*/
/*
+ * "Which order shall we go in?" said Frodo. "Eldest first, or quickest first?
+ * You'll be last either way, Master Peregrin."
+ */
+
+/*
=head1 MRO Functions
These functions are related to the method resolution order of perl classes
struct mro_meta*
Perl_mro_meta_init(pTHX_ HV* stash)
{
- void* newmeta;
+ struct mro_meta* newmeta;
assert(stash);
assert(HvAUX(stash));
assert(!(HvAUX(stash)->xhv_mro_meta));
- Newxz(newmeta, sizeof(struct mro_meta), char);
- HvAUX(stash)->xhv_mro_meta = (struct mro_meta*)newmeta;
- ((struct mro_meta*)newmeta)->sub_generation = 1;
+ Newxz(newmeta, 1, struct mro_meta);
+ HvAUX(stash)->xhv_mro_meta = newmeta;
+ newmeta->sub_generation = 1;
/* Manually flag UNIVERSAL as being universal.
This happens early in perl booting (when universal.c
struct mro_meta*
Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
{
- void* newmeta_void;
struct mro_meta* newmeta;
assert(smeta);
- Newx(newmeta_void, sizeof(struct mro_meta), char);
- newmeta = (struct mro_meta*)newmeta_void;
-
- newmeta->mro_which = smeta->mro_which;
- newmeta->sub_generation = smeta->sub_generation;
- newmeta->is_universal = smeta->is_universal;
- newmeta->fake = smeta->fake;
- newmeta->mro_linear_dfs = smeta->mro_linear_dfs
- ? (AV*) SvREFCNT_inc(sv_dup((SV*)smeta->mro_linear_dfs, param))
- : 0;
- newmeta->mro_linear_c3 = smeta->mro_linear_c3
- ? (AV*) SvREFCNT_inc(sv_dup((SV*)smeta->mro_linear_c3, param))
- : 0;
- newmeta->mro_isarev = smeta->mro_isarev
- ? (HV*) SvREFCNT_inc(sv_dup((SV*)smeta->mro_isarev, param))
- : 0;
- newmeta->mro_nextmethod = smeta->mro_nextmethod
- ? (HV*) SvREFCNT_inc(sv_dup((SV*)smeta->mro_nextmethod, param))
- : 0;
+ Newx(newmeta, 1, struct mro_meta);
+ Copy(smeta, newmeta, 1, struct mro_meta);
+
+ if (newmeta->mro_linear_dfs)
+ newmeta->mro_linear_dfs
+ = (AV*) SvREFCNT_inc(sv_dup((SV*)newmeta->mro_linear_dfs, param));
+ if (newmeta->mro_linear_c3)
+ newmeta->mro_linear_c3
+ = (AV*) SvREFCNT_inc(sv_dup((SV*)newmeta->mro_linear_c3, param));
+ if (newmeta->mro_isarev)
+ newmeta->mro_isarev
+ = (HV*) SvREFCNT_inc(sv_dup((SV*)newmeta->mro_isarev, param));
+ if (newmeta->mro_nextmethod)
+ newmeta->mro_nextmethod
+ = (HV*) SvREFCNT_inc(sv_dup((SV*)newmeta->mro_nextmethod, param));
return newmeta;
}
C<level> should be 0 (it is used internally in this
function's recursion).
+You are responsible for C<SvREFCNT_inc()> on the
+return value if you plan to store it anywhere
+semi-permanently (otherwise it might be deleted
+out from under you the next time the cache is
+invalidated).
+
=cut
*/
AV*
GV** gvp;
GV* gv;
AV* av;
- SV** svp;
- I32 items;
- AV* subrv;
- SV** subrv_p;
- I32 subrv_items;
const char* stashname;
struct mro_meta* meta;
stashname);
meta = HvMROMETA(stash);
+
+ /* return cache if valid */
if((retval = meta->mro_linear_dfs)) {
- /* return cache if valid */
return retval;
}
/* not in cache, make a new one */
+
retval = newAV();
av_push(retval, newSVpv(stashname, 0)); /* add ourselves at the top */
+ /* fetch our @ISA */
gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
av = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
- if(av) {
+ if(av && AvFILLp(av) >= 0) {
+
+ /* "stored" is used to keep track of all of the classnames
+ we have added to the MRO so far, so we can do a quick
+ exists check and avoid adding duplicate classnames to
+ the MRO as we go. */
+
HV* stored = (HV*)sv_2mortal((SV*)newHV());
- svp = AvARRAY(av);
- items = AvFILLp(av) + 1;
+ SV **svp = AvARRAY(av);
+ I32 items = AvFILLp(av) + 1;
+
+ /* foreach(@ISA) */
while (items--) {
SV* const sv = *svp++;
HV* const basestash = gv_stashsv(sv, 0);
+ SV *const *subrv_p;
+ I32 subrv_items;
if (!basestash) {
- if(!hv_exists_ent(stored, sv, 0)) {
- av_push(retval, newSVsv(sv));
- hv_store_ent(stored, sv, &PL_sv_undef, 0);
- }
+ /* if no stash exists for this @ISA member,
+ simply add it to the MRO and move on */
+ subrv_p = &sv;
+ subrv_items = 1;
}
else {
- subrv = mro_get_linear_isa_dfs(basestash, level + 1);
- subrv_p = AvARRAY(subrv);
- subrv_items = AvFILLp(subrv) + 1;
- while(subrv_items--) {
- SV* subsv = *subrv_p++;
- if(!hv_exists_ent(stored, subsv, 0)) {
- av_push(retval, newSVsv(subsv));
- hv_store_ent(stored, subsv, &PL_sv_undef, 0);
- }
- }
+ /* otherwise, recurse into ourselves for the MRO
+ of this @ISA member, and append their MRO to ours */
+ const AV *const subrv
+ = mro_get_linear_isa_dfs(basestash, level + 1);
+
+ subrv_p = AvARRAY(subrv);
+ subrv_items = AvFILLp(subrv) + 1;
+ }
+ while(subrv_items--) {
+ SV *const subsv = *subrv_p++;
+ if(!hv_exists_ent(stored, subsv, 0)) {
+ hv_store_ent(stored, subsv, &PL_sv_undef, 0);
+ av_push(retval, newSVsv(subsv));
+ }
}
}
}
+ /* we don't want anyone modifying the cache entry but us,
+ and we do so by replacing it completely */
SvREADONLY_on(retval);
+
meta->mro_linear_dfs = retval;
return retval;
}
C<level> should be 0 (it is used internally in this
function's recursion).
+You are responsible for C<SvREFCNT_inc()> on the
+return value if you plan to store it anywhere
+semi-permanently (otherwise it might be deleted
+out from under you the next time the cache is
+invalidated).
+
=cut
*/
stashname);
meta = HvMROMETA(stash);
+
+ /* return cache if valid */
if((retval = meta->mro_linear_c3)) {
- /* return cache if valid */
return retval;
}
gvp = (GV**)hv_fetchs(stash, "ISA", FALSE);
isa = (gvp && (gv = *gvp) && isGV_with_GP(gv)) ? GvAV(gv) : NULL;
+ /* For a better idea how the rest of this works, see the much clearer
+ pure perl version in Algorithm::C3 0.01:
+ http://search.cpan.org/src/STEVAN/Algorithm-C3-0.01/lib/Algorithm/C3.pm
+ (later versions go about it differently than this code for speed reasons)
+ */
+
if(isa && AvFILLp(isa) >= 0) {
SV** seqs_ptr;
I32 seqs_items;
HV* tails = (HV*)sv_2mortal((SV*)newHV());
AV* seqs = (AV*)sv_2mortal((SV*)newAV());
+ I32* heads;
+
+ /* This builds @seqs, which is an array of arrays.
+ The members of @seqs are the MROs of
+ the members of @ISA, followed by @ISA itself.
+ */
I32 items = AvFILLp(isa) + 1;
SV** isa_ptr = AvARRAY(isa);
while(items--) {
SV* isa_item = *isa_ptr++;
HV* isa_item_stash = gv_stashsv(isa_item, 0);
if(!isa_item_stash) {
- isa_lin = newAV();
+ /* if no stash, make a temporary fake MRO
+ containing just itself */
+ isa_lin = (AV*)sv_2mortal((SV*)newAV());
av_push(isa_lin, newSVsv(isa_item));
}
else {
isa_lin = mro_get_linear_isa_c3(isa_item_stash, level + 1); /* recursion */
}
- av_push(seqs, (SV*)av_make(AvFILLp(isa_lin)+1, AvARRAY(isa_lin)));
+ av_push(seqs, (SV*)isa_lin);
}
- av_push(seqs, (SV*)av_make(AvFILLp(isa)+1, AvARRAY(isa)));
-
+ av_push(seqs, (SV*)isa);
+
+ /* This builds "heads", which as an array of integer array
+ indices, one per seq, which point at the virtual "head"
+ of the seq (initially zero) */
+ Newxz(heads, AvFILLp(seqs)+1, I32);
+
+ /* This builds %tails, which has one key for every class
+ mentioned in the tail of any sequence in @seqs (tail meaning
+ everything after the first class, the "head"). The value
+ is how many times this key appears in the tails of @seqs.
+ */
seqs_ptr = AvARRAY(seqs);
seqs_items = AvFILLp(seqs) + 1;
while(seqs_items--) {
}
}
+ /* This loop won't terminate until we either finish building
+ the MRO, or get an exception. */
while(1) {
SV* seqhead = NULL;
SV* cand = NULL;
SV* val;
HE* tail_entry;
AV* seq;
+ int s;
+
+ /* "foreach $seq (@seqs)" */
SV** avptr = AvARRAY(seqs);
- items = AvFILLp(seqs)+1;
- while(items--) {
+ for(s = 0; s <= AvFILLp(seqs); s++) {
SV** svp;
- seq = (AV*)*avptr++;
- if(AvFILLp(seq) < 0) continue;
- svp = av_fetch(seq, 0, 0);
- seqhead = *svp;
+ seq = (AV*)(avptr[s]);
+ if(!seq) continue; /* skip empty seqs */
+ svp = av_fetch(seq, heads[s], 0);
+ seqhead = *svp; /* seqhead = head of this seq */
if(!winner) {
+ /* if we haven't found a winner for this round yet,
+ and this seqhead is not in tails (or the count
+ for it in tails has dropped to zero), then this
+ seqhead is our new winner, and is added to the
+ final MRO immediately */
cand = seqhead;
if((tail_entry = hv_fetch_ent(tails, cand, 0, 0))
&& (val = HeVAL(tail_entry))
- && (SvIVx(val) > 0))
+ && (SvIVX(val) > 0))
continue;
winner = newSVsv(cand);
av_push(retval, winner);
+ /* note however that even when we find a winner,
+ we continue looping over @seqs to do housekeeping */
}
if(!sv_cmp(seqhead, winner)) {
-
- /* this is basically shift(@seq) in void context */
- SvREFCNT_dec(*AvARRAY(seq));
- *AvARRAY(seq) = &PL_sv_undef;
- AvARRAY(seq) = AvARRAY(seq) + 1;
- AvMAX(seq)--;
- AvFILLp(seq)--;
-
- if(AvFILLp(seq) < 0) continue;
- svp = av_fetch(seq, 0, 0);
- seqhead = *svp;
- tail_entry = hv_fetch_ent(tails, seqhead, 0, 0);
- val = HeVAL(tail_entry);
- sv_dec(val);
+ /* Once we have a winner (including the iteration
+ where we first found him), inc the head ptr
+ for any seq which had the winner as a head,
+ NULL out any seq which is now empty,
+ and adjust tails for consistency */
+
+ int new_head = ++heads[s];
+ if(new_head > AvFILLp(seq)) {
+ avptr[s] = NULL;
+ }
+ else {
+ /* Because we know this new seqhead used to be
+ a tail, we can assume it is in tails and has
+ a positive value, which we need to dec */
+ svp = av_fetch(seq, new_head, 0);
+ seqhead = *svp;
+ tail_entry = hv_fetch_ent(tails, seqhead, 0, 0);
+ val = HeVAL(tail_entry);
+ sv_dec(val);
+ }
}
}
- if(!cand) break;
+
+ /* if we found no candidates, we are done building the MRO.
+ !cand means no seqs have any entries left to check */
+ if(!cand) {
+ Safefree(heads);
+ break;
+ }
+
+ /* If we had candidates, but nobody won, then the @ISA
+ hierarchy is not C3-incompatible */
if(!winner) {
+ /* we have to do some cleanup before we croak */
+ SV** svp = AvARRAY(seqs);
+ items = AvFILLp(seqs) + 1;
+ while (items--)
+ *svp++ = NULL;
+
SvREFCNT_dec(retval);
+ Safefree(heads);
+
Perl_croak(aTHX_ "Inconsistent hierarchy during C3 merge of class '%s': "
"merging failed on parent '%"SVf"'", stashname, SVfARG(cand));
}
}
}
+ /* we don't want anyone modifying the cache entry but us,
+ and we do so by replacing it completely */
SvREADONLY_on(retval);
+
meta->mro_linear_c3 = retval;
return retval;
}
for that stash. The return value is a
read-only AV*.
+You are responsible for C<SvREFCNT_inc()> on the
+return value if you plan to store it anywhere
+semi-permanently (otherwise it might be deleted
+out from under you the next time the cache is
+invalidated).
+
=cut
*/
AV*
} else {
Perl_croak(aTHX_ "panic: invalid MRO!");
}
+ return NULL; /* NOT REACHED */
}
/*
=for apidoc mro_isa_changed_in
-Takes the neccesary steps (cache invalidations, mostly)
+Takes the necessary steps (cache invalidations, mostly)
when the @ISA of the given package has changed. Invoked
by the C<setisa> magic, should not need to invoke directly.
while((iter = hv_iternext(isarev))) {
SV* revkey = hv_iterkeysv(iter);
HV* revstash = gv_stashsv(revkey, 0);
- struct mro_meta* revmeta = HvMROMETA(revstash);
+ struct mro_meta* revmeta;
+
+ if(!revstash) continue;
+ revmeta = HvMROMETA(revstash);
SvREFCNT_dec((SV*)revmeta->mro_linear_dfs);
SvREFCNT_dec((SV*)revmeta->mro_linear_c3);
revmeta->mro_linear_dfs = NULL;
}
}
- /* we're starting at the 2nd element, skipping ourselves here */
+ /* Now iterate our MRO (parents), and do a few things:
+ 1) instantiate with the "fake" flag if they don't exist
+ 2) flag them as universal if we are universal
+ 3) Add everything from our isarev to their isarev
+ */
+
+ /* We're starting at the 2nd element, skipping ourselves here */
linear_mro = mro_get_linear_isa(stash);
svp = AvARRAY(linear_mro) + 1;
items = AvFILLp(linear_mro);
+
while (items--) {
SV* const sv = *svp++;
struct mro_meta* mrometa;
if(!mroisarev)
mroisarev = mrometa->mro_isarev = newHV();
- if(!hv_exists(mroisarev, stashname, strlen(stashname)))
- hv_store(mroisarev, stashname, strlen(stashname), &PL_sv_yes, 0);
+ /* This hash only ever contains PL_sv_yes. Storing it over itself is
+ almost as cheap as calling hv_exists, so on aggregate we expect to
+ save time by not making two calls to the common HV code for the
+ case where it doesn't exist. */
+
+ hv_store(mroisarev, stashname, strlen(stashname), &PL_sv_yes, 0);
if(isarev) {
hv_iterinit(isarev);
while((iter = hv_iternext(isarev))) {
SV* revkey = hv_iterkeysv(iter);
- if(!hv_exists_ent(mroisarev, revkey, 0))
- hv_store_ent(mroisarev, revkey, &PL_sv_yes, 0);
+ hv_store_ent(mroisarev, revkey, &PL_sv_yes, 0);
}
}
}
/*
=for apidoc mro_method_changed_in
-Like C<mro_isa_changed_in>, but invalidates method
-caching on any child classes of the given stash, so
-that they might notice the changes in this one.
+Invalidates method caching on any child classes
+of the given stash, so that they might notice
+the changes in this one.
Ideally, all instances of C<PL_sub_generation++> in
-the perl source should be replaced by calls to this.
-Some already are, but some are more difficult to
-replace.
+the perl source outside of C<mro.c> should be
+replaced by calls to this. This conversion is
+nearly complete.
Perl has always had problems with method caches
getting out of sync when one directly manipulates
while((iter = hv_iternext(isarev))) {
SV* revkey = hv_iterkeysv(iter);
HV* revstash = gv_stashsv(revkey, 0);
- struct mro_meta* mrometa = HvMROMETA(revstash);
+ struct mro_meta* mrometa;
+
+ if(!revstash) continue;
+ mrometa = HvMROMETA(revstash);
mrometa->sub_generation++;
if(mrometa->mro_nextmethod)
hv_clear(mrometa->mro_nextmethod);
/* If we made it to here, we found our context */
+ /* Initialize the next::method cache for this stash
+ if necessary */
selfmeta = HvMROMETA(selfstash);
if(!(nmcache = selfmeta->mro_nextmethod)) {
nmcache = selfmeta->mro_nextmethod = newHV();
}
- if((cache_entry = hv_fetch_ent(nmcache, sv, 0, 0))) {
+ /* Use the cached coderef if it exists */
+ else if((cache_entry = hv_fetch_ent(nmcache, sv, 0, 0))) {
SV* val = HeVAL(cache_entry);
if(val == &PL_sv_undef) {
if(throw_nomethod)
linear_svp = AvARRAY(linear_av);
items = AvFILLp(linear_av) + 1;
+ /* Walk down our MRO, skipping everything up
+ to the contextually enclosing class */
while (items--) {
linear_sv = *linear_svp++;
assert(linear_sv);
break;
}
+ /* Now search the remainder of the MRO for the
+ same method name as the contextually enclosing
+ method */
if(items > 0) {
while (items--) {
linear_sv = *linear_svp++;
if (SvTYPE(candidate) != SVt_PVGV)
gv_init(candidate, curstash, subname, subname_len, TRUE);
+
+ /* Notably, we only look for real entries, not method cache
+ entries, because in C3 the method cache of a parent is not
+ valid for the child */
if (SvTYPE(candidate) == SVt_PVGV && (cand_cv = GvCV(candidate)) && !GvCVGEN(candidate)) {
SvREFCNT_inc_simple_void_NN((SV*)cand_cv);
hv_store_ent(nmcache, newSVsv(sv), (SV*)cand_cv, 0);
XS(XS_mro_get_mro);
XS(XS_mro_get_isarev);
XS(XS_mro_is_universal);
-XS(XS_mro_get_global_sub_generation);
-XS(XS_mro_invalidate_all_method_caches);
+XS(XS_mro_get_global_sub_gen);
+XS(XS_mro_invalidate_method_caches);
XS(XS_mro_get_sub_generation);
XS(XS_mro_method_changed_in);
XS(XS_next_can);
newXSproto("mro::get_mro", XS_mro_get_mro, file, "$");
newXSproto("mro::get_isarev", XS_mro_get_isarev, file, "$");
newXSproto("mro::is_universal", XS_mro_is_universal, file, "$");
- newXSproto("mro::get_global_sub_generation", XS_mro_get_global_sub_generation, file, "");
- newXSproto("mro::invalidate_all_method_caches", XS_mro_invalidate_all_method_caches, file, "");
+ newXSproto("mro::get_global_sub_generation", XS_mro_get_global_sub_gen, file, "");
+ newXSproto("mro::invalidate_all_method_caches", XS_mro_invalidate_method_caches, file, "");
newXSproto("mro::get_sub_generation", XS_mro_get_sub_generation, file, "$");
newXSproto("mro::method_changed_in", XS_mro_method_changed_in, file, "$");
newXS("next::can", XS_next_can, file);
class_stash = gv_stashsv(classname, 0);
if(!class_stash) Perl_croak(aTHX_ "No such class: '%"SVf"'!", SVfARG(classname));
- HvMROMETA(class_stash)->is_universal
- ? XSRETURN_YES
- : XSRETURN_NO;
+ if (HvMROMETA(class_stash)->is_universal)
+ XSRETURN_YES;
+ else
+ XSRETURN_NO;
}
-XS(XS_mro_get_global_sub_generation)
+XS(XS_mro_get_global_sub_gen)
{
dVAR;
dXSARGS;
XSRETURN(1);
}
-XS(XS_mro_invalidate_all_method_caches)
+XS(XS_mro_invalidate_method_caches)
{
dVAR;
dXSARGS;
https://perl5.git.perl.org / perl5.git / blobdiff