#else
EXTERN_INLINE StgInfoTable *lockClosure(StgClosure *p);
+EXTERN_INLINE StgInfoTable *tryLockClosure(StgClosure *p);
EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info);
#if defined(THREADED_RTS)
} while (1);
}
-EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info)
+EXTERN_INLINE StgInfoTable *tryLockClosure(StgClosure *p)
{
- // This is a strictly ordered write, so we need a write_barrier():
- write_barrier();
- p->header.info = info;
+ StgWord info;
+ info = xchg((P_)(void *)&p->header.info, (W_)&stg_WHITEHOLE_info);
+ if (info != (W_)&stg_WHITEHOLE_info) {
+ return (StgInfoTable *)info;
+ } else {
+ return NULL;
+ }
}
#else /* !THREADED_RTS */
lockClosure(StgClosure *p)
{ return (StgInfoTable *)p->header.info; }
-EXTERN_INLINE void
-unlockClosure(StgClosure *p STG_UNUSED, const StgInfoTable *info STG_UNUSED)
-{ /* nothing */ }
+EXTERN_INLINE StgInfoTable *
+tryLockClosure(StgClosure *p)
+{ return (StgInfoTable *)p->header.info; }
#endif /* THREADED_RTS */
+EXTERN_INLINE 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;
+}
+
// Handy specialised versions of lockClosure()/unlockClosure()
EXTERN_INLINE void lockTSO(StgTSO *tso);
EXTERN_INLINE void lockTSO(StgTSO *tso)