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mro.c
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mro.c
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/* mro.c
*
* Copyright (c) 2007 Brandon L Black
* Copyright (c) 2007, 2008 Larry Wall and others
*
* You may distribute under the terms of either the GNU General Public
* License or the Artistic License, as specified in the README file.
*
*/
/*
* 'Which order shall we go in?' said Frodo. 'Eldest first, or quickest first?
* You'll be last either way, Master Peregrin.'
*
* [p.101 of _The Lord of the Rings_, I/iii: "A Conspiracy Unmasked"]
*/
/*
=head1 MRO Functions
These functions are related to the method resolution order of perl classes
=cut
*/
#include "EXTERN.h"
#define PERL_IN_MRO_C
#include "perl.h"
static const struct mro_alg dfs_alg =
{S_mro_get_linear_isa_dfs, "dfs", 3, 0, 0};
SV *
Perl_mro_get_private_data(pTHX_ struct mro_meta *const smeta,
const struct mro_alg *const which)
{
SV **data;
PERL_ARGS_ASSERT_MRO_GET_PRIVATE_DATA;
data = (SV **)Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
which->name, which->length, which->kflags,
HV_FETCH_JUST_SV, NULL, which->hash);
if (!data)
return NULL;
/* If we've been asked to look up the private data for the current MRO, then
cache it. */
if (smeta->mro_which == which)
smeta->mro_linear_current = *data;
return *data;
}
SV *
Perl_mro_set_private_data(pTHX_ struct mro_meta *const smeta,
const struct mro_alg *const which, SV *const data)
{
PERL_ARGS_ASSERT_MRO_SET_PRIVATE_DATA;
if (!smeta->mro_linear_all) {
if (smeta->mro_which == which) {
/* If all we need to store is the current MRO's data, then don't use
memory on a hash with 1 element - store it direct, and signal
this by leaving the would-be-hash NULL. */
smeta->mro_linear_current = data;
return data;
} else {
HV *const hv = newHV();
/* Start with 2 buckets. It's unlikely we'll need more. */
HvMAX(hv) = 1;
smeta->mro_linear_all = hv;
if (smeta->mro_linear_current) {
/* If we were storing something directly, put it in the hash
before we lose it. */
Perl_mro_set_private_data(aTHX_ smeta, smeta->mro_which,
smeta->mro_linear_current);
}
}
}
/* We get here if we're storing more than one linearisation for this stash,
or the linearisation we are storing is not that if its current MRO. */
if (smeta->mro_which == which) {
/* If we've been asked to store the private data for the current MRO,
then cache it. */
smeta->mro_linear_current = data;
}
if (!Perl_hv_common(aTHX_ smeta->mro_linear_all, NULL,
which->name, which->length, which->kflags,
HV_FETCH_ISSTORE, data, which->hash)) {
Perl_croak(aTHX_ "panic: hv_store() failed in set_mro_private_data() "
"for '%.*s' %d", (int) which->length, which->name,
which->kflags);
}
return data;
}
const struct mro_alg *
Perl_mro_get_from_name(pTHX_ SV *name) {
SV **data;
PERL_ARGS_ASSERT_MRO_GET_FROM_NAME;
data = (SV **)Perl_hv_common(aTHX_ PL_registered_mros, name, NULL, 0, 0,
HV_FETCH_JUST_SV, NULL, 0);
if (!data)
return NULL;
assert(SvTYPE(*data) == SVt_IV);
assert(SvIOK(*data));
return INT2PTR(const struct mro_alg *, SvUVX(*data));
}
/*
=for apidoc mro_register
Registers a custom mro plugin. See L<perlmroapi> for details.
=cut
*/
void
Perl_mro_register(pTHX_ const struct mro_alg *mro) {
SV *wrapper = newSVuv(PTR2UV(mro));
PERL_ARGS_ASSERT_MRO_REGISTER;
if (!Perl_hv_common(aTHX_ PL_registered_mros, NULL,
mro->name, mro->length, mro->kflags,
HV_FETCH_ISSTORE, wrapper, mro->hash)) {
SvREFCNT_dec(wrapper);
Perl_croak(aTHX_ "panic: hv_store() failed in mro_register() "
"for '%.*s' %d", (int) mro->length, mro->name, mro->kflags);
}
}
struct mro_meta*
Perl_mro_meta_init(pTHX_ HV* stash)
{
struct mro_meta* newmeta;
PERL_ARGS_ASSERT_MRO_META_INIT;
assert(HvAUX(stash));
assert(!(HvAUX(stash)->xhv_mro_meta));
Newxz(newmeta, 1, struct mro_meta);
HvAUX(stash)->xhv_mro_meta = newmeta;
newmeta->cache_gen = 1;
newmeta->pkg_gen = 1;
newmeta->mro_which = &dfs_alg;
return newmeta;
}
#if defined(USE_ITHREADS)
/* for sv_dup on new threads */
struct mro_meta*
Perl_mro_meta_dup(pTHX_ struct mro_meta* smeta, CLONE_PARAMS* param)
{
struct mro_meta* newmeta;
PERL_ARGS_ASSERT_MRO_META_DUP;
Newx(newmeta, 1, struct mro_meta);
Copy(smeta, newmeta, 1, struct mro_meta);
if (newmeta->mro_linear_all) {
newmeta->mro_linear_all
= MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_linear_all, param));
/* This is just acting as a shortcut pointer, and will be automatically
updated on the first get. */
newmeta->mro_linear_current = NULL;
} else if (newmeta->mro_linear_current) {
/* Only the current MRO is stored, so this owns the data. */
newmeta->mro_linear_current
= sv_dup_inc((const SV *)newmeta->mro_linear_current, param);
}
if (newmeta->mro_nextmethod)
newmeta->mro_nextmethod
= MUTABLE_HV(sv_dup_inc((const SV *)newmeta->mro_nextmethod, param));
if (newmeta->isa)
newmeta->isa
= MUTABLE_HV(sv_dup_inc((const SV *)newmeta->isa, param));
return newmeta;
}
#endif /* USE_ITHREADS */
/*
=for apidoc mro_get_linear_isa_dfs
Returns the Depth-First Search linearization of @ISA
the given stash. The return value is a read-only AV*.
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
*/
static AV*
S_mro_get_linear_isa_dfs(pTHX_ HV *stash, U32 level)
{
AV* retval;
GV** gvp;
GV* gv;
AV* av;
const HEK* stashhek;
struct mro_meta* meta;
SV *our_name;
HV *stored = NULL;
PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA_DFS;
assert(HvAUX(stash));
stashhek
= HvAUX(stash)->xhv_name_u.xhvnameu_name && HvENAME_HEK_NN(stash)
? HvENAME_HEK_NN(stash)
: HvNAME_HEK(stash);
if (!stashhek)
Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
if (level > 100)
Perl_croak(aTHX_
"Recursive inheritance detected in package '%"HEKf"'",
HEKfARG(stashhek));
meta = HvMROMETA(stash);
/* return cache if valid */
if((retval = MUTABLE_AV(MRO_GET_PRIVATE_DATA(meta, &dfs_alg)))) {
return retval;
}
/* not in cache, make a new one */
retval = MUTABLE_AV(sv_2mortal(MUTABLE_SV(newAV())));
/* We use this later in this function, but don't need a reference to it
beyond the end of this function, so reference count is fine. */
our_name = newSVhek(stashhek);
av_push(retval, our_name); /* 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;
/* "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.
It's then retained to be re-used as a fast lookup for ->isa(), by adding
our own name and "UNIVERSAL" to it. */
if(av && AvFILLp(av) >= 0) {
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 no stash exists for this @ISA member,
simply add it to the MRO and move on */
subrv_p = &sv;
subrv_items = 1;
}
else {
/* otherwise, recurse into ourselves for the MRO
of this @ISA member, and append their MRO to ours.
The recursive call could throw an exception, which
has memory management implications here, hence the use of
the mortal. */
const AV *const subrv
= mro_get_linear_isa_dfs(basestash, level + 1);
subrv_p = AvARRAY(subrv);
subrv_items = AvFILLp(subrv) + 1;
}
if (stored) {
while(subrv_items--) {
SV *const subsv = *subrv_p++;
/* LVALUE fetch will create a new undefined SV if necessary
*/
HE *const he = hv_fetch_ent(stored, subsv, 1, 0);
assert(he);
if(HeVAL(he) != &PL_sv_undef) {
/* It was newly created. Steal it for our new SV, and
replace it in the hash with the "real" thing. */
SV *const val = HeVAL(he);
HEK *const key = HeKEY_hek(he);
HeVAL(he) = &PL_sv_undef;
/* Save copying by making a shared hash key scalar. We
inline this here rather than calling
Perl_newSVpvn_share because we already have the
scalar, and we already have the hash key. */
assert(SvTYPE(val) == SVt_NULL);
sv_upgrade(val, SVt_PV);
SvPV_set(val, HEK_KEY(share_hek_hek(key)));
SvCUR_set(val, HEK_LEN(key));
SvREADONLY_on(val);
SvFAKE_on(val);
SvPOK_on(val);
if (HEK_UTF8(key))
SvUTF8_on(val);
av_push(retval, val);
}
}
} else {
/* We are the first (or only) parent. We can short cut the
complexity above, because our @ISA is simply us prepended
to our parent's @ISA, and our ->isa cache is simply our
parent's, with our name added. */
/* newSVsv() is slow. This code is only faster if we can avoid
it by ensuring that SVs in the arrays are shared hash key
scalar SVs, because we can "copy" them very efficiently.
Although to be fair, we can't *ensure* this, as a reference
to the internal array is returned by mro::get_linear_isa(),
so we'll have to be defensive just in case someone faffed
with it. */
if (basestash) {
SV **svp;
stored = MUTABLE_HV(sv_2mortal((SV*)newHVhv(HvMROMETA(basestash)->isa)));
av_extend(retval, subrv_items);
AvFILLp(retval) = subrv_items;
svp = AvARRAY(retval);
while(subrv_items--) {
SV *const val = *subrv_p++;
*++svp = SvIsCOW_shared_hash(val)
? newSVhek(SvSHARED_HEK_FROM_PV(SvPVX(val)))
: newSVsv(val);
}
} else {
/* They have no stash. So create ourselves an ->isa cache
as if we'd copied it from what theirs should be. */
stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
(void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
av_push(retval,
newSVhek(HeKEY_hek(hv_store_ent(stored, sv,
&PL_sv_undef, 0))));
}
}
}
} else {
/* We have no parents. */
stored = MUTABLE_HV(sv_2mortal(MUTABLE_SV(newHV())));
(void) hv_store(stored, "UNIVERSAL", 9, &PL_sv_undef, 0);
}
(void) hv_store_ent(stored, our_name, &PL_sv_undef, 0);
SvREFCNT_inc_simple_void_NN(stored);
SvTEMP_off(stored);
SvREADONLY_on(stored);
meta->isa = stored;
/* now that we're past the exception dangers, grab our own reference to
the AV we're about to use for the result. The reference owned by the
mortals' stack will be released soon, so everything will balance. */
SvREFCNT_inc_simple_void_NN(retval);
SvTEMP_off(retval);
/* we don't want anyone modifying the cache entry but us,
and we do so by replacing it completely */
SvREADONLY_on(retval);
return MUTABLE_AV(Perl_mro_set_private_data(aTHX_ meta, &dfs_alg,
MUTABLE_SV(retval)));
}
/*
=for apidoc mro_get_linear_isa
Returns the mro linearisation for the given stash. By default, this
will be whatever C<mro_get_linear_isa_dfs> returns unless some
other MRO is in effect for the 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*
Perl_mro_get_linear_isa(pTHX_ HV *stash)
{
struct mro_meta* meta;
AV *isa;
PERL_ARGS_ASSERT_MRO_GET_LINEAR_ISA;
if(!SvOOK(stash))
Perl_croak(aTHX_ "Can't linearize anonymous symbol table");
meta = HvMROMETA(stash);
if (!meta->mro_which)
Perl_croak(aTHX_ "panic: invalid MRO!");
isa = meta->mro_which->resolve(aTHX_ stash, 0);
if (meta->mro_which != &dfs_alg) { /* skip for dfs, for speed */
SV * const namesv =
(HvENAME(stash)||HvNAME(stash))
? newSVhek(HvENAME_HEK(stash)
? HvENAME_HEK(stash)
: HvNAME_HEK(stash))
: NULL;
if(namesv && (AvFILLp(isa) == -1 || !sv_eq(*AvARRAY(isa), namesv)))
{
AV * const old = isa;
SV **svp;
SV **ovp = AvARRAY(old);
SV * const * const oend = ovp + AvFILLp(old) + 1;
isa = (AV *)sv_2mortal((SV *)newAV());
av_extend(isa, AvFILLp(isa) = AvFILLp(old)+1);
*AvARRAY(isa) = namesv;
svp = AvARRAY(isa)+1;
while (ovp < oend) *svp++ = SvREFCNT_inc(*ovp++);
}
else SvREFCNT_dec(namesv);
}
if (!meta->isa) {
HV *const isa_hash = newHV();
/* Linearisation didn't build it for us, so do it here. */
SV *const *svp = AvARRAY(isa);
SV *const *const svp_end = svp + AvFILLp(isa) + 1;
const HEK *canon_name = HvENAME_HEK(stash);
if (!canon_name) canon_name = HvNAME_HEK(stash);
while (svp < svp_end) {
(void) hv_store_ent(isa_hash, *svp++, &PL_sv_undef, 0);
}
(void) hv_common(isa_hash, NULL, HEK_KEY(canon_name),
HEK_LEN(canon_name), HEK_FLAGS(canon_name),
HV_FETCH_ISSTORE, &PL_sv_undef,
HEK_HASH(canon_name));
(void) hv_store(isa_hash, "UNIVERSAL", 9, &PL_sv_undef, 0);
SvREADONLY_on(isa_hash);
meta->isa = isa_hash;
}
return isa;
}
/*
=for apidoc mro_isa_changed_in
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.
=cut
*/
/* Macro to avoid repeating the code five times. */
#define CLEAR_LINEAR(mEta) \
if (mEta->mro_linear_all) { \
SvREFCNT_dec(MUTABLE_SV(mEta->mro_linear_all)); \
mEta->mro_linear_all = NULL; \
/* This is just acting as a shortcut pointer. */ \
mEta->mro_linear_current = NULL; \
} else if (mEta->mro_linear_current) { \
/* Only the current MRO is stored, so this owns the data. */ \
SvREFCNT_dec(mEta->mro_linear_current); \
mEta->mro_linear_current = NULL; \
}
void
Perl_mro_isa_changed_in(pTHX_ HV* stash)
{
dVAR;
HV* isarev;
AV* linear_mro;
HE* iter;
SV** svp;
I32 items;
bool is_universal;
struct mro_meta * meta;
HV *isa = NULL;
const char * const stashname = HvENAME_get(stash);
const STRLEN stashname_len = HvENAMELEN_get(stash);
const bool stashname_utf8 = HvENAMEUTF8(stash) ? 1 : 0;
PERL_ARGS_ASSERT_MRO_ISA_CHANGED_IN;
if(!stashname)
Perl_croak(aTHX_ "Can't call mro_isa_changed_in() on anonymous symbol table");
/* wipe out the cached linearizations for this stash */
meta = HvMROMETA(stash);
CLEAR_LINEAR(meta);
if (meta->isa) {
/* Steal it for our own purposes. */
isa = (HV *)sv_2mortal((SV *)meta->isa);
meta->isa = NULL;
}
/* Inc the package generation, since our @ISA changed */
meta->pkg_gen++;
/* Wipe the global method cache if this package
is UNIVERSAL or one of its parents */
svp = hv_fetch(PL_isarev, stashname,
stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, 0);
isarev = svp ? MUTABLE_HV(*svp) : NULL;
if((stashname_len == 9 && strEQ(stashname, "UNIVERSAL"))
|| (isarev && hv_exists(isarev, "UNIVERSAL", 9))) {
PL_sub_generation++;
is_universal = TRUE;
}
else { /* Wipe the local method cache otherwise */
meta->cache_gen++;
is_universal = FALSE;
}
/* wipe next::method cache too */
if(meta->mro_nextmethod) hv_clear(meta->mro_nextmethod);
/* Iterate the isarev (classes that are our children),
wiping out their linearization, method and isa caches
and upating PL_isarev. */
if(isarev) {
HV *isa_hashes = NULL;
/* We have to iterate through isarev twice to avoid a chicken and
* egg problem: if A inherits from B and both are in isarev, A might
* be processed before B and use B’s previous linearisation.
*/
/* First iteration: Wipe everything, but stash away the isa hashes
* since we still need them for updating PL_isarev.
*/
if(hv_iterinit(isarev)) {
/* Only create the hash if we need it; i.e., if isarev has
any elements. */
isa_hashes = (HV *)sv_2mortal((SV *)newHV());
}
while((iter = hv_iternext(isarev))) {
HV* revstash = gv_stashsv(hv_iterkeysv(iter), 0);
struct mro_meta* revmeta;
if(!revstash) continue;
revmeta = HvMROMETA(revstash);
CLEAR_LINEAR(revmeta);
if(!is_universal)
revmeta->cache_gen++;
if(revmeta->mro_nextmethod)
hv_clear(revmeta->mro_nextmethod);
(void)
hv_store(
isa_hashes, (const char*)&revstash, sizeof(HV *),
revmeta->isa ? (SV *)revmeta->isa : &PL_sv_undef, 0
);
revmeta->isa = NULL;
}
/* Second pass: Update PL_isarev. We can just use isa_hashes to
* avoid another round of stash lookups. */
/* isarev might be deleted from PL_isarev during this loop, so hang
* on to it. */
SvREFCNT_inc_simple_void_NN(sv_2mortal((SV *)isarev));
if(isa_hashes) {
hv_iterinit(isa_hashes);
while((iter = hv_iternext(isa_hashes))) {
HV* const revstash = *(HV **)HEK_KEY(HeKEY_hek(iter));
HV * const isa = (HV *)HeVAL(iter);
const HEK *namehek;
/* We're starting at the 2nd element, skipping revstash */
linear_mro = mro_get_linear_isa(revstash);
svp = AvARRAY(linear_mro) + 1;
items = AvFILLp(linear_mro);
namehek = HvENAME_HEK(revstash);
if (!namehek) namehek = HvNAME_HEK(revstash);
while (items--) {
SV* const sv = *svp++;
HV* mroisarev;
HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
/* That fetch should not fail. But if it had to create
a new SV for us, then will need to upgrade it to an
HV (which sv_upgrade() can now do for us). */
mroisarev = MUTABLE_HV(HeVAL(he));
SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
/* 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. */
(void)
hv_store(
mroisarev, HEK_KEY(namehek),
HEK_UTF8(namehek) ? -HEK_LEN(namehek) : HEK_LEN(namehek),
&PL_sv_yes, 0
);
}
if((SV *)isa != &PL_sv_undef)
mro_clean_isarev(
isa, HEK_KEY(namehek), HEK_LEN(namehek),
HvMROMETA(revstash)->isa, (HEK_UTF8(namehek) ? SVf_UTF8 : 0)
);
}
}
}
/* Now iterate our MRO (parents), adding ourselves and 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++;
HV* mroisarev;
HE *he = hv_fetch_ent(PL_isarev, sv, TRUE, 0);
/* That fetch should not fail. But if it had to create a new SV for
us, then will need to upgrade it to an HV (which sv_upgrade() can
now do for us. */
mroisarev = MUTABLE_HV(HeVAL(he));
SvUPGRADE(MUTABLE_SV(mroisarev), SVt_PVHV);
/* 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. */
(void)hv_store(mroisarev, stashname,
stashname_utf8 ? -(I32)stashname_len : (I32)stashname_len, &PL_sv_yes, 0);
}
/* Delete our name from our former parents’ isarevs. */
if(isa && HvARRAY(isa))
mro_clean_isarev(isa, stashname, stashname_len, meta->isa,
(stashname_utf8 ? SVf_UTF8 : 0) );
}
/* Deletes name from all the isarev entries listed in isa */
STATIC void
S_mro_clean_isarev(pTHX_ HV * const isa, const char * const name,
const STRLEN len, HV * const exceptions, U32 flags)
{
HE* iter;
PERL_ARGS_ASSERT_MRO_CLEAN_ISAREV;
/* Delete our name from our former parents’ isarevs. */
if(isa && HvARRAY(isa) && hv_iterinit(isa)) {
SV **svp;
while((iter = hv_iternext(isa))) {
I32 klen;
const char * const key = hv_iterkey(iter, &klen);
if(exceptions && hv_exists(exceptions, key, HeKUTF8(iter) ? -klen : klen))
continue;
svp = hv_fetch(PL_isarev, key, HeKUTF8(iter) ? -klen : klen, 0);
if(svp) {
HV * const isarev = (HV *)*svp;
(void)hv_delete(isarev, name, (flags & SVf_UTF8) ? -(I32)len : (I32)len, G_DISCARD);
if(!HvARRAY(isarev) || !HvUSEDKEYS(isarev))
(void)hv_delete(PL_isarev, key,
HeKUTF8(iter) ? -klen : klen, G_DISCARD);
}
}
}
}
/*
=for apidoc mro_package_moved
Call this function to signal to a stash that it has been assigned to
another spot in the stash hierarchy. C<stash> is the stash that has been
assigned. C<oldstash> is the stash it replaces, if any. C<gv> is the glob
that is actually being assigned to.
This can also be called with a null first argument to
indicate that C<oldstash> has been deleted.
This function invalidates isa caches on the old stash, on all subpackages
nested inside it, and on the subclasses of all those, including
non-existent packages that have corresponding entries in C<stash>.
It also sets the effective names (C<HvENAME>) on all the stashes as
appropriate.
If the C<gv> is present and is not in the symbol table, then this function
simply returns. This checked will be skipped if C<flags & 1>.
=cut
*/
void
Perl_mro_package_moved(pTHX_ HV * const stash, HV * const oldstash,
const GV * const gv, U32 flags)
{
SV *namesv;
HEK **namep;
I32 name_count;
HV *stashes;
HE* iter;
PERL_ARGS_ASSERT_MRO_PACKAGE_MOVED;
assert(stash || oldstash);
/* Determine the name(s) of the location that stash was assigned to
* or from which oldstash was removed.
*
* We cannot reliably use the name in oldstash, because it may have
* been deleted from the location in the symbol table that its name
* suggests, as in this case:
*
* $globref = \*foo::bar::;
* Symbol::delete_package("foo");
* *$globref = \%baz::;
* *$globref = *frelp::;
* # calls mro_package_moved(%frelp::, %baz::, *$globref, NULL, 0)
*
* So we get it from the gv. But, since the gv may no longer be in the
* symbol table, we check that first. The only reliable way to tell is
* to see whether its stash has an effective name and whether the gv
* resides in that stash under its name. That effective name may be
* different from what gv_fullname4 would use.
* If flags & 1, the caller has asked us to skip the check.
*/
if(!(flags & 1)) {
SV **svp;
if(
!GvSTASH(gv) || !HvENAME(GvSTASH(gv)) ||
!(svp = hv_fetch(GvSTASH(gv), GvNAME(gv),
GvNAMEUTF8(gv) ? -GvNAMELEN(gv) : GvNAMELEN(gv), 0)) ||
*svp != (SV *)gv
) return;
}
assert(SvOOK(GvSTASH(gv)));
assert(GvNAMELEN(gv));
assert(GvNAME(gv)[GvNAMELEN(gv) - 1] == ':');
assert(GvNAMELEN(gv) == 1 || GvNAME(gv)[GvNAMELEN(gv) - 2] == ':');
name_count = HvAUX(GvSTASH(gv))->xhv_name_count;
if (!name_count) {
name_count = 1;
namep = &HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_name;
}
else {
namep = HvAUX(GvSTASH(gv))->xhv_name_u.xhvnameu_names;
if (name_count < 0) ++namep, name_count = -name_count - 1;
}
if (name_count == 1) {
if (HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)) {
namesv = GvNAMELEN(gv) == 1
? newSVpvs_flags(":", SVs_TEMP)
: newSVpvs_flags("", SVs_TEMP);
}
else {
namesv = sv_2mortal(newSVhek(*namep));
if (GvNAMELEN(gv) == 1) sv_catpvs(namesv, ":");
else sv_catpvs(namesv, "::");
}
if (GvNAMELEN(gv) != 1) {
sv_catpvn_flags(
namesv, GvNAME(gv), GvNAMELEN(gv) - 2,
/* skip trailing :: */
GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
);
}
}
else {
SV *aname;
namesv = sv_2mortal((SV *)newAV());
while (name_count--) {
if(HEK_LEN(*namep) == 4 && strnEQ(HEK_KEY(*namep), "main", 4)){
aname = GvNAMELEN(gv) == 1
? newSVpvs(":")
: newSVpvs("");
namep++;
}
else {
aname = newSVhek(*namep++);
if (GvNAMELEN(gv) == 1) sv_catpvs(aname, ":");
else sv_catpvs(aname, "::");
}
if (GvNAMELEN(gv) != 1) {
sv_catpvn_flags(
aname, GvNAME(gv), GvNAMELEN(gv) - 2,
/* skip trailing :: */
GvNAMEUTF8(gv) ? SV_CATUTF8 : SV_CATBYTES
);
}
av_push((AV *)namesv, aname);
}
}
/* Get a list of all the affected classes. */
/* We cannot simply pass them all to mro_isa_changed_in to avoid
the list, as that function assumes that only one package has
changed. It does not work with:
@foo::ISA = qw( B B::B );
*B:: = delete $::{"A::"};
as neither B nor B::B can be updated before the other, since they
will reset caches on foo, which will see either B or B::B with the
wrong name. The names must be set on *all* affected stashes before
we do anything else. (And linearisations must be cleared, too.)
*/
stashes = (HV *) sv_2mortal((SV *)newHV());
mro_gather_and_rename(
stashes, (HV *) sv_2mortal((SV *)newHV()),
stash, oldstash, namesv
);
/* Once the caches have been wiped on all the classes, call
mro_isa_changed_in on each. */
hv_iterinit(stashes);
while((iter = hv_iternext(stashes))) {
HV * const stash = *(HV **)HEK_KEY(HeKEY_hek(iter));
if(HvENAME(stash)) {
/* We have to restore the original meta->isa (that
mro_gather_and_rename set aside for us) this way, in case
one class in this list is a superclass of a another class
that we have already encountered. In such a case, meta->isa
will have been overwritten without old entries being deleted
from PL_isarev. */
struct mro_meta * const meta = HvMROMETA(stash);
if(meta->isa != (HV *)HeVAL(iter)){
SvREFCNT_dec(meta->isa);
meta->isa
= HeVAL(iter) == &PL_sv_yes
? NULL
: (HV *)HeVAL(iter);
HeVAL(iter) = NULL; /* We donated our reference count. */
}
mro_isa_changed_in(stash);
}
}
}
void
S_mro_gather_and_rename(pTHX_ HV * const stashes, HV * const seen_stashes,
HV *stash, HV *oldstash, SV *namesv)
{
register XPVHV* xhv;
register HE *entry;
I32 riter = -1;
I32 items = 0;
const bool stash_had_name = stash && HvENAME(stash);
bool fetched_isarev = FALSE;
HV *seen = NULL;
HV *isarev = NULL;
SV **svp = NULL;
PERL_ARGS_ASSERT_MRO_GATHER_AND_RENAME;
/* We use the seen_stashes hash to keep track of which packages have
been encountered so far. This must be separate from the main list of
stashes, as we need to distinguish between stashes being assigned
and stashes being replaced/deleted. (A nested stash can be on both
sides of an assignment. We cannot simply skip iterating through a
stash on the right if we have seen it on the left, as it will not
get its ename assigned to it.)
To avoid allocating extra SVs, instead of a bitfield we can make
bizarre use of immortals:
&PL_sv_undef: seen on the left (oldstash)
&PL_sv_no : seen on the right (stash)
&PL_sv_yes : seen on both sides
*/
if(oldstash) {
/* Add to the big list. */
struct mro_meta * meta;
HE * const entry
= (HE *)
hv_common(
seen_stashes, NULL, (const char *)&oldstash, sizeof(HV *), 0,
HV_FETCH_LVALUE|HV_FETCH_EMPTY_HE, NULL, 0
);
if(HeVAL(entry) == &PL_sv_undef || HeVAL(entry) == &PL_sv_yes) {
oldstash = NULL;
goto check_stash;
}
HeVAL(entry)
= HeVAL(entry) == &PL_sv_no ? &PL_sv_yes : &PL_sv_undef;
meta = HvMROMETA(oldstash);
(void)
hv_store(
stashes, (const char *)&oldstash, sizeof(HV *),
meta->isa
? SvREFCNT_inc_simple_NN((SV *)meta->isa)
: &PL_sv_yes,
0
);
CLEAR_LINEAR(meta);
/* Update the effective name. */
if(HvENAME_get(oldstash)) {
const HEK * const enamehek = HvENAME_HEK(oldstash);
if(SvTYPE(namesv) == SVt_PVAV) {
items = AvFILLp((AV *)namesv) + 1;
svp = AvARRAY((AV *)namesv);
}
else {
items = 1;
svp = &namesv;
}
while (items--) {
const U32 name_utf8 = SvUTF8(*svp);
STRLEN len;
const char *name = SvPVx_const(*svp++, len);
if(PL_stashcache)
(void)hv_delete(PL_stashcache, name, name_utf8 ? -(I32)len : (I32)len, G_DISCARD);
hv_ename_delete(oldstash, name, len, name_utf8);
if (!fetched_isarev) {
/* If the name deletion caused a name change, then we
* are not going to call mro_isa_changed_in with this
* name (and not at all if it has become anonymous) so
* we need to delete old isarev entries here, both
* those in the superclasses and this class’s own list
* of subclasses. We simply delete the latter from
* PL_isarev, since we still need it. hv_delete morti-
* fies it for us, so sv_2mortal is not necessary. */
if(HvENAME_HEK(oldstash) != enamehek) {
if(meta->isa && HvARRAY(meta->isa))
mro_clean_isarev(meta->isa, name, len, 0, name_utf8);
isarev = (HV *)hv_delete(PL_isarev, name,
name_utf8 ? -(I32)len : (I32)len, 0);
fetched_isarev=TRUE;
}
}
}
}
}
check_stash:
if(stash) {
if(SvTYPE(namesv) == SVt_PVAV) {
items = AvFILLp((AV *)namesv) + 1;
svp = AvARRAY((AV *)namesv);
}
else {
items = 1;
svp = &namesv;
}
while (items--) {
const U32 name_utf8 = SvUTF8(*svp);
STRLEN len;
const char *name = SvPVx_const(*svp++, len);
hv_ename_add(stash, name, len, name_utf8);
}
/* Add it to the big list if it needs
* mro_isa_changed_in called on it. That happens if it was
* detached from the symbol table (so it had no HvENAME) before
* being assigned to the spot named by the ‘name’ variable, because
* its cached isa linearisation is now stale (the effective name
* having changed), and subclasses will then use that cache when
* mro_package_moved calls mro_isa_changed_in. (See