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/* ----------------------------------------------------------------------------
*
* (c) The GHC Team, 2005
*
* Macros for THREADED_RTS support
*
* -------------------------------------------------------------------------- */
#ifndef SMPCLOSUREOPS_H
#define SMPCLOSUREOPS_H
#if defined(THREADED_RTS)
/* -----------------------------------------------------------------------------
* Locking/unlocking closures
*
* This is used primarily in the implementation of MVars.
* -------------------------------------------------------------------------- */
#define SPIN_COUNT 4000
#ifdef KEEP_LOCKCLOSURE
// We want a callable copy of lockClosure() so that we can refer to it
// from .cmm files compiled using the native codegen.
extern StgInfoTable *lockClosure(StgClosure *p);
INLINE_ME
#else
INLINE_HEADER
#endif
StgInfoTable *
lockClosure(StgClosure *p)
{
StgWord info;
do {
nat i = 0;
do {
info = xchg((P_)(void *)&p->header.info, (W_)&stg_WHITEHOLE_info);
if (info != (W_)&stg_WHITEHOLE_info) return (StgInfoTable *)info;
} while (++i < SPIN_COUNT);
yieldThread();
} while (1);
}
INLINE_HEADER void
unlockClosure(StgClosure *p, const StgInfoTable *info)
{
// This is a strictly ordered write, so we need a write_barrier():
write_barrier();
p->header.info = info;
}
#else /* !THREADED_RTS */
INLINE_HEADER StgInfoTable *
lockClosure(StgClosure *p)
{ return (StgInfoTable *)p->header.info; }
INLINE_HEADER void
unlockClosure(StgClosure *p STG_UNUSED, const StgInfoTable *info STG_UNUSED)
{ /* nothing */ }
#endif /* THREADED_RTS */
// Handy specialised versions of lockClosure()/unlockClosure()
INLINE_HEADER void lockTSO(StgTSO *tso)
{ lockClosure((StgClosure *)tso); }
INLINE_HEADER void unlockTSO(StgTSO *tso)
{ unlockClosure((StgClosure*)tso, (const StgInfoTable *)&stg_TSO_info); }
#endif /* SMPCLOSUREOPS_H */
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