postgresql/src/include/utils/memutils.h

/*-------------------------------------------------------------------------
 *
 * memutils.h--
 *	  this file contains general memory alignment, allocation
 *	  and manipulation stuff that used to be spread out
 *	  between the following files:
 *
 *		align.h							alignment macros
 *		aset.h							memory allocation set stuff
 *		oset.h							  (used by aset.h)
 *		(bit.h							bit array type / extern)
 *		clib.h							mem routines
 *		limit.h							max bits/byte, etc.
 *
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: memutils.h,v 1.20 1999/02/06 16:50:33 wieck Exp $
 *
 * NOTES
 *	  some of the information in this file will be moved to
 *	  other files, (like MaxHeapTupleSize and MaxAttributeSize).
 *
 *-------------------------------------------------------------------------
 */
#ifndef MEMUTILS_H
#define MEMUTILS_H


#ifdef NOT_USED
/*****************************************************************************
 *		align.h			- alignment macros									 *
 ****************************************************************************
 [TRH] Let the compiler decide what alignment it uses instead of
tending
   we know better.
   GCC (at least v2.5.8 and up) has an __alignof__ keyword.
   However, we cannot use it here since on some architectures it reports
   just a _recommended_ alignment instead of the actual alignment used in
   padding structures (or at least, this is how I understand gcc).
   So define a macro that gives us the _actual_ alignment inside a struct.
   {{note: assumes that alignment size is always a power of 2.}}
 */
#define _ALIGNSIZE(TYPE)		offsetof(struct { char __c; TYPE __t;}, __t)
#define _ALIGN(TYPE, LEN) \
		(((long)(LEN) + (_ALIGNSIZE(TYPE) - 1)) & ~(_ALIGNSIZE(TYPE) - 1))
#define SHORTALIGN(LEN)			_ALIGN(short, (LEN))
#define INTALIGN(LEN)			_ALIGN(int, (LEN))
#define LONGALIGN(LEN)			_ALIGN(long, (LEN))
#define DOUBLEALIGN(LEN)		_ALIGN(double, (LEN))
#define MAXALIGN(LEN)			_ALIGN(double, (LEN))

#endif	 /* 0 */

/*
 *		SHORTALIGN(LEN) - length (or address) aligned for shorts
 */
#define SHORTALIGN(LEN)\
		(((long)(LEN) + (sizeof (short) - 1)) & ~(sizeof (short) - 1))

#if defined(m68k)
#define INTALIGN(LEN)	 SHORTALIGN(LEN)
#else
#define INTALIGN(LEN)\
		(((long)(LEN) + (sizeof (int) - 1)) & ~(sizeof (int) -1))
#endif

/*
 *		LONGALIGN(LEN)	- length (or address) aligned for longs
 */
#if (defined(sun) && ! defined(sparc)) || defined(m68k)
#define LONGALIGN(LEN)	SHORTALIGN(LEN)
#elif defined (__alpha)

 /*
  * even though "long alignment" should really be on 8-byte boundaries for
  * linuxalpha, we want the strictest alignment to be on 4-byte (int)
  * boundaries, because otherwise things break when they try to use the
  * FormData_pg_* structures.  --djm 12/12/96
  */
#define LONGALIGN(LEN)\
		(((long)(LEN) + (sizeof (int) - 1)) & ~(sizeof (int) -1))
#else
#define LONGALIGN(LEN)\
		(((long)(LEN) + (sizeof (long) - 1)) & ~(sizeof (long) -1))
#endif

#if defined(m68k)
#define DOUBLEALIGN(LEN) SHORTALIGN(LEN)
#define MAXALIGN(LEN)	 SHORTALIGN(LEN)
#elif ! defined(sco)
#define DOUBLEALIGN(LEN)\
		(((long)(LEN) + (sizeof (double) - 1)) & ~(sizeof (double) -1))

#define MAXALIGN(LEN)\
		(((long)(LEN) + (sizeof (double) - 1)) & ~(sizeof (double) -1))
#else
#define DOUBLEALIGN(LEN) INTALIGN(LEN)
#define MAXALIGN(LEN)	 INTALIGN(LEN)
#endif

/*****************************************************************************
 *	  oset.h --			Fixed format ordered set definitions.				 *
 *****************************************************************************/
/* Note:
 *		Fixed format ordered sets are <EXPLAIN>.
 *		XXX This is a preliminary version.	Work is needed to explain
 *		XXX semantics of the external definitions.	Otherwise, the
 *		XXX functional interface should not change.
 *
 */

typedef struct OrderedElemData OrderedElemData;
typedef OrderedElemData *OrderedElem;

typedef struct OrderedSetData OrderedSetData;
typedef OrderedSetData *OrderedSet;

struct OrderedElemData
{
	OrderedElem next;			/* Next elem or &this->set->dummy		*/
	OrderedElem prev;			/* Previous elem or &this->set->head	*/
	OrderedSet	set;			/* Parent set							*/
};

struct OrderedSetData
{
	OrderedElem head;			/* First elem or &this->dummy			*/
	OrderedElem dummy;			/* (hack) Terminator == NULL			*/
	OrderedElem tail;			/* Last elem or &this->head				*/
	Offset		offset;			/* Offset from struct base to elem		*/
	/* this could be signed short int! */
};

extern void OrderedSetInit(OrderedSet set, Offset offset);
extern bool OrderedSetContains(OrderedSet set, OrderedElem elem);
extern Pointer OrderedSetGetHead(OrderedSet set);
extern Pointer OrderedElemGetPredecessor(OrderedElem elem);
extern Pointer OrderedElemGetSuccessor(OrderedElem elem);
extern void OrderedElemPop(OrderedElem elem);
extern void OrderedElemPushInto(OrderedElem elem, OrderedSet Set);

/*****************************************************************************
 *	  aset.h --			Allocation set definitions.							 *
 *****************************************************************************/
/*
 * Description:
 *		An allocation set is a set containing allocated elements.  When
 *		an allocation is requested for a set, memory is allocated and a
 *		pointer is returned.  Subsequently, this memory may be freed or
 *		reallocated.  In addition, an allocation set may be reset which
 *		will cause all allocated memory to be freed.
 *
 *		Allocations may occur in four different modes.	The mode of
 *		allocation does not affect the behavior of allocations except in
 *		terms of performance.  The allocation mode is set at the time of
 *		set initialization.  Once the mode is chosen, it cannot be changed
 *		unless the set is reinitialized.
 *
 *		"Dynamic" mode forces all allocations to occur in a heap.  This
 *		is a good mode to use when small memory segments are allocated
 *		and freed very frequently.	This is a good choice when allocation
 *		characteristics are unknown.  This is the default mode.
 *
 *		"Static" mode attemts to allocate space as efficiently as possible
 *		without regard to freeing memory.  This mode should be chosen only
 *		when it is known that many allocations will occur but that very
 *		little of the allocated memory will be explicitly freed.
 *
 *		"Tunable" mode is a hybrid of dynamic and static modes.  The
 *		tunable mode will use static mode allocation except when the
 *		allocation request exceeds a size limit supplied at the time of set
 *		initialization.  "Big" objects are allocated using dynamic mode.
 *
 *		"Bounded" mode attempts to allocate space efficiently given a limit
 *		on space consumed by the allocation set.  This restriction can be
 *		considered a "soft" restriction, because memory segments will
 *		continue to be returned after the limit is exceeded.  The limit is
 *		specified at the time of set initialization like for tunable mode.
 *
 * Note:
 *		Allocation sets are not automatically reset on a system reset.
 *		Higher level code is responsible for cleaning up.
 *
 *		There may other modes in the future.
 */

/*
 * AllocPointer --
 *		Aligned pointer which may be a member of an allocation set.
 */
typedef Pointer AllocPointer;

/*
 * AllocMode --
 *		Mode of allocation for an allocation set.
 *
 * Note:
 *		See above for a description of the various nodes.
 */
typedef enum AllocMode
{
	DynamicAllocMode,			/* always dynamically allocate */
	StaticAllocMode,			/* always "statically" allocate */
	TunableAllocMode,			/* allocations are "tuned" */
	BoundedAllocMode			/* allocations bounded to fixed usage */
} AllocMode;

#define DefaultAllocMode		DynamicAllocMode

/*
 * AllocBlock --
 *		Small pieces of memory are taken from bigger blocks of
 *		memory with a size aligned to a power of two. These
 *		pieces are not free's separately, instead they are reused
 *		for the next allocation of a fitting size.
 */
typedef struct AllocBlockData {
	struct AllocSetData			*aset;
	struct AllocBlockData		*next;
	char						*freeptr;
	char						*endptr;
} AllocBlockData;

typedef AllocBlockData *AllocBlock;

/*
 * AllocChunk --
 *		The prefix of each piece of memory in an AllocBlock
 */
typedef struct AllocChunkData {
	void						*aset;
	Size						size;
} AllocChunkData;

typedef AllocChunkData *AllocChunk;

/*
 * AllocSet --
 *		Allocation set.
 */
typedef struct AllocSetData
{
	struct AllocBlockData		*blocks;
	struct AllocChunkData		*freelist[8];
	/* Note: this will change in the future to support other modes */
} AllocSetData;

typedef AllocSetData *AllocSet;

/*
 * AllocPointerIsValid --
 *		True iff pointer is valid allocation pointer.
 */
#define AllocPointerIsValid(pointer) PointerIsValid(pointer)

/*
 * AllocSetIsValid --
 *		True iff set is valid allocation set.
 */
#define AllocSetIsValid(set) PointerIsValid(set)

extern void AllocSetInit(AllocSet set, AllocMode mode, Size limit);

extern void AllocSetReset(AllocSet set);

extern bool AllocSetContains(AllocSet set, AllocPointer pointer);
extern AllocPointer AllocSetAlloc(AllocSet set, Size size);
extern void AllocSetFree(AllocSet set, AllocPointer pointer);
extern AllocPointer AllocSetRealloc(AllocSet set, AllocPointer pointer,
				Size size);

extern void AllocSetDump(AllocSet set);

/*****************************************************************************
 *	  clib.h --			Standard C library definitions						 *
 *****************************************************************************/
/*
 * Note:
 *		This file is OPERATING SYSTEM dependent!!!
 *
 */

/*
 *		LibCCopyLength is only used within this file. -cim 6/12/90
 *
 */
typedef int LibCCopyLength;

/*
 * MemoryCopy --
 *		Copies fixed length block of memory to another.
 */
#define MemoryCopy(toBuffer, fromBuffer, length)\
	memcpy(toBuffer, fromBuffer, length)

/*****************************************************************************
 *	  limit.h --		POSTGRES limit definitions.							 *
 *****************************************************************************/

#define MaxBitsPerByte	8

typedef uint32 AttributeSize;	/* XXX should be defined elsewhere */

#define MaxHeapTupleSize		0x7fffffff
#define MaxAttributeSize		0x7fffffff

#define MaxIndexAttributeNumber 7


#endif	 /* MEMUTILS_H */