//-----------------------------------------------------------------------------
// Wrap an unsafe call in a mutex to assure safety
// Biggest error issues are:
// 1. Timeout (probably handler doesn't exist)
// 2. Handler can be destroyed at any time.
//-----------------------------------------------------------------------------
IPCFuncCallSource::EError IPCFuncCallSource::DoThreadSafeCall()
{
DWORD dwErr;
EError err = Ok;
#if defined(ENABLE_TIMING)
g_time.Reset();
g_time.Start();
#endif
HANDLE hStartEnum = NULL;
HANDLE hDoneEnum = NULL;
HANDLE hWrapCall = NULL;
DWORD dwWaitRet;
// Check if we have a handler (handler creates the events) and
// abort if not. Do this check asap to optimize the most common
// case of no handler.
hStartEnum = WszOpenEvent(EVENT_ALL_ACCESS,
FALSE,
FixupName(StartEnumEventName));
if (hStartEnum == NULL)
{
dwErr = GetLastError();
err = Fail_NoHandler;
goto errExit;
}
hDoneEnum = WszOpenEvent(EVENT_ALL_ACCESS,
FALSE,
FixupName(DoneEnumEventName));
if (hDoneEnum == NULL)
{
dwErr = GetLastError();
err = Fail_NoHandler;
goto errExit;
}
// Need to create the mutex
hWrapCall = WszCreateMutex(NULL, FALSE, FixupName(WrapMutexName));
if (hWrapCall == NULL)
{
dwErr = GetLastError();
err = Fail_CreateMutex;
goto errExit;
}
// Wait for our turn
dwWaitRet = WaitForSingleObject(hWrapCall, START_ENUM_TIMEOUT);
dwErr = GetLastError();
switch(dwWaitRet) {
case WAIT_OBJECT_0:
// Good case. All other cases are errors and goto errExit.
break;
case WAIT_TIMEOUT:
err = Fail_Timeout_Lock;
goto errExit;
break;
default:
err = Failed;
goto errExit;
break;
}
// Our turn: Make the function call
{
BOOL fSetOK = 0;
// Reset the 'Done event' to make sure that Handler sets it after they start.
ResetEvent(hDoneEnum);
dwErr = GetLastError();
// Signal Handler to execute callback
fSetOK = SetEvent(hStartEnum);
dwErr = GetLastError();
// Now wait for handler to finish.
dwWaitRet = WaitForSingleObject(hDoneEnum, START_ENUM_TIMEOUT);
dwErr = GetLastError();
switch (dwWaitRet)
{
case WAIT_OBJECT_0:
break;
case WAIT_TIMEOUT:
err = Fail_Timeout_Call;
break;
default:
err = Failed;
break;
}
ReleaseMutex(hWrapCall);
dwErr = GetLastError();
} // End function call
errExit:
// Close all handles
if (hStartEnum != NULL)
{
CloseHandle(hStartEnum);
hStartEnum = NULL;
}
if (hDoneEnum != NULL)
{
CloseHandle(hDoneEnum);
hDoneEnum = NULL;
}
if (hWrapCall != NULL)
{
CloseHandle(hWrapCall);
hWrapCall = NULL;
}
#if defined(ENABLE_TIMING)
g_time.End();
DWORD dwTime = g_time.GetEllapsedMS();
#endif
return err;
}
