3 * Copyright (c) 2007 Brandon L Black
4 * Copyright (c) 2007, 2008, 2009, 2010, 2011 Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
9 * This was 'mro.c', but changed because there is another mro.c in /ext, and
10 * the os390 loader can't cope with this situation (which involves the two
11 * files calling functions defined in the other)
15 * 'Which order shall we go in?' said Frodo. 'Eldest first, or quickest first?
16 * You'll be last either way, Master Peregrin.'
18 * [p.101 of _The Lord of the Rings_, I/iii: "A Conspiracy Unmasked"]
23 These functions are related to the method resolution order of perl classes
24 Also see L<perlmroapi>.
33 static const struct mro_alg dfs_alg =
34 {S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};
37 Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
38 const struct mro_alg *const which)
41 PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;
43 data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
44 which->name, which->length, which->kflags,
45 HV_FETCH_JUST_SV, NULL, which->hash);
49 /* If we've been asked to look up the private data for the current MRO, then
51 if (smeta->mro_which == which)
52 smeta->mro_linear_current = *data;
58 Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
59 const struct mro_alg *const which, SV *const data)
61 PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;
63 if (!smeta->mro_linear_all) {
64 if (smeta->mro_which == which) {
65 /* If all we need to store is the current MRO's data, then don't use
66 memory on a hash with 1 element - store it direct, and signal
67 this by leaving the would-be-hash NULL. */
68 smeta->mro_linear_current = data;
71 HV *const hv = newHV();
72 /* Start with 2 buckets. It's unlikely we'll need more. */
74 smeta->mro_linear_all = hv;
76 if (smeta->mro_linear_current) {
77 /* If we were storing something directly, put it in the hash
79 Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which,
80 smeta->mro_linear_current);
85 /* We get here if we're storing more than one linearisation for this stash,
86 or the linearisation we are storing is not that if its current MRO. */
88 if (smeta->mro_which == which) {
89 /* If we've been asked to store the private data for the current MRO,
91 smeta->mro_linear_current = data;
94 if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
95 which->name, which->length, which->kflags,
96 HV_FETCH_ISSTORE, data, which->hash)) {
97 Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
98 "for '%.*s' %d", (int) which->length, which->name,
105 const struct mro_alg *
106 Perl_mro_get_from_name(pTHX_ SV *name) {
109 PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;
111 data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
112 HV_FETCH_JUST_SV, NULL, 0);
115 assert(SvTYPE(*data) == SVt_IV);
116 assert(SvIOK(*data));
117 return INT2PTR(const struct mro_alg *, SvUVX(*data));
121 =for apidoc mro_register
122 Registers a custom mro plugin. See L<perlmroapi> for details on this and other
129 Perl_mro_register(pTHX_ const struct mro_alg *mro) {
130 SV *wrapper = newSVuv(PTR2UV(mro));
132 PERL_ARGS_ASSERT_MRO_REGISTER;
135 if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
136 mro->name, mro->length, mro->kflags,
137 HV_FETCH_ISSTORE, wrapper, mro->hash)) {
138 SvREFCNT_dec_NN(wrapper);
139 Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
140 "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
145 Perl_mro_meta_init(pTHX_ HV* stash)
147 struct mro_meta* newmeta;
149 PERL_ARGS_ASSERT_MRO_META_INIT;
151 assert(HvAUX(stash));
152 assert(!(HvAUX(stash)->xhv_mro_meta));
153 Newxz(newmeta, 1, struct mro_meta);
154 HvAUX(stash)->xhv_mro_meta = newmeta;
155 newmeta->cache_gen = 1;
156 newmeta->pkg_gen = 1;
157 newmeta->mro_which = &dfs_alg;
162 #if defined(USE_ITHREADS)
164 /* for sv_dup on new threads */
166 Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
168 struct mro_meta* newmeta;
170 PERL_ARGS_ASSERT_MRO_META_DUP;
172 Newx(newmeta, 1, struct mro_meta);
173 Copy(smeta, newmeta, 1, struct mro_meta);
175 if (newmeta->mro_linear_all) {
176 newmeta->mro_linear_all
177 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
178 /* This is just acting as a shortcut pointer, and will be automatically
179 updated on the first get. */
180 newmeta->mro_linear_current = NULL;
181 } else if (newmeta->mro_linear_current) {
182 /* Only the current MRO is stored, so this owns the data. */
183 newmeta->mro_linear_current
184 = sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
187 if (newmeta->mro_nextmethod)
188 newmeta->mro_nextmethod
189 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
192 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
194 newmeta->super = NULL;
196 /* clear the destructor cache */
197 newmeta->destroy = NULL;
198 newmeta->destroy_gen = 0;
203 #endif /* USE_ITHREADS */
206 =for apidoc mro_get_linear_isa_dfs
208 Returns the Depth-First Search linearization of C<@ISA>
209 the given stash. The return value is a read-only AV*.
210 C<level> should be 0 (it is used internally in this
211 function's recursion).
213 You are responsible for C<SvREFCNT_inc()> on the
214 return value if you plan to store it anywhere
215 semi-permanently (otherwise it might be deleted
216 out from under you the next time the cache is
222 S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
229 struct mro_meta* meta;
233 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
234 assert(HvAUX(stash));
237 = HvAUX(stash)->xhv_name_u.xhvnameu_name && HvENAME_HEK_NN(stash)
238 ? HvENAME_HEK_NN(stash)
242 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
246 "Recursive inheritance detected in package '%" HEKf "'",
249 meta = HvMROMETA(stash);
251 /* return cache if valid */
252 if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
256 /* not in cache, make a new one */
258 retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
259 /* We use this later in this function, but don't need a reference to it
260 beyond the end of this function, so reference count is fine. */
261 our_name = newSVhek(stashhek);
262 av_push(retval, our_name); /* add ourselves at the top */
265 gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
266 av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
268 /* "stored" is used to keep track of all of the classnames we have added to
269 the MRO so far, so we can do a quick exists check and avoid adding
270 duplicate classnames to the MRO as we go.
271 It's then retained to be re-used as a fast lookup for ->isa(), by adding
272 our own name and "UNIVERSAL" to it. */
274 if(av && AvFILLp(av) >= 0) {
276 SV **svp = AvARRAY(av);
277 I32 items = AvFILLp(av) + 1;
281 SV* const sv = *svp ? *svp : &PL_sv_undef;
282 HV* const basestash = gv_stashsv(sv, 0);
288 /* if no stash exists for this @ISA member,
289 simply add it to the MRO and move on */
294 /* otherwise, recurse into ourselves for the MRO
295 of this @ISA member, and append their MRO to ours.
296 The recursive call could throw an exception, which
297 has memory management implications here, hence the use of
299 const AV *const subrv
300 = mro_get_linear_isa_dfs(basestash, level + 1);
302 subrv_p = AvARRAY(subrv);
303 subrv_items = AvFILLp(subrv) + 1;
306 while(subrv_items--) {
307 SV *const subsv = *subrv_p++;
308 /* LVALUE fetch will create a new undefined SV if necessary
310 HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
312 if(HeVAL(he) != &PL_sv_undef) {
313 /* It was newly created. Steal it for our new SV, and
314 replace it in the hash with the "real" thing. */
315 SV *const val = HeVAL(he);
316 HEK *const key = HeKEY_hek(he);
318 HeVAL(he) = &PL_sv_undef;
320 av_push(retval, val);
324 /* We are the first (or only) parent. We can short cut the
325 complexity above, because our @ISA is simply us prepended
326 to our parent's @ISA, and our ->isa cache is simply our
327 parent's, with our name added. */
328 /* newSVsv() is slow. This code is only faster if we can avoid
329 it by ensuring that SVs in the arrays are shared hash key
330 scalar SVs, because we can "copy" them very efficiently.
331 Although to be fair, we can't *ensure* this, as a reference
332 to the internal array is returned by mro::get_linear_isa(),
333 so we'll have to be defensive just in case someone faffed
337 stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
338 av_extend(retval, subrv_items);
339 AvFILLp(retval) = subrv_items;
340 svp = AvARRAY(retval);
341 while(subrv_items--) {
342 SV *const val = *subrv_p++;
343 *++svp = SvIsCOW_shared_hash(val)
344 ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
348 /* They have no stash. So create ourselves an ->isa cache
349 as if we'd copied it from what theirs should be. */
350 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
351 (void) hv_stores(stored, "UNIVERSAL", &PL_sv_undef);
353 newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
359 /* We have no parents. */
360 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
361 (void) hv_stores(stored, "UNIVERSAL", &PL_sv_undef);
364 (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
366 SvREFCNT_inc_simple_void_NN(stored);
368 SvREADONLY_on(stored);
372 /* now that we're past the exception dangers, grab our own reference to
373 the AV we're about to use for the result. The reference owned by the
374 mortals' stack will be released soon, so everything will balance. */
375 SvREFCNT_inc_simple_void_NN(retval);
378 /* we don't want anyone modifying the cache entry but us,
379 and we do so by replacing it completely */
380 SvREADONLY_on(retval);
382 return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
383 MUTABLE_SV(retval)));
387 =for apidoc mro_get_linear_isa
389 Returns the mro linearisation for the given stash. By default, this
390 will be whatever C<mro_get_linear_isa_dfs> returns unless some
391 other MRO is in effect for the stash. The return value is a
394 You are responsible for C<SvREFCNT_inc()> on the
395 return value if you plan to store it anywhere
396 semi-permanently (otherwise it might be deleted
397 out from under you the next time the cache is
403 Perl_mro_get_linear_isa(pTHX_ HV *stash)
405 struct mro_meta* meta;
408 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
410 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
412 meta = HvMROMETA(stash);
413 if (!meta->mro_which)
414 Perl_croak(aTHX_ "panic: invalid MRO!");
415 isa = meta->mro_which->resolve(aTHX_ stash, 0);
417 if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
419 (HvENAME(stash)||HvNAME(stash))
420 ? newSVhek(HvENAME_HEK(stash)
425 if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
427 AV * const old = isa;
429 SV **ovp = AvARRAY(old);
430 SV * const * const oend = ovp + AvFILLp(old) + 1;
431 isa = (AV *)sv_2mortal((SV *)newAV());
432 av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
433 *AvARRAY(isa) = namesv;
434 svp = AvARRAY(isa)+1;
435 while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
437 else SvREFCNT_dec(namesv);
441 HV *const isa_hash = newHV();
442 /* Linearisation didn't build it for us, so do it here. */
443 I32 count = AvFILLp(isa) + 1;
444 SV *const *svp = AvARRAY(isa);
445 SV *const *const svp_end = svp + count;
446 const HEK *canon_name = HvENAME_HEK(stash);
447 if (!canon_name) canon_name = HvNAME_HEK(stash);
449 if (count > PERL_HASH_DEFAULT_HvMAX) {
450 hv_ksplit(isa_hash, count);
453 while (svp < svp_end) {
454 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
457 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
458 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
459 HV_FETCH_ISSTORE, &PL_sv_undef,
460 HEK_HASH(canon_name));
461 (void) hv_stores(isa_hash, "UNIVERSAL", &PL_sv_undef);
463 SvREADONLY_on(isa_hash);
465 meta->isa = isa_hash;
472 =for apidoc mro_isa_changed_in
474 Takes the necessary steps (cache invalidations, mostly)
475 when the C<@ISA> of the given package has changed. Invoked
476 by the C<setisa> magic, should not need to invoke directly.
481 /* Macro to avoid repeating the code five times. */
482 #define CLEAR_LINEAR(mEta) \
483 if (mEta->mro_linear_all) { \
484 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
485 mEta->mro_linear_all = NULL; \
486 /* This is just acting as a shortcut pointer. */ \
487 mEta->mro_linear_current = NULL; \
488 } else if (mEta->mro_linear_current) { \
489 /* Only the current MRO is stored, so this owns the data. */ \
490 SvREFCNT_dec(mEta->mro_linear_current); \
491 mEta->mro_linear_current = NULL; \
495 Perl_mro_isa_changed_in(pTHX_ HV* stash)
503 struct mro_meta * meta;
506 const HEK * const stashhek = HvENAME_HEK(stash);
507 const char * const stashname = HvENAME_get(stash);
508 const STRLEN stashname_len = HvENAMELEN_get(stash);
510 PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
513 Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
516 /* wipe out the cached linearizations for this stash */
517 meta = HvMROMETA(stash);
520 /* Steal it for our own purposes. */
521 isa = (HV *)sv_2mortal((SV *)meta->isa);
525 /* Inc the package generation, since our @ISA changed */
528 /* Wipe the global method cache if this package
529 is UNIVERSAL or one of its parents */
531 svp = hv_fetchhek(PL_isarev, stashhek, 0);
532 isarev = svp ? MUTABLE_HV(*svp) : NULL;
534 if((memEQs(stashname, stashname_len, "UNIVERSAL"))
535 || (isarev && hv_existss(isarev, "UNIVERSAL"))) {
539 else { /* Wipe the local method cache otherwise */
541 is_universal = FALSE;
544 /* wipe next::method cache too */
545 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
547 /* Changes to @ISA might turn overloading on */
549 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
550 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
552 /* DESTROY can be cached in meta. */
553 meta->destroy_gen = 0;
555 /* Iterate the isarev (classes that are our children),
556 wiping out their linearization, method and isa caches
557 and upating PL_isarev. */
559 HV *isa_hashes = NULL;
561 /* We have to iterate through isarev twice to avoid a chicken and
562 * egg problem: if A inherits from B and both are in isarev, A might
563 * be processed before B and use B's previous linearisation.
566 /* First iteration: Wipe everything, but stash away the isa hashes
567 * since we still need them for updating PL_isarev.
570 if(hv_iterinit(isarev)) {
571 /* Only create the hash if we need it; i.e., if isarev has
573 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
575 while((iter = hv_iternext(isarev))) {
576 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
577 struct mro_meta* revmeta;
579 if(!revstash) continue;
580 revmeta = HvMROMETA(revstash);
581 CLEAR_LINEAR(revmeta);
583 revmeta->cache_gen++;
584 if(revmeta->mro_nextmethod)
585 hv_clear(revmeta->mro_nextmethod);
586 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
590 isa_hashes, (const char*)&revstash, sizeof(HV *),
591 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
596 /* Second pass: Update PL_isarev. We can just use isa_hashes to
597 * avoid another round of stash lookups. */
599 /* isarev might be deleted from PL_isarev during this loop, so hang
601 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
604 hv_iterinit(isa_hashes);
605 while((iter = hv_iternext(isa_hashes))) {
606 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
607 HV * const isa = (HV *)HeVAL(iter);
610 /* We're starting at the 2nd element, skipping revstash */
611 linear_mro = mro_get_linear_isa(revstash);
612 svp = AvARRAY(linear_mro) + 1;
613 items = AvFILLp(linear_mro);
615 namehek = HvENAME_HEK(revstash);
616 if (!namehek) namehek = HvNAME_HEK(revstash);
619 SV* const sv = *svp++;
622 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
624 /* That fetch should not fail. But if it had to create
625 a new SV for us, then will need to upgrade it to an
626 HV (which sv_upgrade() can now do for us). */
628 mroisarev = MUTABLE_HV(HeVAL(he));
630 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
632 /* This hash only ever contains PL_sv_yes. Storing it
633 over itself is almost as cheap as calling hv_exists,
634 so on aggregate we expect to save time by not making
635 two calls to the common HV code for the case where
639 hv_storehek(mroisarev, namehek, &PL_sv_yes);
642 if ((SV *)isa != &PL_sv_undef) {
645 isa, HEK_KEY(namehek), HEK_LEN(namehek),
646 HvMROMETA(revstash)->isa, HEK_HASH(namehek),
654 /* Now iterate our MRO (parents), adding ourselves and everything from
655 our isarev to their isarev.
658 /* We're starting at the 2nd element, skipping ourselves here */
659 linear_mro = mro_get_linear_isa(stash);
660 svp = AvARRAY(linear_mro) + 1;
661 items = AvFILLp(linear_mro);
664 SV* const sv = *svp++;
667 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
669 /* That fetch should not fail. But if it had to create a new SV for
670 us, then will need to upgrade it to an HV (which sv_upgrade() can
673 mroisarev = MUTABLE_HV(HeVAL(he));
675 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
677 /* This hash only ever contains PL_sv_yes. Storing it over itself is
678 almost as cheap as calling hv_exists, so on aggregate we expect to
679 save time by not making two calls to the common HV code for the
680 case where it doesn't exist. */
682 (void)hv_storehek(mroisarev, stashhek, &PL_sv_yes);
685 /* Delete our name from our former parents' isarevs. */
686 if(isa && HvARRAY(isa))
687 mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
688 HEK_HASH(stashhek), HEK_UTF8(stashhek));
691 /* Deletes name from all the isarev entries listed in isa */
693 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
694 const STRLEN len, HV * const exceptions, U32 hash,
699 PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
701 /* Delete our name from our former parents' isarevs. */
702 if(HvARRAY(isa) && hv_iterinit(isa)) {
704 while((iter = hv_iternext(isa))) {
705 HEK *key = HeKEY_hek(iter);
706 if(exceptions && hv_existshek(exceptions, key))
708 svp = hv_fetchhek(PL_isarev, key, 0);
710 HV * const isarev = (HV *)*svp;
711 (void)hv_common(isarev, NULL, name, len, flags,
712 G_DISCARD|HV_DELETE, NULL, hash);
713 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
714 (void)hv_deletehek(PL_isarev, key, G_DISCARD);
721 =for apidoc mro_package_moved
723 Call this function to signal to a stash that it has been assigned to
724 another spot in the stash hierarchy. C<stash> is the stash that has been
725 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
726 that is actually being assigned to.
728 This can also be called with a null first argument to
729 indicate that C<oldstash> has been deleted.
731 This function invalidates isa caches on the old stash, on all subpackages
732 nested inside it, and on the subclasses of all those, including
733 non-existent packages that have corresponding entries in C<stash>.
735 It also sets the effective names (C<HvENAME>) on all the stashes as
738 If the C<gv> is present and is not in the symbol table, then this function
739 simply returns. This checked will be skipped if C<flags & 1>.
744 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
745 const GV * const gv, U32 flags)
753 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
754 assert(stash || oldstash);
756 /* Determine the name(s) of the location that stash was assigned to
757 * or from which oldstash was removed.
759 * We cannot reliably use the name in oldstash, because it may have
760 * been deleted from the location in the symbol table that its name
761 * suggests, as in this case:
763 * $globref = \*foo::bar::;
764 * Symbol::delete_package("foo");
765 * *$globref = \%baz::;
766 * *$globref = *frelp::;
767 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
769 * So we get it from the gv. But, since the gv may no longer be in the
770 * symbol table, we check that first. The only reliable way to tell is
771 * to see whether its stash has an effective name and whether the gv
772 * resides in that stash under its name. That effective name may be
773 * different from what gv_fullname4 would use.
774 * If flags & 1, the caller has asked us to skip the check.
779 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
780 !(svp = hv_fetchhek(GvSTASH(gv), GvNAME_HEK(gv), 0)) ||
784 assert(SvOOK(GvSTASH(gv)));
785 assert(GvNAMELEN(gv));
786 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
787 assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
788 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
791 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
794 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
795 if (name_count < 0) ++namep, name_count = -name_count - 1;
797 if (name_count == 1) {
798 if (memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")) {
799 namesv = GvNAMELEN(gv) == 1
800 ? newSVpvs_flags(":", SVs_TEMP)
801 : newSVpvs_flags("", SVs_TEMP);
804 namesv = sv_2mortal(newSVhek(*namep));
805 if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
806 else sv_catpvs(namesv, "::");
808 if (GvNAMELEN(gv) != 1) {
810 namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
811 /* skip trailing :: */
812 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
818 namesv = sv_2mortal((SV *)newAV());
819 while (name_count--) {
820 if(memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")){
821 aname = GvNAMELEN(gv) == 1
827 aname = newSVhek(*namep++);
828 if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
829 else sv_catpvs(aname, "::");
831 if (GvNAMELEN(gv) != 1) {
833 aname, GvNAME(gv), GvNAMELEN(gv) - 2,
834 /* skip trailing :: */
835 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
838 av_push((AV *)namesv, aname);
842 /* Get a list of all the affected classes. */
843 /* We cannot simply pass them all to mro_isa_changed_in to avoid
844 the list, as that function assumes that only one package has
845 changed. It does not work with:
847 @foo::ISA = qw( B B::B );
848 *B:: = delete $::{"A::"};
850 as neither B nor B::B can be updated before the other, since they
851 will reset caches on foo, which will see either B or B::B with the
852 wrong name. The names must be set on *all* affected stashes before
853 we do anything else. (And linearisations must be cleared, too.)
855 stashes = (HV *) sv_2mortal((SV *)newHV());
856 mro_gather_and_rename(
857 stashes, (HV *) sv_2mortal((SV *)newHV()),
858 stash, oldstash, namesv
861 /* Once the caches have been wiped on all the classes, call
862 mro_isa_changed_in on each. */
863 hv_iterinit(stashes);
864 while((iter = hv_iternext(stashes))) {
865 HV * const this_stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
866 if(HvENAME(this_stash)) {
867 /* We have to restore the original meta->isa (that
868 mro_gather_and_rename set aside for us) this way, in case
869 one class in this list is a superclass of a another class
870 that we have already encountered. In such a case, meta->isa
871 will have been overwritten without old entries being deleted
873 struct mro_meta * const meta = HvMROMETA(this_stash);
874 if(meta->isa != (HV *)HeVAL(iter)){
875 SvREFCNT_dec(meta->isa);
877 = HeVAL(iter) == &PL_sv_yes
880 HeVAL(iter) = NULL; /* We donated our reference count. */
882 mro_isa_changed_in(this_stash);
888 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
889 HV *stash, HV *oldstash, SV *namesv)
895 const bool stash_had_name = stash && HvENAME(stash);
896 bool fetched_isarev = FALSE;
901 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
903 /* We use the seen_stashes hash to keep track of which packages have
904 been encountered so far. This must be separate from the main list of
905 stashes, as we need to distinguish between stashes being assigned
906 and stashes being replaced/deleted. (A nested stash can be on both
907 sides of an assignment. We cannot simply skip iterating through a
908 stash on the right if we have seen it on the left, as it will not
909 get its ename assigned to it.)
911 To avoid allocating extra SVs, instead of a bitfield we can make
912 bizarre use of immortals:
914 &PL_sv_undef: seen on the left (oldstash)
915 &PL_sv_no : seen on the right (stash)
916 &PL_sv_yes : seen on both sides
921 /* Add to the big list. */
922 struct mro_meta * meta;
926 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
927 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
929 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
934 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
935 meta = HvMROMETA(oldstash);
938 stashes, (const char *)&oldstash, sizeof(HV *),
940 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
946 /* Update the effective name. */
947 if(HvENAME_get(oldstash)) {
948 const HEK * const enamehek = HvENAME_HEK(oldstash);
949 if(SvTYPE(namesv) == SVt_PVAV) {
950 items = AvFILLp((AV *)namesv) + 1;
951 svp = AvARRAY((AV *)namesv);
958 const U32 name_utf8 = SvUTF8(*svp);
960 const char *name = SvPVx_const(*svp, len);
962 DEBUG_o(Perl_deb(aTHX_ "mro_gather_and_rename clearing PL_stashcache for '%" SVf "'\n",
964 (void)hv_delete_ent(PL_stashcache, *svp, G_DISCARD, 0);
966 hv_ename_delete(oldstash, name, len, name_utf8);
968 if (!fetched_isarev) {
969 /* If the name deletion caused a name change, then we
970 * are not going to call mro_isa_changed_in with this
971 * name (and not at all if it has become anonymous) so
972 * we need to delete old isarev entries here, both
973 * those in the superclasses and this class's own list
974 * of subclasses. We simply delete the latter from
975 * PL_isarev, since we still need it. hv_delete morti-
976 * fies it for us, so sv_2mortal is not necessary. */
977 if(HvENAME_HEK(oldstash) != enamehek) {
978 if(meta->isa && HvARRAY(meta->isa))
979 mro_clean_isarev(meta->isa, name, len, 0, 0,
980 name_utf8 ? HVhek_UTF8 : 0);
981 isarev = (HV *)hv_delete_ent(PL_isarev, *svp, 0, 0);
992 if(SvTYPE(namesv) == SVt_PVAV) {
993 items = AvFILLp((AV *)namesv) + 1;
994 svp = AvARRAY((AV *)namesv);
1001 const U32 name_utf8 = SvUTF8(*svp);
1003 const char *name = SvPVx_const(*svp++, len);
1004 hv_ename_add(stash, name, len, name_utf8);
1007 /* Add it to the big list if it needs
1008 * mro_isa_changed_in called on it. That happens if it was
1009 * detached from the symbol table (so it had no HvENAME) before
1010 * being assigned to the spot named by the 'name' variable, because
1011 * its cached isa linearisation is now stale (the effective name
1012 * having changed), and subclasses will then use that cache when
1013 * mro_package_moved calls mro_isa_changed_in. (See
1016 * If it did have a name, then its previous name is still
1017 * used in isa caches, and there is no need for
1018 * mro_package_moved to call mro_isa_changed_in.
1024 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1025 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1027 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1031 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1034 struct mro_meta * const meta = HvMROMETA(stash);
1037 stashes, (const char *)&stash, sizeof(HV *),
1039 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1048 if(!stash && !oldstash)
1049 /* Both stashes have been encountered already. */
1052 /* Add all the subclasses to the big list. */
1053 if(!fetched_isarev) {
1054 /* If oldstash is not null, then we can use its HvENAME to look up
1055 the isarev hash, since all its subclasses will be listed there.
1056 It will always have an HvENAME. It the HvENAME was removed
1057 above, then fetch_isarev will be true, and this code will not be
1060 If oldstash is null, then this is an empty spot with no stash in
1061 it, so subclasses could be listed in isarev hashes belonging to
1062 any of the names, so we have to check all of them.
1064 assert(!oldstash || HvENAME(oldstash));
1066 /* Extra variable to avoid a compiler warning */
1067 const HEK * const hvename = HvENAME_HEK(oldstash);
1068 fetched_isarev = TRUE;
1069 svp = hv_fetchhek(PL_isarev, hvename, 0);
1070 if (svp) isarev = MUTABLE_HV(*svp);
1072 else if(SvTYPE(namesv) == SVt_PVAV) {
1073 items = AvFILLp((AV *)namesv) + 1;
1074 svp = AvARRAY((AV *)namesv);
1082 isarev || !fetched_isarev
1084 while (fetched_isarev || items--) {
1087 if (!fetched_isarev) {
1088 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1089 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1092 hv_iterinit(isarev);
1093 while((iter = hv_iternext(isarev))) {
1094 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1095 struct mro_meta * meta;
1097 if(!revstash) continue;
1098 meta = HvMROMETA(revstash);
1101 stashes, (const char *)&revstash, sizeof(HV *),
1103 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1110 if (fetched_isarev) break;
1114 /* This is partly based on code in hv_iternext_flags. We are not call-
1115 ing that here, as we want to avoid resetting the hash iterator. */
1117 /* Skip the entire loop if the hash is empty. */
1118 if(oldstash && HvTOTALKEYS(oldstash)) {
1119 xhv = (XPVHV*)SvANY(oldstash);
1120 seen = (HV *) sv_2mortal((SV *)newHV());
1122 /* Iterate through entries in the oldstash, adding them to the
1123 list, meanwhile doing the equivalent of $seen{$key} = 1.
1126 while (++riter <= (I32)xhv->xhv_max) {
1127 entry = (HvARRAY(oldstash))[riter];
1129 /* Iterate through the entries in this list */
1130 for(; entry; entry = HeNEXT(entry)) {
1134 /* If this entry is not a glob, ignore it.
1136 if (!isGV(HeVAL(entry))) continue;
1138 key = hv_iterkey(entry, &len);
1139 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1140 || (len == 1 && key[0] == ':')) {
1141 HV * const oldsubstash = GvHV(HeVAL(entry));
1143 HV *substash = NULL;
1145 /* Avoid main::main::main::... */
1146 if(oldsubstash == oldstash) continue;
1148 stashentry = stash ? hv_fetchhek(stash, HeKEY_hek(entry), 0) : NULL;
1152 stashentry && *stashentry && isGV(*stashentry)
1153 && (substash = GvHV(*stashentry))
1155 || (oldsubstash && HvENAME_get(oldsubstash))
1158 /* Add :: and the key (minus the trailing ::)
1161 if(SvTYPE(namesv) == SVt_PVAV) {
1163 items = AvFILLp((AV *)namesv) + 1;
1164 svp = AvARRAY((AV *)namesv);
1165 subname = sv_2mortal((SV *)newAV());
1167 aname = newSVsv(*svp++);
1169 sv_catpvs(aname, ":");
1171 sv_catpvs(aname, "::");
1175 ? SV_CATUTF8 : SV_CATBYTES
1178 av_push((AV *)subname, aname);
1182 subname = sv_2mortal(newSVsv(namesv));
1183 if (len == 1) sv_catpvs(subname, ":");
1185 sv_catpvs(subname, "::");
1187 subname, key, len-2,
1188 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1192 mro_gather_and_rename(
1193 stashes, seen_stashes,
1194 substash, oldsubstash, subname
1198 (void)hv_storehek(seen, HeKEY_hek(entry), &PL_sv_yes);
1204 /* Skip the entire loop if the hash is empty. */
1205 if (stash && HvTOTALKEYS(stash)) {
1206 xhv = (XPVHV*)SvANY(stash);
1209 /* Iterate through the new stash, skipping $seen{$key} items,
1210 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1211 while (++riter <= (I32)xhv->xhv_max) {
1212 entry = (HvARRAY(stash))[riter];
1214 /* Iterate through the entries in this list */
1215 for(; entry; entry = HeNEXT(entry)) {
1219 /* If this entry is not a glob, ignore it.
1221 if (!isGV(HeVAL(entry))) continue;
1223 key = hv_iterkey(entry, &len);
1224 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1225 || (len == 1 && key[0] == ':')) {
1228 /* If this entry was seen when we iterated through the
1229 oldstash, skip it. */
1230 if(seen && hv_existshek(seen, HeKEY_hek(entry))) continue;
1232 /* We get here only if this stash has no corresponding
1233 entry in the stash being replaced. */
1235 substash = GvHV(HeVAL(entry));
1239 /* Avoid checking main::main::main::... */
1240 if(substash == stash) continue;
1242 /* Add :: and the key (minus the trailing ::)
1244 if(SvTYPE(namesv) == SVt_PVAV) {
1246 items = AvFILLp((AV *)namesv) + 1;
1247 svp = AvARRAY((AV *)namesv);
1248 subname = sv_2mortal((SV *)newAV());
1250 aname = newSVsv(*svp++);
1252 sv_catpvs(aname, ":");
1254 sv_catpvs(aname, "::");
1258 ? SV_CATUTF8 : SV_CATBYTES
1261 av_push((AV *)subname, aname);
1265 subname = sv_2mortal(newSVsv(namesv));
1266 if (len == 1) sv_catpvs(subname, ":");
1268 sv_catpvs(subname, "::");
1270 subname, key, len-2,
1271 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1275 mro_gather_and_rename(
1276 stashes, seen_stashes,
1277 substash, NULL, subname
1287 =for apidoc mro_method_changed_in
1289 Invalidates method caching on any child classes
1290 of the given stash, so that they might notice
1291 the changes in this one.
1293 Ideally, all instances of C<PL_sub_generation++> in
1294 perl source outside of F<mro.c> should be
1295 replaced by calls to this.
1297 Perl automatically handles most of the common
1298 ways a method might be redefined. However, there
1299 are a few ways you could change a method in a stash
1300 without the cache code noticing, in which case you
1301 need to call this method afterwards:
1303 1) Directly manipulating the stash HV entries from
1306 2) Assigning a reference to a readonly scalar
1307 constant into a stash entry in order to create
1308 a constant subroutine (like F<constant.pm>
1311 This same method is available from pure perl
1312 via, C<mro::method_changed_in(classname)>.
1317 Perl_mro_method_changed_in(pTHX_ HV *stash)
1319 const char * const stashname = HvENAME_get(stash);
1320 const STRLEN stashname_len = HvENAMELEN_get(stash);
1322 SV ** const svp = hv_fetchhek(PL_isarev, HvENAME_HEK(stash), 0);
1323 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1325 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1328 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1330 /* Inc the package generation, since a local method changed */
1331 HvMROMETA(stash)->pkg_gen++;
1333 /* DESTROY can be cached in meta */
1334 HvMROMETA(stash)->destroy_gen = 0;
1336 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1337 invalidate all method caches globally */
1338 if((memEQs(stashname, stashname_len, "UNIVERSAL"))
1339 || (isarev && hv_existss(isarev, "UNIVERSAL"))) {
1340 PL_sub_generation++;
1344 /* else, invalidate the method caches of all child classes,
1349 hv_iterinit(isarev);
1350 while((iter = hv_iternext(isarev))) {
1351 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1352 struct mro_meta* mrometa;
1354 if(!revstash) continue;
1355 mrometa = HvMROMETA(revstash);
1356 mrometa->cache_gen++;
1357 if(mrometa->mro_nextmethod)
1358 hv_clear(mrometa->mro_nextmethod);
1359 mrometa->destroy_gen = 0;
1363 /* The method change may be due to *{$package . "::()"} = \&nil; in
1366 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
1367 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
1371 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1373 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1375 PERL_ARGS_ASSERT_MRO_SET_MRO;
1378 Perl_croak(aTHX_ "Invalid mro name: '%" SVf "'", name);
1380 if(meta->mro_which != which) {
1381 if (meta->mro_linear_current && !meta->mro_linear_all) {
1382 /* If we were storing something directly, put it in the hash before
1384 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1385 MUTABLE_SV(meta->mro_linear_current));
1387 meta->mro_which = which;
1388 /* Scrub our cached pointer to the private data. */
1389 meta->mro_linear_current = NULL;
1390 /* Only affects local method cache, not
1391 even child classes */
1393 if(meta->mro_nextmethod)
1394 hv_clear(meta->mro_nextmethod);
1400 XS(XS_mro_method_changed_in);
1403 Perl_boot_core_mro(pTHX)
1405 static const char file[] = __FILE__;
1407 Perl_mro_register(aTHX_ &dfs_alg);
1409 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1412 XS(XS_mro_method_changed_in)
1419 croak_xs_usage(cv, "classname");
1423 class_stash = gv_stashsv(classname, 0);
1424 if(!class_stash) Perl_croak(aTHX_ "No such class: '%" SVf "'!", SVfARG(classname));
1426 mro_method_changed_in(class_stash);
1432 * ex: set ts=8 sts=4 sw=4 et: