path: root/rts/RtsAPI.c

/* ----------------------------------------------------------------------------
 *
 * (c) The GHC Team, 1998-2001
 *
 * API for invoking Haskell functions via the RTS
 *
 * --------------------------------------------------------------------------*/

#include "PosixSource.h"
#include "Rts.h"
#include "OSThreads.h"
#include "RtsAPI.h"
#include "SchedAPI.h"
#include "RtsFlags.h"
#include "RtsUtils.h"
#include "Prelude.h"
#include "Schedule.h"
#include "Capability.h"
#include "Stable.h"

#include <stdlib.h>

/* ----------------------------------------------------------------------------
   Building Haskell objects from C datatypes.

   TODO: Currently this code does not tag created pointers,
         however it is not unsafe (the contructor code will do it)
         just inefficient.
   ------------------------------------------------------------------------- */
HaskellObj
rts_mkChar (Capability *cap, HsChar c)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap, CONSTR_sizeW(0,1));
  SET_HDR(p, Czh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgWord)(StgChar)c;
  return p;
}

HaskellObj
rts_mkInt (Capability *cap, HsInt i)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, Izh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgInt)i;
  return p;
}

HaskellObj
rts_mkInt8 (Capability *cap, HsInt8 i)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, I8zh_con_info, CCS_SYSTEM);
  /* Make sure we mask out the bits above the lowest 8 */
  p->payload[0]  = (StgClosure *)(StgInt)((unsigned)i & 0xff);
  return p;
}

HaskellObj
rts_mkInt16 (Capability *cap, HsInt16 i)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, I16zh_con_info, CCS_SYSTEM);
  /* Make sure we mask out the relevant bits */
  p->payload[0]  = (StgClosure *)(StgInt)((unsigned)i & 0xffff);
  return p;
}

HaskellObj
rts_mkInt32 (Capability *cap, HsInt32 i)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, I32zh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgInt)((unsigned)i & 0xffffffff);
  return p;
}

HaskellObj
rts_mkInt64 (Capability *cap, HsInt64 i)
{
  llong *tmp;
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,2));
  SET_HDR(p, I64zh_con_info, CCS_SYSTEM);
  tmp  = (llong*)&(p->payload[0]);
  *tmp = (StgInt64)i;
  return p;
}

HaskellObj
rts_mkWord (Capability *cap, HsWord i)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, Wzh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgWord)i;
  return p;
}

HaskellObj
rts_mkWord8 (Capability *cap, HsWord8 w)
{
  /* see rts_mkInt* comments */
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, W8zh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgWord)(w & 0xff);
  return p;
}

HaskellObj
rts_mkWord16 (Capability *cap, HsWord16 w)
{
  /* see rts_mkInt* comments */
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, W16zh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgWord)(w & 0xffff);
  return p;
}

HaskellObj
rts_mkWord32 (Capability *cap, HsWord32 w)
{
  /* see rts_mkInt* comments */
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, W32zh_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)(StgWord)(w & 0xffffffff);
  return p;
}

HaskellObj
rts_mkWord64 (Capability *cap, HsWord64 w)
{
  ullong *tmp;

  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,2));
  /* see mk_Int8 comment */
  SET_HDR(p, W64zh_con_info, CCS_SYSTEM);
  tmp  = (ullong*)&(p->payload[0]);
  *tmp = (StgWord64)w;
  return p;
}

HaskellObj
rts_mkFloat (Capability *cap, HsFloat f)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,1));
  SET_HDR(p, Fzh_con_info, CCS_SYSTEM);
  ASSIGN_FLT((P_)p->payload, (StgFloat)f);
  return p;
}

HaskellObj
rts_mkDouble (Capability *cap, HsDouble d)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,CONSTR_sizeW(0,sizeofW(StgDouble)));
  SET_HDR(p, Dzh_con_info, CCS_SYSTEM);
  ASSIGN_DBL((P_)p->payload, (StgDouble)d);
  return p;
}

HaskellObj
rts_mkStablePtr (Capability *cap, HsStablePtr s)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,sizeofW(StgHeader)+1);
  SET_HDR(p, StablePtr_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)s;
  return p;
}

HaskellObj
rts_mkPtr (Capability *cap, HsPtr a)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,sizeofW(StgHeader)+1);
  SET_HDR(p, Ptr_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)a;
  return p;
}

HaskellObj
rts_mkFunPtr (Capability *cap, HsFunPtr a)
{
  StgClosure *p = (StgClosure *)allocateLocal(cap,sizeofW(StgHeader)+1);
  SET_HDR(p, FunPtr_con_info, CCS_SYSTEM);
  p->payload[0]  = (StgClosure *)a;
  return p;
}

HaskellObj
rts_mkBool (Capability *cap STG_UNUSED, HsBool b)
{
  if (b) {
    return (StgClosure *)True_closure;
  } else {
    return (StgClosure *)False_closure;
  }
}

HaskellObj
rts_mkString (Capability *cap, char *s)
{
  return rts_apply(cap, (StgClosure *)unpackCString_closure, rts_mkPtr(cap,s));
}

HaskellObj
rts_apply (Capability *cap, HaskellObj f, HaskellObj arg)
{
    StgThunk *ap;

    ap = (StgThunk *)allocateLocal(cap,sizeofW(StgThunk) + 2);
    SET_HDR(ap, (StgInfoTable *)&stg_ap_2_upd_info, CCS_SYSTEM);
    ap->payload[0] = f;
    ap->payload[1] = arg;
    return (StgClosure *)ap;
}

/* ----------------------------------------------------------------------------
   Deconstructing Haskell objects

   We would like to assert that we have the right kind of object in
   each case, but this is problematic because in GHCi the info table
   for the D# constructor (say) might be dynamically loaded.  Hence we
   omit these assertions for now.
   ------------------------------------------------------------------------- */

HsChar
rts_getChar (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Czh_con_info ||
    //        p->header.info == Czh_static_info);
    return (StgChar)(StgWord)(UNTAG_CLOSURE(p)->payload[0]);
}

HsInt
rts_getInt (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Izh_con_info ||
    //        p->header.info == Izh_static_info);
    return (HsInt)(UNTAG_CLOSURE(p)->payload[0]);
}

HsInt8
rts_getInt8 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == I8zh_con_info ||
    //        p->header.info == I8zh_static_info);
    return (HsInt8)(HsInt)(UNTAG_CLOSURE(p)->payload[0]);
}

HsInt16
rts_getInt16 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == I16zh_con_info ||
    //        p->header.info == I16zh_static_info);
    return (HsInt16)(HsInt)(UNTAG_CLOSURE(p)->payload[0]);
}

HsInt32
rts_getInt32 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == I32zh_con_info ||
    //        p->header.info == I32zh_static_info);
  return (HsInt32)(HsInt)(UNTAG_CLOSURE(p)->payload[0]);
}

HsInt64
rts_getInt64 (HaskellObj p)
{
    HsInt64* tmp;
    // See comment above:
    // ASSERT(p->header.info == I64zh_con_info ||
    //        p->header.info == I64zh_static_info);
    tmp = (HsInt64*)&(UNTAG_CLOSURE(p)->payload[0]);
    return *tmp;
}
HsWord
rts_getWord (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Wzh_con_info ||
    //        p->header.info == Wzh_static_info);
    return (HsWord)(UNTAG_CLOSURE(p)->payload[0]);
}

HsWord8
rts_getWord8 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == W8zh_con_info ||
    //        p->header.info == W8zh_static_info);
    return (HsWord8)(HsWord)(UNTAG_CLOSURE(p)->payload[0]);
}

HsWord16
rts_getWord16 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == W16zh_con_info ||
    //        p->header.info == W16zh_static_info);
    return (HsWord16)(HsWord)(UNTAG_CLOSURE(p)->payload[0]);
}

HsWord32
rts_getWord32 (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == W32zh_con_info ||
    //        p->header.info == W32zh_static_info);
    return (HsWord32)(HsWord)(UNTAG_CLOSURE(p)->payload[0]);
}


HsWord64
rts_getWord64 (HaskellObj p)
{
    HsWord64* tmp;
    // See comment above:
    // ASSERT(p->header.info == W64zh_con_info ||
    //        p->header.info == W64zh_static_info);
    tmp = (HsWord64*)&(UNTAG_CLOSURE(p)->payload[0]);
    return *tmp;
}

HsFloat
rts_getFloat (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Fzh_con_info ||
    //        p->header.info == Fzh_static_info);
    return (float)(PK_FLT((P_)UNTAG_CLOSURE(p)->payload));
}

HsDouble
rts_getDouble (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Dzh_con_info ||
    //        p->header.info == Dzh_static_info);
    return (double)(PK_DBL((P_)UNTAG_CLOSURE(p)->payload));
}

HsStablePtr
rts_getStablePtr (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == StablePtr_con_info ||
    //        p->header.info == StablePtr_static_info);
    return (StgStablePtr)(UNTAG_CLOSURE(p)->payload[0]);
}

HsPtr
rts_getPtr (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == Ptr_con_info ||
    //        p->header.info == Ptr_static_info);
    return (Capability *)(UNTAG_CLOSURE(p)->payload[0]);
}

HsFunPtr
rts_getFunPtr (HaskellObj p)
{
    // See comment above:
    // ASSERT(p->header.info == FunPtr_con_info ||
    //        p->header.info == FunPtr_static_info);
    return (void *)(UNTAG_CLOSURE(p)->payload[0]);
}

HsBool
rts_getBool (HaskellObj p)
{
    StgInfoTable *info;

    info = get_itbl((StgClosure *)UNTAG_CLOSURE(p));
    if (info->srt_bitmap == 0) { // srt_bitmap is the constructor tag
	return 0;
    } else {
	return 1;
    }
}

/* -----------------------------------------------------------------------------
   Creating threads
   -------------------------------------------------------------------------- */

INLINE_HEADER void pushClosure   (StgTSO *tso, StgWord c) {
  tso->sp--;
  tso->sp[0] = (W_) c;
}

StgTSO *
createGenThread (Capability *cap, nat stack_size,  StgClosure *closure)
{
  StgTSO *t;
#if defined(GRAN)
  t = createThread (cap, stack_size, NO_PRI);
#else
  t = createThread (cap, stack_size);
#endif
  pushClosure(t, (W_)closure);
  pushClosure(t, (W_)&stg_enter_info);
  return t;
}

StgTSO *
createIOThread (Capability *cap, nat stack_size,  StgClosure *closure)
{
  StgTSO *t;
#if defined(GRAN)
  t = createThread (cap, stack_size, NO_PRI);
#else
  t = createThread (cap, stack_size);
#endif
  pushClosure(t, (W_)&stg_noforceIO_info);
  pushClosure(t, (W_)&stg_ap_v_info);
  pushClosure(t, (W_)closure);
  pushClosure(t, (W_)&stg_enter_info);
  return t;
}

/*
 * Same as above, but also evaluate the result of the IO action
 * to whnf while we're at it.
 */

StgTSO *
createStrictIOThread(Capability *cap, nat stack_size,  StgClosure *closure)
{
  StgTSO *t;
#if defined(GRAN)
  t = createThread(cap, stack_size, NO_PRI);
#else
  t = createThread(cap, stack_size);
#endif
  pushClosure(t, (W_)&stg_forceIO_info);
  pushClosure(t, (W_)&stg_ap_v_info);
  pushClosure(t, (W_)closure);
  pushClosure(t, (W_)&stg_enter_info);
  return t;
}

/* ----------------------------------------------------------------------------
   Evaluating Haskell expressions
   ------------------------------------------------------------------------- */

Capability *
rts_eval (Capability *cap, HaskellObj p, /*out*/HaskellObj *ret)
{
    StgTSO *tso;
    
    tso = createGenThread(cap, RtsFlags.GcFlags.initialStkSize, p);
    return scheduleWaitThread(tso,ret,cap);
}

Capability *
rts_eval_ (Capability *cap, HaskellObj p, unsigned int stack_size, 
	   /*out*/HaskellObj *ret)
{
    StgTSO *tso;

    tso = createGenThread(cap, stack_size, p);
    return scheduleWaitThread(tso,ret,cap);
}

/*
 * rts_evalIO() evaluates a value of the form (IO a), forcing the action's
 * result to WHNF before returning.
 */
Capability *
rts_evalIO (Capability *cap, HaskellObj p, /*out*/HaskellObj *ret)
{
    StgTSO* tso; 
    
    tso = createStrictIOThread(cap, RtsFlags.GcFlags.initialStkSize, p);
    return scheduleWaitThread(tso,ret,cap);
}

/*
 * rts_evalStableIO() is suitable for calling from Haskell.  It
 * evaluates a value of the form (StablePtr (IO a)), forcing the
 * action's result to WHNF before returning.  The result is returned
 * in a StablePtr.
 */
Capability *
rts_evalStableIO (Capability *cap, HsStablePtr s, /*out*/HsStablePtr *ret)
{
    StgTSO* tso;
    StgClosure *p, *r;
    SchedulerStatus stat;
    
    p = (StgClosure *)deRefStablePtr(s);
    tso = createStrictIOThread(cap, RtsFlags.GcFlags.initialStkSize, p);
    // async exceptions are always blocked by default in the created
    // thread.  See #1048.
    tso->flags |= TSO_BLOCKEX | TSO_INTERRUPTIBLE;
    cap = scheduleWaitThread(tso,&r,cap);
    stat = rts_getSchedStatus(cap);

    if (stat == Success && ret != NULL) {
	ASSERT(r != NULL);
	*ret = getStablePtr((StgPtr)r);
    }

    return cap;
}

/*
 * Like rts_evalIO(), but doesn't force the action's result.
 */
Capability *
rts_evalLazyIO (Capability *cap, HaskellObj p, /*out*/HaskellObj *ret)
{
    StgTSO *tso;

    tso = createIOThread(cap, RtsFlags.GcFlags.initialStkSize, p);
    return scheduleWaitThread(tso,ret,cap);
}

Capability *
rts_evalLazyIO_ (Capability *cap, HaskellObj p, unsigned int stack_size, 
		 /*out*/HaskellObj *ret)
{
    StgTSO *tso;

    tso = createIOThread(cap, stack_size, p);
    return scheduleWaitThread(tso,ret,cap);
}

/* Convenience function for decoding the returned status. */

void
rts_checkSchedStatus (char* site, Capability *cap)
{
    SchedulerStatus rc = cap->running_task->stat;
    switch (rc) {
    case Success:
	return;
    case Killed:
	errorBelch("%s: uncaught exception",site);
	stg_exit(EXIT_FAILURE);
    case Interrupted:
	errorBelch("%s: interrupted", site);
	stg_exit(EXIT_FAILURE);
    default:
	errorBelch("%s: Return code (%d) not ok",(site),(rc));	
	stg_exit(EXIT_FAILURE);
    }
}

SchedulerStatus
rts_getSchedStatus (Capability *cap)
{
    return cap->running_task->stat;
}

Capability *
rts_lock (void)
{
    Capability *cap;
    Task *task;

    // ToDo: get rid of this lock in the common case.  We could store
    // a free Task in thread-local storage, for example.  That would
    // leave just one lock on the path into the RTS: cap->lock when
    // acquiring the Capability.
    ACQUIRE_LOCK(&sched_mutex);
    task = newBoundTask();
    RELEASE_LOCK(&sched_mutex);

    cap = NULL;
    waitForReturnCapability(&cap, task);
    return (Capability *)cap;
}

// Exiting the RTS: we hold a Capability that is not necessarily the
// same one that was originally returned by rts_lock(), because
// rts_evalIO() etc. may return a new one.  Now that we have
// investigated the return value, we can release the Capability,
// and free the Task (in that order).

void
rts_unlock (Capability *cap)
{
    Task *task;

    task = cap->running_task;
    ASSERT_FULL_CAPABILITY_INVARIANTS(cap,task);

    // slightly delicate ordering of operations below, pay attention!

    // We are no longer a bound task/thread.  This is important,
    // because the GC can run when we release the Capability below,
    // and we don't want it to treat this as a live TSO pointer.
    task->tso = NULL;

    // Now release the Capability.  With the capability released, GC
    // may happen.  NB. does not try to put the current Task on the
    // worker queue.
    releaseCapability(cap);

    // Finally, we can release the Task to the free list.
    boundTaskExiting(task);
}