3 * Copyright (c) 2007 Brandon L Black
4 * Copyright (c) 2007, 2008 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.
12 * 'Which order shall we go in?' said Frodo. 'Eldest first, or quickest first?
13 * You'll be last either way, Master Peregrin.'
15 * [p.101 of _The Lord of the Rings_, I/iii: "A Conspiracy Unmasked"]
21 These functions are related to the method resolution order of perl classes
30 static const struct mro_alg dfs_alg =
31 {S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};
34 Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
35 const struct mro_alg *const which)
38 PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;
40 data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
41 which->name, which->length, which->kflags,
42 HV_FETCH_JUST_SV, NULL, which->hash);
46 /* If we've been asked to look up the private data for the current MRO, then
48 if (smeta->mro_which == which)
49 smeta->mro_linear_current = *data;
55 Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
56 const struct mro_alg *const which, SV *const data)
58 PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;
60 if (!smeta->mro_linear_all) {
61 if (smeta->mro_which == which) {
62 /* If all we need to store is the current MRO's data, then don't use
63 memory on a hash with 1 element - store it direct, and signal
64 this by leaving the would-be-hash NULL. */
65 smeta->mro_linear_current = data;
68 HV *const hv = newHV();
69 /* Start with 2 buckets. It's unlikely we'll need more. */
71 smeta->mro_linear_all = hv;
73 if (smeta->mro_linear_current) {
74 /* If we were storing something directly, put it in the hash
76 Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which,
77 smeta->mro_linear_current);
82 /* We get here if we're storing more than one linearisation for this stash,
83 or the linearisation we are storing is not that if its current MRO. */
85 if (smeta->mro_which == which) {
86 /* If we've been asked to store the private data for the current MRO,
88 smeta->mro_linear_current = data;
91 if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
92 which->name, which->length, which->kflags,
93 HV_FETCH_ISSTORE, data, which->hash)) {
94 Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
95 "for '%.*s' %d", (int) which->length, which->name,
102 const struct mro_alg *
103 Perl_mro_get_from_name(pTHX_ SV *name) {
106 PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;
108 data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
109 HV_FETCH_JUST_SV, NULL, 0);
112 assert(SvTYPE(*data) == SVt_IV);
113 assert(SvIOK(*data));
114 return INT2PTR(const struct mro_alg *, SvUVX(*data));
118 Perl_mro_register(pTHX_ const struct mro_alg *mro) {
119 SV *wrapper = newSVuv(PTR2UV(mro));
121 PERL_ARGS_ASSERT_MRO_REGISTER;
124 if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
125 mro->name, mro->length, mro->kflags,
126 HV_FETCH_ISSTORE, wrapper, mro->hash)) {
127 SvREFCNT_dec(wrapper);
128 Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
129 "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
134 Perl_mro_meta_init(pTHX_ HV* stash)
136 struct mro_meta* newmeta;
138 PERL_ARGS_ASSERT_MRO_META_INIT;
139 assert(HvAUX(stash));
140 assert(!(HvAUX(stash)->xhv_mro_meta));
141 Newxz(newmeta, 1, struct mro_meta);
142 HvAUX(stash)->xhv_mro_meta = newmeta;
143 newmeta->cache_gen = 1;
144 newmeta->pkg_gen = 1;
145 newmeta->mro_which = &dfs_alg;
150 #if defined(USE_ITHREADS)
152 /* for sv_dup on new threads */
154 Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
156 struct mro_meta* newmeta;
158 PERL_ARGS_ASSERT_MRO_META_DUP;
160 Newx(newmeta, 1, struct mro_meta);
161 Copy(smeta, newmeta, 1, struct mro_meta);
163 if (newmeta->mro_linear_all) {
164 newmeta->mro_linear_all
165 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
166 /* This is just acting as a shortcut pointer, and will be automatically
167 updated on the first get. */
168 newmeta->mro_linear_current = NULL;
169 } else if (newmeta->mro_linear_current) {
170 /* Only the current MRO is stored, so this owns the data. */
171 newmeta->mro_linear_current
172 = sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
175 if (newmeta->mro_nextmethod)
176 newmeta->mro_nextmethod
177 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
180 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
185 #endif /* USE_ITHREADS */
188 =for apidoc mro_get_linear_isa_dfs
190 Returns the Depth-First Search linearization of @ISA
191 the given stash. The return value is a read-only AV*.
192 C<level> should be 0 (it is used internally in this
193 function's recursion).
195 You are responsible for C<SvREFCNT_inc()> on the
196 return value if you plan to store it anywhere
197 semi-permanently (otherwise it might be deleted
198 out from under you the next time the cache is
204 S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
211 struct mro_meta* meta;
215 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
216 assert(HvAUX(stash));
219 = HvAUX(stash)->xhv_name && HvENAME_HEK_NN(stash)
220 ? HvENAME_HEK_NN(stash)
224 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
227 Perl_croak(aTHX_ "Recursive inheritance detected in package '%s'",
230 meta = HvMROMETA(stash);
232 /* return cache if valid */
233 if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
237 /* not in cache, make a new one */
239 retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
240 /* We use this later in this function, but don't need a reference to it
241 beyond the end of this function, so reference count is fine. */
242 our_name = newSVhek(stashhek);
243 av_push(retval, our_name); /* add ourselves at the top */
246 gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
247 av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
249 /* "stored" is used to keep track of all of the classnames we have added to
250 the MRO so far, so we can do a quick exists check and avoid adding
251 duplicate classnames to the MRO as we go.
252 It's then retained to be re-used as a fast lookup for ->isa(), by adding
253 our own name and "UNIVERSAL" to it. */
255 if(av && AvFILLp(av) >= 0) {
257 SV **svp = AvARRAY(av);
258 I32 items = AvFILLp(av) + 1;
262 SV* const sv = *svp++;
263 HV* const basestash = gv_stashsv(sv, 0);
268 /* if no stash exists for this @ISA member,
269 simply add it to the MRO and move on */
274 /* otherwise, recurse into ourselves for the MRO
275 of this @ISA member, and append their MRO to ours.
276 The recursive call could throw an exception, which
277 has memory management implications here, hence the use of
279 const AV *const subrv
280 = mro_get_linear_isa_dfs(basestash, level + 1);
282 subrv_p = AvARRAY(subrv);
283 subrv_items = AvFILLp(subrv) + 1;
286 while(subrv_items--) {
287 SV *const subsv = *subrv_p++;
288 /* LVALUE fetch will create a new undefined SV if necessary
290 HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
292 if(HeVAL(he) != &PL_sv_undef) {
293 /* It was newly created. Steal it for our new SV, and
294 replace it in the hash with the "real" thing. */
295 SV *const val = HeVAL(he);
296 HEK *const key = HeKEY_hek(he);
298 HeVAL(he) = &PL_sv_undef;
299 /* Save copying by making a shared hash key scalar. We
300 inline this here rather than calling
301 Perl_newSVpvn_share because we already have the
302 scalar, and we already have the hash key. */
303 assert(SvTYPE(val) == SVt_NULL);
304 sv_upgrade(val, SVt_PV);
305 SvPV_set(val, HEK_KEY(share_hek_hek(key)));
306 SvCUR_set(val, HEK_LEN(key));
313 av_push(retval, val);
317 /* We are the first (or only) parent. We can short cut the
318 complexity above, because our @ISA is simply us prepended
319 to our parent's @ISA, and our ->isa cache is simply our
320 parent's, with our name added. */
321 /* newSVsv() is slow. This code is only faster if we can avoid
322 it by ensuring that SVs in the arrays are shared hash key
323 scalar SVs, because we can "copy" them very efficiently.
324 Although to be fair, we can't *ensure* this, as a reference
325 to the internal array is returned by mro::get_linear_isa(),
326 so we'll have to be defensive just in case someone faffed
330 stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
331 av_extend(retval, subrv_items);
332 AvFILLp(retval) = subrv_items;
333 svp = AvARRAY(retval);
334 while(subrv_items--) {
335 SV *const val = *subrv_p++;
336 *++svp = SvIsCOW_shared_hash(val)
337 ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
341 /* They have no stash. So create ourselves an ->isa cache
342 as if we'd copied it from what theirs should be. */
343 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
344 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
346 newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
352 /* We have no parents. */
353 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
354 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
357 (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
359 SvREFCNT_inc_simple_void_NN(stored);
361 SvREADONLY_on(stored);
365 /* now that we're past the exception dangers, grab our own reference to
366 the AV we're about to use for the result. The reference owned by the
367 mortals' stack will be released soon, so everything will balance. */
368 SvREFCNT_inc_simple_void_NN(retval);
371 /* we don't want anyone modifying the cache entry but us,
372 and we do so by replacing it completely */
373 SvREADONLY_on(retval);
375 return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
376 MUTABLE_SV(retval)));
380 =for apidoc mro_get_linear_isa
382 Returns either C<mro_get_linear_isa_c3> or
383 C<mro_get_linear_isa_dfs> for the given stash,
384 dependant upon which MRO is in effect
385 for that stash. The return value is a
388 You are responsible for C<SvREFCNT_inc()> on the
389 return value if you plan to store it anywhere
390 semi-permanently (otherwise it might be deleted
391 out from under you the next time the cache is
397 Perl_mro_get_linear_isa(pTHX_ HV *stash)
399 struct mro_meta* meta;
402 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
404 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
406 meta = HvMROMETA(stash);
407 if (!meta->mro_which)
408 Perl_croak(aTHX_ "panic: invalid MRO!");
409 isa = meta->mro_which->resolve(aTHX_ stash, 0);
412 HV *const isa_hash = newHV();
413 /* Linearisation didn't build it for us, so do it here. */
414 SV *const *svp = AvARRAY(isa);
415 SV *const *const svp_end = svp + AvFILLp(isa) + 1;
416 const HEK *canon_name = HvENAME_HEK(stash);
417 if (!canon_name) canon_name = HvNAME_HEK(stash);
419 while (svp < svp_end) {
420 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
423 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
424 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
425 HV_FETCH_ISSTORE, &PL_sv_undef,
426 HEK_HASH(canon_name));
427 (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
429 SvREADONLY_on(isa_hash);
431 meta->isa = isa_hash;
438 =for apidoc mro_isa_changed_in
440 Takes the necessary steps (cache invalidations, mostly)
441 when the @ISA of the given package has changed. Invoked
442 by the C<setisa> magic, should not need to invoke directly.
447 /* Macro to avoid repeating the code five times. */
448 #define CLEAR_LINEAR(mEta) \
449 if (mEta->mro_linear_all) { \
450 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
451 mEta->mro_linear_all = NULL; \
452 /* This is just acting as a shortcut pointer. */ \
453 mEta->mro_linear_current = NULL; \
454 } else if (mEta->mro_linear_current) { \
455 /* Only the current MRO is stored, so this owns the data. */ \
456 SvREFCNT_dec(mEta->mro_linear_current); \
457 mEta->mro_linear_current = NULL; \
461 Perl_mro_isa_changed_in(pTHX_ HV* stash)
470 struct mro_meta * meta;
473 const char * const stashname = HvENAME_get(stash);
474 const STRLEN stashname_len = HvENAMELEN_get(stash);
476 PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
479 Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
482 /* wipe out the cached linearizations for this stash */
483 meta = HvMROMETA(stash);
486 /* Steal it for our own purposes. */
487 isa = (HV *)sv_2mortal((SV *)meta->isa);
491 /* Inc the package generation, since our @ISA changed */
494 /* Wipe the global method cache if this package
495 is UNIVERSAL or one of its parents */
497 svp = hv_fetch(PL_isarev, stashname, stashname_len, 0);
498 isarev = svp ? MUTABLE_HV(*svp) : NULL;
500 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
501 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
505 else { /* Wipe the local method cache otherwise */
507 is_universal = FALSE;
510 /* wipe next::method cache too */
511 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
513 /* Iterate the isarev (classes that are our children),
514 wiping out their linearization, method and isa caches
515 and upating PL_isarev. */
517 HV *isa_hashes = NULL;
519 /* We have to iterate through isarev twice to avoid a chicken and
520 * egg problem: if A inherits from B and both are in isarev, A might
521 * be processed before B and use B’s previous linearisation.
524 /* First iteration: Wipe everything, but stash away the isa hashes
525 * since we still need them for updating PL_isarev.
528 if(hv_iterinit(isarev)) {
529 /* Only create the hash if we need it; i.e., if isarev has
531 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
533 while((iter = hv_iternext(isarev))) {
535 const char* const revkey = hv_iterkey(iter, &len);
536 HV* revstash = gv_stashpvn(revkey, len, 0);
537 struct mro_meta* revmeta;
539 if(!revstash) continue;
540 revmeta = HvMROMETA(revstash);
541 CLEAR_LINEAR(revmeta);
543 revmeta->cache_gen++;
544 if(revmeta->mro_nextmethod)
545 hv_clear(revmeta->mro_nextmethod);
549 isa_hashes, (const char*)&revstash, sizeof(HV *),
550 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
555 /* Second pass: Update PL_isarev. We can just use isa_hashes to
556 * avoid another round of stash lookups. */
558 /* isarev might be deleted from PL_isarev during this loop, so hang
560 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
563 hv_iterinit(isa_hashes);
564 while((iter = hv_iternext(isa_hashes))) {
565 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
566 HV * const isa = (HV *)HeVAL(iter);
569 /* We're starting at the 2nd element, skipping revstash */
570 linear_mro = mro_get_linear_isa(revstash);
571 svp = AvARRAY(linear_mro) + 1;
572 items = AvFILLp(linear_mro);
574 namehek = HvENAME_HEK(revstash);
575 if (!namehek) namehek = HvNAME_HEK(revstash);
578 SV* const sv = *svp++;
581 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
583 /* That fetch should not fail. But if it had to create
584 a new SV for us, then will need to upgrade it to an
585 HV (which sv_upgrade() can now do for us). */
587 mroisarev = MUTABLE_HV(HeVAL(he));
589 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
591 /* This hash only ever contains PL_sv_yes. Storing it
592 over itself is almost as cheap as calling hv_exists,
593 so on aggregate we expect to save time by not making
594 two calls to the common HV code for the case where
599 mroisarev, HEK_KEY(namehek), HEK_LEN(namehek),
604 if((SV *)isa != &PL_sv_undef)
606 isa, HEK_KEY(namehek), HEK_LEN(namehek),
607 HvMROMETA(revstash)->isa
613 /* Now iterate our MRO (parents), adding ourselves and everything from
614 our isarev to their isarev.
617 /* We're starting at the 2nd element, skipping ourselves here */
618 linear_mro = mro_get_linear_isa(stash);
619 svp = AvARRAY(linear_mro) + 1;
620 items = AvFILLp(linear_mro);
623 SV* const sv = *svp++;
626 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
628 /* That fetch should not fail. But if it had to create a new SV for
629 us, then will need to upgrade it to an HV (which sv_upgrade() can
632 mroisarev = MUTABLE_HV(HeVAL(he));
634 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
636 /* This hash only ever contains PL_sv_yes. Storing it over itself is
637 almost as cheap as calling hv_exists, so on aggregate we expect to
638 save time by not making two calls to the common HV code for the
639 case where it doesn't exist. */
641 (void)hv_store(mroisarev, stashname, stashname_len, &PL_sv_yes, 0);
644 /* Delete our name from our former parents’ isarevs. */
645 if(isa && HvARRAY(isa))
646 mro_clean_isarev(isa, stashname, stashname_len, meta->isa);
649 /* Deletes name from all the isarev entries listed in isa */
651 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
652 const STRLEN len, HV * const exceptions)
656 PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
658 /* Delete our name from our former parents’ isarevs. */
659 if(isa && HvARRAY(isa) && hv_iterinit(isa)) {
661 while((iter = hv_iternext(isa))) {
663 const char * const key = hv_iterkey(iter, &klen);
664 if(exceptions && hv_exists(exceptions, key, klen)) continue;
665 svp = hv_fetch(PL_isarev, key, klen, 0);
667 HV * const isarev = (HV *)*svp;
668 (void)hv_delete(isarev, name, len, G_DISCARD);
669 if(!HvARRAY(isarev) || !HvKEYS(isarev))
670 (void)hv_delete(PL_isarev, key, klen, G_DISCARD);
677 =for apidoc mro_package_moved
679 Call this function to signal to a stash that it has been assigned to
680 another spot in the stash hierarchy. C<stash> is the stash that has been
681 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
682 that is actually being assigned to. C<newname> and C<newname_len> are the
683 full name of the GV. If these last two arguments are omitted, they can be
684 inferred from C<gv>. C<gv> can be omitted if C<newname> is given.
686 This can also be called with a null first argument to
687 indicate that C<oldstash> has been deleted.
689 This function invalidates isa caches on the old stash, on all subpackages
690 nested inside it, and on the subclasses of all those, including
691 non-existent packages that have corresponding entries in C<stash>.
693 It also sets the effective names (C<HvENAME>) on all the stashes as
696 If the C<gv> is present and is not in the symbol table, then this function
697 simply returns. This checked will be skipped if C<newname_len> is set to 1
698 and C<newname> is null.
703 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
704 const GV *gv, const char *newname,
710 assert(stash || oldstash);
711 assert(gv || newname);
713 /* Determine the name of the location that stash was assigned to
714 * or from which oldstash was removed.
716 * We cannot reliably use the name in oldstash, because it may have
717 * been deleted from the location in the symbol table that its name
718 * suggests, as in this case:
720 * $globref = \*foo::bar::;
721 * Symbol::delete_package("foo");
722 * *$globref = \%baz::;
723 * *$globref = *frelp::;
724 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
726 * If newname is not null, then we trust that the caller gave us the
727 * right name. Otherwise, we get it from the gv. But if the gv is not
728 * in the symbol table, then we just return. We skip that check,
729 * however, if newname_len is 1 and newname is null.
732 SV * const namesv = sv_newmortal();
734 gv_fullname4(namesv, gv, NULL, 0);
736 && gv_fetchsv(namesv, GV_NOADD_NOINIT, SVt_PVGV) != gv ) return;
737 newname = SvPV_const(namesv, len);
738 newname_len = len - 2; /* skip trailing :: */
741 /* Get a list of all the affected classes. */
742 /* We cannot simply pass them all to mro_isa_changed_in to avoid
743 the list, as that function assumes that only one package has
744 changed. It does not work with:
746 @foo::ISA = qw( B B::B );
747 *B:: = delete $::{"A::"};
749 as neither B nor B::B can be updated before the other, since they
750 will reset caches on foo, which will see either B or B::B with the
751 wrong name. The names must be set on *all* affected stashes before
752 we do anything else. (And linearisations must be cleared, too.)
754 stashes = (HV *) sv_2mortal((SV *)newHV());
755 mro_gather_and_rename(
756 stashes, (HV *) sv_2mortal((SV *)newHV()),
757 stash, oldstash, newname, newname_len
760 /* Once the caches have been wiped on all the classes, call
761 mro_isa_changed_in on each. */
762 hv_iterinit(stashes);
763 while((iter = hv_iternext(stashes))) {
764 HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
766 /* We have to restore the original meta->isa (that
767 mro_gather_and_rename set aside for us) this way, in case
768 one class in this list is a superclass of a another class
769 that we have already encountered. In such a case, meta->isa
770 will have been overwritten without old entries being deleted
772 struct mro_meta * const meta = HvMROMETA(stash);
773 if(meta->isa != (HV *)HeVAL(iter)){
774 SvREFCNT_dec(meta->isa);
776 = HeVAL(iter) == &PL_sv_yes
779 HeVAL(iter) = NULL; /* We donated our reference count. */
781 mro_isa_changed_in(stash);
787 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
788 HV *stash, HV *oldstash, const char *name,
794 const bool stash_had_name = stash && HvENAME(stash);
799 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
801 /* We use the seen_stashes hash to keep track of which packages have
802 been encountered so far. This must be separate from the main list of
803 stashes, as we need to distinguish between stashes being assigned
804 and stashes being replaced/deleted. (A nested stash can be on both
805 sides of an assignment. We cannot simply skip iterating through a
806 stash on the right if we have seen it on the left, as it will not
807 get its ename assigned to it.)
809 To avoid allocating extra SVs, instead of a bitfield we can make
810 bizarre use of immortals:
812 &PL_sv_undef: seen on the left (oldstash)
813 &PL_sv_no : seen on the right (stash)
814 &PL_sv_yes : seen on both sides
819 /* Add to the big list. */
820 struct mro_meta * meta;
824 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
825 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
827 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
832 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
833 meta = HvMROMETA(oldstash);
836 stashes, (const char *)&oldstash, sizeof(HV *),
838 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
844 /* Update the effective name. */
845 if(HvENAME_get(oldstash)) {
846 const HEK * const enamehek = HvENAME_HEK(oldstash);
849 hv_delete(PL_stashcache, name, namlen, G_DISCARD);
850 hv_ename_delete(oldstash, name, namlen);
852 /* If the name deletion caused a name change, then we are not
853 * going to call mro_isa_changed_in with this name (and not at all
854 * if it has become anonymous) so we need to delete old isarev
855 * entries here, both those in the superclasses and this class’s
856 * own list of subclasses. We simply delete the latter from
857 * from PL_isarev, since we still need it. hv_delete mortifies it
858 * for us, so sv_2mortal is not necessary. */
859 if(HvENAME_HEK(oldstash) != enamehek) {
860 if(meta->isa && HvARRAY(meta->isa))
861 mro_clean_isarev(meta->isa, name, namlen, NULL);
862 isarev = (HV *)hv_delete(PL_isarev, name, namlen, 0);
868 hv_ename_add(stash, name, namlen);
870 /* Add it to the big list if it needs
871 * mro_isa_changed_in called on it. That happens if it was
872 * detached from the symbol table (so it had no HvENAME) before
873 * being assigned to the spot named by the ‘name’ variable, because
874 * its cached isa linerisation is now stale (the effective name
875 * having changed), and subclasses will then use that cache when
876 * mro_package_moved calls mro_isa_changed_in. (See
879 * If it did have a name, then its previous name is still
880 * used in isa caches, and there is no need for
881 * mro_package_moved to call mro_isa_changed_in.
887 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
888 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
890 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
894 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
897 struct mro_meta * const meta = HvMROMETA(stash);
900 stashes, (const char *)&stash, sizeof(HV *),
902 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
911 if(!stash && !oldstash)
912 /* Both stashes have been encountered already. */
915 /* Add all the subclasses to the big list. */
919 (svp = hv_fetch(PL_isarev, name, namlen, 0))
920 && (isarev = MUTABLE_HV(*svp))
925 while((iter = hv_iternext(isarev))) {
927 const char* const revkey = hv_iterkey(iter, &len);
928 HV* revstash = gv_stashpvn(revkey, len, 0);
929 struct mro_meta * meta;
931 if(!revstash) continue;
932 meta = HvMROMETA(revstash);
935 stashes, (const char *)&revstash, sizeof(HV *),
937 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
946 (!stash || !HvARRAY(stash)) && (!oldstash || !HvARRAY(oldstash))
949 /* This is partly based on code in hv_iternext_flags. We are not call-
950 ing that here, as we want to avoid resetting the hash iterator. */
952 /* Skip the entire loop if the hash is empty. */
953 if(oldstash && HvUSEDKEYS(oldstash)) {
954 xhv = (XPVHV*)SvANY(oldstash);
955 seen = (HV *) sv_2mortal((SV *)newHV());
957 /* Iterate through entries in the oldstash, adding them to the
958 list, meanwhile doing the equivalent of $seen{$key} = 1.
961 while (++riter <= (I32)xhv->xhv_max) {
962 entry = (HvARRAY(oldstash))[riter];
964 /* Iterate through the entries in this list */
965 for(; entry; entry = HeNEXT(entry)) {
969 /* If this entry is not a glob, ignore it.
971 if (!isGV(HeVAL(entry))) continue;
973 key = hv_iterkey(entry, &len);
974 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
975 HV * const oldsubstash = GvHV(HeVAL(entry));
976 SV ** const stashentry
977 = stash ? hv_fetch(stash, key, len, 0) : NULL;
980 /* Avoid main::main::main::... */
981 if(oldsubstash == oldstash) continue;
985 stashentry && *stashentry
986 && (substash = GvHV(*stashentry))
988 || (oldsubstash && HvENAME_get(oldsubstash))
991 /* Add :: and the key (minus the trailing ::)
994 = newSVpvn_flags(name, namlen, SVs_TEMP);
998 sv_catpvs(namesv, "::");
999 sv_catpvn(namesv, key, len-2);
1000 name = SvPV_const(namesv, namlen);
1001 mro_gather_and_rename(
1002 stashes, seen_stashes,
1003 substash, oldsubstash, name, namlen
1008 (void)hv_store(seen, key, len, &PL_sv_yes, 0);
1014 /* Skip the entire loop if the hash is empty. */
1015 if (stash && HvUSEDKEYS(stash)) {
1016 xhv = (XPVHV*)SvANY(stash);
1019 /* Iterate through the new stash, skipping $seen{$key} items,
1020 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1021 while (++riter <= (I32)xhv->xhv_max) {
1022 entry = (HvARRAY(stash))[riter];
1024 /* Iterate through the entries in this list */
1025 for(; entry; entry = HeNEXT(entry)) {
1029 /* If this entry is not a glob, ignore it.
1031 if (!isGV(HeVAL(entry))) continue;
1033 key = hv_iterkey(entry, &len);
1034 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
1037 /* If this entry was seen when we iterated through the
1038 oldstash, skip it. */
1039 if(seen && hv_exists(seen, key, len)) continue;
1041 /* We get here only if this stash has no corresponding
1042 entry in the stash being replaced. */
1044 substash = GvHV(HeVAL(entry));
1047 const char *subname;
1050 /* Avoid checking main::main::main::... */
1051 if(substash == stash) continue;
1053 /* Add :: and the key (minus the trailing ::)
1056 = newSVpvn_flags(name, namlen, SVs_TEMP);
1057 sv_catpvs(namesv, "::");
1058 sv_catpvn(namesv, key, len-2);
1059 subname = SvPV_const(namesv, subnamlen);
1060 mro_gather_and_rename(
1061 stashes, seen_stashes,
1062 substash, NULL, subname, subnamlen
1072 =for apidoc mro_method_changed_in
1074 Invalidates method caching on any child classes
1075 of the given stash, so that they might notice
1076 the changes in this one.
1078 Ideally, all instances of C<PL_sub_generation++> in
1079 perl source outside of C<mro.c> should be
1080 replaced by calls to this.
1082 Perl automatically handles most of the common
1083 ways a method might be redefined. However, there
1084 are a few ways you could change a method in a stash
1085 without the cache code noticing, in which case you
1086 need to call this method afterwards:
1088 1) Directly manipulating the stash HV entries from
1091 2) Assigning a reference to a readonly scalar
1092 constant into a stash entry in order to create
1093 a constant subroutine (like constant.pm
1096 This same method is available from pure perl
1097 via, C<mro::method_changed_in(classname)>.
1102 Perl_mro_method_changed_in(pTHX_ HV *stash)
1104 const char * const stashname = HvENAME_get(stash);
1105 const STRLEN stashname_len = HvENAMELEN_get(stash);
1107 SV ** const svp = hv_fetch(PL_isarev, stashname, stashname_len, 0);
1108 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1110 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1113 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1115 /* Inc the package generation, since a local method changed */
1116 HvMROMETA(stash)->pkg_gen++;
1118 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1119 invalidate all method caches globally */
1120 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1121 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1122 PL_sub_generation++;
1126 /* else, invalidate the method caches of all child classes,
1131 hv_iterinit(isarev);
1132 while((iter = hv_iternext(isarev))) {
1134 const char* const revkey = hv_iterkey(iter, &len);
1135 HV* const revstash = gv_stashpvn(revkey, len, 0);
1136 struct mro_meta* mrometa;
1138 if(!revstash) continue;
1139 mrometa = HvMROMETA(revstash);
1140 mrometa->cache_gen++;
1141 if(mrometa->mro_nextmethod)
1142 hv_clear(mrometa->mro_nextmethod);
1148 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1150 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1152 PERL_ARGS_ASSERT_MRO_SET_MRO;
1155 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1157 if(meta->mro_which != which) {
1158 if (meta->mro_linear_current && !meta->mro_linear_all) {
1159 /* If we were storing something directly, put it in the hash before
1161 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1162 MUTABLE_SV(meta->mro_linear_current));
1164 meta->mro_which = which;
1165 /* Scrub our cached pointer to the private data. */
1166 meta->mro_linear_current = NULL;
1167 /* Only affects local method cache, not
1168 even child classes */
1170 if(meta->mro_nextmethod)
1171 hv_clear(meta->mro_nextmethod);
1177 XS(XS_mro_method_changed_in);
1180 Perl_boot_core_mro(pTHX)
1183 static const char file[] = __FILE__;
1185 Perl_mro_register(aTHX_ &dfs_alg);
1187 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1190 XS(XS_mro_method_changed_in)
1198 croak_xs_usage(cv, "classname");
1202 class_stash = gv_stashsv(classname, 0);
1203 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1205 mro_method_changed_in(class_stash);
1212 * c-indentation-style: bsd
1214 * indent-tabs-mode: t
1217 * ex: set ts=8 sts=4 sw=4 noet: