//+---------------------------------------------------------------------------
//
//  Microsoft Windows
//  Copyright (C) Microsoft Corporation, 1993 - 1993.
//
//  File:	shrtbl.cxx
//
//  Contents:	shared memory tables - client side
//
//  Classes:	CDllShrdTbl - DLL version of the class
//
//  History:	12-May-94   Rickhi	Created
//
//  Notes:	This class caches various tables in shared memory. The
//		tables are typically small, used by all OLE processes,
//		rarely change, and are expensive to lookup manually in
//		the registry, hence they are cached in shared memory.
//
//		The caches are created by the SCM (which has write access),
//		and read by OLE32.DLL (which has read access).	Cache
//		coherency is maintained via RegistryNotifications and an
//		Rpc call to the SCM.
//
//----------------------------------------------------------------------------

#include    <ole2int.h>
#include    <shrtbl.hxx>
#include    <resolver.hxx>
#include    <objact.hxx>


//+-------------------------------------------------------------------------
//
//  Member:	CDllShrdTbl::CDllShrdTbl
//
//  Synopsis:	constructor for the client side shared memory table
//
//  Arguments:	[hr] - return code from the creation
//
//--------------------------------------------------------------------------
CDllShrdTbl::CDllShrdTbl(HRESULT &hr) :
    _pShrdTblHdr(NULL),
    _dwSeqNum(0)
{
    _mxs.Init(SHRDTBL_MUTEX_NAME, FALSE);
    // create/open the event for registry change notifications

    hr = S_OK;
    _hRegEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, SHRDTBL_EVENT_NAME);

    if (_hRegEvent == NULL)
    {
	hr = HRESULT_FROM_WIN32(GetLastError());

        CairoleDebugOut((DEB_ERROR,
            "CDllShrdTbl::CDllShrdTbl OpenEvent Failed hr = %lx\n", hr));
    }
}



//+-------------------------------------------------------------------------
//
//  Member:	CDllShrdTbl::GetSharedMem
//
//  Synopsis:	returns the ptr to the shared memory table, initializing
//		or re-syncing it if necessary, and calling the SCM if the
//		registry information has changed.
//
//  Arguments:	none
//
//  Effects:	_pShrdTblHdr may be changed, table headers may be updated.
//
//  Notes:	thread safety is the responsibility of the caller.
//
//--------------------------------------------------------------------------
SShrdTblHdr * CDllShrdTbl::GetSharedMem(void)
{
    if (_pShrdTblHdr == NULL)
    {
	// must init the shared mem block. We subtract off the
	// hdr size so we dont cause us to go over a page boundary
	// for just 8 bytes of header!

	HRESULT hr = _smb.Init(SHRDTBL_NAME,
		  SHRDTBL_MAX_SIZE - _smb.GetHdrSize(), // reserve size
		  SHRDTBL_MIN_SIZE - _smb.GetHdrSize(), // commit size
		  NULL,		    //	shared mem base
		  NULL,		    //	security descriptor
		  FALSE);	    //	Dont create if doesnt exist

	if (hr == S_OK)
	{
	    _pShrdTblHdr = (SShrdTblHdr *) _smb.GetBase();
	}
    }

    if (_pShrdTblHdr)
    {
	// test the RegNotify event to see if has been signalled

	if (WaitForSingleObject(_hRegEvent, 0) == WAIT_OBJECT_0)
	{
        // the change event has been signalled indicating the registry
        // has changed. Update() resets the Notify in the SCM, since 
	// the Notify must be done in the SCM due to the way RegNCKV 
        // works.
        

	    gResolver.UpdateShrdTbls();
	}

	if (_dwSeqNum != _pShrdTblHdr->dwSeqNum)
	{
	    // the sequence numbers dont match, grow my view of the
	    // block if necessary
	    _smb.Sync();

	    _pShrdTblHdr = (SShrdTblHdr *) _smb.GetBase();

	    // update the tables
	    Update();
	}
    }

    return _pShrdTblHdr;
}


//+-------------------------------------------------------------------------
//
//  Member:	CDllShrdTbl::Update
//
//  Synopsis:	intializes the client side of the shared mem table
//
//  Arguments:	none
//
//  Effects:	updates the shared table headers, and the sequence #
//
//  Notes:	thread safety is the responsibility of the caller.
//
//--------------------------------------------------------------------------
void CDllShrdTbl::Update(void)
{

    if (_pShrdTblHdr != NULL)
    {
	//  remember the sequence number
	_dwSeqNum = _pShrdTblHdr->dwSeqNum;

	//  intialize the client side tables
	BYTE *pTbl;

	if (_pShrdTblHdr->OffsIIDTbl != 0)
	{
	    pTbl = (BYTE *)_pShrdTblHdr + _pShrdTblHdr->OffsIIDTbl;
	    _PSClsidTbl.Initialize(pTbl);
	}

	if (_pShrdTblHdr->OffsPatTbl != 0)
	{
	    pTbl = (BYTE *)_pShrdTblHdr + _pShrdTblHdr->OffsPatTbl;
	    _PatternTbl.Initialize(pTbl);
	}

	if (_pShrdTblHdr->OffsExtTbl != 0)
	{
	    pTbl = (BYTE *)_pShrdTblHdr + _pShrdTblHdr->OffsExtTbl;
	    _FileExtTbl.Initialize(pTbl);
	}
    }
}