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"]
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 =for apidoc mro_register
119 Registers a custom mro plugin. See L<perlmroapi> for details.
125 Perl_mro_register(pTHX_ const struct mro_alg *mro) {
126 SV *wrapper = newSVuv(PTR2UV(mro));
128 PERL_ARGS_ASSERT_MRO_REGISTER;
131 if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
132 mro->name, mro->length, mro->kflags,
133 HV_FETCH_ISSTORE, wrapper, mro->hash)) {
134 SvREFCNT_dec_NN(wrapper);
135 Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
136 "for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
141 Perl_mro_meta_init(pTHX_ HV* stash)
143 struct mro_meta* newmeta;
145 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++;
273 HV* const basestash = gv_stashsv(sv, 0);
278 /* if no stash exists for this @ISA member,
279 simply add it to the MRO and move on */
284 /* otherwise, recurse into ourselves for the MRO
285 of this @ISA member, and append their MRO to ours.
286 The recursive call could throw an exception, which
287 has memory management implications here, hence the use of
289 const AV *const subrv
290 = mro_get_linear_isa_dfs(basestash, level + 1);
292 subrv_p = AvARRAY(subrv);
293 subrv_items = AvFILLp(subrv) + 1;
296 while(subrv_items--) {
297 SV *const subsv = *subrv_p++;
298 /* LVALUE fetch will create a new undefined SV if necessary
300 HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
302 if(HeVAL(he) != &PL_sv_undef) {
303 /* It was newly created. Steal it for our new SV, and
304 replace it in the hash with the "real" thing. */
305 SV *const val = HeVAL(he);
306 HEK *const key = HeKEY_hek(he);
308 HeVAL(he) = &PL_sv_undef;
309 /* Save copying by making a shared hash key scalar. We
310 inline this here rather than calling
311 Perl_newSVpvn_share because we already have the
312 scalar, and we already have the hash key. */
313 assert(SvTYPE(val) == SVt_NULL);
314 sv_upgrade(val, SVt_PV);
315 SvPV_set(val, HEK_KEY(share_hek_hek(key)));
316 SvCUR_set(val, HEK_LEN(key));
322 av_push(retval, val);
326 /* We are the first (or only) parent. We can short cut the
327 complexity above, because our @ISA is simply us prepended
328 to our parent's @ISA, and our ->isa cache is simply our
329 parent's, with our name added. */
330 /* newSVsv() is slow. This code is only faster if we can avoid
331 it by ensuring that SVs in the arrays are shared hash key
332 scalar SVs, because we can "copy" them very efficiently.
333 Although to be fair, we can't *ensure* this, as a reference
334 to the internal array is returned by mro::get_linear_isa(),
335 so we'll have to be defensive just in case someone faffed
339 stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
340 av_extend(retval, subrv_items);
341 AvFILLp(retval) = subrv_items;
342 svp = AvARRAY(retval);
343 while(subrv_items--) {
344 SV *const val = *subrv_p++;
345 *++svp = SvIsCOW_shared_hash(val)
346 ? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
350 /* They have no stash. So create ourselves an ->isa cache
351 as if we'd copied it from what theirs should be. */
352 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
353 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
355 newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
361 /* We have no parents. */
362 stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
363 (void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
366 (void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
368 SvREFCNT_inc_simple_void_NN(stored);
370 SvREADONLY_on(stored);
374 /* now that we're past the exception dangers, grab our own reference to
375 the AV we're about to use for the result. The reference owned by the
376 mortals' stack will be released soon, so everything will balance. */
377 SvREFCNT_inc_simple_void_NN(retval);
380 /* we don't want anyone modifying the cache entry but us,
381 and we do so by replacing it completely */
382 SvREADONLY_on(retval);
384 return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
385 MUTABLE_SV(retval)));
389 =for apidoc mro_get_linear_isa
391 Returns the mro linearisation for the given stash. By default, this
392 will be whatever C<mro_get_linear_isa_dfs> returns unless some
393 other MRO is in effect for the stash. The return value is a
396 You are responsible for C<SvREFCNT_inc()> on the
397 return value if you plan to store it anywhere
398 semi-permanently (otherwise it might be deleted
399 out from under you the next time the cache is
405 Perl_mro_get_linear_isa(pTHX_ HV *stash)
407 struct mro_meta* meta;
410 PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
412 Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
414 meta = HvMROMETA(stash);
415 if (!meta->mro_which)
416 Perl_croak(aTHX_ "panic: invalid MRO!");
417 isa = meta->mro_which->resolve(aTHX_ stash, 0);
419 if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
421 (HvENAME(stash)||HvNAME(stash))
422 ? newSVhek(HvENAME_HEK(stash)
427 if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
429 AV * const old = isa;
431 SV **ovp = AvARRAY(old);
432 SV * const * const oend = ovp + AvFILLp(old) + 1;
433 isa = (AV *)sv_2mortal((SV *)newAV());
434 av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
435 *AvARRAY(isa) = namesv;
436 svp = AvARRAY(isa)+1;
437 while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
439 else SvREFCNT_dec(namesv);
443 HV *const isa_hash = newHV();
444 /* Linearisation didn't build it for us, so do it here. */
445 SV *const *svp = AvARRAY(isa);
446 SV *const *const svp_end = svp + AvFILLp(isa) + 1;
447 const HEK *canon_name = HvENAME_HEK(stash);
448 if (!canon_name) canon_name = HvNAME_HEK(stash);
450 while (svp < svp_end) {
451 (void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
454 (void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
455 HEK_LEN(canon_name), HEK_FLAGS(canon_name),
456 HV_FETCH_ISSTORE, &PL_sv_undef,
457 HEK_HASH(canon_name));
458 (void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
460 SvREADONLY_on(isa_hash);
462 meta->isa = isa_hash;
469 =for apidoc mro_isa_changed_in
471 Takes the necessary steps (cache invalidations, mostly)
472 when the @ISA of the given package has changed. Invoked
473 by the C<setisa> magic, should not need to invoke directly.
478 /* Macro to avoid repeating the code five times. */
479 #define CLEAR_LINEAR(mEta) \
480 if (mEta->mro_linear_all) { \
481 SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
482 mEta->mro_linear_all = NULL; \
483 /* This is just acting as a shortcut pointer. */ \
484 mEta->mro_linear_current = NULL; \
485 } else if (mEta->mro_linear_current) { \
486 /* Only the current MRO is stored, so this owns the data. */ \
487 SvREFCNT_dec(mEta->mro_linear_current); \
488 mEta->mro_linear_current = NULL; \
492 Perl_mro_isa_changed_in(pTHX_ HV* stash)
501 struct mro_meta * meta;
504 const char * const stashname = HvENAME_get(stash);
505 const STRLEN stashname_len = HvENAMELEN_get(stash);
506 const bool stashname_utf8 = HvENAMEUTF8(stash) ? 1 : 0;
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_fetch(PL_isarev, stashname,
530 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, 0);
531 isarev = svp ? MUTABLE_HV(*svp) : NULL;
533 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
534 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
538 else { /* Wipe the local method cache otherwise */
540 is_universal = FALSE;
543 /* wipe next::method cache too */
544 if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
546 /* Changes to @ISA might turn overloading on */
549 /* DESTROY can be cached in SvSTASH. */
550 if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;
552 /* Iterate the isarev (classes that are our children),
553 wiping out their linearization, method and isa caches
554 and upating PL_isarev. */
556 HV *isa_hashes = NULL;
558 /* We have to iterate through isarev twice to avoid a chicken and
559 * egg problem: if A inherits from B and both are in isarev, A might
560 * be processed before B and use B's previous linearisation.
563 /* First iteration: Wipe everything, but stash away the isa hashes
564 * since we still need them for updating PL_isarev.
567 if(hv_iterinit(isarev)) {
568 /* Only create the hash if we need it; i.e., if isarev has
570 isa_hashes = (HV *)sv_2mortal((SV *)newHV());
572 while((iter = hv_iternext(isarev))) {
573 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
574 struct mro_meta* revmeta;
576 if(!revstash) continue;
577 revmeta = HvMROMETA(revstash);
578 CLEAR_LINEAR(revmeta);
580 revmeta->cache_gen++;
581 if(revmeta->mro_nextmethod)
582 hv_clear(revmeta->mro_nextmethod);
583 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
587 isa_hashes, (const char*)&revstash, sizeof(HV *),
588 revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
593 /* Second pass: Update PL_isarev. We can just use isa_hashes to
594 * avoid another round of stash lookups. */
596 /* isarev might be deleted from PL_isarev during this loop, so hang
598 SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
601 hv_iterinit(isa_hashes);
602 while((iter = hv_iternext(isa_hashes))) {
603 HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
604 HV * const isa = (HV *)HeVAL(iter);
607 /* We're starting at the 2nd element, skipping revstash */
608 linear_mro = mro_get_linear_isa(revstash);
609 svp = AvARRAY(linear_mro) + 1;
610 items = AvFILLp(linear_mro);
612 namehek = HvENAME_HEK(revstash);
613 if (!namehek) namehek = HvNAME_HEK(revstash);
616 SV* const sv = *svp++;
619 HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
621 /* That fetch should not fail. But if it had to create
622 a new SV for us, then will need to upgrade it to an
623 HV (which sv_upgrade() can now do for us). */
625 mroisarev = MUTABLE_HV(HeVAL(he));
627 SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
629 /* This hash only ever contains PL_sv_yes. Storing it
630 over itself is almost as cheap as calling hv_exists,
631 so on aggregate we expect to save time by not making
632 two calls to the common HV code for the case where
637 mroisarev, HEK_KEY(namehek),
638 HEK_UTF8(namehek) ? -HEK_LEN(namehek) : HEK_LEN(namehek),
643 if((SV *)isa != &PL_sv_undef)
645 isa, HEK_KEY(namehek), HEK_LEN(namehek),
646 HvMROMETA(revstash)->isa, (HEK_UTF8(namehek) ? SVf_UTF8 : 0)
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_store(mroisarev, stashname,
681 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, &PL_sv_yes, 0);
684 /* Delete our name from our former parents' isarevs. */
685 if(isa && HvARRAY(isa))
686 mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
687 (stashname_utf8 ? SVf_UTF8 : 0) );
690 /* Deletes name from all the isarev entries listed in isa */
692 S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
693 const STRLEN len, HV * const exceptions, U32 flags)
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_delete(isarev, name, (flags & SVf_UTF8) ? -(I32)len : (I32)len, G_DISCARD);
711 if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
712 (void)hv_delete(PL_isarev, key,
713 HeKUTF8(iter) ? -klen : klen, G_DISCARD);
720 =for apidoc mro_package_moved
722 Call this function to signal to a stash that it has been assigned to
723 another spot in the stash hierarchy. C<stash> is the stash that has been
724 assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
725 that is actually being assigned to.
727 This can also be called with a null first argument to
728 indicate that C<oldstash> has been deleted.
730 This function invalidates isa caches on the old stash, on all subpackages
731 nested inside it, and on the subclasses of all those, including
732 non-existent packages that have corresponding entries in C<stash>.
734 It also sets the effective names (C<HvENAME>) on all the stashes as
737 If the C<gv> is present and is not in the symbol table, then this function
738 simply returns. This checked will be skipped if C<flags & 1>.
743 Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
744 const GV * const gv, U32 flags)
752 PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
753 assert(stash || oldstash);
755 /* Determine the name(s) of the location that stash was assigned to
756 * or from which oldstash was removed.
758 * We cannot reliably use the name in oldstash, because it may have
759 * been deleted from the location in the symbol table that its name
760 * suggests, as in this case:
762 * $globref = \*foo::bar::;
763 * Symbol::delete_package("foo");
764 * *$globref = \%baz::;
765 * *$globref = *frelp::;
766 * # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
768 * So we get it from the gv. But, since the gv may no longer be in the
769 * symbol table, we check that first. The only reliable way to tell is
770 * to see whether its stash has an effective name and whether the gv
771 * resides in that stash under its name. That effective name may be
772 * different from what gv_fullname4 would use.
773 * If flags & 1, the caller has asked us to skip the check.
778 !GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
779 !(svp = hv_fetch(GvSTASH(gv), GvNAME(gv),
780 GvNAMEUTF8(gv) ? -GvNAMELEN(gv) : GvNAMELEN(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, name_utf8);
981 isarev = (HV *)hv_delete(PL_isarev, name,
982 name_utf8 ? -(I32)len : (I32)len, 0);
991 if(SvTYPE(namesv) == SVt_PVAV) {
992 items = AvFILLp((AV *)namesv) + 1;
993 svp = AvARRAY((AV *)namesv);
1000 const U32 name_utf8 = SvUTF8(*svp);
1002 const char *name = SvPVx_const(*svp++, len);
1003 hv_ename_add(stash, name, len, name_utf8);
1006 /* Add it to the big list if it needs
1007 * mro_isa_changed_in called on it. That happens if it was
1008 * detached from the symbol table (so it had no HvENAME) before
1009 * being assigned to the spot named by the 'name' variable, because
1010 * its cached isa linearisation is now stale (the effective name
1011 * having changed), and subclasses will then use that cache when
1012 * mro_package_moved calls mro_isa_changed_in. (See
1015 * If it did have a name, then its previous name is still
1016 * used in isa caches, and there is no need for
1017 * mro_package_moved to call mro_isa_changed_in.
1023 seen_stashes, NULL, (const char *)&stash, sizeof(HV *), 0,
1024 HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
1026 if(HeVAL(entry) == &PL_sv_yes || HeVAL(entry) == &PL_sv_no)
1030 = HeVAL(entry) == &PL_sv_undef ? &PL_sv_yes : &PL_sv_no;
1033 struct mro_meta * const meta = HvMROMETA(stash);
1036 stashes, (const char *)&stash, sizeof(HV *),
1038 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1047 if(!stash && !oldstash)
1048 /* Both stashes have been encountered already. */
1051 /* Add all the subclasses to the big list. */
1052 if(!fetched_isarev) {
1053 /* If oldstash is not null, then we can use its HvENAME to look up
1054 the isarev hash, since all its subclasses will be listed there.
1055 It will always have an HvENAME. It the HvENAME was removed
1056 above, then fetch_isarev will be true, and this code will not be
1059 If oldstash is null, then this is an empty spot with no stash in
1060 it, so subclasses could be listed in isarev hashes belonging to
1061 any of the names, so we have to check all of them.
1063 assert(!oldstash || HvENAME(oldstash));
1065 /* Extra variable to avoid a compiler warning */
1066 char * const hvename = HvENAME(oldstash);
1067 fetched_isarev = TRUE;
1068 svp = hv_fetch(PL_isarev, hvename,
1069 HvENAMEUTF8(oldstash)
1070 ? -HvENAMELEN_get(oldstash)
1071 : HvENAMELEN_get(oldstash), 0);
1072 if (svp) isarev = MUTABLE_HV(*svp);
1074 else if(SvTYPE(namesv) == SVt_PVAV) {
1075 items = AvFILLp((AV *)namesv) + 1;
1076 svp = AvARRAY((AV *)namesv);
1084 isarev || !fetched_isarev
1086 while (fetched_isarev || items--) {
1089 if (!fetched_isarev) {
1090 HE * const he = hv_fetch_ent(PL_isarev, *svp++, 0, 0);
1091 if (!he || !(isarev = MUTABLE_HV(HeVAL(he)))) continue;
1094 hv_iterinit(isarev);
1095 while((iter = hv_iternext(isarev))) {
1096 HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1097 struct mro_meta * meta;
1099 if(!revstash) continue;
1100 meta = HvMROMETA(revstash);
1103 stashes, (const char *)&revstash, sizeof(HV *),
1105 ? SvREFCNT_inc_simple_NN((SV *)meta->isa)
1112 if (fetched_isarev) break;
1116 /* This is partly based on code in hv_iternext_flags. We are not call-
1117 ing that here, as we want to avoid resetting the hash iterator. */
1119 /* Skip the entire loop if the hash is empty. */
1120 if(oldstash && HvUSEDKEYS(oldstash)) {
1121 xhv = (XPVHV*)SvANY(oldstash);
1122 seen = (HV *) sv_2mortal((SV *)newHV());
1124 /* Iterate through entries in the oldstash, adding them to the
1125 list, meanwhile doing the equivalent of $seen{$key} = 1.
1128 while (++riter <= (I32)xhv->xhv_max) {
1129 entry = (HvARRAY(oldstash))[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] == ':')
1142 || (len == 1 && key[0] == ':')) {
1143 HV * const oldsubstash = GvHV(HeVAL(entry));
1144 SV ** const stashentry
1145 = stash ? hv_fetch(stash, key, HeUTF8(entry) ? -(I32)len : (I32)len, 0) : NULL;
1146 HV *substash = NULL;
1148 /* Avoid main::main::main::... */
1149 if(oldsubstash == oldstash) continue;
1153 stashentry && *stashentry
1154 && (substash = GvHV(*stashentry))
1156 || (oldsubstash && HvENAME_get(oldsubstash))
1159 /* Add :: and the key (minus the trailing ::)
1162 if(SvTYPE(namesv) == SVt_PVAV) {
1164 items = AvFILLp((AV *)namesv) + 1;
1165 svp = AvARRAY((AV *)namesv);
1166 subname = sv_2mortal((SV *)newAV());
1168 aname = newSVsv(*svp++);
1170 sv_catpvs(aname, ":");
1172 sv_catpvs(aname, "::");
1176 ? SV_CATUTF8 : SV_CATBYTES
1179 av_push((AV *)subname, aname);
1183 subname = sv_2mortal(newSVsv(namesv));
1184 if (len == 1) sv_catpvs(subname, ":");
1186 sv_catpvs(subname, "::");
1188 subname, key, len-2,
1189 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1193 mro_gather_and_rename(
1194 stashes, seen_stashes,
1195 substash, oldsubstash, subname
1199 (void)hv_store(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len, &PL_sv_yes, 0);
1205 /* Skip the entire loop if the hash is empty. */
1206 if (stash && HvUSEDKEYS(stash)) {
1207 xhv = (XPVHV*)SvANY(stash);
1210 /* Iterate through the new stash, skipping $seen{$key} items,
1211 calling mro_gather_and_rename(stashes,seen,entry,NULL, ...). */
1212 while (++riter <= (I32)xhv->xhv_max) {
1213 entry = (HvARRAY(stash))[riter];
1215 /* Iterate through the entries in this list */
1216 for(; entry; entry = HeNEXT(entry)) {
1220 /* If this entry is not a glob, ignore it.
1222 if (!isGV(HeVAL(entry))) continue;
1224 key = hv_iterkey(entry, &len);
1225 if ((len > 1 && key[len-2] == ':' && key[len-1] == ':')
1226 || (len == 1 && key[0] == ':')) {
1229 /* If this entry was seen when we iterated through the
1230 oldstash, skip it. */
1231 if(seen && hv_exists(seen, key, HeUTF8(entry) ? -(I32)len : (I32)len)) continue;
1233 /* We get here only if this stash has no corresponding
1234 entry in the stash being replaced. */
1236 substash = GvHV(HeVAL(entry));
1240 /* Avoid checking main::main::main::... */
1241 if(substash == stash) continue;
1243 /* Add :: and the key (minus the trailing ::)
1245 if(SvTYPE(namesv) == SVt_PVAV) {
1247 items = AvFILLp((AV *)namesv) + 1;
1248 svp = AvARRAY((AV *)namesv);
1249 subname = sv_2mortal((SV *)newAV());
1251 aname = newSVsv(*svp++);
1253 sv_catpvs(aname, ":");
1255 sv_catpvs(aname, "::");
1259 ? SV_CATUTF8 : SV_CATBYTES
1262 av_push((AV *)subname, aname);
1266 subname = sv_2mortal(newSVsv(namesv));
1267 if (len == 1) sv_catpvs(subname, ":");
1269 sv_catpvs(subname, "::");
1271 subname, key, len-2,
1272 HeUTF8(entry) ? SV_CATUTF8 : SV_CATBYTES
1276 mro_gather_and_rename(
1277 stashes, seen_stashes,
1278 substash, NULL, subname
1288 =for apidoc mro_method_changed_in
1290 Invalidates method caching on any child classes
1291 of the given stash, so that they might notice
1292 the changes in this one.
1294 Ideally, all instances of C<PL_sub_generation++> in
1295 perl source outside of F<mro.c> should be
1296 replaced by calls to this.
1298 Perl automatically handles most of the common
1299 ways a method might be redefined. However, there
1300 are a few ways you could change a method in a stash
1301 without the cache code noticing, in which case you
1302 need to call this method afterwards:
1304 1) Directly manipulating the stash HV entries from
1307 2) Assigning a reference to a readonly scalar
1308 constant into a stash entry in order to create
1309 a constant subroutine (like constant.pm
1312 This same method is available from pure perl
1313 via, C<mro::method_changed_in(classname)>.
1318 Perl_mro_method_changed_in(pTHX_ HV *stash)
1320 const char * const stashname = HvENAME_get(stash);
1321 const STRLEN stashname_len = HvENAMELEN_get(stash);
1322 const bool stashname_utf8 = HvENAMEUTF8(stash) ? 1 : 0;
1324 SV ** const svp = hv_fetch(PL_isarev, stashname,
1325 stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, 0);
1326 HV * const isarev = svp ? MUTABLE_HV(*svp) : NULL;
1328 PERL_ARGS_ASSERT_MRO_METHOD_CHANGED_IN;
1331 Perl_croak(aTHX_ "Can't call mro_method_changed_in() on anonymous symbol table");
1333 /* Inc the package generation, since a local method changed */
1334 HvMROMETA(stash)->pkg_gen++;
1336 /* DESTROY can be cached in SvSTASH. */
1337 if (!SvOBJECT(stash)) SvSTASH(stash) = NULL;
1339 /* If stash is UNIVERSAL, or one of UNIVERSAL's parents,
1340 invalidate all method caches globally */
1341 if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
1342 || (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
1343 PL_sub_generation++;
1347 /* else, invalidate the method caches of all child classes,
1352 hv_iterinit(isarev);
1353 while((iter = hv_iternext(isarev))) {
1354 HV* const revstash = gv_stashsv(hv_iterkeysv(iter), 0);
1355 struct mro_meta* mrometa;
1357 if(!revstash) continue;
1358 mrometa = HvMROMETA(revstash);
1359 mrometa->cache_gen++;
1360 if(mrometa->mro_nextmethod)
1361 hv_clear(mrometa->mro_nextmethod);
1362 if (!SvOBJECT(revstash)) SvSTASH(revstash) = NULL;
1366 /* The method change may be due to *{$package . "::()"} = \&nil; in
1372 Perl_mro_set_mro(pTHX_ struct mro_meta *const meta, SV *const name)
1374 const struct mro_alg *const which = Perl_mro_get_from_name(aTHX_ name);
1376 PERL_ARGS_ASSERT_MRO_SET_MRO;
1379 Perl_croak(aTHX_ "Invalid mro name: '%"SVf"'", name);
1381 if(meta->mro_which != which) {
1382 if (meta->mro_linear_current && !meta->mro_linear_all) {
1383 /* If we were storing something directly, put it in the hash before
1385 Perl_mro_set_private_data(aTHX_ meta, meta->mro_which,
1386 MUTABLE_SV(meta->mro_linear_current));
1388 meta->mro_which = which;
1389 /* Scrub our cached pointer to the private data. */
1390 meta->mro_linear_current = NULL;
1391 /* Only affects local method cache, not
1392 even child classes */
1394 if(meta->mro_nextmethod)
1395 hv_clear(meta->mro_nextmethod);
1401 XS(XS_mro_method_changed_in);
1404 Perl_boot_core_mro(pTHX)
1407 static const char file[] = __FILE__;
1409 Perl_mro_register(aTHX_ &dfs_alg);
1411 newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
1414 XS(XS_mro_method_changed_in)
1422 croak_xs_usage(cv, "classname");
1426 class_stash = gv_stashsv(classname, 0);
1427 if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
1429 mro_method_changed_in(class_stash);
1436 * c-indentation-style: bsd
1438 * indent-tabs-mode: nil
1441 * ex: set ts=8 sts=4 sw=4 et: