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 SV *const *svp = AvARRAY(isa);
444 SV *const *const svp_end = svp + AvFILLp(isa) + 1;
445 const HEK *canon_name = HvENAME_HEK(stash);
446 if (!canon_name) canon_name = HvNAME_HEK(stash);
448 while (svp < svp_end) {
449 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
452 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
453 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
454 HV_FETCH_ISSTORE, &PL_sv_undef,
455 HEK_HASH(canon_name));
456 (void) hv_stores(isa_hash, "UNIVERSAL", &PL_sv_undef);
458 SvREADONLY_on(isa_hash);
460 meta->isa = isa_hash;
467 =for apidoc mro_isa_changed_in
469 Takes the necessary steps (cache invalidations, mostly)
470 when the C<@ISA> of the given package has changed. Invoked
471 by the C<setisa> magic, should not need to invoke directly.
476 /* Macro to avoid repeating the code five times. */
477 #define CLEAR_LINEAR(mEta) \
478 if (mEta->mro_linear_all) { \
479 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
480 mEta->mro_linear_all = NULL; \
481 /* This is just acting as a shortcut pointer. */ \
482 mEta->mro_linear_current = NULL; \
483 } else if (mEta->mro_linear_current) { \
484 /* Only the current MRO is stored, so this owns the data. */ \
485 SvREFCNT_dec(mEta->mro_linear_current); \
486 mEta->mro_linear_current = NULL; \
490 Perl_mro_isa_changed_in(pTHX_ HV* stash)
498 struct mro_meta * meta;
501 const HEK * const stashhek = HvENAME_HEK(stash);
502 const char * const stashname = HvENAME_get(stash);
503 const STRLEN stashname_len = HvENAMELEN_get(stash);
505 PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
508 Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
511 /* wipe out the cached linearizations for this stash */
512 meta = HvMROMETA(stash);
515 /* Steal it for our own purposes. */
516 isa = (HV *)sv_2mortal((SV *)meta->isa);
520 /* Inc the package generation, since our @ISA changed */
523 /* Wipe the global method cache if this package
524 is UNIVERSAL or one of its parents */
526 svp = hv_fetchhek(PL_isarev, stashhek, 0);
527 isarev = svp ? MUTABLE_HV(*svp) : NULL;
529 if((memEQs(stashname, stashname_len, "UNIVERSAL"))
530 || (isarev && hv_existss(isarev, "UNIVERSAL"))) {
534 else { /* Wipe the local method cache otherwise */
536 is_universal = FALSE;
539 /* wipe next::method cache too */
540 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
542 /* Changes to @ISA might turn overloading on */
544 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
545 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
547 /* DESTROY can be cached in meta. */
548 meta->destroy_gen = 0;
550 /* Iterate the isarev (classes that are our children),
551 wiping out their linearization, method and isa caches
552 and upating PL_isarev. */
554 HV *isa_hashes = NULL;
556 /* We have to iterate through isarev twice to avoid a chicken and
557 * egg problem: if A inherits from B and both are in isarev, A might
558 * be processed before B and use B's previous linearisation.
561 /* First iteration: Wipe everything, but stash away the isa hashes
562 * since we still need them for updating PL_isarev.
565 if(hv_iterinit(isarev)) {
566 /* Only create the hash if we need it; i.e., if isarev has
568 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
570 while((iter = hv_iternext(isarev))) {
571 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
572 struct mro_meta* revmeta;
574 if(!revstash) continue;
575 revmeta = HvMROMETA(revstash);
576 CLEAR_LINEAR(revmeta);
578 revmeta->cache_gen++;
579 if(revmeta->mro_nextmethod)
580 hv_clear(revmeta->mro_nextmethod);
581 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
585 isa_hashes, (const char*)&revstash, sizeof(HV *),
586 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
591 /* Second pass: Update PL_isarev. We can just use isa_hashes to
592 * avoid another round of stash lookups. */
594 /* isarev might be deleted from PL_isarev during this loop, so hang
596 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
599 hv_iterinit(isa_hashes);
600 while((iter = hv_iternext(isa_hashes))) {
601 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
602 HV * const isa = (HV *)HeVAL(iter);
605 /* We're starting at the 2nd element, skipping revstash */
606 linear_mro = mro_get_linear_isa(revstash);
607 svp = AvARRAY(linear_mro) + 1;
608 items = AvFILLp(linear_mro);
610 namehek = HvENAME_HEK(revstash);
611 if (!namehek) namehek = HvNAME_HEK(revstash);
614 SV* const sv = *svp++;
617 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
619 /* That fetch should not fail. But if it had to create
620 a new SV for us, then will need to upgrade it to an
621 HV (which sv_upgrade() can now do for us). */
623 mroisarev = MUTABLE_HV(HeVAL(he));
625 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
627 /* This hash only ever contains PL_sv_yes. Storing it
628 over itself is almost as cheap as calling hv_exists,
629 so on aggregate we expect to save time by not making
630 two calls to the common HV code for the case where
634 hv_storehek(mroisarev, namehek, &PL_sv_yes);
637 if ((SV *)isa != &PL_sv_undef) {
640 isa, HEK_KEY(namehek), HEK_LEN(namehek),
641 HvMROMETA(revstash)->isa, HEK_HASH(namehek),
649 /* Now iterate our MRO (parents), adding ourselves and everything from
650 our isarev to their isarev.
653 /* We're starting at the 2nd element, skipping ourselves here */
654 linear_mro = mro_get_linear_isa(stash);
655 svp = AvARRAY(linear_mro) + 1;
656 items = AvFILLp(linear_mro);
659 SV* const sv = *svp++;
662 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
664 /* That fetch should not fail. But if it had to create a new SV for
665 us, then will need to upgrade it to an HV (which sv_upgrade() can
668 mroisarev = MUTABLE_HV(HeVAL(he));
670 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
672 /* This hash only ever contains PL_sv_yes. Storing it over itself is
673 almost as cheap as calling hv_exists, so on aggregate we expect to
674 save time by not making two calls to the common HV code for the
675 case where it doesn't exist. */
677 (void)hv_storehek(mroisarev, stashhek, &PL_sv_yes);
680 /* Delete our name from our former parents' isarevs. */
681 if(isa && HvARRAY(isa))
682 mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
683 HEK_HASH(stashhek), HEK_UTF8(stashhek));
686 /* Deletes name from all the isarev entries listed in isa */
688 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
689 const STRLEN len, HV * const exceptions, U32 hash,
694 PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
696 /* Delete our name from our former parents' isarevs. */
697 if(HvARRAY(isa) && hv_iterinit(isa)) {
699 while((iter = hv_iternext(isa))) {
701 const char * const key = hv_iterkey(iter, &klen);
702 if(exceptions && hv_exists(exceptions, key, HeKUTF8(iter) ? -klen : klen))
704 svp = hv_fetch(PL_isarev, key, HeKUTF8(iter) ? -klen : klen, 0);
706 HV * const isarev = (HV *)*svp;
707 (void)hv_common(isarev, NULL, name, len, flags,
708 G_DISCARD|HV_DELETE, NULL, hash);
709 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
710 (void)hv_delete(PL_isarev, key,
711 HeKUTF8(iter) ? -klen : klen, G_DISCARD);
718 =for apidoc mro_package_moved
720 Call this function to signal to a stash that it has been assigned to
721 another spot in the stash hierarchy. C<stash> is the stash that has been
722 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
723 that is actually being assigned to.
725 This can also be called with a null first argument to
726 indicate that C<oldstash> has been deleted.
728 This function invalidates isa caches on the old stash, on all subpackages
729 nested inside it, and on the subclasses of all those, including
730 non-existent packages that have corresponding entries in C<stash>.
732 It also sets the effective names (C<HvENAME>) on all the stashes as
735 If the C<gv> is present and is not in the symbol table, then this function
736 simply returns. This checked will be skipped if C<flags & 1>.
741 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
742 const GV * const gv, U32 flags)
750 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
751 assert(stash || oldstash);
753 /* Determine the name(s) of the location that stash was assigned to
754 * or from which oldstash was removed.
756 * We cannot reliably use the name in oldstash, because it may have
757 * been deleted from the location in the symbol table that its name
758 * suggests, as in this case:
760 * $globref = \*foo::bar::;
761 * Symbol::delete_package("foo");
762 * *$globref = \%baz::;
763 * *$globref = *frelp::;
764 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
766 * So we get it from the gv. But, since the gv may no longer be in the
767 * symbol table, we check that first. The only reliable way to tell is
768 * to see whether its stash has an effective name and whether the gv
769 * resides in that stash under its name. That effective name may be
770 * different from what gv_fullname4 would use.
771 * If flags & 1, the caller has asked us to skip the check.
776 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
777 !(svp = hv_fetchhek(GvSTASH(gv), GvNAME_HEK(gv), 0)) ||
781 assert(SvOOK(GvSTASH(gv)));
782 assert(GvNAMELEN(gv));
783 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
784 assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
785 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
788 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
791 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
792 if (name_count < 0) ++namep, name_count = -name_count - 1;
794 if (name_count == 1) {
795 if (memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")) {
796 namesv = GvNAMELEN(gv) == 1
797 ? newSVpvs_flags(":", SVs_TEMP)
798 : newSVpvs_flags("", SVs_TEMP);
801 namesv = sv_2mortal(newSVhek(*namep));
802 if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
803 else sv_catpvs(namesv, "::");
805 if (GvNAMELEN(gv) != 1) {
807 namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
808 /* skip trailing :: */
809 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
815 namesv = sv_2mortal((SV *)newAV());
816 while (name_count--) {
817 if(memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")){
818 aname = GvNAMELEN(gv) == 1
824 aname = newSVhek(*namep++);
825 if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
826 else sv_catpvs(aname, "::");
828 if (GvNAMELEN(gv) != 1) {
830 aname, GvNAME(gv), GvNAMELEN(gv) - 2,
831 /* skip trailing :: */
832 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
835 av_push((AV *)namesv, aname);
839 /* Get a list of all the affected classes. */
840 /* We cannot simply pass them all to mro_isa_changed_in to avoid
841 the list, as that function assumes that only one package has
842 changed. It does not work with:
844 @foo::ISA = qw( B B::B );
845 *B:: = delete $::{"A::"};
847 as neither B nor B::B can be updated before the other, since they
848 will reset caches on foo, which will see either B or B::B with the
849 wrong name. The names must be set on *all* affected stashes before
850 we do anything else. (And linearisations must be cleared, too.)
852 stashes = (HV *) sv_2mortal((SV *)newHV());
853 mro_gather_and_rename(
854 stashes, (HV *) sv_2mortal((SV *)newHV()),
855 stash, oldstash, namesv
858 /* Once the caches have been wiped on all the classes, call
859 mro_isa_changed_in on each. */
860 hv_iterinit(stashes);
861 while((iter = hv_iternext(stashes))) {
862 HV * const this_stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
863 if(HvENAME(this_stash)) {
864 /* We have to restore the original meta->isa (that
865 mro_gather_and_rename set aside for us) this way, in case
866 one class in this list is a superclass of a another class
867 that we have already encountered. In such a case, meta->isa
868 will have been overwritten without old entries being deleted
870 struct mro_meta * const meta = HvMROMETA(this_stash);
871 if(meta->isa != (HV *)HeVAL(iter)){
872 SvREFCNT_dec(meta->isa);
874 = HeVAL(iter) == &PL_sv_yes
877 HeVAL(iter) = NULL; /* We donated our reference count. */
879 mro_isa_changed_in(this_stash);
885 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
886 HV *stash, HV *oldstash, SV *namesv)
892 const bool stash_had_name = stash && HvENAME(stash);
893 bool fetched_isarev = FALSE;
898 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
900 /* We use the seen_stashes hash to keep track of which packages have
901 been encountered so far. This must be separate from the main list of
902 stashes, as we need to distinguish between stashes being assigned
903 and stashes being replaced/deleted. (A nested stash can be on both
904 sides of an assignment. We cannot simply skip iterating through a
905 stash on the right if we have seen it on the left, as it will not
906 get its ename assigned to it.)
908 To avoid allocating extra SVs, instead of a bitfield we can make
909 bizarre use of immortals:
911 &PL_sv_undef: seen on the left (oldstash)
912 &PL_sv_no : seen on the right (stash)
913 &PL_sv_yes : seen on both sides
918 /* Add to the big list. */
919 struct mro_meta * meta;
923 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
924 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
926 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
931 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
932 meta = HvMROMETA(oldstash);
935 stashes, (const char *)&oldstash, sizeof(HV *),
937 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
943 /* Update the effective name. */
944 if(HvENAME_get(oldstash)) {
945 const HEK * const enamehek = HvENAME_HEK(oldstash);
946 if(SvTYPE(namesv) == SVt_PVAV) {
947 items = AvFILLp((AV *)namesv) + 1;
948 svp = AvARRAY((AV *)namesv);
955 const U32 name_utf8 = SvUTF8(*svp);
957 const char *name = SvPVx_const(*svp, len);
959 DEBUG_o(Perl_deb(aTHX_ "mro_gather_and_rename clearing PL_stashcache for '%" SVf "'\n",
961 (void)hv_delete(PL_stashcache, name, name_utf8 ? -(I32)len : (I32)len, G_DISCARD);
964 hv_ename_delete(oldstash, name, len, name_utf8);
966 if (!fetched_isarev) {
967 /* If the name deletion caused a name change, then we
968 * are not going to call mro_isa_changed_in with this
969 * name (and not at all if it has become anonymous) so
970 * we need to delete old isarev entries here, both
971 * those in the superclasses and this class's own list
972 * of subclasses. We simply delete the latter from
973 * PL_isarev, since we still need it. hv_delete morti-
974 * fies it for us, so sv_2mortal is not necessary. */
975 if(HvENAME_HEK(oldstash) != enamehek) {
976 if(meta->isa && HvARRAY(meta->isa))
977 mro_clean_isarev(meta->isa, name, len, 0, 0,
978 name_utf8 ? HVhek_UTF8 : 0);
979 isarev = (HV *)hv_delete(PL_isarev, name,
980 name_utf8 ? -(I32)len : (I32)len, 0);
989 if(SvTYPE(namesv) == SVt_PVAV) {
990 items = AvFILLp((AV *)namesv) + 1;
991 svp = AvARRAY((AV *)namesv);
998 const U32 name_utf8 = SvUTF8(*svp);
1000 const char *name = SvPVx_const(*svp++, len);
1001 hv_ename_add(stash, name, len, name_utf8);
1004 /* Add it to the big list if it needs
1005 * mro_isa_changed_in called on it. That happens if it was
1006 * detached from the symbol table (so it had no HvENAME) before
1007 * being assigned to the spot named by the 'name' variable, because
1008 * its cached isa linearisation is now stale (the effective name
1009 * having changed), and subclasses will then use that cache when
1010 * mro_package_moved calls mro_isa_changed_in. (See
1013 * If it did have a name, then its previous name is still
1014 * used in isa caches, and there is no need for
1015 * mro_package_moved to call mro_isa_changed_in.
1021 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1022 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1024 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1028 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1031 struct mro_meta * const meta = HvMROMETA(stash);
1034 stashes, (const char *)&stash, sizeof(HV *),
1036 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1045 if(!stash && !oldstash)
1046 /* Both stashes have been encountered already. */
1049 /* Add all the subclasses to the big list. */
1050 if(!fetched_isarev) {
1051 /* If oldstash is not null, then we can use its HvENAME to look up
1052 the isarev hash, since all its subclasses will be listed there.
1053 It will always have an HvENAME. It the HvENAME was removed
1054 above, then fetch_isarev will be true, and this code will not be
1057 If oldstash is null, then this is an empty spot with no stash in
1058 it, so subclasses could be listed in isarev hashes belonging to
1059 any of the names, so we have to check all of them.
1061 assert(!oldstash || HvENAME(oldstash));
1063 /* Extra variable to avoid a compiler warning */
1064 const HEK * const hvename = HvENAME_HEK(oldstash);
1065 fetched_isarev = TRUE;
1066 svp = hv_fetchhek(PL_isarev, hvename, 0);
1067 if (svp) isarev = MUTABLE_HV(*svp);
1069 else if(SvTYPE(namesv) == SVt_PVAV) {
1070 items = AvFILLp((AV *)namesv) + 1;
1071 svp = AvARRAY((AV *)namesv);
1079 isarev || !fetched_isarev
1081 while (fetched_isarev || items--) {
1084 if (!fetched_isarev) {
1085 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1086 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1089 hv_iterinit(isarev);
1090 while((iter = hv_iternext(isarev))) {
1091 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1092 struct mro_meta * meta;
1094 if(!revstash) continue;
1095 meta = HvMROMETA(revstash);
1098 stashes, (const char *)&revstash, sizeof(HV *),
1100 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1107 if (fetched_isarev) break;
1111 /* This is partly based on code in hv_iternext_flags. We are not call-
1112 ing that here, as we want to avoid resetting the hash iterator. */
1114 /* Skip the entire loop if the hash is empty. */
1115 if(oldstash && HvUSEDKEYS(oldstash)) {
1116 xhv = (XPVHV*)SvANY(oldstash);
1117 seen = (HV *) sv_2mortal((SV *)newHV());
1119 /* Iterate through entries in the oldstash, adding them to the
1120 list, meanwhile doing the equivalent of $seen{$key} = 1.
1123 while (++riter <= (I32)xhv->xhv_max) {
1124 entry = (HvARRAY(oldstash))[riter];
1126 /* Iterate through the entries in this list */
1127 for(; entry; entry = HeNEXT(entry)) {
1131 /* If this entry is not a glob, ignore it.
1133 if (!isGV(HeVAL(entry))) continue;
1135 key = hv_iterkey(entry, &len);
1136 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1137 || (len == 1 && key[0] == ':')) {
1138 HV * const oldsubstash = GvHV(HeVAL(entry));
1139 SV ** const stashentry
1140 = stash ? hv_fetch(stash, key, HeUTF8(entry) ? -(I32)len : (I32)len, 0) : NULL;
1141 HV *substash = NULL;
1143 /* Avoid main::main::main::... */
1144 if(oldsubstash == oldstash) continue;
1148 stashentry && *stashentry && isGV(*stashentry)
1149 && (substash = GvHV(*stashentry))
1151 || (oldsubstash && HvENAME_get(oldsubstash))
1154 /* Add :: and the key (minus the trailing ::)
1157 if(SvTYPE(namesv) == SVt_PVAV) {
1159 items = AvFILLp((AV *)namesv) + 1;
1160 svp = AvARRAY((AV *)namesv);
1161 subname = sv_2mortal((SV *)newAV());
1163 aname = newSVsv(*svp++);
1165 sv_catpvs(aname, ":");
1167 sv_catpvs(aname, "::");
1171 ? SV_CATUTF8 : SV_CATBYTES
1174 av_push((AV *)subname, aname);
1178 subname = sv_2mortal(newSVsv(namesv));
1179 if (len == 1) sv_catpvs(subname, ":");
1181 sv_catpvs(subname, "::");
1183 subname, key, len-2,
1184 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1188 mro_gather_and_rename(
1189 stashes, seen_stashes,
1190 substash, oldsubstash, subname
1194 (void)hv_store(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len, &PL_sv_yes, 0);
1200 /* Skip the entire loop if the hash is empty. */
1201 if (stash && HvUSEDKEYS(stash)) {
1202 xhv = (XPVHV*)SvANY(stash);
1205 /* Iterate through the new stash, skipping $seen{$key} items,
1206 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1207 while (++riter <= (I32)xhv->xhv_max) {
1208 entry = (HvARRAY(stash))[riter];
1210 /* Iterate through the entries in this list */
1211 for(; entry; entry = HeNEXT(entry)) {
1215 /* If this entry is not a glob, ignore it.
1217 if (!isGV(HeVAL(entry))) continue;
1219 key = hv_iterkey(entry, &len);
1220 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1221 || (len == 1 && key[0] == ':')) {
1224 /* If this entry was seen when we iterated through the
1225 oldstash, skip it. */
1226 if(seen && hv_exists(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len)) continue;
1228 /* We get here only if this stash has no corresponding
1229 entry in the stash being replaced. */
1231 substash = GvHV(HeVAL(entry));
1235 /* Avoid checking main::main::main::... */
1236 if(substash == stash) continue;
1238 /* Add :: and the key (minus the trailing ::)
1240 if(SvTYPE(namesv) == SVt_PVAV) {
1242 items = AvFILLp((AV *)namesv) + 1;
1243 svp = AvARRAY((AV *)namesv);
1244 subname = sv_2mortal((SV *)newAV());
1246 aname = newSVsv(*svp++);
1248 sv_catpvs(aname, ":");
1250 sv_catpvs(aname, "::");
1254 ? SV_CATUTF8 : SV_CATBYTES
1257 av_push((AV *)subname, aname);
1261 subname = sv_2mortal(newSVsv(namesv));
1262 if (len == 1) sv_catpvs(subname, ":");
1264 sv_catpvs(subname, "::");
1266 subname, key, len-2,
1267 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1271 mro_gather_and_rename(
1272 stashes, seen_stashes,
1273 substash, NULL, subname
1283 =for apidoc mro_method_changed_in
1285 Invalidates method caching on any child classes
1286 of the given stash, so that they might notice
1287 the changes in this one.
1289 Ideally, all instances of C<PL_sub_generation++> in
1290 perl source outside of F<mro.c> should be
1291 replaced by calls to this.
1293 Perl automatically handles most of the common
1294 ways a method might be redefined. However, there
1295 are a few ways you could change a method in a stash
1296 without the cache code noticing, in which case you
1297 need to call this method afterwards:
1299 1) Directly manipulating the stash HV entries from
1302 2) Assigning a reference to a readonly scalar
1303 constant into a stash entry in order to create
1304 a constant subroutine (like F<constant.pm>
1307 This same method is available from pure perl
1308 via, C<mro::method_changed_in(classname)>.
1313 Perl_mro_method_changed_in(pTHX_ HV *stash)
1315 const char * const stashname = HvENAME_get(stash);
1316 const STRLEN stashname_len = HvENAMELEN_get(stash);
1318 SV ** const svp = hv_fetchhek(PL_isarev, HvENAME_HEK(stash), 0);
1319 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1321 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1324 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1326 /* Inc the package generation, since a local method changed */
1327 HvMROMETA(stash)->pkg_gen++;
1329 /* DESTROY can be cached in meta */
1330 HvMROMETA(stash)->destroy_gen = 0;
1332 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1333 invalidate all method caches globally */
1334 if((memEQs(stashname, stashname_len, "UNIVERSAL"))
1335 || (isarev && hv_existss(isarev, "UNIVERSAL"))) {
1336 PL_sub_generation++;
1340 /* else, invalidate the method caches of all child classes,
1345 hv_iterinit(isarev);
1346 while((iter = hv_iternext(isarev))) {
1347 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1348 struct mro_meta* mrometa;
1350 if(!revstash) continue;
1351 mrometa = HvMROMETA(revstash);
1352 mrometa->cache_gen++;
1353 if(mrometa->mro_nextmethod)
1354 hv_clear(mrometa->mro_nextmethod);
1355 mrometa->destroy_gen = 0;
1359 /* The method change may be due to *{$package . "::()"} = \&nil; in
1362 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
1363 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
1367 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1369 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1371 PERL_ARGS_ASSERT_MRO_SET_MRO;
1374 Perl_croak(aTHX_ "Invalid mro name: '%" SVf "'", name);
1376 if(meta->mro_which != which) {
1377 if (meta->mro_linear_current && !meta->mro_linear_all) {
1378 /* If we were storing something directly, put it in the hash before
1380 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1381 MUTABLE_SV(meta->mro_linear_current));
1383 meta->mro_which = which;
1384 /* Scrub our cached pointer to the private data. */
1385 meta->mro_linear_current = NULL;
1386 /* Only affects local method cache, not
1387 even child classes */
1389 if(meta->mro_nextmethod)
1390 hv_clear(meta->mro_nextmethod);
1396 XS(XS_mro_method_changed_in);
1399 Perl_boot_core_mro(pTHX)
1401 static const char file[] = __FILE__;
1403 Perl_mro_register(aTHX_ &dfs_alg);
1405 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1408 XS(XS_mro_method_changed_in)
1415 croak_xs_usage(cv, "classname");
1419 class_stash = gv_stashsv(classname, 0);
1420 if(!class_stash) Perl_croak(aTHX_ "No such class: '%" SVf "'!", SVfARG(classname));
1422 mro_method_changed_in(class_stash);
1428 * ex: set ts=8 sts=4 sw=4 et: