/*-------------------------------------------------------------------------
 *
 * sinval.c
 *	  POSTGRES shared cache invalidation communication code.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.16 1999/07/15 22:39:49 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
/* #define INVALIDDEBUG 1 */

#include <sys/types.h>

#include "postgres.h"

#include "storage/backendid.h"
#include "storage/sinval.h"
#include "storage/sinvaladt.h"

extern SISeg *shmInvalBuffer;	/* the shared buffer segment, set by */

 /* SISegmentAttach()			   */
extern BackendId MyBackendId;
extern BackendTag MyBackendTag;

SPINLOCK	SInvalLock = (SPINLOCK) NULL;

/****************************************************************************/
/*	CreateSharedInvalidationState()		 Create a buffer segment			*/
/*																			*/
/*	should be called only by the POSTMASTER									*/
/****************************************************************************/
void
CreateSharedInvalidationState(IPCKey key, int maxBackends)
{
	int			status;

	/*
	 * REMOVED SISyncKill(IPCKeyGetSIBufferMemorySemaphoreKey(key));
	 * SISyncInit(IPCKeyGetSIBufferMemorySemaphoreKey(key));
	 */

	/* SInvalLock gets set in spin.c, during spinlock init */
	status = SISegmentInit(true, IPCKeyGetSIBufferMemoryBlock(key),
						   maxBackends);

	if (status == -1)
		elog(FATAL, "CreateSharedInvalidationState: failed segment init");
}

/****************************************************************************/
/*	AttachSharedInvalidationState(key)	 Attach a buffer segment			*/
/*																			*/
/*	should be called only by the POSTMASTER									*/
/****************************************************************************/
void
AttachSharedInvalidationState(IPCKey key)
{
	int			status;

	if (key == PrivateIPCKey)
	{
		CreateSharedInvalidationState(key, 16);
		return;
	}
	/* SInvalLock gets set in spin.c, during spinlock init */
	status = SISegmentInit(false, IPCKeyGetSIBufferMemoryBlock(key), 0);

	if (status == -1)
		elog(FATAL, "AttachSharedInvalidationState: failed segment init");
}

void
InitSharedInvalidationState(void)
{
	SpinAcquire(SInvalLock);
	if (!SIBackendInit(shmInvalBuffer))
	{
		SpinRelease(SInvalLock);
		elog(FATAL, "Backend cache invalidation initialization failed");
	}
	SpinRelease(SInvalLock);
}

/*
 * RegisterSharedInvalid
 *	Returns a new local cache invalidation state containing a new entry.
 *
 * Note:
 *	Assumes hash index is valid.
 *	Assumes item pointer is valid.
 */
/****************************************************************************/
/*	RegisterSharedInvalid(cacheId, hashIndex, pointer)						*/
/*																			*/
/*	register a message in the buffer										*/
/*	should be called by a backend											*/
/****************************************************************************/
void
RegisterSharedInvalid(int cacheId,		/* XXX */
					  Index hashIndex,
					  ItemPointer pointer)
{
	SharedInvalidData newInvalid;

	/*
	 * This code has been hacked to accept two types of messages.  This
	 * might be treated more generally in the future.
	 *
	 * (1) cacheId= system cache id hashIndex= system cache hash index for a
	 * (possibly) cached tuple pointer= pointer of (possibly) cached tuple
	 *
	 * (2) cacheId= special non-syscache id hashIndex= object id contained in
	 * (possibly) cached relation descriptor pointer= null
	 */

	newInvalid.cacheId = cacheId;
	newInvalid.hashIndex = hashIndex;

	if (ItemPointerIsValid(pointer))
		ItemPointerCopy(pointer, &newInvalid.pointerData);
	else
		ItemPointerSetInvalid(&newInvalid.pointerData);

	SpinAcquire(SInvalLock);
	if (!SISetDataEntry(shmInvalBuffer, &newInvalid))
	{
		/* buffer full */
		/* release a message, mark process cache states to be invalid */
		SISetProcStateInvalid(shmInvalBuffer);

		if (!SIDelDataEntry(shmInvalBuffer))
		{
			/* inconsistent buffer state -- shd never happen */
			SpinRelease(SInvalLock);
			elog(FATAL, "RegisterSharedInvalid: inconsistent buffer state");
		}

		/* write again */
		SISetDataEntry(shmInvalBuffer, &newInvalid);
	}
	SpinRelease(SInvalLock);
}

/*
 * InvalidateSharedInvalid
 *	Processes all entries in a shared cache invalidation state.
 */
/****************************************************************************/
/*	InvalidateSharedInvalid(invalFunction, resetFunction)					*/
/*																			*/
/*	invalidate a message in the buffer	 (read and clean up)				*/
/*	should be called by a backend											*/
/****************************************************************************/
void
			InvalidateSharedInvalid(void (*invalFunction) (),
									void (*resetFunction) ())
{
	SpinAcquire(SInvalLock);
	SIReadEntryData(shmInvalBuffer, MyBackendId,
					invalFunction, resetFunction);

	SIDelExpiredDataEntries(shmInvalBuffer);
	SpinRelease(SInvalLock);
}
