requestcount.h

pci 底层驱动

//
//  File:   requestcount.h
//  Description: The definition and implementation of class RequestCount
//
//  Created:  Wed. Jan 15, 2003
//
//
// Copyright and Disclaimer:
//
//   ---------------------------------------------------------------
//   THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
//   EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//   IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//   PARTICULAR PURPOSE.
//
//   IN NO EVENT SHALL CONEXANT BE LIABLE TO ANY PARTY FOR DIRECT,
//   INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
//   INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE
//   AND ITS DOCUMENTATION, EVEN IF CONEXANT HAS BEEN ADVISED OF THE
//   POSSIBILITY OF SUCH DAMAGE.
//
//   Copyright (c) 2000-2001 Conexant Systems, Inc.
//
//   All Rights Reserved.
//   ---------------------------------------------------------------
//
// Module Revision Id:
//
//

#ifndef _REQUEST_COUNT_H_
#define _REQUEST_COUNT_H_

/////////////////////////////////////////////////////////////////////////////////////////
//class RequestCount is a very simple class which keeps track of the number of IRPs 
// currently being processed in the driver.  
//
// The class provides members increment() and decrement() to change the request count
//  as IRPs are received and completed.
//
// Member wait() waits for the request count to go to 0, necessary if the device is 
// being removed.
//
// The class is very simple, and all functions are inline.
//

class RequestCount
{
public:
    RequestCount();

    //Wait for all requests to complete
    VOID wait();

    //increment and decrement the request count.
    VOID increment();
    VOID decrement();

private:
    LONG  _request_count;
    KEVENT _all_requests_complete;
};

inline RequestCount::RequestCount():
_request_count(0)
{
    KeInitializeEvent( &_all_requests_complete,
                       NotificationEvent,
                       TRUE );
}

inline VOID RequestCount::wait()
{
    KeWaitForSingleObject(
        &_all_requests_complete,
        Executive,
        KernelMode,
        TRUE,
        NULL);
}

inline VOID RequestCount::increment()
{
    LONG count = InterlockedIncrement(&_request_count);

    if(count == 1)
    {
        KeClearEvent(&_all_requests_complete);
    }

    dbgLogInfo(("Request Count incremented to %d\n", count));
}

inline VOID RequestCount::decrement()
{
    LONG count = InterlockedDecrement(&_request_count);
    ASSERT(count >= 0 );

    dbgLogInfo(("Request Count decremented to %d\n", count));

    if (count == 0 )
    {
        //Signal the event whenever there are no pending requests.
        dbgLogTrace(("last request completed, signalling event\n"));
        KeSetEvent( 
            &_all_requests_complete,
            0, 
            FALSE );
    }

}

#endif