Coro/Coro/State.xs

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include "libcoro/coro.c"

#ifdef HAVE_MMAP
# include <unistd.h>
# include <sys/mman.h>
#endif

#define MAY_FLUSH /* increases codesize */

#define SUB_INIT "Coro::State::initialize"

#define TRANSFER_SAVE_DEFAV     0x00000001
#define TRANSFER_SAVE_DEFSV     0x00000002
#define TRANSFER_SAVE_ERRSV     0x00000004
#define TRANSFER_SAVE_CCTXT     0x00000008

#define TRANSFER_SAVE_ALL       -1

struct coro {
  /* the optional C context */
  coro_context cctx;
  void *sptr;
  long ssize;

  /* optionally saved, might be zero */
  AV *defav;
  SV *defsv;
  SV *errsv;
  
  /* saved global state not related to stacks */
  U8 dowarn;

  /* the stacks and related info (callchain etc..) */
  PERL_SI *curstackinfo;
  AV *curstack;
  AV *mainstack;
  SV **stack_sp;
  OP *op;
  SV **curpad;
  SV **stack_base;
  SV **stack_max;
  SV **tmps_stack;
  I32 tmps_floor;
  I32 tmps_ix;
  I32 tmps_max;
  I32 *markstack;
  I32 *markstack_ptr;
  I32 *markstack_max;
  I32 *scopestack;
  I32 scopestack_ix;
  I32 scopestack_max;
  ANY *savestack;
  I32 savestack_ix;
  I32 savestack_max;
  OP **retstack;
  I32 retstack_ix;
  I32 retstack_max;
  COP *curcop;
  JMPENV start_env;
  JMPENV *top_env;

  /* data associated with this coroutine (initial args) */
  AV *args;
};

typedef struct coro *Coro__State;
typedef struct coro *Coro__State_or_hashref;

static AV *main_mainstack; /* used to differentiate between $main and others */
static HV *coro_state_stash;
static HV *padlist_cache;

/* mostly copied from op.c:cv_clone2 */
STATIC AV *
clone_padlist (AV *protopadlist)
{
  AV *av;
  I32 ix;
  AV *protopad_name = (AV *) * av_fetch (protopadlist, 0, FALSE);
  AV *protopad = (AV *) * av_fetch (protopadlist, 1, FALSE);
  SV **pname = AvARRAY (protopad_name);
  SV **ppad = AvARRAY (protopad);
  I32 fname = AvFILLp (protopad_name);
  I32 fpad = AvFILLp (protopad);
  AV *newpadlist, *newpad_name, *newpad;
  SV **npad;

  newpad_name = newAV ();
  for (ix = fname; ix >= 0; ix--)
    av_store (newpad_name, ix, SvREFCNT_inc (pname[ix]));

  newpad = newAV ();
  av_fill (newpad, AvFILLp (protopad));
  npad = AvARRAY (newpad);

  newpadlist = newAV ();
  AvREAL_off (newpadlist);
  av_store (newpadlist, 0, (SV *) newpad_name);
  av_store (newpadlist, 1, (SV *) newpad);

  av = newAV ();                /* will be @_ */
  av_extend (av, 0);
  av_store (newpad, 0, (SV *) av);
  AvFLAGS (av) = AVf_REIFY;

  for (ix = fpad; ix > 0; ix--)
    {
      SV *namesv = (ix <= fname) ? pname[ix] : Nullsv;
      if (namesv && namesv != &PL_sv_undef)
        {
          char *name = SvPVX (namesv);        /* XXX */
          if (SvFLAGS (namesv) & SVf_FAKE || *name == '&')
            {                        /* lexical from outside? */
              npad[ix] = SvREFCNT_inc (ppad[ix]);
            }
          else
            {                        /* our own lexical */
              SV *sv;
              if (*name == '&')
                sv = SvREFCNT_inc (ppad[ix]);
              else if (*name == '@')
                sv = (SV *) newAV ();
              else if (*name == '%')
                sv = (SV *) newHV ();
              else
                sv = NEWSV (0, 0);
              if (!SvPADBUSY (sv))
                SvPADMY_on (sv);
              npad[ix] = sv;
            }
        }
      else if (IS_PADGV (ppad[ix]) || IS_PADCONST (ppad[ix]))
        {
          npad[ix] = SvREFCNT_inc (ppad[ix]);
        }
      else
        {
          SV *sv = NEWSV (0, 0);
          SvPADTMP_on (sv);
          npad[ix] = sv;
        }
    }

#if 0 /* return -ENOTUNDERSTOOD */
    /* Now that vars are all in place, clone nested closures. */

    for (ix = fpad; ix > 0; ix--) {
        SV* namesv = (ix <= fname) ? pname[ix] : Nullsv;
        if (namesv
            && namesv != &PL_sv_undef
            && !(SvFLAGS(namesv) & SVf_FAKE)
            && *SvPVX(namesv) == '&'
            && CvCLONE(ppad[ix]))
        {
            CV *kid = cv_clone((CV*)ppad[ix]);
            SvREFCNT_dec(ppad[ix]);
            CvCLONE_on(kid);
            SvPADMY_on(kid);
            npad[ix] = (SV*)kid;
        }
    }
#endif

  return newpadlist;
}

#ifdef MAY_FLUSH
STATIC AV *
free_padlist (AV *padlist)
{
  /* may be during global destruction */
  if (SvREFCNT(padlist))
    {
      I32 i = AvFILLp(padlist);
      while (i >= 0)
        {
          SV **svp = av_fetch(padlist, i--, FALSE);
          SV *sv = svp ? *svp : Nullsv;
          if (sv)
            SvREFCNT_dec(sv);
        }

      SvREFCNT_dec((SV*)padlist);
  }
}
#endif

/* the next two functions merely cache the padlists */
STATIC void
get_padlist (CV *cv)
{
  SV **he = hv_fetch (padlist_cache, (void *)&cv, sizeof (CV *), 0);

  if (he && AvFILLp ((AV *)*he) >= 0)
    CvPADLIST (cv) = (AV *)av_pop ((AV *)*he);
  else
    CvPADLIST (cv) = clone_padlist (CvPADLIST (cv));
}

STATIC void
put_padlist (CV *cv)
{
  SV **he = hv_fetch (padlist_cache, (void *)&cv, sizeof (CV *), 1);

  if (SvTYPE (*he) != SVt_PVAV)
    {
      SvREFCNT_dec (*he);
      *he = (SV *)newAV ();
    }

  av_push ((AV *)*he, (SV *)CvPADLIST (cv));
}

#ifdef MAY_FLUSH
STATIC void
flush_padlist_cache ()
{
  HV *hv = padlist_cache;
  padlist_cache = newHV ();

  if (hv_iterinit (hv))
    {
      HE *he;
      AV *padlist;

      while (!!(he = hv_iternext (hv)))
        {
          AV *av = (AV *)HeVAL(he);

          /* casting is fun. */
          while (&PL_sv_undef != (SV *)(padlist = (AV *)av_pop (av)))
            free_padlist (padlist);
        }
    }

  SvREFCNT_dec (hv);
}
#endif

#define SB do {
#define SE } while (0)

#define LOAD(state)       SB load_state(aTHX_ (state)); SPAGAIN;         SE
#define SAVE(state,flags) SB PUTBACK; save_state(aTHX_ (state),(flags)); SE

#define REPLACE_SV(sv,val) SB SvREFCNT_dec(sv); (sv) = (val); SE

static void
load_state(pTHX_ Coro__State c)
{
  PL_dowarn = c->dowarn;

  PL_curstackinfo = c->curstackinfo;
  PL_curstack = c->curstack;
  PL_mainstack = c->mainstack;
  PL_stack_sp = c->stack_sp;
  PL_op = c->op;
  PL_curpad = c->curpad;
  PL_stack_base = c->stack_base;
  PL_stack_max = c->stack_max;
  PL_tmps_stack = c->tmps_stack;
  PL_tmps_floor = c->tmps_floor;
  PL_tmps_ix = c->tmps_ix;
  PL_tmps_max = c->tmps_max;
  PL_markstack = c->markstack;
  PL_markstack_ptr = c->markstack_ptr;
  PL_markstack_max = c->markstack_max;
  PL_scopestack = c->scopestack;
  PL_scopestack_ix = c->scopestack_ix;
  PL_scopestack_max = c->scopestack_max;
  PL_savestack = c->savestack;
  PL_savestack_ix = c->savestack_ix;
  PL_savestack_max = c->savestack_max;
  PL_retstack = c->retstack;
  PL_retstack_ix = c->retstack_ix;
  PL_retstack_max = c->retstack_max;
  PL_curcop = c->curcop;
  PL_start_env = c->start_env;
  PL_top_env = c->top_env;

  if (c->defav) REPLACE_SV (GvAV (PL_defgv), c->defav);
  if (c->defsv) REPLACE_SV (DEFSV          , c->defsv);
  if (c->errsv) REPLACE_SV (ERRSV          , c->errsv);

  {
    dSP;
    CV *cv;

    /* now do the ugly restore mess */
    while ((cv = (CV *)POPs))
      {
        AV *padlist = (AV *)POPs;

        if (padlist)
          {
            put_padlist (cv); /* mark this padlist as available */
            CvPADLIST(cv) = padlist;
#ifdef USE_THREADS
            /*CvOWNER(cv) = (struct perl_thread *)POPs;*/
#endif
          }

        ++CvDEPTH(cv);
      }

    PUTBACK;
  }
}

static void
save_state(pTHX_ Coro__State c, int flags)
{
  {
    dSP;
    I32 cxix = cxstack_ix;
    PERL_CONTEXT *ccstk = cxstack;
    PERL_SI *top_si = PL_curstackinfo;

    /*
     * the worst thing you can imagine happens first - we have to save
     * (and reinitialize) all cv's in the whole callchain :(
     */

    PUSHs (Nullsv);
    /* this loop was inspired by pp_caller */
    for (;;)
      {
        do
          {
            PERL_CONTEXT *cx = &ccstk[cxix--];

            if (CxTYPE(cx) == CXt_SUB)
              {
                CV *cv = cx->blk_sub.cv;
                if (CvDEPTH(cv))
                  {
#ifdef USE_THREADS
                    /*XPUSHs ((SV *)CvOWNER(cv));*/
                    /*CvOWNER(cv) = 0;*/
                    /*error must unlock this cv etc.. etc...*/
#endif
                    EXTEND (SP, CvDEPTH(cv)*2);

                    while (--CvDEPTH(cv))
                      {
                        /* this tells the restore code to increment CvDEPTH */
                        PUSHs (Nullsv);
                        PUSHs ((SV *)cv);
                      }

                    PUSHs ((SV *)CvPADLIST(cv));
                    PUSHs ((SV *)cv);

                    get_padlist (cv); /* this is a monster */
                  }
              }
            else if (CxTYPE(cx) == CXt_FORMAT)
              {
                /* I never used formats, so how should I know how these are implemented? */
                /* my bold guess is as a simple, plain sub... */
                croak ("CXt_FORMAT not yet handled. Don't switch coroutines from within formats");
              }
          }
        while (cxix >= 0);

        if (top_si->si_type == PERLSI_MAIN)
          break;

        top_si = top_si->si_prev;
        ccstk = top_si->si_cxstack;
        cxix = top_si->si_cxix;
      }

    PUTBACK;
  }

  c->defav = flags & TRANSFER_SAVE_DEFAV ? (AV *)SvREFCNT_inc (GvAV (PL_defgv)) : 0;
  c->defsv = flags & TRANSFER_SAVE_DEFSV ?       SvREFCNT_inc (DEFSV)           : 0;
  c->errsv = flags & TRANSFER_SAVE_ERRSV ?       SvREFCNT_inc (ERRSV)           : 0;

  /* I have not the slightest idea of why av_reify is necessary */
  /* but if it's missing the defav contents magically get replaced sometimes */
  if (c->defav)
    av_reify (c->defav);

  c->dowarn = PL_dowarn;

  c->curstackinfo = PL_curstackinfo;
  c->curstack = PL_curstack;
  c->mainstack = PL_mainstack;
  c->stack_sp = PL_stack_sp;
  c->op = PL_op;
  c->curpad = PL_curpad;
  c->stack_base = PL_stack_base;
  c->stack_max = PL_stack_max;
  c->tmps_stack = PL_tmps_stack;
  c->tmps_floor = PL_tmps_floor;
  c->tmps_ix = PL_tmps_ix;
  c->tmps_max = PL_tmps_max;
  c->markstack = PL_markstack;
  c->markstack_ptr = PL_markstack_ptr;
  c->markstack_max = PL_markstack_max;
  c->scopestack = PL_scopestack;
  c->scopestack_ix = PL_scopestack_ix;
  c->scopestack_max = PL_scopestack_max;
  c->savestack = PL_savestack;
  c->savestack_ix = PL_savestack_ix;
  c->savestack_max = PL_savestack_max;
  c->retstack = PL_retstack;
  c->retstack_ix = PL_retstack_ix;
  c->retstack_max = PL_retstack_max;
  c->curcop = PL_curcop;
  c->start_env = PL_start_env;
  c->top_env = PL_top_env;
}

/*
 * allocate various perl stacks. This is an exact copy
 * of perl.c:init_stacks, except that it uses less memory
 * on the assumption that coroutines do not usually need
 * a lot of stackspace.
 */
STATIC void
coro_init_stacks (pTHX)
{
    PL_curstackinfo = new_stackinfo(96, 1024/sizeof(PERL_CONTEXT) - 1);
    PL_curstackinfo->si_type = PERLSI_MAIN;
    PL_curstack = PL_curstackinfo->si_stack;
    PL_mainstack = PL_curstack;         /* remember in case we switch stacks */

    PL_stack_base = AvARRAY(PL_curstack);
    PL_stack_sp = PL_stack_base;
    PL_stack_max = PL_stack_base + AvMAX(PL_curstack);

    New(50,PL_tmps_stack,64,SV*);
    PL_tmps_floor = -1;
    PL_tmps_ix = -1;
    PL_tmps_max = 64;

    New(54,PL_markstack,12,I32);
    PL_markstack_ptr = PL_markstack;
    PL_markstack_max = PL_markstack + 12;

    SET_MARK_OFFSET;

    New(54,PL_scopestack,12,I32);
    PL_scopestack_ix = 0;
    PL_scopestack_max = 12;

    New(54,PL_savestack,64,ANY);
    PL_savestack_ix = 0;
    PL_savestack_max = 64;

    New(54,PL_retstack,8,OP*);
    PL_retstack_ix = 0;
    PL_retstack_max = 8;
}

/*
 * destroy the stacks, the callchain etc...
 * still there is a memleak of 128 bytes...
 */
STATIC void
destroy_stacks(pTHX)
{
  /* is this ugly, I ask? */
  while (PL_scopestack_ix)
    LEAVE;

  /* sure it is, but more important: is it correct?? :/ */
  while (PL_tmps_ix > PL_tmps_floor) /* should only ever be one iteration */
    FREETMPS;

  while (PL_curstackinfo->si_next)
    PL_curstackinfo = PL_curstackinfo->si_next;

  while (PL_curstackinfo)
    {
      PERL_SI *p = PL_curstackinfo->si_prev;

      {
        dSP;
        SWITCHSTACK (PL_curstack, PL_curstackinfo->si_stack);
        PUTBACK; /* possibly superfluous */
      }

      dounwind(-1);

      SvREFCNT_dec(PL_curstackinfo->si_stack);
      Safefree(PL_curstackinfo->si_cxstack);
      Safefree(PL_curstackinfo);
      PL_curstackinfo = p;
  }

  Safefree(PL_tmps_stack);
  Safefree(PL_markstack);
  Safefree(PL_scopestack);
  Safefree(PL_savestack);
  Safefree(PL_retstack);
}

static void
allocate_stack (Coro__State ctx)
{
#ifdef HAVE_MMAP 
  ctx->ssize = 128 * 1024 * sizeof (long); /* mmap should do allocate-on-use */
  ctx->sptr = mmap (0, ctx->ssize, PROT_EXEC|PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, 0, 0);
  if (ctx->sptr == (void *)-1)
#endif
    {
      /*FIXME*//*D*//* reasonable stack size! */
      ctx->ssize = 4096 * sizeof (long);
      New (0, ctx->sptr, 4096, long);
    }
}

static void
deallocate_stack (Coro__State ctx)
{
#ifdef HAVE_MMAP
  munmap (ctx->sptr, ctx->ssize);
#else
  Safefree (ctx->sptr);
#endif
}

/* might go away together with optional SAVE_CCTXT */
static void
setup_coro (void *arg)
{
  /*
   * emulate part of the perl startup here.
   */
  dSP;
  Coro__State ctx = (Coro__State)arg;
  SV *sub_init = (SV*)get_cv(SUB_INIT, FALSE);

  coro_init_stacks (aTHX);
  JMPENV_BOOTSTRAP;
  SPAGAIN;

  /*PL_curcop = 0;*/
  SvREFCNT_dec (GvAV (PL_defgv));
  GvAV (PL_defgv) = ctx->args;

  if (ctx->sptr)
    {
      PUSHMARK(SP);
      PUTBACK;
      (void) call_sv (sub_init, G_VOID|G_NOARGS);
      croak ("FATAL: CCTXT coroutine returned!");
    }
  else
    {
      UNOP myop;

      PL_op = (OP *)&myop;

      Zero(&myop, 1, UNOP);
      myop.op_next = Nullop;
      myop.op_flags = OPf_WANT_VOID;

      PUSHMARK(SP);
      XPUSHs (sub_init);
      /*
       * the next line is slightly wrong, as PL_op->op_next
       * is actually being executed so we skip the first op.
       * that doesn't matter, though, since it is only
       * pp_nextstate and we never return...
       * ah yes, and I don't care anyways ;)
       */
      PUTBACK;
      PL_op = pp_entersub();
      SPAGAIN;

      ENTER; /* necessary e.g. for dounwind */
    }
}

STATIC void
transfer(pTHX_ struct coro *prev, struct coro *next, int flags)
{
  dSP;

  if (prev != next)
    {
      /*
       * this could be done in newprocess which would lead to
       * extremely elegant and fast (basically just SAVE/LOAD)
       * code here, but lazy allocation of stacks has also
       * some virtues and the overhead of the if() is nil.
       */
      if (next->mainstack)
        {
          SAVE (prev, flags);
          LOAD (next);

          /* mark this state as in-use */
          next->mainstack = 0;
          next->tmps_ix = -2;

          if (flags & TRANSFER_SAVE_CCTXT)
            {
              if (!next->ssize)
                croak ("destination coroutine has no CCTXT (%p, %d)", next->sptr, next->ssize);

              if (!prev->ssize)
                prev->ssize = 1; /* mark cctx as valid ;) */

              coro_transfer (&(prev->cctx), &(next->cctx));
            }

        }
      else if (next->tmps_ix == -2)
        croak ("tried to transfer to running coroutine");
      else
        {
          SAVE (prev, -1); /* first get rid of the old state */

          if (flags & TRANSFER_SAVE_CCTXT)
            {
              if (!next->ssize)
                {
                  allocate_stack (next);
                  coro_create (&(next->cctx),
                               setup_coro, (void *)next,
                               next->sptr, next->ssize);
                }

              if (!prev->ssize)
                prev->ssize = 1; /* mark cctx as valid ;) */

              coro_transfer (&(prev->cctx), &(next->cctx));
            }
          else
            setup_coro (next);
        }
    }
}

MODULE = Coro::State                PACKAGE = Coro::State

PROTOTYPES: ENABLE

BOOT:
{       /* {} necessary for stoopid perl-5.6.x */
        coro_state_stash = gv_stashpvn ("Coro::State", 10, TRUE);

        newCONSTSUB (coro_state_stash, "SAVE_DEFAV", newSViv (TRANSFER_SAVE_DEFAV));
        newCONSTSUB (coro_state_stash, "SAVE_DEFSV", newSViv (TRANSFER_SAVE_DEFSV));
        newCONSTSUB (coro_state_stash, "SAVE_ERRSV", newSViv (TRANSFER_SAVE_ERRSV));
        newCONSTSUB (coro_state_stash, "SAVE_CCTXT", newSViv (TRANSFER_SAVE_CCTXT));

        if (!padlist_cache)
          padlist_cache = newHV ();

        main_mainstack = PL_mainstack;
}

Coro::State
_newprocess(args)
        SV *    args
        PROTOTYPE: $
        CODE:
        Coro__State coro;

        if (!SvROK (args) || SvTYPE (SvRV (args)) != SVt_PVAV)
          croak ("Coro::State::_newprocess expects an arrayref");
        
        New (0, coro, 1, struct coro);

        coro->args = (AV *)SvREFCNT_inc (SvRV (args));
        coro->mainstack = 0; /* actual work is done inside transfer */
        coro->sptr = 0;
        coro->ssize = 0;

        RETVAL = coro;
        OUTPUT:
        RETVAL

void
transfer(prev, next, flags = TRANSFER_SAVE_ALL)
        Coro::State_or_hashref  prev
        Coro::State_or_hashref  next
        int                     flags
        PROTOTYPE: @
        CODE:
        transfer (aTHX_ prev, next, flags);

void
DESTROY(coro)
        Coro::State     coro
        CODE:

        if (coro->mainstack && coro->mainstack != main_mainstack)
          {
            struct coro temp;

            SAVE(aTHX_ (&temp), TRANSFER_SAVE_ALL);
            LOAD(aTHX_ coro);

            destroy_stacks (aTHX);

            LOAD((&temp)); /* this will get rid of defsv etc.. */

            coro->mainstack = 0;
          }

        if (coro->sptr)
          {
            deallocate_stack (coro);
            coro->sptr = 0;
          }

        Safefree (coro);

void
flush()
        CODE:
#ifdef MAY_FLUSH
        flush_padlist_cache ();
#endif

MODULE = Coro::State                PACKAGE = Coro::Cont

# this is slightly dirty

void
yield(...)
        PROTOTYPE: @
        CODE:
        static SV *returnstk;
        SV *sv;
        AV *defav = GvAV (PL_defgv);
        struct coro *prev, *next;

        if (!returnstk)
          returnstk = SvRV (get_sv ("Coro::Cont::return", FALSE));

        /* set up @_ -- ugly */
        av_clear (defav);
        av_fill (defav, items - 1);
        while (items--)
          av_store (defav, items, SvREFCNT_inc (ST(items)));

        mg_get (returnstk); /* isn't documentation wrong for mg_get? */
        sv = av_pop ((AV *)SvRV (returnstk));
        prev = (struct coro *)SvIV ((SV*)SvRV (*av_fetch ((AV *)SvRV (sv), 0, 0)));
        next = (struct coro *)SvIV ((SV*)SvRV (*av_fetch ((AV *)SvRV (sv), 1, 0)));
        SvREFCNT_dec (sv);

        transfer(aTHX_ prev, next, 0);

Revision:	1.13
Committed:	Mon Jul 23 22:09:39 2001 UTC (22 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.12:	+191 -78 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	#include "EXTERN.h"
2			#include "perl.h"
3			#include "XSUB.h"
4
5	root	1.13	#include "libcoro/coro.c"
6
7			#ifdef HAVE_MMAP
8			# include <unistd.h>
9			# include <sys/mman.h>
10	root	1.3	#endif
11
12	root	1.7	#define MAY_FLUSH /* increases codesize */
13
14	root	1.11	#define SUB_INIT "Coro::State::initialize"
15	root	1.8
16	root	1.12	#define TRANSFER_SAVE_DEFAV 0x00000001
17			#define TRANSFER_SAVE_DEFSV 0x00000002
18			#define TRANSFER_SAVE_ERRSV 0x00000004
19	root	1.13	#define TRANSFER_SAVE_CCTXT 0x00000008
20	root	1.7
21	root	1.12	#define TRANSFER_SAVE_ALL -1
22	root	1.7
23	root	1.1	struct coro {
24	root	1.13	/* the optional C context */
25			coro_context cctx;
26			void *sptr;
27			long ssize;
28
29	root	1.7	/* optionally saved, might be zero */
30	root	1.3	AV *defav;
31	root	1.7	SV *defsv;
32			SV *errsv;
33	root	1.1
34	root	1.7	/* saved global state not related to stacks */
35			U8 dowarn;
36
37			/* the stacks and related info (callchain etc..) */
38	root	1.1	PERL_SI *curstackinfo;
39			AV *curstack;
40			AV *mainstack;
41			SV **stack_sp;
42			OP *op;
43			SV **curpad;
44			SV **stack_base;
45			SV **stack_max;
46			SV **tmps_stack;
47			I32 tmps_floor;
48			I32 tmps_ix;
49			I32 tmps_max;
50			I32 *markstack;
51			I32 *markstack_ptr;
52			I32 *markstack_max;
53			I32 *scopestack;
54			I32 scopestack_ix;
55			I32 scopestack_max;
56			ANY *savestack;
57			I32 savestack_ix;
58			I32 savestack_max;
59			OP **retstack;
60			I32 retstack_ix;
61			I32 retstack_max;
62			COP *curcop;
63	root	1.13	JMPENV start_env;
64			JMPENV *top_env;
65	root	1.1
66	root	1.7	/* data associated with this coroutine (initial args) */
67	root	1.3	AV *args;
68	root	1.1	};
69
70			typedef struct coro *Coro__State;
71			typedef struct coro *Coro__State_or_hashref;
72
73	root	1.12	static AV main_mainstack; / used to differentiate between $main and others */
74	root	1.13	static HV *coro_state_stash;
75	root	1.3	static HV *padlist_cache;
76
77			/* mostly copied from op.c:cv_clone2 */
78			STATIC AV *
79			clone_padlist (AV *protopadlist)
80			{
81			AV *av;
82			I32 ix;
83			AV protopad_name = (AV ) * av_fetch (protopadlist, 0, FALSE);
84			AV protopad = (AV ) * av_fetch (protopadlist, 1, FALSE);
85			SV **pname = AvARRAY (protopad_name);
86			SV **ppad = AvARRAY (protopad);
87			I32 fname = AvFILLp (protopad_name);
88			I32 fpad = AvFILLp (protopad);
89			AV newpadlist, newpad_name, *newpad;
90			SV **npad;
91
92			newpad_name = newAV ();
93			for (ix = fname; ix >= 0; ix--)
94			av_store (newpad_name, ix, SvREFCNT_inc (pname[ix]));
95
96			newpad = newAV ();
97			av_fill (newpad, AvFILLp (protopad));
98			npad = AvARRAY (newpad);
99
100			newpadlist = newAV ();
101			AvREAL_off (newpadlist);
102			av_store (newpadlist, 0, (SV *) newpad_name);
103			av_store (newpadlist, 1, (SV *) newpad);
104
105			av = newAV (); /* will be @_ */
106			av_extend (av, 0);
107			av_store (newpad, 0, (SV *) av);
108			AvFLAGS (av) = AVf_REIFY;
109
110			for (ix = fpad; ix > 0; ix--)
111			{
112			SV *namesv = (ix <= fname) ? pname[ix] : Nullsv;
113			if (namesv && namesv != &PL_sv_undef)
114			{
115			char name = SvPVX (namesv); / XXX */
116			if (SvFLAGS (namesv) & SVf_FAKE \|\| *name == '&')
117			{ /* lexical from outside? */
118			npad[ix] = SvREFCNT_inc (ppad[ix]);
119			}
120			else
121			{ /* our own lexical */
122			SV *sv;
123			if (*name == '&')
124			sv = SvREFCNT_inc (ppad[ix]);
125			else if (*name == '@')
126			sv = (SV *) newAV ();
127			else if (*name == '%')
128			sv = (SV *) newHV ();
129			else
130			sv = NEWSV (0, 0);
131			if (!SvPADBUSY (sv))
132			SvPADMY_on (sv);
133			npad[ix] = sv;
134			}
135			}
136			else if (IS_PADGV (ppad[ix]) \|\| IS_PADCONST (ppad[ix]))
137			{
138			npad[ix] = SvREFCNT_inc (ppad[ix]);
139			}
140			else
141			{
142			SV *sv = NEWSV (0, 0);
143			SvPADTMP_on (sv);
144			npad[ix] = sv;
145			}
146			}
147
148	root	1.7	#if 0 /* return -ENOTUNDERSTOOD */
149	root	1.3	/* Now that vars are all in place, clone nested closures. */
150
151			for (ix = fpad; ix > 0; ix--) {
152			SV* namesv = (ix <= fname) ? pname[ix] : Nullsv;
153			if (namesv
154			&& namesv != &PL_sv_undef
155			&& !(SvFLAGS(namesv) & SVf_FAKE)
156			&& *SvPVX(namesv) == '&'
157			&& CvCLONE(ppad[ix]))
158			{
159			CV kid = cv_clone((CV)ppad[ix]);
160			SvREFCNT_dec(ppad[ix]);
161			CvCLONE_on(kid);
162			SvPADMY_on(kid);
163			npad[ix] = (SV*)kid;
164			}
165			}
166			#endif
167
168			return newpadlist;
169			}
170
171	root	1.7	#ifdef MAY_FLUSH
172	root	1.3	STATIC AV *
173			free_padlist (AV *padlist)
174			{
175			/* may be during global destruction */
176			if (SvREFCNT(padlist))
177			{
178			I32 i = AvFILLp(padlist);
179			while (i >= 0)
180			{
181			SV **svp = av_fetch(padlist, i--, FALSE);
182			SV sv = svp ? svp : Nullsv;
183			if (sv)
184			SvREFCNT_dec(sv);
185			}
186
187			SvREFCNT_dec((SV*)padlist);
188			}
189			}
190	root	1.7	#endif
191	root	1.3
192	root	1.7	/* the next two functions merely cache the padlists */
193	root	1.4	STATIC void
194			get_padlist (CV *cv)
195	root	1.3	{
196	root	1.4	SV *he = hv_fetch (padlist_cache, (void )&cv, sizeof (CV *), 0);
197
198			if (he && AvFILLp ((AV )he) >= 0)
199			CvPADLIST (cv) = (AV )av_pop ((AV )*he);
200			else
201			CvPADLIST (cv) = clone_padlist (CvPADLIST (cv));
202			}
203
204			STATIC void
205			put_padlist (CV *cv)
206			{
207			SV *he = hv_fetch (padlist_cache, (void )&cv, sizeof (CV *), 1);
208
209			if (SvTYPE (*he) != SVt_PVAV)
210			{
211			SvREFCNT_dec (*he);
212			he = (SV )newAV ();
213			}
214
215			av_push ((AV )he, (SV *)CvPADLIST (cv));
216	root	1.3	}
217
218	root	1.7	#ifdef MAY_FLUSH
219			STATIC void
220			flush_padlist_cache ()
221			{
222			HV *hv = padlist_cache;
223			padlist_cache = newHV ();
224
225			if (hv_iterinit (hv))
226			{
227			HE *he;
228			AV *padlist;
229
230			while (!!(he = hv_iternext (hv)))
231			{
232			AV av = (AV )HeVAL(he);
233
234			/* casting is fun. */
235			while (&PL_sv_undef != (SV )(padlist = (AV )av_pop (av)))
236			free_padlist (padlist);
237			}
238			}
239
240			SvREFCNT_dec (hv);
241			}
242			#endif
243
244			#define SB do {
245			#define SE } while (0)
246
247	root	1.13	#define LOAD(state) SB load_state(aTHX_ (state)); SPAGAIN; SE
248			#define SAVE(state,flags) SB PUTBACK; save_state(aTHX_ (state),(flags)); SE
249	root	1.7
250			#define REPLACE_SV(sv,val) SB SvREFCNT_dec(sv); (sv) = (val); SE
251
252			static void
253			load_state(pTHX_ Coro__State c)
254			{
255			PL_dowarn = c->dowarn;
256
257			PL_curstackinfo = c->curstackinfo;
258			PL_curstack = c->curstack;
259			PL_mainstack = c->mainstack;
260			PL_stack_sp = c->stack_sp;
261			PL_op = c->op;
262			PL_curpad = c->curpad;
263			PL_stack_base = c->stack_base;
264			PL_stack_max = c->stack_max;
265			PL_tmps_stack = c->tmps_stack;
266			PL_tmps_floor = c->tmps_floor;
267			PL_tmps_ix = c->tmps_ix;
268			PL_tmps_max = c->tmps_max;
269			PL_markstack = c->markstack;
270			PL_markstack_ptr = c->markstack_ptr;
271			PL_markstack_max = c->markstack_max;
272			PL_scopestack = c->scopestack;
273			PL_scopestack_ix = c->scopestack_ix;
274			PL_scopestack_max = c->scopestack_max;
275			PL_savestack = c->savestack;
276			PL_savestack_ix = c->savestack_ix;
277			PL_savestack_max = c->savestack_max;
278			PL_retstack = c->retstack;
279			PL_retstack_ix = c->retstack_ix;
280			PL_retstack_max = c->retstack_max;
281			PL_curcop = c->curcop;
282	root	1.13	PL_start_env = c->start_env;
283			PL_top_env = c->top_env;
284	root	1.7
285			if (c->defav) REPLACE_SV (GvAV (PL_defgv), c->defav);
286			if (c->defsv) REPLACE_SV (DEFSV , c->defsv);
287			if (c->errsv) REPLACE_SV (ERRSV , c->errsv);
288
289			{
290			dSP;
291			CV *cv;
292
293			/* now do the ugly restore mess */
294			while ((cv = (CV *)POPs))
295			{
296			AV padlist = (AV )POPs;
297
298			if (padlist)
299			{
300			put_padlist (cv); /* mark this padlist as available */
301			CvPADLIST(cv) = padlist;
302			#ifdef USE_THREADS
303			/CvOWNER(cv) = (struct perl_thread )POPs;*/
304			#endif
305			}
306
307			++CvDEPTH(cv);
308			}
309
310			PUTBACK;
311			}
312			}
313
314	root	1.3	static void
315	root	1.7	save_state(pTHX_ Coro__State c, int flags)
316	root	1.3	{
317			{
318			dSP;
319			I32 cxix = cxstack_ix;
320	root	1.11	PERL_CONTEXT *ccstk = cxstack;
321	root	1.3	PERL_SI *top_si = PL_curstackinfo;
322
323			/*
324			* the worst thing you can imagine happens first - we have to save
325			* (and reinitialize) all cv's in the whole callchain :(
326			*/
327
328			PUSHs (Nullsv);
329			/* this loop was inspired by pp_caller */
330			for (;;)
331			{
332	root	1.11	do
333	root	1.3	{
334	root	1.4	PERL_CONTEXT *cx = &ccstk[cxix--];
335	root	1.3
336			if (CxTYPE(cx) == CXt_SUB)
337			{
338			CV *cv = cx->blk_sub.cv;
339			if (CvDEPTH(cv))
340			{
341			#ifdef USE_THREADS
342	root	1.7	/XPUSHs ((SV )CvOWNER(cv));*/
343			/CvOWNER(cv) = 0;/
344			/error must unlock this cv etc.. etc.../
345	root	1.3	#endif
346	root	1.7	EXTEND (SP, CvDEPTH(cv)*2);
347
348			while (--CvDEPTH(cv))
349			{
350			/* this tells the restore code to increment CvDEPTH */
351			PUSHs (Nullsv);
352			PUSHs ((SV *)cv);
353			}
354
355	root	1.3	PUSHs ((SV *)CvPADLIST(cv));
356			PUSHs ((SV *)cv);
357
358	root	1.7	get_padlist (cv); /* this is a monster */
359	root	1.3	}
360			}
361			else if (CxTYPE(cx) == CXt_FORMAT)
362			{
363			/* I never used formats, so how should I know how these are implemented? */
364			/* my bold guess is as a simple, plain sub... */
365			croak ("CXt_FORMAT not yet handled. Don't switch coroutines from within formats");
366			}
367			}
368	root	1.7	while (cxix >= 0);
369	root	1.3
370			if (top_si->si_type == PERLSI_MAIN)
371			break;
372
373			top_si = top_si->si_prev;
374			ccstk = top_si->si_cxstack;
375			cxix = top_si->si_cxix;
376			}
377
378			PUTBACK;
379			}
380
381	root	1.12	c->defav = flags & TRANSFER_SAVE_DEFAV ? (AV *)SvREFCNT_inc (GvAV (PL_defgv)) : 0;
382			c->defsv = flags & TRANSFER_SAVE_DEFSV ? SvREFCNT_inc (DEFSV) : 0;
383			c->errsv = flags & TRANSFER_SAVE_ERRSV ? SvREFCNT_inc (ERRSV) : 0;
384	root	1.7
385	root	1.11	/* I have not the slightest idea of why av_reify is necessary */
386			/* but if it's missing the defav contents magically get replaced sometimes */
387			if (c->defav)
388			av_reify (c->defav);
389
390	root	1.3	c->dowarn = PL_dowarn;
391	root	1.7
392	root	1.3	c->curstackinfo = PL_curstackinfo;
393			c->curstack = PL_curstack;
394			c->mainstack = PL_mainstack;
395			c->stack_sp = PL_stack_sp;
396			c->op = PL_op;
397			c->curpad = PL_curpad;
398			c->stack_base = PL_stack_base;
399			c->stack_max = PL_stack_max;
400			c->tmps_stack = PL_tmps_stack;
401			c->tmps_floor = PL_tmps_floor;
402			c->tmps_ix = PL_tmps_ix;
403			c->tmps_max = PL_tmps_max;
404			c->markstack = PL_markstack;
405			c->markstack_ptr = PL_markstack_ptr;
406			c->markstack_max = PL_markstack_max;
407			c->scopestack = PL_scopestack;
408			c->scopestack_ix = PL_scopestack_ix;
409			c->scopestack_max = PL_scopestack_max;
410			c->savestack = PL_savestack;
411			c->savestack_ix = PL_savestack_ix;
412			c->savestack_max = PL_savestack_max;
413			c->retstack = PL_retstack;
414			c->retstack_ix = PL_retstack_ix;
415			c->retstack_max = PL_retstack_max;
416			c->curcop = PL_curcop;
417	root	1.13	c->start_env = PL_start_env;
418			c->top_env = PL_top_env;
419			}
420
421			/*
422			* allocate various perl stacks. This is an exact copy
423			* of perl.c:init_stacks, except that it uses less memory
424			* on the assumption that coroutines do not usually need
425			* a lot of stackspace.
426			*/
427			STATIC void
428			coro_init_stacks (pTHX)
429			{
430			PL_curstackinfo = new_stackinfo(96, 1024/sizeof(PERL_CONTEXT) - 1);
431			PL_curstackinfo->si_type = PERLSI_MAIN;
432			PL_curstack = PL_curstackinfo->si_stack;
433			PL_mainstack = PL_curstack; /* remember in case we switch stacks */
434
435			PL_stack_base = AvARRAY(PL_curstack);
436			PL_stack_sp = PL_stack_base;
437			PL_stack_max = PL_stack_base + AvMAX(PL_curstack);
438
439			New(50,PL_tmps_stack,64,SV*);
440			PL_tmps_floor = -1;
441			PL_tmps_ix = -1;
442			PL_tmps_max = 64;
443
444			New(54,PL_markstack,12,I32);
445			PL_markstack_ptr = PL_markstack;
446			PL_markstack_max = PL_markstack + 12;
447
448			SET_MARK_OFFSET;
449
450			New(54,PL_scopestack,12,I32);
451			PL_scopestack_ix = 0;
452			PL_scopestack_max = 12;
453
454			New(54,PL_savestack,64,ANY);
455			PL_savestack_ix = 0;
456			PL_savestack_max = 64;
457
458			New(54,PL_retstack,8,OP*);
459			PL_retstack_ix = 0;
460			PL_retstack_max = 8;
461	root	1.3	}
462	root	1.1
463	root	1.7	/*
464			* destroy the stacks, the callchain etc...
465			* still there is a memleak of 128 bytes...
466			*/
467	root	1.1	STATIC void
468	root	1.4	destroy_stacks(pTHX)
469	root	1.1	{
470	root	1.4	/* is this ugly, I ask? */
471			while (PL_scopestack_ix)
472			LEAVE;
473
474	root	1.7	/* sure it is, but more important: is it correct?? :/ */
475			while (PL_tmps_ix > PL_tmps_floor) /* should only ever be one iteration */
476			FREETMPS;
477
478	root	1.4	while (PL_curstackinfo->si_next)
479			PL_curstackinfo = PL_curstackinfo->si_next;
480
481			while (PL_curstackinfo)
482			{
483			PERL_SI *p = PL_curstackinfo->si_prev;
484
485	root	1.7	{
486			dSP;
487			SWITCHSTACK (PL_curstack, PL_curstackinfo->si_stack);
488			PUTBACK; /* possibly superfluous */
489			}
490
491			dounwind(-1);
492
493	root	1.4	SvREFCNT_dec(PL_curstackinfo->si_stack);
494			Safefree(PL_curstackinfo->si_cxstack);
495			Safefree(PL_curstackinfo);
496			PL_curstackinfo = p;
497			}
498
499			Safefree(PL_tmps_stack);
500			Safefree(PL_markstack);
501			Safefree(PL_scopestack);
502			Safefree(PL_savestack);
503			Safefree(PL_retstack);
504	root	1.1	}
505
506	root	1.13	static void
507			allocate_stack (Coro__State ctx)
508			{
509			#ifdef HAVE_MMAP
510			ctx->ssize = 128 * 1024 * sizeof (long); /* mmap should do allocate-on-use */
511			ctx->sptr = mmap (0, ctx->ssize, PROT_EXEC\|PROT_READ\|PROT_WRITE, MAP_PRIVATE\|MAP_ANON, 0, 0);
512			if (ctx->sptr == (void *)-1)
513			#endif
514			{
515			/FIXME//D//* reasonable stack size! */
516			ctx->ssize = 4096 * sizeof (long);
517			New (0, ctx->sptr, 4096, long);
518			}
519			}
520
521			static void
522			deallocate_stack (Coro__State ctx)
523			{
524			#ifdef HAVE_MMAP
525			munmap (ctx->sptr, ctx->ssize);
526			#else
527			Safefree (ctx->sptr);
528			#endif
529			}
530
531			/* might go away together with optional SAVE_CCTXT */
532			static void
533			setup_coro (void *arg)
534			{
535			/*
536			* emulate part of the perl startup here.
537			*/
538			dSP;
539			Coro__State ctx = (Coro__State)arg;
540			SV sub_init = (SV)get_cv(SUB_INIT, FALSE);
541
542			coro_init_stacks (aTHX);
543			JMPENV_BOOTSTRAP;
544			SPAGAIN;
545
546			/PL_curcop = 0;/
547			SvREFCNT_dec (GvAV (PL_defgv));
548			GvAV (PL_defgv) = ctx->args;
549
550			if (ctx->sptr)
551			{
552			PUSHMARK(SP);
553			PUTBACK;
554			(void) call_sv (sub_init, G_VOID\|G_NOARGS);
555			croak ("FATAL: CCTXT coroutine returned!");
556			}
557			else
558			{
559			UNOP myop;
560
561			PL_op = (OP *)&myop;
562
563			Zero(&myop, 1, UNOP);
564			myop.op_next = Nullop;
565			myop.op_flags = OPf_WANT_VOID;
566
567			PUSHMARK(SP);
568			XPUSHs (sub_init);
569			/*
570			* the next line is slightly wrong, as PL_op->op_next
571			* is actually being executed so we skip the first op.
572			* that doesn't matter, though, since it is only
573			* pp_nextstate and we never return...
574			* ah yes, and I don't care anyways ;)
575			*/
576			PUTBACK;
577			PL_op = pp_entersub();
578			SPAGAIN;
579
580			ENTER; /* necessary e.g. for dounwind */
581			}
582			}
583
584	root	1.8	STATIC void
585			transfer(pTHX_ struct coro prev, struct coro next, int flags)
586			{
587			dSP;
588
589			if (prev != next)
590			{
591			/*
592			* this could be done in newprocess which would lead to
593	root	1.13	* extremely elegant and fast (basically just SAVE/LOAD)
594	root	1.8	* code here, but lazy allocation of stacks has also
595			* some virtues and the overhead of the if() is nil.
596			*/
597			if (next->mainstack)
598			{
599			SAVE (prev, flags);
600			LOAD (next);
601	root	1.13
602	root	1.8	/* mark this state as in-use */
603			next->mainstack = 0;
604			next->tmps_ix = -2;
605	root	1.13
606			if (flags & TRANSFER_SAVE_CCTXT)
607			{
608			if (!next->ssize)
609			croak ("destination coroutine has no CCTXT (%p, %d)", next->sptr, next->ssize);
610
611			if (!prev->ssize)
612			prev->ssize = 1; /* mark cctx as valid ;) */
613
614			coro_transfer (&(prev->cctx), &(next->cctx));
615			}
616
617	root	1.8	}
618			else if (next->tmps_ix == -2)
619	root	1.13	croak ("tried to transfer to running coroutine");
620	root	1.8	else
621			{
622			SAVE (prev, -1); /* first get rid of the old state */
623
624	root	1.13	if (flags & TRANSFER_SAVE_CCTXT)
625			{
626			if (!next->ssize)
627			{
628			allocate_stack (next);
629			coro_create (&(next->cctx),
630			setup_coro, (void *)next,
631			next->sptr, next->ssize);
632			}
633	root	1.8
634	root	1.13	if (!prev->ssize)
635			prev->ssize = 1; /* mark cctx as valid ;) */
636	root	1.8
637	root	1.13	coro_transfer (&(prev->cctx), &(next->cctx));
638			}
639			else
640			setup_coro (next);
641	root	1.8	}
642			}
643			}
644	root	1.3
645			MODULE = Coro::State PACKAGE = Coro::State
646	root	1.1
647			PROTOTYPES: ENABLE
648
649	root	1.3	BOOT:
650	root	1.11	{ /* {} necessary for stoopid perl-5.6.x */
651	root	1.13	coro_state_stash = gv_stashpvn ("Coro::State", 10, TRUE);
652	root	1.7
653	root	1.13	newCONSTSUB (coro_state_stash, "SAVE_DEFAV", newSViv (TRANSFER_SAVE_DEFAV));
654			newCONSTSUB (coro_state_stash, "SAVE_DEFSV", newSViv (TRANSFER_SAVE_DEFSV));
655			newCONSTSUB (coro_state_stash, "SAVE_ERRSV", newSViv (TRANSFER_SAVE_ERRSV));
656			newCONSTSUB (coro_state_stash, "SAVE_CCTXT", newSViv (TRANSFER_SAVE_CCTXT));
657	root	1.7
658	root	1.3	if (!padlist_cache)
659			padlist_cache = newHV ();
660	root	1.12
661			main_mainstack = PL_mainstack;
662	root	1.9	}
663	root	1.3
664	root	1.1	Coro::State
665	root	1.3	_newprocess(args)
666			SV * args
667			PROTOTYPE: $
668	root	1.1	CODE:
669			Coro__State coro;
670	root	1.3
671			if (!SvROK (args) \|\| SvTYPE (SvRV (args)) != SVt_PVAV)
672	root	1.7	croak ("Coro::State::_newprocess expects an arrayref");
673	root	1.1
674			New (0, coro, 1, struct coro);
675
676	root	1.13	coro->args = (AV *)SvREFCNT_inc (SvRV (args));
677	root	1.1	coro->mainstack = 0; /* actual work is done inside transfer */
678	root	1.13	coro->sptr = 0;
679			coro->ssize = 0;
680	root	1.1
681			RETVAL = coro;
682			OUTPUT:
683			RETVAL
684
685			void
686	root	1.12	transfer(prev, next, flags = TRANSFER_SAVE_ALL)
687	root	1.3	Coro::State_or_hashref prev
688			Coro::State_or_hashref next
689	root	1.7	int flags
690	root	1.8	PROTOTYPE: @
691	root	1.1	CODE:
692	root	1.8	transfer (aTHX_ prev, next, flags);
693	root	1.1
694			void
695			DESTROY(coro)
696	root	1.3	Coro::State coro
697	root	1.1	CODE:
698
699	root	1.12	if (coro->mainstack && coro->mainstack != main_mainstack)
700	root	1.1	{
701			struct coro temp;
702
703	root	1.12	SAVE(aTHX_ (&temp), TRANSFER_SAVE_ALL);
704	root	1.3	LOAD(aTHX_ coro);
705	root	1.1
706	root	1.13	destroy_stacks (aTHX);
707	root	1.1
708	root	1.7	LOAD((&temp)); /* this will get rid of defsv etc.. */
709	root	1.13
710			coro->mainstack = 0;
711			}
712
713			if (coro->sptr)
714			{
715			deallocate_stack (coro);
716			coro->sptr = 0;
717	root	1.1	}
718
719			Safefree (coro);
720	root	1.12
721	root	1.7	void
722			flush()
723			CODE:
724			#ifdef MAY_FLUSH
725			flush_padlist_cache ();
726			#endif
727	root	1.1
728	root	1.8	MODULE = Coro::State PACKAGE = Coro::Cont
729
730	root	1.13	# this is slightly dirty
731	root	1.8
732			void
733	root	1.13	yield(...)
734	root	1.8	PROTOTYPE: @
735			CODE:
736			static SV *returnstk;
737			SV *sv;
738			AV *defav = GvAV (PL_defgv);
739			struct coro prev, next;
740
741			if (!returnstk)
742			returnstk = SvRV (get_sv ("Coro::Cont::return", FALSE));
743
744	root	1.11	/* set up @_ -- ugly */
745	root	1.8	av_clear (defav);
746			av_fill (defav, items - 1);
747			while (items--)
748			av_store (defav, items, SvREFCNT_inc (ST(items)));
749
750			mg_get (returnstk); /* isn't documentation wrong for mg_get? */
751			sv = av_pop ((AV *)SvRV (returnstk));
752			prev = (struct coro )SvIV ((SV)SvRV (av_fetch ((AV )SvRV (sv), 0, 0)));
753			next = (struct coro )SvIV ((SV)SvRV (av_fetch ((AV )SvRV (sv), 1, 0)));
754			SvREFCNT_dec (sv);
755	root	1.13
756			transfer(aTHX_ prev, next, 0);
757	root	1.1