389 void
 390 Perl_sharedsv_free(pTHX_ shared_sv *shared)
 391 {
 392     if (shared) {
 393         dTHXc;
 394         SHARED_EDIT;
 395         SvREFCNT_dec(SHAREDSvPTR(shared));
 396         SHARED_RELEASE;
 397     }
 398 }
 399
 400 void
 401 Perl_sharedsv_share(pTHX_ SV *sv)
 402 {
 403     switch(SvTYPE(sv)) {
 404     case SVt_PVGV:
 405         Perl_croak(aTHX_ "Cannot share globs yet");
 406         break;
 407
 408     case SVt_PVCV:
 409         Perl_croak(aTHX_ "Cannot share subs yet");
 410         break;
 411
 412     default:
 413         ENTER_LOCK;
 414         Perl_sharedsv_associate(aTHX_ &sv, 0, 0);
 415         LEAVE_LOCK;
 416         SvSETMAGIC(sv);
 417         break;
 418     }
 419 }
 420
 421 #if defined(WIN32) || defined(OS2)
 422 #  define ABS2RELMILLI(abs)        \
 423     do {                                \
 424         abs -= (double)time(NULL);      \
 425         if (abs > 0) { abs *= 1000; }   \
 426         else         { abs  = 0;    }   \
 427     } while (0)
 428 #endif /* WIN32 || OS2 */
 429
 430 bool
 431 Perl_sharedsv_cond_timedwait(perl_cond *cond, perl_mutex *mut, double abs)
 432 {
 433 #if defined(NETWARE) || defined(FAKE_THREADS) || defined(I_MACH_CTHREADS)
 434     Perl_croak_nocontext("cond_timedwait not supported on this platform");
 435 #else
 436 #  ifdef WIN32
 437     int got_it = 0;
 438
 439     ABS2RELMILLI(abs);
 440
 441     cond->waiters++;
 442     MUTEX_UNLOCK(mut);
 443     /* See comments in win32/win32thread.h COND_WAIT vis-a-vis race */
 444     switch (WaitForSingleObject(cond->sem, (DWORD)abs)) {
 445         case WAIT_OBJECT_0:   got_it = 1; break;
 446         case WAIT_TIMEOUT:                break;
 447         default:
 448             /* WAIT_FAILED? WAIT_ABANDONED? others? */
 449             Perl_croak_nocontext("panic: cond_timedwait (%ld)",GetLastError());
 450             break;
 451     }
 452     MUTEX_LOCK(mut);
 453     cond->waiters--;
 454     return got_it;
 455 #  else
 456 #    ifdef OS2
 457     int rc, got_it = 0;
 458     STRLEN n_a;
 459
 460     ABS2RELMILLI(abs);
 461
 462     if ((rc = DosResetEventSem(*cond,&n_a)) && (rc != ERROR_ALREADY_RESET))
 463         Perl_rc = rc, croak_with_os2error("panic: cond_timedwait-reset");
 464     MUTEX_UNLOCK(mut);
 465     if (CheckOSError(DosWaitEventSem(*cond,abs))
 466         && (rc != ERROR_INTERRUPT))
 467         croak_with_os2error("panic: cond_timedwait");
 468     if (rc == ERROR_INTERRUPT) errno = EINTR;
 469     MUTEX_LOCK(mut);
 470     return got_it;
 471 #    else         /* hope you're I_PTHREAD! */
 472     struct timespec ts;
 473     int got_it = 0;
 474
 475     ts.tv_sec = (long)abs;
 476     abs -= (NV)ts.tv_sec;
 477     ts.tv_nsec = (long)(abs * 1000000000.0);
 478
 479     switch (pthread_cond_timedwait(cond, mut, &ts)) {
 480         case 0:         got_it = 1; break;
 481         case ETIMEDOUT:             break;
 482         default:
 483             Perl_croak_nocontext("panic: cond_timedwait");
 484             break;
 485     }
 486     return got_it;
 487 #    endif /* OS2 */
 488 #  endif /* WIN32 */
 489 #endif /* NETWARE || FAKE_THREADS || I_MACH_CTHREADS */
 490 }
 491
 492 /* MAGIC (in mg.h sense) hooks */
 493
 494 int
 495 sharedsv_scalar_mg_get(pTHX_ SV *sv, MAGIC *mg)
 496 {
 497     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 498     assert(shared);
 499
 500     ENTER_LOCK;
 501     if (SHAREDSvPTR(shared)) {
 502         if (SvROK(SHAREDSvPTR(shared))) {
 503             SV *obj = Nullsv;
 504             Perl_sharedsv_associate(aTHX_ &obj, SvRV(SHAREDSvPTR(shared)), NULL);
 505             sv_setsv_nomg(sv, &PL_sv_undef);
 506             SvRV_set(sv, obj);
 507             SvROK_on(sv);
 508
 509         }
 510         else {
 511             sv_setsv_nomg(sv, SHAREDSvPTR(shared));
 512         }
 513     }
 514     LEAVE_LOCK;
 515     return 0;
 516 }
 517
 518 void
 519 sharedsv_scalar_store(pTHX_ SV *sv, shared_sv *shared)
 520 {
 521     dTHXc;
 522     bool allowed = TRUE;
 523     if (SvROK(sv)) {
 524         shared_sv* target = Perl_sharedsv_find(aTHX_ SvRV(sv));
 525         if (target) {
 526             SV *tmp;
 527             SHARED_CONTEXT;
 528             tmp = newRV(SHAREDSvPTR(target));
 529             sv_setsv_nomg(SHAREDSvPTR(shared), tmp);
 530             SvREFCNT_dec(tmp);
 531             if(SvOBJECT(SvRV(sv))) {
 532               SV* fake_stash = newSVpv(HvNAME_get(SvSTASH(SvRV(sv))),0);
 533               SvOBJECT_on(SHAREDSvPTR(target));
 534               SvSTASH_set(SHAREDSvPTR(target), (HV*)fake_stash);
 535             }
 536             CALLER_CONTEXT;
 537         }
 538         else {
 539             allowed = FALSE;
 540         }
 541     }
 542     else {
 543         SvTEMP_off(sv);
 544         SHARED_CONTEXT;
 545         sv_setsv_nomg(SHAREDSvPTR(shared), sv);
 546         if(SvOBJECT(sv)) {
 547           SV* fake_stash = newSVpv(HvNAME_get(SvSTASH(sv)),0);
 548           SvOBJECT_on(SHAREDSvPTR(shared));
 549           SvSTASH_set(SHAREDSvPTR(shared), (HV*)fake_stash);
 550         }
 551         CALLER_CONTEXT;
 552     }
 553     if (!allowed) {
 554         Perl_croak(aTHX_ "Invalid value for shared scalar");
 555     }
 556 }
 557
 558 int
 559 sharedsv_scalar_mg_set(pTHX_ SV *sv, MAGIC *mg)
 560 {
 561     shared_sv *shared;
 562     ENTER_LOCK;
 563     /* We call associate to potentially upgrade shared side SV */
 564     shared = Perl_sharedsv_associate(aTHX_ &sv, Nullsv, (shared_sv *) mg->mg_ptr);
 565     assert(shared);
 566     sharedsv_scalar_store(aTHX_ sv, shared);
 567     LEAVE_LOCK;
 568     return 0;
 569 }
 570
 571 int
 572 sharedsv_scalar_mg_free(pTHX_ SV *sv, MAGIC *mg)
 573 {
 574     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 575 #if 0
 576     assert (SvREFCNT(SHAREDSvPTR(shared)) < 1000);
 577 #endif
 578     Perl_sharedsv_free(aTHX_ shared);
 579     return 0;
 580 }
 581
 582 int
 583 sharedsv_scalar_mg_clear(pTHX_ SV *sv, MAGIC *mg)
 584 {
 585     return 0;
 586 }
 587
 588 /*
 589  * Called during cloning of new threads
 590  */
 591 int
 592 sharedsv_scalar_mg_dup(pTHX_ MAGIC *mg, CLONE_PARAMS *param)
 593 {
 594     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 595     if (shared) {
 596         SvREFCNT_inc(SHAREDSvPTR(shared));
 597     }
 598     return 0;
 599 }
 600
 601 MGVTBL sharedsv_scalar_vtbl = {
 602  sharedsv_scalar_mg_get,        /* get */
 603  sharedsv_scalar_mg_set,        /* set */
 604  0,                             /* len */
 605  sharedsv_scalar_mg_clear,      /* clear */
 606  sharedsv_scalar_mg_free,       /* free */
 607  0,                             /* copy */
 608  sharedsv_scalar_mg_dup         /* dup */
 609 };
 610
 611 /* Now the arrays/hashes stuff */
 612 int
 613 sharedsv_elem_mg_FETCH(pTHX_ SV *sv, MAGIC *mg)
 614 {
 615     dTHXc;
 616     shared_sv *shared = SV_to_sharedsv(aTHX_ mg->mg_obj);
 617     shared_sv *target = Perl_sharedsv_find(aTHX_ sv);
 618     SV** svp;
 619
 620     assert ( shared );
 621     assert ( SHAREDSvPTR(shared) );
 622
 623     ENTER_LOCK;
 624     if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 625         assert ( mg->mg_ptr == 0 );
 626         SHARED_CONTEXT;
 627         svp = av_fetch((AV*) SHAREDSvPTR(shared), mg->mg_len, 0);
 628     }
 629     else {
 630         char *key = mg->mg_ptr;
 631         STRLEN len = mg->mg_len;
 632         assert ( mg->mg_ptr != 0 );
 633         if (mg->mg_len == HEf_SVKEY) {
 634            key = SvPV((SV *) mg->mg_ptr, len);
 635         }
 636         SHARED_CONTEXT;
 637         svp = hv_fetch((HV*) SHAREDSvPTR(shared), key, len, 0);
 638     }
 639     CALLER_CONTEXT;
 640     if (svp) {
 641         /* Exists in the array */
 642         if (SvROK(*svp)) {
 643             SV *obj = Nullsv;
 644             Perl_sharedsv_associate(aTHX_ &obj, SvRV(*svp), NULL);
 645             sv_setsv_nomg(sv, &PL_sv_undef);
 646             SvRV_set(sv, obj);
 647             SvROK_on(sv);
 648             SvSETMAGIC(sv);
 649         }
 650         else {
 651             target = Perl_sharedsv_associate(aTHX_ &sv, *svp, target);
 652             sv_setsv(sv, *svp);
 653         }
 654     }
 655     else {
 656         /* Not in the array */
 657         sv_setsv(sv, &PL_sv_undef);
 658     }
 659     LEAVE_LOCK;
 660     return 0;
 661 }
 662
 663 int
 664 sharedsv_elem_mg_STORE(pTHX_ SV *sv, MAGIC *mg)
 665 {
 666     dTHXc;
 667     shared_sv *shared = SV_to_sharedsv(aTHX_ mg->mg_obj);
 668     shared_sv *target;
 669     SV **svp;
 670     /* Theory - SV itself is magically shared - and we have ordered the
 671        magic such that by the time we get here it has been stored
 672        to its shared counterpart
 673      */
 674     ENTER_LOCK;
 675     assert(shared);
 676     assert(SHAREDSvPTR(shared));
 677     if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 678         assert ( mg->mg_ptr == 0 );
 679         SHARED_CONTEXT;
 680         svp = av_fetch((AV*) SHAREDSvPTR(shared), mg->mg_len, 1);
 681     }
 682     else {
 683         char *key = mg->mg_ptr;
 684         STRLEN len = mg->mg_len;
 685         assert ( mg->mg_ptr != 0 );
 686         if (mg->mg_len == HEf_SVKEY)
 687            key = SvPV((SV *) mg->mg_ptr, len);
 688         SHARED_CONTEXT;
 689         svp = hv_fetch((HV*) SHAREDSvPTR(shared), key, len, 1);
 690     }
 691     CALLER_CONTEXT;
 692     target = Perl_sharedsv_associate(aTHX_ &sv, *svp, 0);
 693     sharedsv_scalar_store(aTHX_ sv, target);
 694     LEAVE_LOCK;
 695     return 0;
 696 }
 697
 698 int
 699 sharedsv_elem_mg_DELETE(pTHX_ SV *sv, MAGIC *mg)
 700 {
 701     dTHXc;
 702     MAGIC *shmg;
 703     shared_sv *shared = SV_to_sharedsv(aTHX_ mg->mg_obj);
 704     ENTER_LOCK;
 705     sharedsv_elem_mg_FETCH(aTHX_ sv, mg);
 706     if ((shmg = mg_find(sv, PERL_MAGIC_shared_scalar)))
 707         sharedsv_scalar_mg_get(aTHX_ sv, shmg);
 708     if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 709         SHARED_CONTEXT;
 710         av_delete((AV*) SHAREDSvPTR(shared), mg->mg_len, G_DISCARD);
 711     }
 712     else {
 713         char *key = mg->mg_ptr;
 714         STRLEN len = mg->mg_len;
 715         assert ( mg->mg_ptr != 0 );
 716         if (mg->mg_len == HEf_SVKEY)
 717            key = SvPV((SV *) mg->mg_ptr, len);
 718         SHARED_CONTEXT;
 719         hv_delete((HV*) SHAREDSvPTR(shared), key, len, G_DISCARD);
 720     }
 721     CALLER_CONTEXT;
 722     LEAVE_LOCK;
 723     return 0;
 724 }
 725
 726 int
 727 sharedsv_elem_mg_free(pTHX_ SV *sv, MAGIC *mg)
 728 {
 729     Perl_sharedsv_free(aTHX_ SV_to_sharedsv(aTHX_ mg->mg_obj));
 730     return 0;
 731 }
 732
 733 int
 734 sharedsv_elem_mg_dup(pTHX_ MAGIC *mg, CLONE_PARAMS *param)
 735 {
 736     shared_sv *shared = SV_to_sharedsv(aTHX_ mg->mg_obj);
 737     SvREFCNT_inc(SHAREDSvPTR(shared));
 738     mg->mg_flags |= MGf_DUP;
 739     return 0;
 740 }
 741
 742 MGVTBL sharedsv_elem_vtbl = {
 743  sharedsv_elem_mg_FETCH,        /* get */
 744  sharedsv_elem_mg_STORE,        /* set */
 745  0,                             /* len */
 746  sharedsv_elem_mg_DELETE,       /* clear */
 747  sharedsv_elem_mg_free,         /* free */
 748  0,                             /* copy */
 749  sharedsv_elem_mg_dup           /* dup */
 750 };
 751
 752 U32
 753 sharedsv_array_mg_FETCHSIZE(pTHX_ SV *sv, MAGIC *mg)
 754 {
 755     dTHXc;
 756     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 757     U32 val;
 758     SHARED_EDIT;
 759     if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 760         val = av_len((AV*) SHAREDSvPTR(shared));
 761     }
 762     else {
 763         /* not actually defined by tie API but ... */
 764         val = HvKEYS((HV*) SHAREDSvPTR(shared));
 765     }
 766     SHARED_RELEASE;
 767     return val;
 768 }
 769
 770 int
 771 sharedsv_array_mg_CLEAR(pTHX_ SV *sv, MAGIC *mg)
 772 {
 773     dTHXc;
 774     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 775     SHARED_EDIT;
 776     if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 777         av_clear((AV*) SHAREDSvPTR(shared));
 778     }
 779     else {
 780         hv_clear((HV*) SHAREDSvPTR(shared));
 781     }
 782     SHARED_RELEASE;
 783     return 0;
 784 }
 785
 786 int
 787 sharedsv_array_mg_free(pTHX_ SV *sv, MAGIC *mg)
 788 {
 789     Perl_sharedsv_free(aTHX_ (shared_sv *) mg->mg_ptr);
 790     return 0;
 791 }
 792
 793 /*
 794  * This is called when perl is about to access an element of
 795  * the array -
 796  */
 797 int
 798 sharedsv_array_mg_copy(pTHX_ SV *sv, MAGIC* mg,
 799                        SV *nsv, const char *name, int namlen)
 800 {
 801     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 802     MAGIC *nmg = sv_magicext(nsv,mg->mg_obj,
 803                             toLOWER(mg->mg_type),&sharedsv_elem_vtbl,
 804                             name, namlen);
 805     ENTER_LOCK;
 806     SvREFCNT_inc(SHAREDSvPTR(shared));
 807     LEAVE_LOCK;
 808     nmg->mg_flags |= MGf_DUP;
 809     return 1;
 810 }
 811
 812 int
 813 sharedsv_array_mg_dup(pTHX_ MAGIC *mg, CLONE_PARAMS *param)
 814 {
 815     shared_sv *shared = (shared_sv *) mg->mg_ptr;
 816     SvREFCNT_inc(SHAREDSvPTR(shared));
 817     mg->mg_flags |= MGf_DUP;
 818     return 0;
 819 }
 820
 821 MGVTBL sharedsv_array_vtbl = {
 822  0,                             /* get */
 823  0,                             /* set */
 824  sharedsv_array_mg_FETCHSIZE,   /* len */
 825  sharedsv_array_mg_CLEAR,       /* clear */
 826  sharedsv_array_mg_free,        /* free */
 827  sharedsv_array_mg_copy,        /* copy */
 828  sharedsv_array_mg_dup          /* dup */
 829 };
 830
 831 =for apidoc sharedsv_unlock
 832
 833 Recursively unlocks a shared sv.
 834
 835 =cut
 836
 837 void
 838 Perl_sharedsv_unlock(pTHX_ shared_sv* ssv)
 839 {
 840     recursive_lock_release(aTHX_ &ssv->lock);
 841 }
 842
 843 =for apidoc sharedsv_lock
 844
 845 Recursive locks on a sharedsv.
 846 Locks are dynamically scoped at the level of the first lock.
 847
 848 =cut
 849
 850 void
 851 Perl_sharedsv_lock(pTHX_ shared_sv* ssv)
 852 {
 853     if (!ssv)
 854         return;
 855     recursive_lock_acquire(aTHX_ &ssv->lock, __FILE__, __LINE__);
 856 }
 857
 858 /* handles calls from lock() builtin via PL_lockhook */
 859
 860 void
 861 Perl_sharedsv_locksv(pTHX_ SV *sv)
 862 {
 863     shared_sv* shared;
 864
 865     if(SvROK(sv))
 866         sv = SvRV(sv);
 867     shared = Perl_sharedsv_find(aTHX_ sv);
 868     if(!shared)
 869        croak("lock can only be used on shared values");
 870     Perl_sharedsv_lock(aTHX_ shared);
 871 }
 872
 873 =head1 Shared SV Functions
 874
 875 =for apidoc sharedsv_init
 876
 877 Saves a space for keeping SVs wider than an interpreter,
 878
 879 =cut
 880
 881 void
 882 Perl_sharedsv_init(pTHX)
 883 {
 884   dTHXc;
 885   /* This pair leaves us in shared context ... */
 886   PL_sharedsv_space = perl_alloc();
 887   perl_construct(PL_sharedsv_space);
 888   CALLER_CONTEXT;
 889   recursive_lock_init(aTHX_ &PL_sharedsv_lock);
 890   PL_lockhook = &Perl_sharedsv_locksv;
 891   PL_sharehook = &Perl_sharedsv_share;
 892 }
 893
 894 #endif /* USE_ITHREADS */
 895
 896 MODULE = threads::shared        PACKAGE = threads::shared::tie
 897
 898 PROTOTYPES: DISABLE
 899
 900 #ifdef USE_ITHREADS
 901
 902 void
 903 PUSH(shared_sv *shared, ...)
 904 CODE:
 905         dTHXc;
 906         int i;
 907         for(i = 1; i < items; i++) {
 908             SV* tmp = newSVsv(ST(i));
 909             shared_sv *target;
 910             ENTER_LOCK;
 911             target = Perl_sharedsv_associate(aTHX_ &tmp, Nullsv, 0);
 912             sharedsv_scalar_store(aTHX_ tmp, target);
 913             SHARED_CONTEXT;
 914             av_push((AV*) SHAREDSvPTR(shared), SHAREDSvPTR(target));
 915             SvREFCNT_inc(SHAREDSvPTR(target));
 916             SHARED_RELEASE;
 917             SvREFCNT_dec(tmp);
 918         }
 919
 920 void
 921 UNSHIFT(shared_sv *shared, ...)
 922 CODE:
 923         dTHXc;
 924         int i;
 925         ENTER_LOCK;
 926         SHARED_CONTEXT;
 927         av_unshift((AV*)SHAREDSvPTR(shared), items - 1);
 928         CALLER_CONTEXT;
 929         for(i = 1; i < items; i++) {
 930             SV* tmp = newSVsv(ST(i));
 931             shared_sv *target = Perl_sharedsv_associate(aTHX_ &tmp, Nullsv, 0);
 932             sharedsv_scalar_store(aTHX_ tmp, target);
 933             SHARED_CONTEXT;
 934             av_store((AV*) SHAREDSvPTR(shared), i - 1, SHAREDSvPTR(target));
 935             SvREFCNT_inc(SHAREDSvPTR(target));
 936             CALLER_CONTEXT;
 937             SvREFCNT_dec(tmp);
 938         }
 939         LEAVE_LOCK;
 940
 941 void
 942 POP(shared_sv *shared)
 943 CODE:
 944         dTHXc;
 945         SV* sv;
 946         ENTER_LOCK;
 947         SHARED_CONTEXT;
 948         sv = av_pop((AV*)SHAREDSvPTR(shared));
 949         CALLER_CONTEXT;
 950         ST(0) = sv_newmortal();
 951         Perl_sharedsv_associate(aTHX_ &ST(0), sv, 0);
 952         SvREFCNT_dec(sv);
 953         LEAVE_LOCK;
 954         XSRETURN(1);
 955
 956 void
 957 SHIFT(shared_sv *shared)
 958 CODE:
 959         dTHXc;
 960         SV* sv;
 961         ENTER_LOCK;
 962         SHARED_CONTEXT;
 963         sv = av_shift((AV*)SHAREDSvPTR(shared));
 964         CALLER_CONTEXT;
 965         ST(0) = sv_newmortal();
 966         Perl_sharedsv_associate(aTHX_ &ST(0), sv, 0);
 967         SvREFCNT_dec(sv);
 968         LEAVE_LOCK;
 969         XSRETURN(1);
 970
 971 void
 972 EXTEND(shared_sv *shared, IV count)
 973 CODE:
 974         dTHXc;
 975         SHARED_EDIT;
 976         av_extend((AV*)SHAREDSvPTR(shared), count);
 977         SHARED_RELEASE;
 978
 979 void
 980 STORESIZE(shared_sv *shared,IV count)
 981 CODE:
 982         dTHXc;
 983         SHARED_EDIT;
 984         av_fill((AV*) SHAREDSvPTR(shared), count);
 985         SHARED_RELEASE;
 986
 987
 988
 989
 990 void
 991 EXISTS(shared_sv *shared, SV *index)
 992 CODE:
 993         dTHXc;
 994         bool exists;
 995         if (SvTYPE(SHAREDSvPTR(shared)) == SVt_PVAV) {
 996             SHARED_EDIT;
 997             exists = av_exists((AV*) SHAREDSvPTR(shared), SvIV(index));
 998         }
 999         else {
1000             STRLEN len;
1001             char *key = SvPV(index,len);
1002             SHARED_EDIT;
1003             exists = hv_exists((HV*) SHAREDSvPTR(shared), key, len);
1004         }
1005         SHARED_RELEASE;
1006         ST(0) = (exists) ? &PL_sv_yes : &PL_sv_no;
1007         XSRETURN(1);
1008
1009
1010 void
1011 FIRSTKEY(shared_sv *shared)
1012 CODE:
1013         dTHXc;
1014         char* key = NULL;
1015         I32 len = 0;
1016         HE* entry;
1017         ENTER_LOCK;
1018         SHARED_CONTEXT;
1019         hv_iterinit((HV*) SHAREDSvPTR(shared));
1020         entry = hv_iternext((HV*) SHAREDSvPTR(shared));
1021         if (entry) {
1022                 key = hv_iterkey(entry,&len);
1023                 CALLER_CONTEXT;
1024                 ST(0) = sv_2mortal(newSVpv(key, len));
1025         } else {
1026              CALLER_CONTEXT;
1027              ST(0) = &PL_sv_undef;
1028         }
1029         LEAVE_LOCK;
1030         XSRETURN(1);
1031
1032 void
1033 NEXTKEY(shared_sv *shared, SV *oldkey)
1034 CODE:
1035         dTHXc;
1036         char* key = NULL;
1037         I32 len = 0;
1038         HE* entry;
1039         ENTER_LOCK;
1040         SHARED_CONTEXT;
1041         entry = hv_iternext((HV*) SHAREDSvPTR(shared));
1042         if (entry) {
1043                 key = hv_iterkey(entry,&len);
1044                 CALLER_CONTEXT;
1045                 ST(0) = sv_2mortal(newSVpv(key, len));
1046         } else {
1047              CALLER_CONTEXT;
1048              ST(0) = &PL_sv_undef;
1049         }
1050         LEAVE_LOCK;
1051         XSRETURN(1);
1052
1053 MODULE = threads::shared                PACKAGE = threads::shared
1054
1055 PROTOTYPES: ENABLE
1056
1057 void
1058 _id(SV *ref)
1059         PROTOTYPE: \[$@%]
1060 CODE:
1061         shared_sv *shared;
1062         ref = SvRV(ref);
1063         if(SvROK(ref))
1064             ref = SvRV(ref);
1065         if( (shared = Perl_sharedsv_find(aTHX_ ref)) ){
1066             ST(0) = sv_2mortal(newSViv(PTR2IV(shared)));
1067             XSRETURN(1);
1068         }
1069         XSRETURN_UNDEF;
1070
1071
1072 void
1073 _refcnt(SV *ref)
1074         PROTOTYPE: \[$@%]
1075 CODE:
1076         shared_sv *shared;
1077         ref = SvRV(ref);
1078         if(SvROK(ref))
1079             ref = SvRV(ref);
1080         if( (shared = Perl_sharedsv_find(aTHX_ ref)) ){
1081           if (SHAREDSvPTR(shared)) {
1082             ST(0) = sv_2mortal(newSViv(SvREFCNT(SHAREDSvPTR(shared))));
1083             XSRETURN(1);
1084           }
1085           else {
1086              Perl_warn(aTHX_ "%" SVf " s=%p has no shared SV",ST(0),shared);
1087           }
1088         }
1089         else {
1090              Perl_warn(aTHX_ "%" SVf " is not shared",ST(0));
1091         }
1092         XSRETURN_UNDEF;
1093
1094 SV*
1095 share(SV *ref)
1096         PROTOTYPE: \[$@%]
1097         CODE:
1098         if(!SvROK(ref))
1099             Perl_croak(aTHX_ "Argument to share needs to be passed as ref");
1100         ref = SvRV(ref);
1101         if(SvROK(ref))
1102             ref = SvRV(ref);
1103         Perl_sharedsv_share(aTHX_ ref);
1104         RETVAL = newRV(ref);
1105         OUTPUT:
1106         RETVAL
1107
1108 void
1109 lock_enabled(SV *ref)
1110         PROTOTYPE: \[$@%]
1111         CODE:
1112         shared_sv* shared;
1113         if(!SvROK(ref))
1114             Perl_croak(aTHX_ "Argument to lock needs to be passed as ref");
1115         ref = SvRV(ref);
1116         if(SvROK(ref))
1117             ref = SvRV(ref);
1118         shared = Perl_sharedsv_find(aTHX_ ref);
1119         if(!shared)
1120            croak("lock can only be used on shared values");
1121         Perl_sharedsv_lock(aTHX_ shared);
1122
1123 void
1124 cond_wait_enabled(SV *ref_cond, SV *ref_lock = 0)
1125         PROTOTYPE: \[$@%];\[$@%]
1126         PREINIT:
1127         shared_sv* shared;
1128         perl_cond* user_condition;
1129         int locks;
1130         int same = 0;
1131
1132         CODE:
1133         if (!ref_lock || ref_lock == ref_cond) same = 1;
1134
1135         if(!SvROK(ref_cond))
1136             Perl_croak(aTHX_ "Argument to cond_wait needs to be passed as ref");
1137         ref_cond = SvRV(ref_cond);
1138         if(SvROK(ref_cond))
1139             ref_cond = SvRV(ref_cond);
1140         shared = Perl_sharedsv_find(aTHX_ ref_cond);
1141         if(!shared)
1142             croak("cond_wait can only be used on shared values");
1143
1144         user_condition = &shared->user_cond;
1145         if (! same) {
1146             if (!SvROK(ref_lock))
1147                 Perl_croak(aTHX_ "cond_wait lock needs to be passed as ref");
1148             ref_lock = SvRV(ref_lock);
1149             if (SvROK(ref_lock)) ref_lock = SvRV(ref_lock);
1150             shared = Perl_sharedsv_find(aTHX_ ref_lock);
1151             if (!shared)
1152                 croak("cond_wait lock must be a shared value");
1153         }
1154         if(shared->lock.owner != aTHX)
1155             croak("You need a lock before you can cond_wait");
1156         /* Stealing the members of the lock object worries me - NI-S */
1157         MUTEX_LOCK(&shared->lock.mutex);
1158         shared->lock.owner = NULL;
1159         locks = shared->lock.locks;
1160         shared->lock.locks = 0;
1161
1162         /* since we are releasing the lock here we need to tell other
1163         people that is ok to go ahead and use it */
1164         COND_SIGNAL(&shared->lock.cond);
1165         COND_WAIT(user_condition, &shared->lock.mutex);
1166         while(shared->lock.owner != NULL) {
1167             /* OK -- must reacquire the lock */
1168             COND_WAIT(&shared->lock.cond, &shared->lock.mutex);
1169         }
1170         shared->lock.owner = aTHX;
1171         shared->lock.locks = locks;
1172         MUTEX_UNLOCK(&shared->lock.mutex);
1173
1174 int
1175 cond_timedwait_enabled(SV *ref_cond, double abs, SV *ref_lock = 0)
1176         PROTOTYPE: \[$@%]$;\[$@%]
1177         PREINIT:
1178         shared_sv* shared;
1179         perl_cond* user_condition;
1180         int locks;
1181         int same = 0;
1182
1183         CODE:
1184         if (!ref_lock || ref_cond == ref_lock) same = 1;
1185
1186         if(!SvROK(ref_cond))
1187             Perl_croak(aTHX_ "Argument to cond_timedwait needs to be passed as ref");
1188         ref_cond = SvRV(ref_cond);
1189         if(SvROK(ref_cond))
1190             ref_cond = SvRV(ref_cond);
1191         shared = Perl_sharedsv_find(aTHX_ ref_cond);
1192         if(!shared)
1193             croak("cond_timedwait can only be used on shared values");
1194
1195         user_condition = &shared->user_cond;
1196         if (! same) {
1197             if (!SvROK(ref_lock))
1198                 Perl_croak(aTHX_ "cond_timedwait lock needs to be passed as ref");
1199             ref_lock = SvRV(ref_lock);
1200             if (SvROK(ref_lock)) ref_lock = SvRV(ref_lock);
1201             shared = Perl_sharedsv_find(aTHX_ ref_lock);
1202             if (!shared)
1203                 croak("cond_timedwait lock must be a shared value");
1204         }
1205         if(shared->lock.owner != aTHX)
1206             croak("You need a lock before you can cond_wait");
1207
1208         MUTEX_LOCK(&shared->lock.mutex);
1209         shared->lock.owner = NULL;
1210         locks = shared->lock.locks;
1211         shared->lock.locks = 0;
1212         /* since we are releasing the lock here we need to tell other
1213         people that is ok to go ahead and use it */
1214         COND_SIGNAL(&shared->lock.cond);
1215         RETVAL = Perl_sharedsv_cond_timedwait(user_condition, &shared->lock.mutex, abs);
1216         while (shared->lock.owner != NULL) {
1217             /* OK -- must reacquire the lock... */
1218             COND_WAIT(&shared->lock.cond, &shared->lock.mutex);
1219         }
1220         shared->lock.owner = aTHX;
1221         shared->lock.locks = locks;
1222         MUTEX_UNLOCK(&shared->lock.mutex);
1223
1224         if (RETVAL == 0)
1225             XSRETURN_UNDEF;
1226         OUTPUT:
1227         RETVAL
1228
1229 void
1230 cond_signal_enabled(SV *ref)
1231         PROTOTYPE: \[$@%]
1232         CODE:
1233         shared_sv* shared;
1234         if(!SvROK(ref))
1235             Perl_croak(aTHX_ "Argument to cond_signal needs to be passed as ref");
1236         ref = SvRV(ref);
1237         if(SvROK(ref))
1238             ref = SvRV(ref);
1239         shared = Perl_sharedsv_find(aTHX_ ref);
1240         if(!shared)
1241             croak("cond_signal can only be used on shared values");
1242         if (ckWARN(WARN_THREADS) && shared->lock.owner != aTHX)
1243             Perl_warner(aTHX_ packWARN(WARN_THREADS),
1244                             "cond_signal() called on unlocked variable");
1245         COND_SIGNAL(&shared->user_cond);
1246
1247 void
1248 cond_broadcast_enabled(SV *ref)
1249         PROTOTYPE: \[$@%]
1250         CODE:
1251         shared_sv* shared;
1252         if(!SvROK(ref))
1253             Perl_croak(aTHX_ "Argument to cond_broadcast needs to be passed as ref");
1254         ref = SvRV(ref);
1255         if(SvROK(ref))
1256             ref = SvRV(ref);
1257         shared = Perl_sharedsv_find(aTHX_ ref);
1258         if(!shared)
1259             croak("cond_broadcast can only be used on shared values");
1260         if (ckWARN(WARN_THREADS) && shared->lock.owner != aTHX)
1261             Perl_warner(aTHX_ packWARN(WARN_THREADS),
1262                             "cond_broadcast() called on unlocked variable");
1263         COND_BROADCAST(&shared->user_cond);
1264
1265
1266 SV*
1267 bless(SV* ref, ...);
1268         PROTOTYPE: $;$
1269         CODE:
1270         {
1271           HV* stash;
1272           shared_sv* shared;
1273           if (items == 1)
1274             stash = CopSTASH(PL_curcop);
1275           else {
1276             SV* ssv = ST(1);
1277             STRLEN len;
1278             char *ptr;
1279
1280             if (ssv && !SvGMAGICAL(ssv) && !SvAMAGIC(ssv) && SvROK(ssv))
1281               Perl_croak(aTHX_ "Attempt to bless into a reference");
1282             ptr = SvPV(ssv,len);
1283             if (ckWARN(WARN_MISC) && len == 0)
1284               Perl_warner(aTHX_ packWARN(WARN_MISC),
1285                           "Explicit blessing to '' (assuming package main)");
1286             stash = gv_stashpvn(ptr, len, TRUE);
1287           }
1288           SvREFCNT_inc(ref);
1289           (void)sv_bless(ref, stash);
1290           RETVAL = ref;
1291           shared = Perl_sharedsv_find(aTHX_ ref);
1292           if(shared) {
1293             dTHXc;
1294             ENTER_LOCK;
1295             SHARED_CONTEXT;
1296             {
1297               SV* fake_stash = newSVpv(HvNAME_get(stash),0);
1298               (void)sv_bless(SHAREDSvPTR(shared),(HV*)fake_stash);
1299             }
1300             CALLER_CONTEXT;
1301             LEAVE_LOCK;
1302           }
1303         }
1304         OUTPUT:
1305         RETVAL
1306
1307 #endif /* USE_ITHREADS */
1308
1309 BOOT:
1310 {
1311 #ifdef USE_ITHREADS
1312      Perl_sharedsv_init(aTHX);
1313 #endif /* USE_ITHREADS */
1314 }
1315
1316
1317