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
699 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
700 const GV *gv, const char *newname,
706 assert(stash || oldstash);
707 assert(gv || newname);
709 /* Determine the name of the location that stash was assigned to
710 * or from which oldstash was removed.
712 * We cannot reliably use the name in oldstash, because it may have
713 * been deleted from the location in the symbol table that its name
714 * suggests, as in this case:
716 * $globref = \*foo::bar::;
717 * Symbol::delete_package("foo");
718 * *$globref = \%baz::;
719 * *$globref = *frelp::;
720 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
722 * If newname is not null, then we trust that the caller gave us the
723 * right name. Otherwise, we get it from the gv. But if the gv is not
724 * in the symbol table, then we just return.
727 SV * const namesv = sv_newmortal();
729 gv_fullname4(namesv, gv, NULL, 0);
730 if(gv_fetchsv(namesv, GV_NOADD_NOINIT, SVt_PVGV) != gv) return;
731 newname = SvPV_const(namesv, len);
732 newname_len = len - 2; /* skip trailing :: */
734 if(newname_len < 0) newname_len = -newname_len;
736 /* Get a list of all the affected classes. */
737 /* We cannot simply pass them all to mro_isa_changed_in to avoid
738 the list, as that function assumes that only one package has
739 changed. It does not work with:
741 @foo::ISA = qw( B B::B );
742 *B:: = delete $::{"A::"};
744 as neither B nor B::B can be updated before the other, since they
745 will reset caches on foo, which will see either B or B::B with the
746 wrong name. The names must be set on *all* affected stashes before
747 we do anything else. (And linearisations must be cleared, too.)
749 stashes = (HV *) sv_2mortal((SV *)newHV());
750 mro_gather_and_rename(
751 stashes, (HV *) sv_2mortal((SV *)newHV()),
752 stash, oldstash, newname, newname_len
755 /* Once the caches have been wiped on all the classes, call
756 mro_isa_changed_in on each. */
757 hv_iterinit(stashes);
758 while((iter = hv_iternext(stashes))) {
759 HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
761 /* We have to restore the original meta->isa (that
762 mro_gather_and_rename set aside for us) this way, in case
763 one class in this list is a superclass of a another class
764 that we have already encountered. In such a case, meta->isa
765 will have been overwritten without old entries being deleted
767 struct mro_meta * const meta = HvMROMETA(stash);
768 if(meta->isa != (HV *)HeVAL(iter)){
769 SvREFCNT_dec(meta->isa);
771 = HeVAL(iter) == &PL_sv_yes
774 HeVAL(iter) = NULL; /* We donated our reference count. */
776 mro_isa_changed_in(stash);
782 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
783 HV *stash, HV *oldstash, const char *name,
789 const bool stash_had_name = stash && HvENAME(stash);
794 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
796 /* We use the seen_stashes hash to keep track of which packages have
797 been encountered so far. This must be separate from the main list of
798 stashes, as we need to distinguish between stashes being assigned
799 and stashes being replaced/deleted. (A nested stash can be on both
800 sides of an assignment. We cannot simply skip iterating through a
801 stash on the right if we have seen it on the left, as it will not
802 get its ename assigned to it.)
804 To avoid allocating extra SVs, instead of a bitfield we can make
805 bizarre use of immortals:
807 &PL_sv_undef: seen on the left (oldstash)
808 &PL_sv_no : seen on the right (stash)
809 &PL_sv_yes : seen on both sides
814 /* Add to the big list. */
815 struct mro_meta * meta;
819 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
820 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
822 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
827 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
828 meta = HvMROMETA(oldstash);
831 stashes, (const char *)&oldstash, sizeof(HV *),
833 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
839 /* Update the effective name. */
840 if(HvENAME_get(oldstash)) {
841 const HEK * const enamehek = HvENAME_HEK(oldstash);
844 hv_delete(PL_stashcache, name, namlen, G_DISCARD);
845 hv_ename_delete(oldstash, name, namlen);
847 /* If the name deletion caused a name change, then we are not
848 * going to call mro_isa_changed_in with this name (and not at all
849 * if it has become anonymous) so we need to delete old isarev
850 * entries here, both those in the superclasses and this class’s
851 * own list of subclasses. We simply delete the latter from
852 * from PL_isarev, since we still need it. hv_delete mortifies it
853 * for us, so sv_2mortal is not necessary. */
854 if(HvENAME_HEK(oldstash) != enamehek) {
855 if(meta->isa && HvARRAY(meta->isa))
856 mro_clean_isarev(meta->isa, name, namlen, NULL);
857 isarev = (HV *)hv_delete(PL_isarev, name, namlen, 0);
863 hv_ename_add(stash, name, namlen);
865 /* Add it to the big list if it needs
866 * mro_isa_changed_in called on it. That happens if it was
867 * detached from the symbol table (so it had no HvENAME) before
868 * being assigned to the spot named by the ‘name’ variable, because
869 * its cached isa linerisation is now stale (the effective name
870 * having changed), and subclasses will then use that cache when
871 * mro_package_moved calls mro_isa_changed_in. (See
874 * If it did have a name, then its previous name is still
875 * used in isa caches, and there is no need for
876 * mro_package_moved to call mro_isa_changed_in.
882 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
883 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
885 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
889 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
892 struct mro_meta * const meta = HvMROMETA(stash);
895 stashes, (const char *)&stash, sizeof(HV *),
897 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
906 if(!stash && !oldstash)
907 /* Both stashes have been encountered already. */
910 /* Add all the subclasses to the big list. */
914 (svp = hv_fetch(PL_isarev, name, namlen, 0))
915 && (isarev = MUTABLE_HV(*svp))
920 while((iter = hv_iternext(isarev))) {
922 const char* const revkey = hv_iterkey(iter, &len);
923 HV* revstash = gv_stashpvn(revkey, len, 0);
924 struct mro_meta * meta;
926 if(!revstash) continue;
927 meta = HvMROMETA(revstash);
930 stashes, (const char *)&revstash, sizeof(HV *),
932 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
941 (!stash || !HvARRAY(stash)) && (!oldstash || !HvARRAY(oldstash))
944 /* This is partly based on code in hv_iternext_flags. We are not call-
945 ing that here, as we want to avoid resetting the hash iterator. */
947 /* Skip the entire loop if the hash is empty. */
948 if(oldstash && HvUSEDKEYS(oldstash)) {
949 xhv = (XPVHV*)SvANY(oldstash);
950 seen = (HV *) sv_2mortal((SV *)newHV());
952 /* Iterate through entries in the oldstash, adding them to the
953 list, meanwhile doing the equivalent of $seen{$key} = 1.
956 while (++riter <= (I32)xhv->xhv_max) {
957 entry = (HvARRAY(oldstash))[riter];
959 /* Iterate through the entries in this list */
960 for(; entry; entry = HeNEXT(entry)) {
964 /* If this entry is not a glob, ignore it.
966 if (!isGV(HeVAL(entry))) continue;
968 key = hv_iterkey(entry, &len);
969 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
970 HV * const oldsubstash = GvHV(HeVAL(entry));
971 SV ** const stashentry
972 = stash ? hv_fetch(stash, key, len, 0) : NULL;
975 /* Avoid main::main::main::... */
976 if(oldsubstash == oldstash) continue;
980 stashentry && *stashentry
981 && (substash = GvHV(*stashentry))
983 || (oldsubstash && HvENAME_get(oldsubstash))
986 /* Add :: and the key (minus the trailing ::)
989 = newSVpvn_flags(name, namlen, SVs_TEMP);
993 sv_catpvs(namesv, "::");
994 sv_catpvn(namesv, key, len-2);
995 name = SvPV_const(namesv, namlen);
996 mro_gather_and_rename(
997 stashes, seen_stashes,
998 substash, oldsubstash, name, namlen
1003 (void)hv_store(seen, key, len, &PL_sv_yes, 0);
1009 /* Skip the entire loop if the hash is empty. */
1010 if (stash && HvUSEDKEYS(stash)) {
1011 xhv = (XPVHV*)SvANY(stash);
1014 /* Iterate through the new stash, skipping $seen{$key} items,
1015 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1016 while (++riter <= (I32)xhv->xhv_max) {
1017 entry = (HvARRAY(stash))[riter];
1019 /* Iterate through the entries in this list */
1020 for(; entry; entry = HeNEXT(entry)) {
1024 /* If this entry is not a glob, ignore it.
1026 if (!isGV(HeVAL(entry))) continue;
1028 key = hv_iterkey(entry, &len);
1029 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
1032 /* If this entry was seen when we iterated through the
1033 oldstash, skip it. */
1034 if(seen && hv_exists(seen, key, len)) continue;
1036 /* We get here only if this stash has no corresponding
1037 entry in the stash being replaced. */
1039 substash = GvHV(HeVAL(entry));
1042 const char *subname;
1045 /* Avoid checking main::main::main::... */
1046 if(substash == stash) continue;
1048 /* Add :: and the key (minus the trailing ::)
1051 = newSVpvn_flags(name, namlen, SVs_TEMP);
1052 sv_catpvs(namesv, "::");
1053 sv_catpvn(namesv, key, len-2);
1054 subname = SvPV_const(namesv, subnamlen);
1055 mro_gather_and_rename(
1056 stashes, seen_stashes,
1057 substash, NULL, subname, subnamlen
1067 =for apidoc mro_method_changed_in
1069 Invalidates method caching on any child classes
1070 of the given stash, so that they might notice
1071 the changes in this one.
1073 Ideally, all instances of C<PL_sub_generation++> in
1074 perl source outside of C<mro.c> should be
1075 replaced by calls to this.
1077 Perl automatically handles most of the common
1078 ways a method might be redefined. However, there
1079 are a few ways you could change a method in a stash
1080 without the cache code noticing, in which case you
1081 need to call this method afterwards:
1083 1) Directly manipulating the stash HV entries from
1086 2) Assigning a reference to a readonly scalar
1087 constant into a stash entry in order to create
1088 a constant subroutine (like constant.pm
1091 This same method is available from pure perl
1092 via, C<mro::method_changed_in(classname)>.
1097 Perl_mro_method_changed_in(pTHX_ HV *stash)
1099 const char * const stashname = HvENAME_get(stash);
1100 const STRLEN stashname_len = HvENAMELEN_get(stash);
1102 SV ** const svp = hv_fetch(PL_isarev, stashname, stashname_len, 0);
1103 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1105 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1108 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1110 /* Inc the package generation, since a local method changed */
1111 HvMROMETA(stash)->pkg_gen++;
1113 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1114 invalidate all method caches globally */
1115 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1116 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1117 PL_sub_generation++;
1121 /* else, invalidate the method caches of all child classes,
1126 hv_iterinit(isarev);
1127 while((iter = hv_iternext(isarev))) {
1129 const char* const revkey = hv_iterkey(iter, &len);
1130 HV* const revstash = gv_stashpvn(revkey, len, 0);
1131 struct mro_meta* mrometa;
1133 if(!revstash) continue;
1134 mrometa = HvMROMETA(revstash);
1135 mrometa->cache_gen++;
1136 if(mrometa->mro_nextmethod)
1137 hv_clear(mrometa->mro_nextmethod);
1143 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1145 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1147 PERL_ARGS_ASSERT_MRO_SET_MRO;
1150 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1152 if(meta->mro_which != which) {
1153 if (meta->mro_linear_current && !meta->mro_linear_all) {
1154 /* If we were storing something directly, put it in the hash before
1156 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1157 MUTABLE_SV(meta->mro_linear_current));
1159 meta->mro_which = which;
1160 /* Scrub our cached pointer to the private data. */
1161 meta->mro_linear_current = NULL;
1162 /* Only affects local method cache, not
1163 even child classes */
1165 if(meta->mro_nextmethod)
1166 hv_clear(meta->mro_nextmethod);
1172 XS(XS_mro_method_changed_in);
1175 Perl_boot_core_mro(pTHX)
1178 static const char file[] = __FILE__;
1180 Perl_mro_register(aTHX_ &dfs_alg);
1182 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1185 XS(XS_mro_method_changed_in)
1193 croak_xs_usage(cv, "classname");
1197 class_stash = gv_stashsv(classname, 0);
1198 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1200 mro_method_changed_in(class_stash);
1207 * c-indentation-style: bsd
1209 * indent-tabs-mode: t
1212 * ex: set ts=8 sts=4 sw=4 noet: