3 * Copyright (c) 2007 Brandon L Black
4 * Copyright (c) 2007, 2008, 2009, 2010, 2011 Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
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"]
20 These functions are related to the method resolution order of perl classes
29 static const struct mro_alg dfs_alg =
30 {S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};
33 Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
34 const struct mro_alg *const which)
37 PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;
39 data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
40 which->name, which->length, which->kflags,
41 HV_FETCH_JUST_SV, NULL, which->hash);
45 /* If we've been asked to look up the private data for the current MRO, then
47 if (smeta->mro_which == which)
48 smeta->mro_linear_current = *data;
54 Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
55 const struct mro_alg *const which, SV *const data)
57 PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;
59 if (!smeta->mro_linear_all) {
60 if (smeta->mro_which == which) {
61 /* If all we need to store is the current MRO's data, then don't use
62 memory on a hash with 1 element - store it direct, and signal
63 this by leaving the would-be-hash NULL. */
64 smeta->mro_linear_current = data;
67 HV *const hv = newHV();
68 /* Start with 2 buckets. It's unlikely we'll need more. */
70 smeta->mro_linear_all = hv;
72 if (smeta->mro_linear_current) {
73 /* If we were storing something directly, put it in the hash
75 Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which,
76 smeta->mro_linear_current);
81 /* We get here if we're storing more than one linearisation for this stash,
82 or the linearisation we are storing is not that if its current MRO. */
84 if (smeta->mro_which == which) {
85 /* If we've been asked to store the private data for the current MRO,
87 smeta->mro_linear_current = data;
90 if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
91 which->name, which->length, which->kflags,
92 HV_FETCH_ISSTORE, data, which->hash)) {
93 Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
94 "for '%.*s' %d", (int) which->length, which->name,
101 const struct mro_alg *
102 Perl_mro_get_from_name(pTHX_ SV *name) {
105 PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;
107 data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
108 HV_FETCH_JUST_SV, NULL, 0);
111 assert(SvTYPE(*data) == SVt_IV);
112 assert(SvIOK(*data));
113 return INT2PTR(const struct mro_alg *, SvUVX(*data));
117 =for apidoc mro_register
118 Registers a custom mro plugin. See L<perlmroapi> for details.
124 Perl_mro_register(pTHX_ const struct mro_alg *mro) {
125 SV *wrapper = newSVuv(PTR2UV(mro));
127 PERL_ARGS_ASSERT_MRO_REGISTER;
130 if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
131 mro->name, mro->length, mro->kflags,
132 HV_FETCH_ISSTORE, wrapper, mro->hash)) {
133 SvREFCNT_dec_NN(wrapper);
134 Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
135 "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
140 Perl_mro_meta_init(pTHX_ HV* stash)
142 struct mro_meta* newmeta;
144 PERL_ARGS_ASSERT_MRO_META_INIT;
146 assert(HvAUX(stash));
147 assert(!(HvAUX(stash)->xhv_mro_meta));
148 Newxz(newmeta, 1, struct mro_meta);
149 HvAUX(stash)->xhv_mro_meta = newmeta;
150 newmeta->cache_gen = 1;
151 newmeta->pkg_gen = 1;
152 newmeta->mro_which = &dfs_alg;
157 #if defined(USE_ITHREADS)
159 /* for sv_dup on new threads */
161 Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
163 struct mro_meta* newmeta;
165 PERL_ARGS_ASSERT_MRO_META_DUP;
167 Newx(newmeta, 1, struct mro_meta);
168 Copy(smeta, newmeta, 1, struct mro_meta);
170 if (newmeta->mro_linear_all) {
171 newmeta->mro_linear_all
172 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
173 /* This is just acting as a shortcut pointer, and will be automatically
174 updated on the first get. */
175 newmeta->mro_linear_current = NULL;
176 } else if (newmeta->mro_linear_current) {
177 /* Only the current MRO is stored, so this owns the data. */
178 newmeta->mro_linear_current
179 = sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
182 if (newmeta->mro_nextmethod)
183 newmeta->mro_nextmethod
184 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
187 = MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
189 newmeta->super = NULL;
194 #endif /* USE_ITHREADS */
197 =for apidoc mro_get_linear_isa_dfs
199 Returns the Depth-First Search linearization of @ISA
200 the given stash. The return value is a read-only AV*.
201 C<level> should be 0 (it is used internally in this
202 function's recursion).
204 You are responsible for C<SvREFCNT_inc()> on the
205 return value if you plan to store it anywhere
206 semi-permanently (otherwise it might be deleted
207 out from under you the next time the cache is
213 S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
220 struct mro_meta* meta;
224 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
225 assert(HvAUX(stash));
228 = HvAUX(stash)->xhv_name_u.xhvnameu_name && HvENAME_HEK_NN(stash)
229 ? HvENAME_HEK_NN(stash)
233 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
237 "Recursive inheritance detected in package '%"HEKf"'",
240 meta = HvMROMETA(stash);
242 /* return cache if valid */
243 if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
247 /* not in cache, make a new one */
249 retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
250 /* We use this later in this function, but don't need a reference to it
251 beyond the end of this function, so reference count is fine. */
252 our_name = newSVhek(stashhek);
253 av_push(retval, our_name); /* add ourselves at the top */
256 gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
257 av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
259 /* "stored" is used to keep track of all of the classnames we have added to
260 the MRO so far, so we can do a quick exists check and avoid adding
261 duplicate classnames to the MRO as we go.
262 It's then retained to be re-used as a fast lookup for ->isa(), by adding
263 our own name and "UNIVERSAL" to it. */
265 if(av && AvFILLp(av) >= 0) {
267 SV **svp = AvARRAY(av);
268 I32 items = AvFILLp(av) + 1;
272 SV* const sv = *svp ? *svp : &PL_sv_undef;
273 HV* const basestash = gv_stashsv(sv, 0);
279 /* if no stash exists for this @ISA member,
280 simply add it to the MRO and move on */
285 /* otherwise, recurse into ourselves for the MRO
286 of this @ISA member, and append their MRO to ours.
287 The recursive call could throw an exception, which
288 has memory management implications here, hence the use of
290 const AV *const subrv
291 = mro_get_linear_isa_dfs(basestash, level + 1);
293 subrv_p = AvARRAY(subrv);
294 subrv_items = AvFILLp(subrv) + 1;
297 while(subrv_items--) {
298 SV *const subsv = *subrv_p++;
299 /* LVALUE fetch will create a new undefined SV if necessary
301 HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
303 if(HeVAL(he) != &PL_sv_undef) {
304 /* It was newly created. Steal it for our new SV, and
305 replace it in the hash with the "real" thing. */
306 SV *const val = HeVAL(he);
307 HEK *const key = HeKEY_hek(he);
309 HeVAL(he) = &PL_sv_undef;
310 /* Save copying by making a shared hash key scalar. We
311 inline this here rather than calling
312 Perl_newSVpvn_share because we already have the
313 scalar, and we already have the hash key. */
314 assert(SvTYPE(val) == SVt_NULL);
315 sv_upgrade(val, SVt_PV);
316 SvPV_set(val, HEK_KEY(share_hek_hek(key)));
317 SvCUR_set(val, HEK_LEN(key));
323 av_push(retval, val);
327 /* We are the first (or only) parent. We can short cut the
328 complexity above, because our @ISA is simply us prepended
329 to our parent's @ISA, and our ->isa cache is simply our
330 parent's, with our name added. */
331 /* newSVsv() is slow. This code is only faster if we can avoid
332 it by ensuring that SVs in the arrays are shared hash key
333 scalar SVs, because we can "copy" them very efficiently.
334 Although to be fair, we can't *ensure* this, as a reference
335 to the internal array is returned by mro::get_linear_isa(),
336 so we'll have to be defensive just in case someone faffed
340 stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
341 av_extend(retval, subrv_items);
342 AvFILLp(retval) = subrv_items;
343 svp = AvARRAY(retval);
344 while(subrv_items--) {
345 SV *const val = *subrv_p++;
346 *++svp = SvIsCOW_shared_hash(val)
347 ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
351 /* They have no stash. So create ourselves an ->isa cache
352 as if we'd copied it from what theirs should be. */
353 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
354 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
356 newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
362 /* We have no parents. */
363 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
364 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
367 (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
369 SvREFCNT_inc_simple_void_NN(stored);
371 SvREADONLY_on(stored);
375 /* now that we're past the exception dangers, grab our own reference to
376 the AV we're about to use for the result. The reference owned by the
377 mortals' stack will be released soon, so everything will balance. */
378 SvREFCNT_inc_simple_void_NN(retval);
381 /* we don't want anyone modifying the cache entry but us,
382 and we do so by replacing it completely */
383 SvREADONLY_on(retval);
385 return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
386 MUTABLE_SV(retval)));
390 =for apidoc mro_get_linear_isa
392 Returns the mro linearisation for the given stash. By default, this
393 will be whatever C<mro_get_linear_isa_dfs> returns unless some
394 other MRO is in effect for the stash. The return value is a
397 You are responsible for C<SvREFCNT_inc()> on the
398 return value if you plan to store it anywhere
399 semi-permanently (otherwise it might be deleted
400 out from under you the next time the cache is
406 Perl_mro_get_linear_isa(pTHX_ HV *stash)
408 struct mro_meta* meta;
411 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
413 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
415 meta = HvMROMETA(stash);
416 if (!meta->mro_which)
417 Perl_croak(aTHX_ "panic: invalid MRO!");
418 isa = meta->mro_which->resolve(aTHX_ stash, 0);
420 if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
422 (HvENAME(stash)||HvNAME(stash))
423 ? newSVhek(HvENAME_HEK(stash)
428 if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
430 AV * const old = isa;
432 SV **ovp = AvARRAY(old);
433 SV * const * const oend = ovp + AvFILLp(old) + 1;
434 isa = (AV *)sv_2mortal((SV *)newAV());
435 av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
436 *AvARRAY(isa) = namesv;
437 svp = AvARRAY(isa)+1;
438 while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
440 else SvREFCNT_dec(namesv);
444 HV *const isa_hash = newHV();
445 /* Linearisation didn't build it for us, so do it here. */
446 SV *const *svp = AvARRAY(isa);
447 SV *const *const svp_end = svp + AvFILLp(isa) + 1;
448 const HEK *canon_name = HvENAME_HEK(stash);
449 if (!canon_name) canon_name = HvNAME_HEK(stash);
451 while (svp < svp_end) {
452 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
455 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
456 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
457 HV_FETCH_ISSTORE, &PL_sv_undef,
458 HEK_HASH(canon_name));
459 (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
461 SvREADONLY_on(isa_hash);
463 meta->isa = isa_hash;
470 =for apidoc mro_isa_changed_in
472 Takes the necessary steps (cache invalidations, mostly)
473 when the @ISA of the given package has changed. Invoked
474 by the C<setisa> magic, should not need to invoke directly.
479 /* Macro to avoid repeating the code five times. */
480 #define CLEAR_LINEAR(mEta) \
481 if (mEta->mro_linear_all) { \
482 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
483 mEta->mro_linear_all = NULL; \
484 /* This is just acting as a shortcut pointer. */ \
485 mEta->mro_linear_current = NULL; \
486 } else if (mEta->mro_linear_current) { \
487 /* Only the current MRO is stored, so this owns the data. */ \
488 SvREFCNT_dec(mEta->mro_linear_current); \
489 mEta->mro_linear_current = NULL; \
493 Perl_mro_isa_changed_in(pTHX_ HV* stash)
501 struct mro_meta * meta;
504 const HEK * const stashhek = HvENAME_HEK(stash);
505 const char * const stashname = HvENAME_get(stash);
506 const STRLEN stashname_len = HvENAMELEN_get(stash);
508 PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
511 Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
514 /* wipe out the cached linearizations for this stash */
515 meta = HvMROMETA(stash);
518 /* Steal it for our own purposes. */
519 isa = (HV *)sv_2mortal((SV *)meta->isa);
523 /* Inc the package generation, since our @ISA changed */
526 /* Wipe the global method cache if this package
527 is UNIVERSAL or one of its parents */
529 svp = hv_fetchhek(PL_isarev, stashhek, 0);
530 isarev = svp ? MUTABLE_HV(*svp) : NULL;
532 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
533 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
537 else { /* Wipe the local method cache otherwise */
539 is_universal = FALSE;
542 /* wipe next::method cache too */
543 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
545 /* Changes to @ISA might turn overloading on */
547 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
548 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
550 /* DESTROY can be cached in SvSTASH. */
551 if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;
553 /* Iterate the isarev (classes that are our children),
554 wiping out their linearization, method and isa caches
555 and upating PL_isarev. */
557 HV *isa_hashes = NULL;
559 /* We have to iterate through isarev twice to avoid a chicken and
560 * egg problem: if A inherits from B and both are in isarev, A might
561 * be processed before B and use B's previous linearisation.
564 /* First iteration: Wipe everything, but stash away the isa hashes
565 * since we still need them for updating PL_isarev.
568 if(hv_iterinit(isarev)) {
569 /* Only create the hash if we need it; i.e., if isarev has
571 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
573 while((iter = hv_iternext(isarev))) {
574 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
575 struct mro_meta* revmeta;
577 if(!revstash) continue;
578 revmeta = HvMROMETA(revstash);
579 CLEAR_LINEAR(revmeta);
581 revmeta->cache_gen++;
582 if(revmeta->mro_nextmethod)
583 hv_clear(revmeta->mro_nextmethod);
584 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
588 isa_hashes, (const char*)&revstash, sizeof(HV *),
589 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
594 /* Second pass: Update PL_isarev. We can just use isa_hashes to
595 * avoid another round of stash lookups. */
597 /* isarev might be deleted from PL_isarev during this loop, so hang
599 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
602 hv_iterinit(isa_hashes);
603 while((iter = hv_iternext(isa_hashes))) {
604 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
605 HV * const isa = (HV *)HeVAL(iter);
608 /* We're starting at the 2nd element, skipping revstash */
609 linear_mro = mro_get_linear_isa(revstash);
610 svp = AvARRAY(linear_mro) + 1;
611 items = AvFILLp(linear_mro);
613 namehek = HvENAME_HEK(revstash);
614 if (!namehek) namehek = HvNAME_HEK(revstash);
617 SV* const sv = *svp++;
620 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
622 /* That fetch should not fail. But if it had to create
623 a new SV for us, then will need to upgrade it to an
624 HV (which sv_upgrade() can now do for us). */
626 mroisarev = MUTABLE_HV(HeVAL(he));
628 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
630 /* This hash only ever contains PL_sv_yes. Storing it
631 over itself is almost as cheap as calling hv_exists,
632 so on aggregate we expect to save time by not making
633 two calls to the common HV code for the case where
637 hv_storehek(mroisarev, namehek, &PL_sv_yes);
640 if ((SV *)isa != &PL_sv_undef) {
643 isa, HEK_KEY(namehek), HEK_LEN(namehek),
644 HvMROMETA(revstash)->isa, HEK_HASH(namehek),
652 /* Now iterate our MRO (parents), adding ourselves and everything from
653 our isarev to their isarev.
656 /* We're starting at the 2nd element, skipping ourselves here */
657 linear_mro = mro_get_linear_isa(stash);
658 svp = AvARRAY(linear_mro) + 1;
659 items = AvFILLp(linear_mro);
662 SV* const sv = *svp++;
665 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
667 /* That fetch should not fail. But if it had to create a new SV for
668 us, then will need to upgrade it to an HV (which sv_upgrade() can
671 mroisarev = MUTABLE_HV(HeVAL(he));
673 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
675 /* This hash only ever contains PL_sv_yes. Storing it over itself is
676 almost as cheap as calling hv_exists, so on aggregate we expect to
677 save time by not making two calls to the common HV code for the
678 case where it doesn't exist. */
680 (void)hv_storehek(mroisarev, stashhek, &PL_sv_yes);
683 /* Delete our name from our former parents' isarevs. */
684 if(isa && HvARRAY(isa))
685 mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
686 HEK_HASH(stashhek), HEK_UTF8(stashhek));
689 /* Deletes name from all the isarev entries listed in isa */
691 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
692 const STRLEN len, HV * const exceptions, U32 hash,
697 PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
699 /* Delete our name from our former parents' isarevs. */
700 if(isa && HvARRAY(isa) && hv_iterinit(isa)) {
702 while((iter = hv_iternext(isa))) {
704 const char * const key = hv_iterkey(iter, &klen);
705 if(exceptions && hv_exists(exceptions, key, HeKUTF8(iter) ? -klen : klen))
707 svp = hv_fetch(PL_isarev, key, HeKUTF8(iter) ? -klen : klen, 0);
709 HV * const isarev = (HV *)*svp;
710 (void)hv_common(isarev, NULL, name, len, flags,
711 G_DISCARD|HV_DELETE, NULL, hash);
712 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
713 (void)hv_delete(PL_isarev, key,
714 HeKUTF8(iter) ? -klen : klen, G_DISCARD);
721 =for apidoc mro_package_moved
723 Call this function to signal to a stash that it has been assigned to
724 another spot in the stash hierarchy. C<stash> is the stash that has been
725 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
726 that is actually being assigned to.
728 This can also be called with a null first argument to
729 indicate that C<oldstash> has been deleted.
731 This function invalidates isa caches on the old stash, on all subpackages
732 nested inside it, and on the subclasses of all those, including
733 non-existent packages that have corresponding entries in C<stash>.
735 It also sets the effective names (C<HvENAME>) on all the stashes as
738 If the C<gv> is present and is not in the symbol table, then this function
739 simply returns. This checked will be skipped if C<flags & 1>.
744 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
745 const GV * const gv, U32 flags)
753 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
754 assert(stash || oldstash);
756 /* Determine the name(s) of the location that stash was assigned to
757 * or from which oldstash was removed.
759 * We cannot reliably use the name in oldstash, because it may have
760 * been deleted from the location in the symbol table that its name
761 * suggests, as in this case:
763 * $globref = \*foo::bar::;
764 * Symbol::delete_package("foo");
765 * *$globref = \%baz::;
766 * *$globref = *frelp::;
767 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
769 * So we get it from the gv. But, since the gv may no longer be in the
770 * symbol table, we check that first. The only reliable way to tell is
771 * to see whether its stash has an effective name and whether the gv
772 * resides in that stash under its name. That effective name may be
773 * different from what gv_fullname4 would use.
774 * If flags & 1, the caller has asked us to skip the check.
779 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
780 !(svp = hv_fetchhek(GvSTASH(gv), GvNAME_HEK(gv), 0)) ||
784 assert(SvOOK(GvSTASH(gv)));
785 assert(GvNAMELEN(gv));
786 assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
787 assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
788 name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
791 namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
794 namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
795 if (name_count < 0) ++namep, name_count = -name_count - 1;
797 if (name_count == 1) {
798 if (HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)) {
799 namesv = GvNAMELEN(gv) == 1
800 ? newSVpvs_flags(":", SVs_TEMP)
801 : newSVpvs_flags("", SVs_TEMP);
804 namesv = sv_2mortal(newSVhek(*namep));
805 if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
806 else sv_catpvs(namesv, "::");
808 if (GvNAMELEN(gv) != 1) {
810 namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
811 /* skip trailing :: */
812 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
818 namesv = sv_2mortal((SV *)newAV());
819 while (name_count--) {
820 if(HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)){
821 aname = GvNAMELEN(gv) == 1
827 aname = newSVhek(*namep++);
828 if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
829 else sv_catpvs(aname, "::");
831 if (GvNAMELEN(gv) != 1) {
833 aname, GvNAME(gv), GvNAMELEN(gv) - 2,
834 /* skip trailing :: */
835 GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
838 av_push((AV *)namesv, aname);
842 /* Get a list of all the affected classes. */
843 /* We cannot simply pass them all to mro_isa_changed_in to avoid
844 the list, as that function assumes that only one package has
845 changed. It does not work with:
847 @foo::ISA = qw( B B::B );
848 *B:: = delete $::{"A::"};
850 as neither B nor B::B can be updated before the other, since they
851 will reset caches on foo, which will see either B or B::B with the
852 wrong name. The names must be set on *all* affected stashes before
853 we do anything else. (And linearisations must be cleared, too.)
855 stashes = (HV *) sv_2mortal((SV *)newHV());
856 mro_gather_and_rename(
857 stashes, (HV *) sv_2mortal((SV *)newHV()),
858 stash, oldstash, namesv
861 /* Once the caches have been wiped on all the classes, call
862 mro_isa_changed_in on each. */
863 hv_iterinit(stashes);
864 while((iter = hv_iternext(stashes))) {
865 HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
867 /* We have to restore the original meta->isa (that
868 mro_gather_and_rename set aside for us) this way, in case
869 one class in this list is a superclass of a another class
870 that we have already encountered. In such a case, meta->isa
871 will have been overwritten without old entries being deleted
873 struct mro_meta * const meta = HvMROMETA(stash);
874 if(meta->isa != (HV *)HeVAL(iter)){
875 SvREFCNT_dec(meta->isa);
877 = HeVAL(iter) == &PL_sv_yes
880 HeVAL(iter) = NULL; /* We donated our reference count. */
882 mro_isa_changed_in(stash);
888 S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
889 HV *stash, HV *oldstash, SV *namesv)
895 const bool stash_had_name = stash && HvENAME(stash);
896 bool fetched_isarev = FALSE;
901 PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
903 /* We use the seen_stashes hash to keep track of which packages have
904 been encountered so far. This must be separate from the main list of
905 stashes, as we need to distinguish between stashes being assigned
906 and stashes being replaced/deleted. (A nested stash can be on both
907 sides of an assignment. We cannot simply skip iterating through a
908 stash on the right if we have seen it on the left, as it will not
909 get its ename assigned to it.)
911 To avoid allocating extra SVs, instead of a bitfield we can make
912 bizarre use of immortals:
914 &PL_sv_undef: seen on the left (oldstash)
915 &PL_sv_no : seen on the right (stash)
916 &PL_sv_yes : seen on both sides
921 /* Add to the big list. */
922 struct mro_meta * meta;
926 seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
927 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
929 if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
934 = HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
935 meta = HvMROMETA(oldstash);
938 stashes, (const char *)&oldstash, sizeof(HV *),
940 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
946 /* Update the effective name. */
947 if(HvENAME_get(oldstash)) {
948 const HEK * const enamehek = HvENAME_HEK(oldstash);
949 if(SvTYPE(namesv) == SVt_PVAV) {
950 items = AvFILLp((AV *)namesv) + 1;
951 svp = AvARRAY((AV *)namesv);
958 const U32 name_utf8 = SvUTF8(*svp);
960 const char *name = SvPVx_const(*svp, len);
962 DEBUG_o(Perl_deb(aTHX_ "mro_gather_and_rename clearing PL_stashcache for '%"SVf"'\n",
964 (void)hv_delete(PL_stashcache, name, name_utf8 ? -(I32)len : (I32)len, G_DISCARD);
967 hv_ename_delete(oldstash, name, len, name_utf8);
969 if (!fetched_isarev) {
970 /* If the name deletion caused a name change, then we
971 * are not going to call mro_isa_changed_in with this
972 * name (and not at all if it has become anonymous) so
973 * we need to delete old isarev entries here, both
974 * those in the superclasses and this class's own list
975 * of subclasses. We simply delete the latter from
976 * PL_isarev, since we still need it. hv_delete morti-
977 * fies it for us, so sv_2mortal is not necessary. */
978 if(HvENAME_HEK(oldstash) != enamehek) {
979 if(meta->isa && HvARRAY(meta->isa))
980 mro_clean_isarev(meta->isa, name, len, 0, 0,
981 name_utf8 ? HVhek_UTF8 : 0);
982 isarev = (HV *)hv_delete(PL_isarev, name,
983 name_utf8 ? -(I32)len : (I32)len, 0);
992 if(SvTYPE(namesv) == SVt_PVAV) {
993 items = AvFILLp((AV *)namesv) + 1;
994 svp = AvARRAY((AV *)namesv);
1001 const U32 name_utf8 = SvUTF8(*svp);
1003 const char *name = SvPVx_const(*svp++, len);
1004 hv_ename_add(stash, name, len, name_utf8);
1007 /* Add it to the big list if it needs
1008 * mro_isa_changed_in called on it. That happens if it was
1009 * detached from the symbol table (so it had no HvENAME) before
1010 * being assigned to the spot named by the 'name' variable, because
1011 * its cached isa linearisation is now stale (the effective name
1012 * having changed), and subclasses will then use that cache when
1013 * mro_package_moved calls mro_isa_changed_in. (See
1016 * If it did have a name, then its previous name is still
1017 * used in isa caches, and there is no need for
1018 * mro_package_moved to call mro_isa_changed_in.
1024 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1025 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1027 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1031 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1034 struct mro_meta * const meta = HvMROMETA(stash);
1037 stashes, (const char *)&stash, sizeof(HV *),
1039 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1048 if(!stash && !oldstash)
1049 /* Both stashes have been encountered already. */
1052 /* Add all the subclasses to the big list. */
1053 if(!fetched_isarev) {
1054 /* If oldstash is not null, then we can use its HvENAME to look up
1055 the isarev hash, since all its subclasses will be listed there.
1056 It will always have an HvENAME. It the HvENAME was removed
1057 above, then fetch_isarev will be true, and this code will not be
1060 If oldstash is null, then this is an empty spot with no stash in
1061 it, so subclasses could be listed in isarev hashes belonging to
1062 any of the names, so we have to check all of them.
1064 assert(!oldstash || HvENAME(oldstash));
1066 /* Extra variable to avoid a compiler warning */
1067 const HEK * const hvename = HvENAME_HEK(oldstash);
1068 fetched_isarev = TRUE;
1069 svp = hv_fetchhek(PL_isarev, hvename, 0);
1070 if (svp) isarev = MUTABLE_HV(*svp);
1072 else if(SvTYPE(namesv) == SVt_PVAV) {
1073 items = AvFILLp((AV *)namesv) + 1;
1074 svp = AvARRAY((AV *)namesv);
1082 isarev || !fetched_isarev
1084 while (fetched_isarev || items--) {
1087 if (!fetched_isarev) {
1088 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1089 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1092 hv_iterinit(isarev);
1093 while((iter = hv_iternext(isarev))) {
1094 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1095 struct mro_meta * meta;
1097 if(!revstash) continue;
1098 meta = HvMROMETA(revstash);
1101 stashes, (const char *)&revstash, sizeof(HV *),
1103 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1110 if (fetched_isarev) break;
1114 /* This is partly based on code in hv_iternext_flags. We are not call-
1115 ing that here, as we want to avoid resetting the hash iterator. */
1117 /* Skip the entire loop if the hash is empty. */
1118 if(oldstash && HvUSEDKEYS(oldstash)) {
1119 xhv = (XPVHV*)SvANY(oldstash);
1120 seen = (HV *) sv_2mortal((SV *)newHV());
1122 /* Iterate through entries in the oldstash, adding them to the
1123 list, meanwhile doing the equivalent of $seen{$key} = 1.
1126 while (++riter <= (I32)xhv->xhv_max) {
1127 entry = (HvARRAY(oldstash))[riter];
1129 /* Iterate through the entries in this list */
1130 for(; entry; entry = HeNEXT(entry)) {
1134 /* If this entry is not a glob, ignore it.
1136 if (!isGV(HeVAL(entry))) continue;
1138 key = hv_iterkey(entry, &len);
1139 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1140 || (len == 1 && key[0] == ':')) {
1141 HV * const oldsubstash = GvHV(HeVAL(entry));
1142 SV ** const stashentry
1143 = stash ? hv_fetch(stash, key, HeUTF8(entry) ? -(I32)len : (I32)len, 0) : NULL;
1144 HV *substash = NULL;
1146 /* Avoid main::main::main::... */
1147 if(oldsubstash == oldstash) continue;
1151 stashentry && *stashentry && isGV(*stashentry)
1152 && (substash = GvHV(*stashentry))
1154 || (oldsubstash && HvENAME_get(oldsubstash))
1157 /* 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++);
1168 sv_catpvs(aname, ":");
1170 sv_catpvs(aname, "::");
1174 ? SV_CATUTF8 : SV_CATBYTES
1177 av_push((AV *)subname, aname);
1181 subname = sv_2mortal(newSVsv(namesv));
1182 if (len == 1) sv_catpvs(subname, ":");
1184 sv_catpvs(subname, "::");
1186 subname, key, len-2,
1187 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1191 mro_gather_and_rename(
1192 stashes, seen_stashes,
1193 substash, oldsubstash, subname
1197 (void)hv_store(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len, &PL_sv_yes, 0);
1203 /* Skip the entire loop if the hash is empty. */
1204 if (stash && HvUSEDKEYS(stash)) {
1205 xhv = (XPVHV*)SvANY(stash);
1208 /* Iterate through the new stash, skipping $seen{$key} items,
1209 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1210 while (++riter <= (I32)xhv->xhv_max) {
1211 entry = (HvARRAY(stash))[riter];
1213 /* Iterate through the entries in this list */
1214 for(; entry; entry = HeNEXT(entry)) {
1218 /* If this entry is not a glob, ignore it.
1220 if (!isGV(HeVAL(entry))) continue;
1222 key = hv_iterkey(entry, &len);
1223 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1224 || (len == 1 && key[0] == ':')) {
1227 /* If this entry was seen when we iterated through the
1228 oldstash, skip it. */
1229 if(seen && hv_exists(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len)) continue;
1231 /* We get here only if this stash has no corresponding
1232 entry in the stash being replaced. */
1234 substash = GvHV(HeVAL(entry));
1238 /* Avoid checking main::main::main::... */
1239 if(substash == stash) continue;
1241 /* Add :: and the key (minus the trailing ::)
1243 if(SvTYPE(namesv) == SVt_PVAV) {
1245 items = AvFILLp((AV *)namesv) + 1;
1246 svp = AvARRAY((AV *)namesv);
1247 subname = sv_2mortal((SV *)newAV());
1249 aname = newSVsv(*svp++);
1251 sv_catpvs(aname, ":");
1253 sv_catpvs(aname, "::");
1257 ? SV_CATUTF8 : SV_CATBYTES
1260 av_push((AV *)subname, aname);
1264 subname = sv_2mortal(newSVsv(namesv));
1265 if (len == 1) sv_catpvs(subname, ":");
1267 sv_catpvs(subname, "::");
1269 subname, key, len-2,
1270 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1274 mro_gather_and_rename(
1275 stashes, seen_stashes,
1276 substash, NULL, subname
1286 =for apidoc mro_method_changed_in
1288 Invalidates method caching on any child classes
1289 of the given stash, so that they might notice
1290 the changes in this one.
1292 Ideally, all instances of C<PL_sub_generation++> in
1293 perl source outside of F<mro.c> should be
1294 replaced by calls to this.
1296 Perl automatically handles most of the common
1297 ways a method might be redefined. However, there
1298 are a few ways you could change a method in a stash
1299 without the cache code noticing, in which case you
1300 need to call this method afterwards:
1302 1) Directly manipulating the stash HV entries from
1305 2) Assigning a reference to a readonly scalar
1306 constant into a stash entry in order to create
1307 a constant subroutine (like constant.pm
1310 This same method is available from pure perl
1311 via, C<mro::method_changed_in(classname)>.
1316 Perl_mro_method_changed_in(pTHX_ HV *stash)
1318 const char * const stashname = HvENAME_get(stash);
1319 const STRLEN stashname_len = HvENAMELEN_get(stash);
1321 SV ** const svp = hv_fetchhek(PL_isarev, HvENAME_HEK(stash), 0);
1322 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1324 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1327 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1329 /* Inc the package generation, since a local method changed */
1330 HvMROMETA(stash)->pkg_gen++;
1332 /* DESTROY can be cached in SvSTASH. */
1333 if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;
1335 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1336 invalidate all method caches globally */
1337 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1338 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1339 PL_sub_generation++;
1343 /* else, invalidate the method caches of all child classes,
1348 hv_iterinit(isarev);
1349 while((iter = hv_iternext(isarev))) {
1350 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1351 struct mro_meta* mrometa;
1353 if(!revstash) continue;
1354 mrometa = HvMROMETA(revstash);
1355 mrometa->cache_gen++;
1356 if(mrometa->mro_nextmethod)
1357 hv_clear(mrometa->mro_nextmethod);
1358 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
1362 /* The method change may be due to *{$package . "::()"} = \&nil; in
1365 /* pessimise derefs for now. Will get recalculated by Gv_AMupdate() */
1366 HvAUX(stash)->xhv_aux_flags &= ~HvAUXf_NO_DEREF;
1370 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1372 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1374 PERL_ARGS_ASSERT_MRO_SET_MRO;
1377 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1379 if(meta->mro_which != which) {
1380 if (meta->mro_linear_current && !meta->mro_linear_all) {
1381 /* If we were storing something directly, put it in the hash before
1383 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1384 MUTABLE_SV(meta->mro_linear_current));
1386 meta->mro_which = which;
1387 /* Scrub our cached pointer to the private data. */
1388 meta->mro_linear_current = NULL;
1389 /* Only affects local method cache, not
1390 even child classes */
1392 if(meta->mro_nextmethod)
1393 hv_clear(meta->mro_nextmethod);
1399 XS(XS_mro_method_changed_in);
1402 Perl_boot_core_mro(pTHX)
1404 static const char file[] = __FILE__;
1406 Perl_mro_register(aTHX_ &dfs_alg);
1408 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1411 XS(XS_mro_method_changed_in)
1418 croak_xs_usage(cv, "classname");
1422 class_stash = gv_stashsv(classname, 0);
1423 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1425 mro_method_changed_in(class_stash);
1432 * c-indentation-style: bsd
1434 * indent-tabs-mode: nil
1437 * ex: set ts=8 sts=4 sw=4 et: