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_u.xhvnameu_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.
684 This can also be called with a null first argument to
685 indicate that C<oldstash> has been deleted.
687 This function invalidates isa caches on the old stash, on all subpackages
688 nested inside it, and on the subclasses of all those, including
689 non-existent packages that have corresponding entries in C<stash>.
691 It also sets the effective names (C<HvENAME>) on all the stashes as
694 If the C<gv> is present and is not in the symbol table, then this function
695 simply returns. This checked will be skipped if C<flags & 1>.
700 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
701 const GV * const gv, U32 flags)
709 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
710 assert(stash || oldstash);
712 /* Determine the name(s) of the location that stash was assigned to
713 * or from which oldstash was removed.
715 * We cannot reliably use the name in oldstash, because it may have
716 * been deleted from the location in the symbol table that its name
717 * suggests, as in this case:
719 * $globref = \*foo::bar::;
720 * Symbol::delete_package("foo");
721 * *$globref = \%baz::;
722 * *$globref = *frelp::;
723 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
725 * So we get it from the gv. But, since the gv may no longer be in the
726 * symbol table, we check that first. The only reliable way to tell is
727 * to see whether its stash has an effective name and whether the gv
728 * resides in that stash under its name. That effective name may be
729 * different from what gv_fullname4 would use.
730 * If flags & 1, the caller has asked us to skip the check.
735 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
736 !(svp = hv_fetch(GvSTASH(gv), GvNAME(gv), GvNAMELEN(gv), 0)) ||
740 assert(SvOOK(GvSTASH(gv)));
741 assert(GvNAMELEN(gv) > 1);
742 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
743 assert(GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
744 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
747 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
750 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
751 if (name_count < 0) ++namep, name_count = -name_count - 1;
753 if (name_count == 1) {
754 if (HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)) {
755 namesv = newSVpvs_flags("", SVs_TEMP);
758 namesv = sv_2mortal(newSVhek(*namep));
759 sv_catpvs(namesv, "::");
761 sv_catpvn(namesv, GvNAME(gv), GvNAMELEN(gv) - 2);
762 /* skip trailing :: */
766 namesv = sv_2mortal((SV *)newAV());
767 while (name_count--) {
768 if(HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)){
769 aname = newSVpvs(""); namep++;
772 aname = newSVhek(*namep++);
773 sv_catpvs(aname, "::");
775 sv_catpvn(aname, GvNAME(gv), GvNAMELEN(gv) - 2);
776 /* skip trailing :: */
777 av_push((AV *)namesv, aname);
781 /* Get a list of all the affected classes. */
782 /* We cannot simply pass them all to mro_isa_changed_in to avoid
783 the list, as that function assumes that only one package has
784 changed. It does not work with:
786 @foo::ISA = qw( B B::B );
787 *B:: = delete $::{"A::"};
789 as neither B nor B::B can be updated before the other, since they
790 will reset caches on foo, which will see either B or B::B with the
791 wrong name. The names must be set on *all* affected stashes before
792 we do anything else. (And linearisations must be cleared, too.)
794 stashes = (HV *) sv_2mortal((SV *)newHV());
795 mro_gather_and_rename(
796 stashes, (HV *) sv_2mortal((SV *)newHV()),
797 stash, oldstash, namesv
800 /* Once the caches have been wiped on all the classes, call
801 mro_isa_changed_in on each. */
802 hv_iterinit(stashes);
803 while((iter = hv_iternext(stashes))) {
804 HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
806 /* We have to restore the original meta->isa (that
807 mro_gather_and_rename set aside for us) this way, in case
808 one class in this list is a superclass of a another class
809 that we have already encountered. In such a case, meta->isa
810 will have been overwritten without old entries being deleted
812 struct mro_meta * const meta = HvMROMETA(stash);
813 if(meta->isa != (HV *)HeVAL(iter)){
814 SvREFCNT_dec(meta->isa);
816 = HeVAL(iter) == &PL_sv_yes
819 HeVAL(iter) = NULL; /* We donated our reference count. */
821 mro_isa_changed_in(stash);
827 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
828 HV *stash, HV *oldstash, SV *namesv)
834 const bool stash_had_name = stash && HvENAME(stash);
835 bool fetched_isarev = FALSE;
840 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
842 /* We use the seen_stashes hash to keep track of which packages have
843 been encountered so far. This must be separate from the main list of
844 stashes, as we need to distinguish between stashes being assigned
845 and stashes being replaced/deleted. (A nested stash can be on both
846 sides of an assignment. We cannot simply skip iterating through a
847 stash on the right if we have seen it on the left, as it will not
848 get its ename assigned to it.)
850 To avoid allocating extra SVs, instead of a bitfield we can make
851 bizarre use of immortals:
853 &PL_sv_undef: seen on the left (oldstash)
854 &PL_sv_no : seen on the right (stash)
855 &PL_sv_yes : seen on both sides
860 /* Add to the big list. */
861 struct mro_meta * meta;
865 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
866 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
868 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
873 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
874 meta = HvMROMETA(oldstash);
877 stashes, (const char *)&oldstash, sizeof(HV *),
879 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
885 /* Update the effective name. */
886 if(HvENAME_get(oldstash)) {
887 const HEK * const enamehek = HvENAME_HEK(oldstash);
888 if(SvTYPE(namesv) == SVt_PVAV) {
889 items = AvFILLp((AV *)namesv) + 1;
890 svp = AvARRAY((AV *)namesv);
898 const char *name = SvPVx_const(*svp++, len);
900 (void)hv_delete(PL_stashcache, name, len, G_DISCARD);
901 hv_ename_delete(oldstash, name, len, 0);
903 if (!fetched_isarev) {
904 /* If the name deletion caused a name change, then we
905 * are not going to call mro_isa_changed_in with this
906 * name (and not at all if it has become anonymous) so
907 * we need to delete old isarev entries here, both
908 * those in the superclasses and this class’s own list
909 * of subclasses. We simply delete the latter from
910 * PL_isarev, since we still need it. hv_delete morti-
911 * fies it for us, so sv_2mortal is not necessary. */
912 if(HvENAME_HEK(oldstash) != enamehek) {
913 if(meta->isa && HvARRAY(meta->isa))
914 mro_clean_isarev(meta->isa, name, len, NULL);
915 isarev = (HV *)hv_delete(PL_isarev, name, len, 0);
924 if(SvTYPE(namesv) == SVt_PVAV) {
925 items = AvFILLp((AV *)namesv) + 1;
926 svp = AvARRAY((AV *)namesv);
934 const char *name = SvPVx_const(*svp++, len);
935 hv_ename_add(stash, name, len, 0);
938 /* Add it to the big list if it needs
939 * mro_isa_changed_in called on it. That happens if it was
940 * detached from the symbol table (so it had no HvENAME) before
941 * being assigned to the spot named by the ‘name’ variable, because
942 * its cached isa linearisation is now stale (the effective name
943 * having changed), and subclasses will then use that cache when
944 * mro_package_moved calls mro_isa_changed_in. (See
947 * If it did have a name, then its previous name is still
948 * used in isa caches, and there is no need for
949 * mro_package_moved to call mro_isa_changed_in.
955 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
956 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
958 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
962 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
965 struct mro_meta * const meta = HvMROMETA(stash);
968 stashes, (const char *)&stash, sizeof(HV *),
970 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
979 if(!stash && !oldstash)
980 /* Both stashes have been encountered already. */
983 /* Add all the subclasses to the big list. */
984 if(!fetched_isarev) {
985 /* If oldstash is not null, then we can use its HvENAME to look up
986 the isarev hash, since all its subclasses will be listed there.
987 It will always have an HvENAME. It the HvENAME was removed
988 above, then fetch_isarev will be true, and this code will not be
991 If oldstash is null, then this is an empty spot with no stash in
992 it, so subclasses could be listed in isarev hashes belonging to
993 any of the names, so we have to check all of them.
995 assert(!oldstash || HvENAME(oldstash));
997 /* Extra variable to avoid a compiler warning */
998 char * const hvename = HvENAME(oldstash);
999 fetched_isarev = TRUE;
1000 svp = hv_fetch(PL_isarev, hvename, HvENAMELEN_get(oldstash), 0);
1001 if (svp) isarev = MUTABLE_HV(*svp);
1003 else if(SvTYPE(namesv) == SVt_PVAV) {
1004 items = AvFILLp((AV *)namesv) + 1;
1005 svp = AvARRAY((AV *)namesv);
1013 isarev || !fetched_isarev
1015 while (fetched_isarev || items--) {
1018 if (!fetched_isarev) {
1019 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1020 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1023 hv_iterinit(isarev);
1024 while((iter = hv_iternext(isarev))) {
1026 const char* const revkey = hv_iterkey(iter, &len);
1027 HV* revstash = gv_stashpvn(revkey, len, 0);
1028 struct mro_meta * meta;
1030 if(!revstash) continue;
1031 meta = HvMROMETA(revstash);
1034 stashes, (const char *)&revstash, sizeof(HV *),
1036 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1043 if (fetched_isarev) break;
1047 /* This is partly based on code in hv_iternext_flags. We are not call-
1048 ing that here, as we want to avoid resetting the hash iterator. */
1050 /* Skip the entire loop if the hash is empty. */
1051 if(oldstash && HvUSEDKEYS(oldstash)) {
1052 xhv = (XPVHV*)SvANY(oldstash);
1053 seen = (HV *) sv_2mortal((SV *)newHV());
1055 /* Iterate through entries in the oldstash, adding them to the
1056 list, meanwhile doing the equivalent of $seen{$key} = 1.
1059 while (++riter <= (I32)xhv->xhv_max) {
1060 entry = (HvARRAY(oldstash))[riter];
1062 /* Iterate through the entries in this list */
1063 for(; entry; entry = HeNEXT(entry)) {
1067 /* If this entry is not a glob, ignore it.
1069 if (!isGV(HeVAL(entry))) continue;
1071 key = hv_iterkey(entry, &len);
1072 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
1073 HV * const oldsubstash = GvHV(HeVAL(entry));
1074 SV ** const stashentry
1075 = stash ? hv_fetch(stash, key, len, 0) : NULL;
1076 HV *substash = NULL;
1078 /* Avoid main::main::main::... */
1079 if(oldsubstash == oldstash) continue;
1083 stashentry && *stashentry
1084 && (substash = GvHV(*stashentry))
1086 || (oldsubstash && HvENAME_get(oldsubstash))
1089 /* Add :: and the key (minus the trailing ::)
1092 if(SvTYPE(namesv) == SVt_PVAV) {
1094 items = AvFILLp((AV *)namesv) + 1;
1095 svp = AvARRAY((AV *)namesv);
1096 subname = sv_2mortal((SV *)newAV());
1098 aname = newSVsv(*svp++);
1099 sv_catpvs(aname, "::");
1100 sv_catpvn(aname, key, len-2);
1101 av_push((AV *)subname, aname);
1105 subname = sv_2mortal(newSVsv(namesv));
1106 sv_catpvs(subname, "::");
1107 sv_catpvn(subname, key, len-2);
1109 mro_gather_and_rename(
1110 stashes, seen_stashes,
1111 substash, oldsubstash, subname
1115 (void)hv_store(seen, key, len, &PL_sv_yes, 0);
1121 /* Skip the entire loop if the hash is empty. */
1122 if (stash && HvUSEDKEYS(stash)) {
1123 xhv = (XPVHV*)SvANY(stash);
1126 /* Iterate through the new stash, skipping $seen{$key} items,
1127 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1128 while (++riter <= (I32)xhv->xhv_max) {
1129 entry = (HvARRAY(stash))[riter];
1131 /* Iterate through the entries in this list */
1132 for(; entry; entry = HeNEXT(entry)) {
1136 /* If this entry is not a glob, ignore it.
1138 if (!isGV(HeVAL(entry))) continue;
1140 key = hv_iterkey(entry, &len);
1141 if(len > 1 && key[len-2] == ':' && key[len-1] == ':') {
1144 /* If this entry was seen when we iterated through the
1145 oldstash, skip it. */
1146 if(seen && hv_exists(seen, key, len)) continue;
1148 /* We get here only if this stash has no corresponding
1149 entry in the stash being replaced. */
1151 substash = GvHV(HeVAL(entry));
1155 /* Avoid checking main::main::main::... */
1156 if(substash == stash) continue;
1158 /* Add :: and the key (minus the trailing ::)
1160 if(SvTYPE(namesv) == SVt_PVAV) {
1162 items = AvFILLp((AV *)namesv) + 1;
1163 svp = AvARRAY((AV *)namesv);
1164 subname = sv_2mortal((SV *)newAV());
1166 aname = newSVsv(*svp++);
1167 sv_catpvs(aname, "::");
1168 sv_catpvn(aname, key, len-2);
1169 av_push((AV *)subname, aname);
1173 subname = sv_2mortal(newSVsv(namesv));
1174 sv_catpvs(subname, "::");
1175 sv_catpvn(subname, key, len-2);
1177 mro_gather_and_rename(
1178 stashes, seen_stashes,
1179 substash, NULL, subname
1189 =for apidoc mro_method_changed_in
1191 Invalidates method caching on any child classes
1192 of the given stash, so that they might notice
1193 the changes in this one.
1195 Ideally, all instances of C<PL_sub_generation++> in
1196 perl source outside of C<mro.c> should be
1197 replaced by calls to this.
1199 Perl automatically handles most of the common
1200 ways a method might be redefined. However, there
1201 are a few ways you could change a method in a stash
1202 without the cache code noticing, in which case you
1203 need to call this method afterwards:
1205 1) Directly manipulating the stash HV entries from
1208 2) Assigning a reference to a readonly scalar
1209 constant into a stash entry in order to create
1210 a constant subroutine (like constant.pm
1213 This same method is available from pure perl
1214 via, C<mro::method_changed_in(classname)>.
1219 Perl_mro_method_changed_in(pTHX_ HV *stash)
1221 const char * const stashname = HvENAME_get(stash);
1222 const STRLEN stashname_len = HvENAMELEN_get(stash);
1224 SV ** const svp = hv_fetch(PL_isarev, stashname, stashname_len, 0);
1225 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1227 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1230 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1232 /* Inc the package generation, since a local method changed */
1233 HvMROMETA(stash)->pkg_gen++;
1235 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1236 invalidate all method caches globally */
1237 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1238 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1239 PL_sub_generation++;
1243 /* else, invalidate the method caches of all child classes,
1248 hv_iterinit(isarev);
1249 while((iter = hv_iternext(isarev))) {
1251 const char* const revkey = hv_iterkey(iter, &len);
1252 HV* const revstash = gv_stashpvn(revkey, len, 0);
1253 struct mro_meta* mrometa;
1255 if(!revstash) continue;
1256 mrometa = HvMROMETA(revstash);
1257 mrometa->cache_gen++;
1258 if(mrometa->mro_nextmethod)
1259 hv_clear(mrometa->mro_nextmethod);
1265 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1267 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1269 PERL_ARGS_ASSERT_MRO_SET_MRO;
1272 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1274 if(meta->mro_which != which) {
1275 if (meta->mro_linear_current && !meta->mro_linear_all) {
1276 /* If we were storing something directly, put it in the hash before
1278 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1279 MUTABLE_SV(meta->mro_linear_current));
1281 meta->mro_which = which;
1282 /* Scrub our cached pointer to the private data. */
1283 meta->mro_linear_current = NULL;
1284 /* Only affects local method cache, not
1285 even child classes */
1287 if(meta->mro_nextmethod)
1288 hv_clear(meta->mro_nextmethod);
1294 XS(XS_mro_method_changed_in);
1297 Perl_boot_core_mro(pTHX)
1300 static const char file[] = __FILE__;
1302 Perl_mro_register(aTHX_ &dfs_alg);
1304 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1307 XS(XS_mro_method_changed_in)
1315 croak_xs_usage(cv, "classname");
1319 class_stash = gv_stashsv(classname, 0);
1320 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1322 mro_method_changed_in(class_stash);
1329 * c-indentation-style: bsd
1331 * indent-tabs-mode: t
1334 * ex: set ts=8 sts=4 sw=4 noet: