ccc.cpp

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// $Id: ccc.cpp 751 2006-03-31 15:43:49Z alex $
/* @@tag:xara-cn@@ DO NOT MODIFY THIS LINE
================================XARAHEADERSTART===========================
 
               Xara LX, a vector drawing and manipulation program.
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----------------------------------

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 */
// Implementation file for the ConcurrencyController

#include "camtypes.h"
#include "ccc.h"
#include "gdrawasm.h"

// Place any IMPLEMENT type statements here

CC_IMPLEMENT_MEMDUMP(ConcurrencyController, CC_CLASS_MEMDUMP)
//CC_IMPLEMENT_MEMDUMP(CriticalSection, CC_CLASS_MEMDUMP)

// We want better memory tracking
#define new CAM_DEBUG_NEW

// Change this so TRACEUSERs work for you
#define ME  "Colin"

// Ooh Er! Static Members

ConcurrencyController::UserID ConcurrencyController::s_NextFreeUserID = 0;
ConcurrencyController::UserID ConcurrencyController::s_OneAndOnlyUser = 0;
UINT32 ConcurrencyController::s_NumberOfUsers = 0;

UINT32 ConcurrencyController::s_NumberOfActiveOperations = 0;
const Operation* ConcurrencyController::s_pTheActiveOperation = NULL;

// Functions follow



/********************************************************************************************

>   ConcurrencyController::ConcurrencyController() 

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Default constructor for the ConcurrencyController

********************************************************************************************/
ConcurrencyController::ConcurrencyController() 
{
}

BOOL ConcurrencyController::Init()
{
//  CriticalSection::Init();

    return TRUE;
}

/********************************************************************************************

>   ConcurrencyController::~ConcurrencyController() 

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Default destructor for the ConcurrencyController

********************************************************************************************/
ConcurrencyController::~ConcurrencyController() 
{
    if (s_NumberOfUsers > 1)
    {
        TRACEUSER( ME, _T("ConcurrencyController: Users still active\n"));
    }
//  CriticalSection::DeInit();
}


/********************************************************************************************

>   ConcurrencyController::RESULT ConcurrencyController::StartUser(UserID* pNewUserID)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Default destructor for the ConcurrencyController

********************************************************************************************/
ConcurrencyController::RESULT ConcurrencyController::StartUser(UserID* pNewUserID)
{
    RESULT Result = CCR_OK;

    CriticalSection UpdateUserID;
//  UpdateUserID.Start();

    if (s_NumberOfUsers == 0)
    {
        UserID NewUserID = GetNewUserID();
        if (NewUserID != NULL)
        {
            ++s_NumberOfUsers;
        }
        else
        {
            Result = CCR_TOO_MANY_USERS;
        }
        *pNewUserID = NewUserID;
    }
    else
    {
        Result = CCR_TOO_MANY_USERS;
    }
//  UpdateUserID.End();

    return Result;
}

    
/********************************************************************************************

>   ConcurrencyController::RESULT ConcurrencyController::EndUser(UserID UserWhosDone)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Default destructor for the ConcurrencyController

********************************************************************************************/
ConcurrencyController::RESULT ConcurrencyController::EndUser(UserID UserWhosDone)
{
    RESULT Result = CCR_OK;

    CriticalSection UpdateUserID;
//  UpdateUserID.Start();

    if (UserWhosDone == s_OneAndOnlyUser)
    {
        s_OneAndOnlyUser = NULL;
        --s_NumberOfUsers;
    }
    else
    {
        Result = CCR_INVALID_USER;
    }

//  UpdateUserID.End();

    return Result;
}


/********************************************************************************************

>   ConcurrencyController::RESULT ConcurrencyController::PrepareForOperation(
                                                            const Operation* const pOperation)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Allows or disallows access to Operations.

    Notes:      En ce moment only one op is allowed per application (static scope)

********************************************************************************************/
ConcurrencyController::RESULT ConcurrencyController::PrepareForOperation(
                                                        const Operation* const pOperation)
{
    RESULT Result = CCR_OK;

    CriticalSection UpdateOpTable;
//  UpdateOpTable.Start();

    if (s_NumberOfActiveOperations == 0)
    {
        ERROR2IF(s_pTheActiveOperation != NULL, CCR_INTERNAL_ERROR, "ActiveOp not NULL");
        
        s_pTheActiveOperation = pOperation;
        ++s_NumberOfActiveOperations;
    }
    else
    {
        Result = CCR_TOO_MANY_USERS;
    }
//  UpdateOpTable.End();

    return Result;
}


/********************************************************************************************

>   ConcurrencyController::RESULT ConcurrencyController::FinalizeOperation(
                                                        const Operation* const pOperation)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Default destructor for the ConcurrencyController

********************************************************************************************/
ConcurrencyController::RESULT ConcurrencyController::FinalizeOperation(
                                                        const Operation* const pOperation)
{
    RESULT Result = CCR_OK;

    CriticalSection UpdateOpTable;

    if (pOperation == s_pTheActiveOperation)
    {
        ERROR2IF(s_NumberOfActiveOperations != 1, CCR_INTERNAL_ERROR, "ActiveOps not Unity");

        s_pTheActiveOperation = NULL;
        --s_NumberOfActiveOperations;
    }
    else
    {
        Result = CCR_INVALID_ARGUMENT;
    }

    return Result;
}


/*********************************************************************************************
           
>   ConcurrencyController::RESULT ConcurrencyController::PrepareNodeForUpdate(Node* const pNode)

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    25/02/97

    Inputs:     pNode:  The node to be updated
    Returns:    TRUE if the node can be updated
        FALSE otherwise
    Purpose:    Before updating a node, call this function to ensure the integrity of the 
        document tree.
        This call should be accompanied by a subsequent call to FinalizeNodeUpdate().
        The results of the update are undefined if not.
    See Also:   PrepareNodeForRead()
    
**********************************************************************************************/  
ConcurrencyController::RESULT ConcurrencyController::PrepareNodeForUpdate(Node* const pNode);


/*********************************************************************************************
           
>   ConcurrencyController::RESULT ConcurrencyController::FinalizeNodeUpdate(Node* const pNode)

    Author: Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    25/02/97

    Inputs: pNode:  The node passed in a prior call to PrepareNodeForUpdate()
    Returns:    TRUE if the node was successfully updated
        FALSE otherwise
    Purpose:    Once the given node has been updated in the tree call this function to ensure
        its update is complete.
        This call should be accompanied by a prior call to PrepareForNodeUpdate(). The
        results of the update are undefined if not.
    See Also:   FinalizeNodeRead()
    
**********************************************************************************************/  
ConcurrencyController::RESULT ConcurrencyController::FinalizeNodeUpdate(Node* const pNode);


/*********************************************************************************************
           
>   ConcurrencyController::RESULT ConcurrencyController::PrepareNodeForRead(Node* const pNode)

    Author: Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    25/02/97

    Inputs: pNode:  The node to be read
    Returns:    TRUE if the node can be read
        FALSE otherwise
    Purpose:    Before reading data in a node or passing it as a parameter to a function,
        call this function to ensure the integrity of the document tree.
        This call should be accompanied by a subsequent call to FinalizeNodeRead().
        The results of the read are undefined if not.
    See Also:   PrepareNodeForUpdate()
    
**********************************************************************************************/  
ConcurrencyController::RESULT ConcurrencyController::PrepareNodeForRead(Node* const pNode);


/*********************************************************************************************
           
>   ConcurrencyController::RESULT ConcurrencyController::FinalizeNodeRead(Node* const pNode)

    Author: Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    25/02/97

    Inputs: pNode:  The node that was passed in a previous call to PrepareNodeForRead()
    Returns:    TRUE if the node can be read or updated again.
        FALSE otherwise
    Purpose:    Once the given node has been read or passed as a parameter, call this function 
        to free it for updates.
        This call should be accompanied by a prior call to PrepareNodeForRead(). The
        results of the read are undefined if not.
    See Also:   FinalizeNodeUpdate()
    
**********************************************************************************************/  
ConcurrencyController::RESULT ConcurrencyController::FinalizeNodeRead(Node* const pNode);


/********************************************************************************************

>   UserID ConcurrencyController::GetNewUserID()

    Author:     Colin_Barfoot (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/03/97

    Purpose:    Support function to provide a new user id

    Notes:      Assumes thread-safe access to static members

********************************************************************************************/
ConcurrencyController::UserID ConcurrencyController::GetNewUserID()
{
    UserID NextID = ++s_NextFreeUserID;

    // if the NextID is zero, fail it always
    if (NextID == 0)
    {
        --s_NextFreeUserID;
    }
    return NextID;
}

---