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/* sharedsv.c
*
* Copyright (c) 2001, Larry Wall
*
* You may distribute under the terms of either the GNU General Public
* License or the Artistic License, as specified in the README file.
*
*/
/*
* Contributed by Arthur Bergman arthur@contiller.se
*
* "Hand any two wizards a piece of rope and they would instinctively pull in
* opposite directions."
* --Sourcery
*
*/
#include "EXTERN.h"
#define PERL_IN_SHAREDSV_C
#include "perl.h"
#ifdef USE_ITHREADS
/*
Shared SV
Shared SV is a structure for keeping the backend storage
of shared svs.
*/
/*
=head1 Shared SV Functions
=for apidoc sharedsv_init
Saves a space for keeping SVs wider than an interpreter,
currently only stores a pointer to the first interpreter.
=cut
*/
void
Perl_sharedsv_init(pTHX)
{
PerlInterpreter* old_context = PERL_GET_CONTEXT;
PL_sharedsv_space = perl_alloc();
perl_construct(PL_sharedsv_space);
PERL_SET_CONTEXT(old_context);
MUTEX_INIT(&PL_sharedsv_space_mutex);
}
/*
=for apidoc sharedsv_new
Allocates a new shared sv struct, you must yourself create the SV/AV/HV.
=cut
*/
shared_sv *
Perl_sharedsv_new(pTHX)
{
shared_sv* ssv;
New(2555,ssv,1,shared_sv);
MUTEX_INIT(&ssv->mutex);
COND_INIT(&ssv->cond);
COND_INIT(&ssv->user_cond);
ssv->owner = 0;
ssv->locks = 0;
ssv->index = 0;
return ssv;
}
/*
=for apidoc sharedsv_find
Tries to find if a given SV has a shared backend, either by
looking at magic, or by checking if it is tied again threads::shared.
=cut
*/
shared_sv *
Perl_sharedsv_find(pTHX_ SV* sv)
{
/* does all it can to find a shared_sv struct, returns NULL otherwise */
shared_sv* ssv = NULL;
switch (SvTYPE(sv)) {
case SVt_PVMG:
case SVt_PVAV:
case SVt_PVHV: {
MAGIC* mg = mg_find(sv, PERL_MAGIC_ext);
if(mg) {
if(strcmp(mg->mg_ptr,"threads::shared"))
break;
ssv = INT2PTR(shared_sv *, SvIV(mg->mg_obj));
break;
}
mg = mg_find(sv,PERL_MAGIC_tied);
if(mg) {
SV* obj = SvTIED_obj(sv,mg);
if(sv_derived_from(obj, "threads::shared"))
ssv = INT2PTR(shared_sv *, SvIV(SvRV(obj)));
break;
}
}
}
return ssv;
}
/*
=for apidoc sharedsv_lock
Recursive locks on a sharedsv.
Locks are dynamically scoped at the level of the first lock.
=cut
*/
void
Perl_sharedsv_lock(pTHX_ shared_sv* ssv)
{
if(!ssv)
return;
MUTEX_LOCK(&ssv->mutex);
if(ssv->owner && ssv->owner == my_perl) {
ssv->locks++;
MUTEX_UNLOCK(&ssv->mutex);
return;
}
while(ssv->owner)
COND_WAIT(&ssv->cond,&ssv->mutex);
ssv->locks++;
ssv->owner = my_perl;
if(ssv->locks == 1)
SAVEDESTRUCTOR_X(Perl_sharedsv_unlock_scope,ssv);
MUTEX_UNLOCK(&ssv->mutex);
}
/*
=for apidoc sharedsv_unlock
Recursively unlocks a shared sv.
=cut
*/
void
Perl_sharedsv_unlock(pTHX_ shared_sv* ssv)
{
MUTEX_LOCK(&ssv->mutex);
if(ssv->owner != my_perl) {
Perl_croak(aTHX_ "panic: Perl_sharedsv_unlock unlocking mutex that we don't own");
MUTEX_UNLOCK(&ssv->mutex);
return;
}
if(--ssv->locks == 0) {
ssv->owner = NULL;
COND_SIGNAL(&ssv->cond);
}
MUTEX_UNLOCK(&ssv->mutex);
}
void
Perl_sharedsv_unlock_scope(pTHX_ shared_sv* ssv)
{
MUTEX_LOCK(&ssv->mutex);
if(ssv->owner != my_perl) {
MUTEX_UNLOCK(&ssv->mutex);
return;
}
ssv->locks = 0;
ssv->owner = NULL;
COND_SIGNAL(&ssv->cond);
MUTEX_UNLOCK(&ssv->mutex);
}
/*
=for apidoc sharedsv_thrcnt_inc
Increments the threadcount of a sharedsv.
=cut
*/
void
Perl_sharedsv_thrcnt_inc(pTHX_ shared_sv* ssv)
{
SHAREDSvLOCK(ssv);
SvREFCNT_inc(ssv->sv);
SHAREDSvUNLOCK(ssv);
}
/*
=for apidoc sharedsv_thrcnt_dec
Decrements the threadcount of a shared sv. When a threads frontend is freed
this function should be called.
=cut
*/
void
Perl_sharedsv_thrcnt_dec(pTHX_ shared_sv* ssv)
{
SV* sv;
SHAREDSvLOCK(ssv);
sv = SHAREDSvGET(ssv);
if (SvREFCNT(sv) == 1) {
switch (SvTYPE(sv)) {
case SVt_RV:
if (SvROK(sv))
Perl_sharedsv_thrcnt_dec(aTHX_ INT2PTR(shared_sv *, SvIV(SvRV(sv))));
break;
case SVt_PVAV: {
SV **src_ary = AvARRAY((AV *)sv);
SSize_t items = AvFILLp((AV *)sv) + 1;
while (items-- > 0) {
if(SvTYPE(*src_ary))
Perl_sharedsv_thrcnt_dec(aTHX_ INT2PTR(shared_sv *, SvIV(*src_ary)));
src_ary++;
}
break;
}
case SVt_PVHV: {
HE *entry;
(void)hv_iterinit((HV *)sv);
while ((entry = hv_iternext((HV *)sv)))
Perl_sharedsv_thrcnt_dec(
aTHX_ INT2PTR(shared_sv *, SvIV(hv_iterval((HV *)sv, entry)))
);
break;
}
}
}
Perl_sv_free(PL_sharedsv_space,SHAREDSvGET(ssv));
SHAREDSvUNLOCK(ssv);
}
#endif /* USE_ITHREADS */
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