/*-------------------------------------------------------------------------
 *
 * tqual.h
 *	  POSTGRES "time" qualification definitions.
 *
 *	  Should be moved/renamed...	- vadim 07/28/98
 *
 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $Id: tqual.h,v 1.34 2001/08/26 16:56:03 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef TQUAL_H
#define TQUAL_H

#include "access/htup.h"
#include "access/xact.h"


typedef struct SnapshotData
{
	TransactionId xmin;			/* XID < xmin are visible to me */
	TransactionId xmax;			/* XID >= xmax are invisible to me */
	uint32		xcnt;			/* # of xact ids in xip[] */
	TransactionId *xip;			/* array of xact IDs in progress */
	/* note: all ids in xip[] satisfy xmin <= xip[i] < xmax */
	ItemPointerData tid;		/* required for Dirty snapshot -:( */
} SnapshotData;

typedef SnapshotData *Snapshot;

#define SnapshotNow					((Snapshot) 0x0)
#define SnapshotSelf				((Snapshot) 0x1)
#define SnapshotAny					((Snapshot) 0x2)

extern DLLIMPORT Snapshot SnapshotDirty;
extern DLLIMPORT Snapshot QuerySnapshot;
extern DLLIMPORT Snapshot SerializableSnapshot;

extern bool ReferentialIntegritySnapshotOverride;

#define IsSnapshotNow(snapshot)		((Snapshot) (snapshot) == SnapshotNow)
#define IsSnapshotSelf(snapshot)	((Snapshot) (snapshot) == SnapshotSelf)
#define IsSnapshotAny(snapshot)		((Snapshot) (snapshot) == SnapshotAny)
#define IsSnapshotDirty(snapshot)	((Snapshot) (snapshot) == SnapshotDirty)


/*
 * HeapTupleSatisfiesVisibility
 *		True iff heap tuple satsifies a time qual.
 *
 * Notes:
 *		Assumes heap tuple is valid.
 *		Beware of multiple evaluations of arguments.
 */
#define HeapTupleSatisfiesVisibility(tuple, snapshot) \
( \
	TransactionIdEquals((tuple)->t_data->t_xmax, BootstrapTransactionId) ? \
		false \
	: \
	( \
		IsSnapshotAny(snapshot) ? \
			true \
		: \
			(IsSnapshotSelf(snapshot) ? \
				HeapTupleSatisfiesItself((tuple)->t_data) \
			: \
				(IsSnapshotNow(snapshot) ? \
					HeapTupleSatisfiesNow((tuple)->t_data) \
				: \
					(IsSnapshotDirty(snapshot) ? \
						HeapTupleSatisfiesDirty((tuple)->t_data) \
					: \
						HeapTupleSatisfiesSnapshot((tuple)->t_data, snapshot) \
					) \
			) \
		) \
	) \
)

/* Result codes for HeapTupleSatisfiesUpdate */
#define HeapTupleMayBeUpdated		0
#define HeapTupleInvisible			1
#define HeapTupleSelfUpdated		2
#define HeapTupleUpdated			3
#define HeapTupleBeingUpdated		4

/* Result codes for HeapTupleSatisfiesVacuum */
typedef enum
{
	HEAPTUPLE_DEAD,				/* tuple is dead and deletable */
	HEAPTUPLE_LIVE,				/* tuple is live (committed, no deleter) */
	HEAPTUPLE_RECENTLY_DEAD,	/* tuple is dead, but not deletable yet */
	HEAPTUPLE_INSERT_IN_PROGRESS, /* inserting xact is still in progress */
	HEAPTUPLE_DELETE_IN_PROGRESS /* deleting xact is still in progress */
} HTSV_Result;

extern bool HeapTupleSatisfiesItself(HeapTupleHeader tuple);
extern bool HeapTupleSatisfiesNow(HeapTupleHeader tuple);
extern bool HeapTupleSatisfiesDirty(HeapTupleHeader tuple);
extern bool HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple,
						   Snapshot snapshot);
extern int	HeapTupleSatisfiesUpdate(HeapTuple tuple);
extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
											TransactionId OldestXmin);

extern Snapshot GetSnapshotData(bool serializable);
extern void SetQuerySnapshot(void);
extern void FreeXactSnapshot(void);

#endif	 /* TQUAL_H */
