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))) {
700 HEK *key = HeKEY_hek(iter);
701 if(exceptions && hv_existshek(exceptions, key))
703 svp = hv_fetchhek(PL_isarev, key, 0);
705 HV * const isarev = (HV *)*svp;
706 (void)hv_common(isarev, NULL, name, len, flags,
707 G_DISCARD|HV_DELETE, NULL, hash);
708 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
709 (void)hv_deletehek(PL_isarev, key, G_DISCARD);
716 =for apidoc mro_package_moved
718 Call this function to signal to a stash that it has been assigned to
719 another spot in the stash hierarchy. C<stash> is the stash that has been
720 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
721 that is actually being assigned to.
723 This can also be called with a null first argument to
724 indicate that C<oldstash> has been deleted.
726 This function invalidates isa caches on the old stash, on all subpackages
727 nested inside it, and on the subclasses of all those, including
728 non-existent packages that have corresponding entries in C<stash>.
730 It also sets the effective names (C<HvENAME>) on all the stashes as
733 If the C<gv> is present and is not in the symbol table, then this function
734 simply returns. This checked will be skipped if C<flags & 1>.
739 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
740 const GV * const gv, U32 flags)
748 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
749 assert(stash || oldstash);
751 /* Determine the name(s) of the location that stash was assigned to
752 * or from which oldstash was removed.
754 * We cannot reliably use the name in oldstash, because it may have
755 * been deleted from the location in the symbol table that its name
756 * suggests, as in this case:
758 * $globref = \*foo::bar::;
759 * Symbol::delete_package("foo");
760 * *$globref = \%baz::;
761 * *$globref = *frelp::;
762 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
764 * So we get it from the gv. But, since the gv may no longer be in the
765 * symbol table, we check that first. The only reliable way to tell is
766 * to see whether its stash has an effective name and whether the gv
767 * resides in that stash under its name. That effective name may be
768 * different from what gv_fullname4 would use.
769 * If flags & 1, the caller has asked us to skip the check.
774 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
775 !(svp = hv_fetchhek(GvSTASH(gv), GvNAME_HEK(gv), 0)) ||
779 assert(SvOOK(GvSTASH(gv)));
780 assert(GvNAMELEN(gv));
781 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
782 assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
783 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
786 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
789 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
790 if (name_count < 0) ++namep, name_count = -name_count - 1;
792 if (name_count == 1) {
793 if (memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")) {
794 namesv = GvNAMELEN(gv) == 1
795 ? newSVpvs_flags(":", SVs_TEMP)
796 : newSVpvs_flags("", SVs_TEMP);
799 namesv = sv_2mortal(newSVhek(*namep));
800 if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
801 else sv_catpvs(namesv, "::");
803 if (GvNAMELEN(gv) != 1) {
805 namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
806 /* skip trailing :: */
807 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
813 namesv = sv_2mortal((SV *)newAV());
814 while (name_count--) {
815 if(memEQs(HEK_KEY(*namep), HEK_LEN(*namep), "main")){
816 aname = GvNAMELEN(gv) == 1
822 aname = newSVhek(*namep++);
823 if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
824 else sv_catpvs(aname, "::");
826 if (GvNAMELEN(gv) != 1) {
828 aname, GvNAME(gv), GvNAMELEN(gv) - 2,
829 /* skip trailing :: */
830 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
833 av_push((AV *)namesv, aname);
837 /* Get a list of all the affected classes. */
838 /* We cannot simply pass them all to mro_isa_changed_in to avoid
839 the list, as that function assumes that only one package has
840 changed. It does not work with:
842 @foo::ISA = qw( B B::B );
843 *B:: = delete $::{"A::"};
845 as neither B nor B::B can be updated before the other, since they
846 will reset caches on foo, which will see either B or B::B with the
847 wrong name. The names must be set on *all* affected stashes before
848 we do anything else. (And linearisations must be cleared, too.)
850 stashes = (HV *) sv_2mortal((SV *)newHV());
851 mro_gather_and_rename(
852 stashes, (HV *) sv_2mortal((SV *)newHV()),
853 stash, oldstash, namesv
856 /* Once the caches have been wiped on all the classes, call
857 mro_isa_changed_in on each. */
858 hv_iterinit(stashes);
859 while((iter = hv_iternext(stashes))) {
860 HV * const this_stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
861 if(HvENAME(this_stash)) {
862 /* We have to restore the original meta->isa (that
863 mro_gather_and_rename set aside for us) this way, in case
864 one class in this list is a superclass of a another class
865 that we have already encountered. In such a case, meta->isa
866 will have been overwritten without old entries being deleted
868 struct mro_meta * const meta = HvMROMETA(this_stash);
869 if(meta->isa != (HV *)HeVAL(iter)){
870 SvREFCNT_dec(meta->isa);
872 = HeVAL(iter) == &PL_sv_yes
875 HeVAL(iter) = NULL; /* We donated our reference count. */
877 mro_isa_changed_in(this_stash);
883 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
884 HV *stash, HV *oldstash, SV *namesv)
890 const bool stash_had_name = stash && HvENAME(stash);
891 bool fetched_isarev = FALSE;
896 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
898 /* We use the seen_stashes hash to keep track of which packages have
899 been encountered so far. This must be separate from the main list of
900 stashes, as we need to distinguish between stashes being assigned
901 and stashes being replaced/deleted. (A nested stash can be on both
902 sides of an assignment. We cannot simply skip iterating through a
903 stash on the right if we have seen it on the left, as it will not
904 get its ename assigned to it.)
906 To avoid allocating extra SVs, instead of a bitfield we can make
907 bizarre use of immortals:
909 &PL_sv_undef: seen on the left (oldstash)
910 &PL_sv_no : seen on the right (stash)
911 &PL_sv_yes : seen on both sides
916 /* Add to the big list. */
917 struct mro_meta * meta;
921 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
922 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
924 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
929 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
930 meta = HvMROMETA(oldstash);
933 stashes, (const char *)&oldstash, sizeof(HV *),
935 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
941 /* Update the effective name. */
942 if(HvENAME_get(oldstash)) {
943 const HEK * const enamehek = HvENAME_HEK(oldstash);
944 if(SvTYPE(namesv) == SVt_PVAV) {
945 items = AvFILLp((AV *)namesv) + 1;
946 svp = AvARRAY((AV *)namesv);
953 const U32 name_utf8 = SvUTF8(*svp);
955 const char *name = SvPVx_const(*svp, len);
957 DEBUG_o(Perl_deb(aTHX_ "mro_gather_and_rename clearing PL_stashcache for '%" SVf "'\n",
959 (void)hv_delete_ent(PL_stashcache, *svp, G_DISCARD, 0);
961 hv_ename_delete(oldstash, name, len, name_utf8);
963 if (!fetched_isarev) {
964 /* If the name deletion caused a name change, then we
965 * are not going to call mro_isa_changed_in with this
966 * name (and not at all if it has become anonymous) so
967 * we need to delete old isarev entries here, both
968 * those in the superclasses and this class's own list
969 * of subclasses. We simply delete the latter from
970 * PL_isarev, since we still need it. hv_delete morti-
971 * fies it for us, so sv_2mortal is not necessary. */
972 if(HvENAME_HEK(oldstash) != enamehek) {
973 if(meta->isa && HvARRAY(meta->isa))
974 mro_clean_isarev(meta->isa, name, len, 0, 0,
975 name_utf8 ? HVhek_UTF8 : 0);
976 isarev = (HV *)hv_delete_ent(PL_isarev, *svp, 0, 0);
987 if(SvTYPE(namesv) == SVt_PVAV) {
988 items = AvFILLp((AV *)namesv) + 1;
989 svp = AvARRAY((AV *)namesv);
996 const U32 name_utf8 = SvUTF8(*svp);
998 const char *name = SvPVx_const(*svp++, len);
999 hv_ename_add(stash, name, len, name_utf8);
1002 /* Add it to the big list if it needs
1003 * mro_isa_changed_in called on it. That happens if it was
1004 * detached from the symbol table (so it had no HvENAME) before
1005 * being assigned to the spot named by the 'name' variable, because
1006 * its cached isa linearisation is now stale (the effective name
1007 * having changed), and subclasses will then use that cache when
1008 * mro_package_moved calls mro_isa_changed_in. (See
1011 * If it did have a name, then its previous name is still
1012 * used in isa caches, and there is no need for
1013 * mro_package_moved to call mro_isa_changed_in.
1019 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1020 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1022 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1026 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1029 struct mro_meta * const meta = HvMROMETA(stash);
1032 stashes, (const char *)&stash, sizeof(HV *),
1034 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1043 if(!stash && !oldstash)
1044 /* Both stashes have been encountered already. */
1047 /* Add all the subclasses to the big list. */
1048 if(!fetched_isarev) {
1049 /* If oldstash is not null, then we can use its HvENAME to look up
1050 the isarev hash, since all its subclasses will be listed there.
1051 It will always have an HvENAME. It the HvENAME was removed
1052 above, then fetch_isarev will be true, and this code will not be
1055 If oldstash is null, then this is an empty spot with no stash in
1056 it, so subclasses could be listed in isarev hashes belonging to
1057 any of the names, so we have to check all of them.
1059 assert(!oldstash || HvENAME(oldstash));
1061 /* Extra variable to avoid a compiler warning */
1062 const HEK * const hvename = HvENAME_HEK(oldstash);
1063 fetched_isarev = TRUE;
1064 svp = hv_fetchhek(PL_isarev, hvename, 0);
1065 if (svp) isarev = MUTABLE_HV(*svp);
1067 else if(SvTYPE(namesv) == SVt_PVAV) {
1068 items = AvFILLp((AV *)namesv) + 1;
1069 svp = AvARRAY((AV *)namesv);
1077 isarev || !fetched_isarev
1079 while (fetched_isarev || items--) {
1082 if (!fetched_isarev) {
1083 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1084 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1087 hv_iterinit(isarev);
1088 while((iter = hv_iternext(isarev))) {
1089 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1090 struct mro_meta * meta;
1092 if(!revstash) continue;
1093 meta = HvMROMETA(revstash);
1096 stashes, (const char *)&revstash, sizeof(HV *),
1098 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1105 if (fetched_isarev) break;
1109 /* This is partly based on code in hv_iternext_flags. We are not call-
1110 ing that here, as we want to avoid resetting the hash iterator. */
1112 /* Skip the entire loop if the hash is empty. */
1113 if(oldstash && HvTOTALKEYS(oldstash)) {
1114 xhv = (XPVHV*)SvANY(oldstash);
1115 seen = (HV *) sv_2mortal((SV *)newHV());
1117 /* Iterate through entries in the oldstash, adding them to the
1118 list, meanwhile doing the equivalent of $seen{$key} = 1.
1121 while (++riter <= (I32)xhv->xhv_max) {
1122 entry = (HvARRAY(oldstash))[riter];
1124 /* Iterate through the entries in this list */
1125 for(; entry; entry = HeNEXT(entry)) {
1129 /* If this entry is not a glob, ignore it.
1131 if (!isGV(HeVAL(entry))) continue;
1133 key = hv_iterkey(entry, &len);
1134 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1135 || (len == 1 && key[0] == ':')) {
1136 HV * const oldsubstash = GvHV(HeVAL(entry));
1138 HV *substash = NULL;
1140 /* Avoid main::main::main::... */
1141 if(oldsubstash == oldstash) continue;
1143 stashentry = stash ? hv_fetchhek(stash, HeKEY_hek(entry), 0) : NULL;
1147 stashentry && *stashentry && isGV(*stashentry)
1148 && (substash = GvHV(*stashentry))
1150 || (oldsubstash && HvENAME_get(oldsubstash))
1153 /* Add :: and the key (minus the trailing ::)
1156 if(SvTYPE(namesv) == SVt_PVAV) {
1158 items = AvFILLp((AV *)namesv) + 1;
1159 svp = AvARRAY((AV *)namesv);
1160 subname = sv_2mortal((SV *)newAV());
1162 aname = newSVsv(*svp++);
1164 sv_catpvs(aname, ":");
1166 sv_catpvs(aname, "::");
1170 ? SV_CATUTF8 : SV_CATBYTES
1173 av_push((AV *)subname, aname);
1177 subname = sv_2mortal(newSVsv(namesv));
1178 if (len == 1) sv_catpvs(subname, ":");
1180 sv_catpvs(subname, "::");
1182 subname, key, len-2,
1183 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1187 mro_gather_and_rename(
1188 stashes, seen_stashes,
1189 substash, oldsubstash, subname
1193 (void)hv_storehek(seen, HeKEY_hek(entry), &PL_sv_yes);
1199 /* Skip the entire loop if the hash is empty. */
1200 if (stash && HvTOTALKEYS(stash)) {
1201 xhv = (XPVHV*)SvANY(stash);
1204 /* Iterate through the new stash, skipping $seen{$key} items,
1205 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1206 while (++riter <= (I32)xhv->xhv_max) {
1207 entry = (HvARRAY(stash))[riter];
1209 /* Iterate through the entries in this list */
1210 for(; entry; entry = HeNEXT(entry)) {
1214 /* If this entry is not a glob, ignore it.
1216 if (!isGV(HeVAL(entry))) continue;
1218 key = hv_iterkey(entry, &len);
1219 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1220 || (len == 1 && key[0] == ':')) {
1223 /* If this entry was seen when we iterated through the
1224 oldstash, skip it. */
1225 if(seen && hv_existshek(seen, HeKEY_hek(entry))) continue;
1227 /* We get here only if this stash has no corresponding
1228 entry in the stash being replaced. */
1230 substash = GvHV(HeVAL(entry));
1234 /* Avoid checking main::main::main::... */
1235 if(substash == stash) continue;
1237 /* Add :: and the key (minus the trailing ::)
1239 if(SvTYPE(namesv) == SVt_PVAV) {
1241 items = AvFILLp((AV *)namesv) + 1;
1242 svp = AvARRAY((AV *)namesv);
1243 subname = sv_2mortal((SV *)newAV());
1245 aname = newSVsv(*svp++);
1247 sv_catpvs(aname, ":");
1249 sv_catpvs(aname, "::");
1253 ? SV_CATUTF8 : SV_CATBYTES
1256 av_push((AV *)subname, aname);
1260 subname = sv_2mortal(newSVsv(namesv));
1261 if (len == 1) sv_catpvs(subname, ":");
1263 sv_catpvs(subname, "::");
1265 subname, key, len-2,
1266 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1270 mro_gather_and_rename(
1271 stashes, seen_stashes,
1272 substash, NULL, subname
1282 =for apidoc mro_method_changed_in
1284 Invalidates method caching on any child classes
1285 of the given stash, so that they might notice
1286 the changes in this one.
1288 Ideally, all instances of C<PL_sub_generation++> in
1289 perl source outside of F<mro.c> should be
1290 replaced by calls to this.
1292 Perl automatically handles most of the common
1293 ways a method might be redefined. However, there
1294 are a few ways you could change a method in a stash
1295 without the cache code noticing, in which case you
1296 need to call this method afterwards:
1298 1) Directly manipulating the stash HV entries from
1301 2) Assigning a reference to a readonly scalar
1302 constant into a stash entry in order to create
1303 a constant subroutine (like F<constant.pm>
1306 This same method is available from pure perl
1307 via, C<mro::method_changed_in(classname)>.
1312 Perl_mro_method_changed_in(pTHX_ HV *stash)
1314 const char * const stashname = HvENAME_get(stash);
1315 const STRLEN stashname_len = HvENAMELEN_get(stash);
1317 SV ** const svp = hv_fetchhek(PL_isarev, HvENAME_HEK(stash), 0);
1318 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1320 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1323 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1325 /* Inc the package generation, since a local method changed */
1326 HvMROMETA(stash)->pkg_gen++;
1328 /* DESTROY can be cached in meta */
1329 HvMROMETA(stash)->destroy_gen = 0;
1331 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1332 invalidate all method caches globally */
1333 if((memEQs(stashname, stashname_len, "UNIVERSAL"))
1334 || (isarev && hv_existss(isarev, "UNIVERSAL"))) {
1335 PL_sub_generation++;
1339 /* else, invalidate the method caches of all child classes,
1344 hv_iterinit(isarev);
1345 while((iter = hv_iternext(isarev))) {
1346 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1347 struct mro_meta* mrometa;
1349 if(!revstash) continue;
1350 mrometa = HvMROMETA(revstash);
1351 mrometa->cache_gen++;
1352 if(mrometa->mro_nextmethod)
1353 hv_clear(mrometa->mro_nextmethod);
1354 mrometa->destroy_gen = 0;
1358 /* The method change may be due to *{$package . "::()"} = \&nil; in
1361 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
1362 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
1366 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1368 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1370 PERL_ARGS_ASSERT_MRO_SET_MRO;
1373 Perl_croak(aTHX_ "Invalid mro name: '%" SVf "'", name);
1375 if(meta->mro_which != which) {
1376 if (meta->mro_linear_current && !meta->mro_linear_all) {
1377 /* If we were storing something directly, put it in the hash before
1379 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1380 MUTABLE_SV(meta->mro_linear_current));
1382 meta->mro_which = which;
1383 /* Scrub our cached pointer to the private data. */
1384 meta->mro_linear_current = NULL;
1385 /* Only affects local method cache, not
1386 even child classes */
1388 if(meta->mro_nextmethod)
1389 hv_clear(meta->mro_nextmethod);
1395 XS(XS_mro_method_changed_in);
1398 Perl_boot_core_mro(pTHX)
1400 static const char file[] = __FILE__;
1402 Perl_mro_register(aTHX_ &dfs_alg);
1404 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1407 XS(XS_mro_method_changed_in)
1414 croak_xs_usage(cv, "classname");
1418 class_stash = gv_stashsv(classname, 0);
1419 if(!class_stash) Perl_croak(aTHX_ "No such class: '%" SVf "'!", SVfARG(classname));
1421 mro_method_changed_in(class_stash);
1427 * ex: set ts=8 sts=4 sw=4 et: