RTActorSlot.h

/*
 * Licensed Materials - Property of HCL and/or IBM
 * Copyright HCL Technologies Ltd. 2016, 2021. All Rights Reserved.
 * Copyright IBM Corporation 1999, 2016. All Rights Reserved.
 *
 * U.S. Government Users Restricted Rights -  Use, duplication or 
 * disclosure restricted by GSA ADP Schedule.
 */
 
#ifndef __RTActorSlot_h__
#define __RTActorSlot_h__ included
 
#ifdef PRAGMA
#pragma interface
#endif
 
#ifndef __RTConfig_h__
#include <RTConfig.h>
#endif
 
class RTActor;
 
// If the replication factor, n, of an optional reference satisfies
// ( 2 <= n < threshold ), we allocate n + 1 RTSmallOptional objects.
// The first one serves as the anchor for the free list.
// This depends on two things:
// 1.  size_t is no larger than a pointer, and
// 2.  all addresses allocated on the heap are even.
 
struct RTSmallOptional
{
    RTS_INLINE static int supports( int size );
    RTS_INLINE void       insert( int prev, int next );
    RTS_INLINE int        inuse( void ) const;
    RTS_INLINE void       prev( int );
    RTS_INLINE int        prev( void ) const;
    RTS_INLINE void       next( int );
    RTS_INLINE int        next( void ) const;
 
    RTActor * _actor;
 
    // we assume sizeof( size_t ) <= sizeof( RTActor * )
    static const size_t link_bits = 4 * sizeof( size_t ) - 1;
    static const size_t threshold = 1U << link_bits;
    static const size_t link_mask = threshold - 1;
    static const size_t next_shift = 1U;
    static const size_t prev_shift = next_shift + link_bits;
};
 
// If ( n >= threshold ), we allocate n + 1 RTLargeOptional objects.
// The first one serves as the anchor for the free list.
// The next pointer is nil when the entry has been reserved.
 
struct RTLargeOptional
{
    RTLargeOptional     * next;
    union
    {
        RTLargeOptional * prev;
        RTActor         * actor;
    };
};
 
#if RTS_INLINES
#include <RTActorSlot.inl>
#endif
 
#endif // __RTActorSlot_h__