windows-server-2003/admin/cmdline/cmdevtgprov/triggerfactory.cpp

/*++
Copyright (c) Microsoft Corporation

Module Name:
    TRIGGERFACTORY.CPP

Abstract:
    Contains the class factory. This creates objects when connections are requested.

Author:
    Vasundhara .G

Revision History :
    Vasundhara .G 9-oct-2k : Created It.
--*/

#include "pch.h"
#include "EventConsumerProvider.h"
#include "TriggerProvider.h"
#include "TriggerFactory.h"

CTriggerFactory::CTriggerFactory(
    )
/*++
Routine Description:
    Constructor for CTriggerFactory class   for initialization.

Arguments:
    None.

Return Value:
    None.
--*/
{
    // initialize the reference count variable
    m_dwCount = 0;
}

CTriggerFactory::~CTriggerFactory(
    )
/*++
Routine Description:
    Destructor for CTriggerFactory class for releasing resources.

Arguments:
    None.

Return Value:
    None.
--*/
{
    // there is nothing much to do at this place ... can be inlined, but
}

STDMETHODIMP
CTriggerFactory::QueryInterface(
    IN REFIID riid,
    OUT LPVOID* ppv
    )
/*++
Routine Description:
    QueryInterface required to be overridden for a class derived from IUnknown
    interface.

Arguments:
    [IN] riid : which has the ID value of the interface being called.
    [OUT] ppv : pointer to the interface requested.

Return Value:
    NOERROR if successful.
    E_NOINTERFACE if unsuccessful
--*/
{
    // initialy set to NULL
    *ppv = NULL;

    // check whether interface requested is one we have
    if ( riid == IID_IUnknown || riid == IID_IClassFactory )
    {
        //
        // yes ... we have the requested interface
        *ppv=this;          // set the out parameter for the returning the requested interface
        this->AddRef();     // update the reference count
        return NOERROR;     // inform success
    }

    // interface is not available
    return E_NOINTERFACE;
}

STDMETHODIMP_(ULONG)
CTriggerFactory::AddRef(
    void
    )
/*++
Routine Description:
    Addref required to be overridden for a class derived from IUnknown interface.

Arguments:
    none.

Return Value:
    returns value of reference member.
--*/
{
    // increment the reference count ... thread safe
    return InterlockedIncrement( ( LPLONG ) &m_dwCount );
}

STDMETHODIMP_(ULONG)
CTriggerFactory::Release(
    void
    )
/*++
Routine Description:
    Release required to be overridden for a class derived from IUnknown interface.

Arguments:
    none.

Return Value:
    returns value of reference member, g_lCObj.
--*/
{
    DWORD dwCount;

    // decrement the reference count ( thread safe ) and check whether
    // there are some more references or not ... based on the result value
    dwCount = InterlockedDecrement( ( LPLONG ) &m_dwCount );
    if ( 0 == dwCount )
    {
        // free the current factory instance
        delete this;
    }

    // return the no. of instances references left
    return dwCount;
}

STDMETHODIMP
CTriggerFactory::CreateInstance(
    IN LPUNKNOWN pUnknownOutter,
    IN REFIID riid,
    OUT LPVOID* ppvObject
    )
/*++
Routine Description:
    Creates an object of the specified CLSID and retrieves
    an interface pointer to this object.

Arguments:
    [IN] pUnknownOutter : If the object is being created as part of an
                          aggregate, then pIUnkOuter must be the outer
                          unknown. Otherwise, pIUnkOuter must be NULL.
    [IN] riid           : The IID of the requested interface.
    [OUT] ppvObject     : A pointer to the interface pointer identified by riid.

Return Value:
    NOERROR if successful.
    Otherwise  error value.
--*/
{
    // local variables
    HRESULT hr;
    CTriggerProvider* pProvider = NULL;

    // kick off
    *ppvObject = NULL;
    hr = E_OUTOFMEMORY;
    if ( NULL != pUnknownOutter )
    {
        return CLASS_E_NOAGGREGATION;       // object doesn't support aggregation.
    }
    // create the Initialize object.
    pProvider = new CTriggerProvider();
    if ( NULL == pProvider )
    {
        return E_OUTOFMEMORY;       // ran out of memory
    }
    // get the pointer to the requested interface
    hr = pProvider->QueryInterface( riid, ppvObject );
    if ( FAILED( hr ) )
    {
        delete pProvider;           // interface not available ... de-allocate memory
    }
    // return the appropriate result
    return hr;
}

STDMETHODIMP
CTriggerFactory::LockServer(
    IN BOOL bLock
    )
/*++
Routine Description:
    Increments or decrements the lock count of the DLL.
    If the lock count goes to zero and there are no objects,
    the DLL  is allowed to unload.

arguments:
    [IN] bLock : specifying whether to increment or decrement the lock count.

Returns Value:
    NOERROR always.
--*/
{
    // based on the request update the locks count
    if ( bLock )
    {
        InterlockedIncrement( ( LPLONG ) &g_dwLocks );
    }
    else
    {
        InterlockedDecrement( ( LPLONG ) &g_dwLocks );
    }
    // inform success
    return NOERROR;
}