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/****************************** Module Header ******************************\
* Module Name: monitor.c
*
* Copyright (c) 1991, Microsoft Corporation
*
* Implements functions that handle waiting for an object to be signalled
* asynchronously.
*
* History:
* 01-11-93 Davidc Created.
\***************************************************************************/
#include "precomp.h"
#pragma hdrstop
//
// Define this to enable verbose output for this module
//
// #define DEBUG_MONITOR
#ifdef DEBUG_MONITOR
#define VerbosePrint(s) WLPrint(s)
#else
#define VerbosePrint(s)
#endif
#define LockMonitor(Monitor) RtlEnterCriticalSection( &Monitor->CritSec )
#define UnlockMonitor(Monitor) RtlLeaveCriticalSection( &Monitor->CritSec )
//+---------------------------------------------------------------------------
//
// Function: RefMonitor
//
// Synopsis: Safe Ref Count
//
// Arguments: [Monitor] --
//
// History: 7-12-96 RichardW Created
//
// Notes:
//
//----------------------------------------------------------------------------
VOID
RefMonitor(
POBJECT_MONITOR Monitor)
{
LockMonitor( Monitor );
Monitor->RefCount ++ ;
UnlockMonitor( Monitor );
}
//+---------------------------------------------------------------------------
//
// Function: DerefMonitor
//
// Synopsis: Deref the monitor, cleaning up if refcount goes to zero
//
// Arguments: [Monitor] --
//
// History: 7-12-96 RichardW Created
//
// Notes:
//
//----------------------------------------------------------------------------
VOID
DerefMonitor(
POBJECT_MONITOR Monitor )
{
LockMonitor( Monitor );
DebugLog(( DEB_TRACE, "Deref of Monitor at %x\n", Monitor));
Monitor->RefCount -- ;
if ( Monitor->RefCount == 0 )
{
//
// Clean up time:
//
DebugLog(( DEB_TRACE, "Cleaning up Monitor at %x\n", Monitor ));
if ( Monitor->Thread )
{
CloseHandle( Monitor->Thread );
}
if ( Monitor->Flags & MONITOR_CLOSEOBJ )
{
if ( Monitor->Object != INVALID_HANDLE_VALUE )
{
CloseHandle( Monitor->Object );
}
}
UnlockMonitor( Monitor );
RtlDeleteCriticalSection( &Monitor->CritSec );
Free( Monitor );
}
else
{
UnlockMonitor( Monitor );
}
}
/***************************************************************************\
* FUNCTION: MonitorThread
*
* PURPOSE: Entry point for object monitor thread
*
* RETURNS: Windows error value
*
* HISTORY:
*
* 01-11-93 Davidc Created.
*
\***************************************************************************/
DWORD MonitorThread(
LPVOID lpThreadParameter
)
{
POBJECT_MONITOR Monitor = (POBJECT_MONITOR)lpThreadParameter;
DWORD WaitResult;
NTSTATUS Status;
HANDLE Handle;
//
// Wait forever for object to be signalled
//
LockMonitor( Monitor );
Monitor->Flags |= MONITOR_ACTIVE ;
Handle = Monitor->Object ;
RefMonitor( Monitor );
UnlockMonitor( Monitor );
if ( Handle != INVALID_HANDLE_VALUE )
{
Status = NtWaitForSingleObject( Handle, TRUE, NULL);
if (!NT_SUCCESS(Status) && (Status != STATUS_ALERTED))
{
DebugLog((DEB_ERROR, "MonitorThread: NtWaitForSingleObject returned %x\n", Status));
}
}
else
{
Status = STATUS_SUCCESS ;
}
//
// Notify the appropriate window
//
if (Status != STATUS_ALERTED)
{
PostMessage( Monitor->hwndNotify,
WM_OBJECT_NOTIFY,
(WPARAM)Monitor,
(LPARAM)Monitor->CallerContext
);
}
LockMonitor( Monitor );
if ( Monitor->Flags & MONITOR_CLOSEOBJ )
{
CloseHandle( Handle );
}
Monitor->Object = INVALID_HANDLE_VALUE ;
Monitor->Flags = 0 ;
UnlockMonitor( Monitor );
DerefMonitor( Monitor );
return(ERROR_SUCCESS);
}
/***************************************************************************\
* FUNCTION: CreateObjectMonitor
*
* PURPOSE: Creates a monitor object that will wait on the specified object
* and post a message to the specifed window when the object is
* signalled.
*
* NOTES: The object must have been opened for SYNCHRONIZE access.
* The caller is responsible for closing the object handle
* after the monitor object has been deleted.
*
* RETURNS: Handle to the monitor instance or NULL on failure.
*
* HISTORY:
*
* 01-11-93 Davidc Created.
*
\***************************************************************************/
POBJECT_MONITOR
CreateObjectMonitor(
HANDLE Object,
HWND hwndNotify,
DWORD CallerContext
)
{
POBJECT_MONITOR Monitor;
DWORD ThreadId;
NTSTATUS Status;
//
// Create monitor object
//
Monitor = Alloc(sizeof(OBJECT_MONITOR));
if (Monitor == NULL) {
return(NULL);
}
//
// Initialize monitor fields
//
Status = RtlInitializeCriticalSection( &Monitor->CritSec );
if ( !NT_SUCCESS( Status ) )
{
Free( Monitor );
return( NULL );
}
LockMonitor( Monitor );
Monitor->hwndNotify = hwndNotify;
Monitor->Object = Object;
Monitor->CallerContext = CallerContext;
Monitor->RefCount = 1;
Monitor->Flags = 0 ;
//
// Create the monitor thread
//
Monitor->Thread = CreateThread(
NULL, // Use default ACL
0, // Same stack size
MonitorThread, // Start address
(LPVOID)Monitor, // Parameter
0, // Creation flags
&ThreadId // Get the id back here
);
if (Monitor->Thread == NULL) {
DebugLog((DEB_ERROR, "Failed to create monitor thread, error = %d\n", GetLastError()));
DerefMonitor( Monitor );
return(NULL);
}
UnlockMonitor( Monitor );
return(Monitor);
}
/***************************************************************************\
* FUNCTION: DeleteObjectMonitor
*
* PURPOSE: Deletes an instance of a monitor object
*
* RETURNS: Nothing
*
* HISTORY:
*
* 01-11-93 Davidc Created.
*
\***************************************************************************/
VOID
DeleteObjectMonitor(
POBJECT_MONITOR Monitor,
BOOLEAN fTerminate
)
{
BOOL Result;
if ( fTerminate )
{
CancelObjectMonitor( Monitor );
}
DerefMonitor( Monitor );
}
//+---------------------------------------------------------------------------
//
// Function: CancelObjectMonitor
//
// Synopsis: Interrupts a monitor thread safely.
//
// Arguments: [Monitor] --
//
// History: 7-12-96 RichardW Created
//
// Notes:
//
//----------------------------------------------------------------------------
VOID
CancelObjectMonitor(
POBJECT_MONITOR Monitor )
{
LockMonitor( Monitor );
if ( Monitor->Flags & MONITOR_ACTIVE )
{
NtAlertThread( Monitor->Thread );
}
else
{
Monitor->Object = INVALID_HANDLE_VALUE ;
}
UnlockMonitor( Monitor );
}
//+---------------------------------------------------------------------------
//
// Function: CloseObjectMonitorObject
//
// Synopsis: Tags the handle to be closed when the monitor goes away
//
// Arguments: [Monitor] --
//
// History: 7-19-96 RichardW Created
//
// Notes:
//
//----------------------------------------------------------------------------
VOID
CloseObjectMonitorObject(
POBJECT_MONITOR Monitor
)
{
LockMonitor( Monitor );
Monitor->Flags |= MONITOR_CLOSEOBJ ;
UnlockMonitor( Monitor );
}
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