C++ Visual Studio 2013 Unwinding object - c++

Question

Well, I'm trying to build this line of code, bit I get a compiler error. I've tryed to build without the compiler, but that didn't work either. Its about the __try and __except. Someone told me to move the code in the try block to another function. But I don't understand this:
Error 12 error C2712: Cannot use __try in functions that require
object unwinding
Error 437 error LNK1181: cannot open input file
void MSocketThread::Run()
{
__try{
//throw(pThread);
while (true) { // Waiting for SafeUDP Settting...
DWORD dwVal = WaitForSingleObject(m_KillEvent.GetEvent(), 100);
if (dwVal == WAIT_OBJECT_0) {
return;
}
else if (dwVal == WAIT_TIMEOUT) {
if (m_pSafeUDP)
break;
}
}
WSAEVENT EventArray[WSA_MAXIMUM_WAIT_EVENTS];
WORD wEventIndex = 0;
bool bSendable = false;
WSANETWORKEVENTS NetEvent;
WSAEVENT hFDEvent = WSACreateEvent();
EventArray[wEventIndex++] = hFDEvent;
EventArray[wEventIndex++] = m_ACKEvent.GetEvent();
EventArray[wEventIndex++] = m_SendEvent.GetEvent();
EventArray[wEventIndex++] = m_KillEvent.GetEvent();
WSAEventSelect(m_pSafeUDP->GetLocalSocket(), hFDEvent, FD_READ | FD_WRITE);
while (TRUE) {
DWORD dwReturn = WSAWaitForMultipleEvents(wEventIndex, EventArray, FALSE, SAFEUDP_SAFE_MANAGE_TIME, FALSE);
if (dwReturn == WSA_WAIT_TIMEOUT) { // Time
m_pSafeUDP->LockNetLink();
SafeSendManage();
m_pSafeUDP->UnlockNetLink();
}
else if (dwReturn == WSA_WAIT_EVENT_0) { // Socket Event
WSAEnumNetworkEvents(m_pSafeUDP->GetLocalSocket(), hFDEvent, &NetEvent);
if ((NetEvent.lNetworkEvents & FD_READ) == FD_READ) {
// OutputDebugString("SUDP> FD_READ \n");
m_pSafeUDP->LockNetLink();
Recv();
m_pSafeUDP->UnlockNetLink();
}
if ((NetEvent.lNetworkEvents & FD_WRITE) == FD_WRITE) {
bSendable = true;
// OutputDebugString("SUDP> FD_WRITE \n");
}
}
else if (dwReturn == WSA_WAIT_EVENT_0 + 1) { // ACK Send Event
// OutputDebugString("SUDP> ACK_EVENT \n");
FlushACK();
}
else if (dwReturn == WSA_WAIT_EVENT_0 + 2) { // Packet Send Event
// OutputDebugString("SUDP> SEND_EVENT \n");
if (bSendable == true)
FlushSend();
}
else if (dwReturn == WSA_WAIT_EVENT_0 + 3) { // Kill the Thread
break; // Stop Thread
}
}
WSACloseEvent(hFDEvent);
// Clear Queues
LockSend();
{
for (SendListItor itor = m_SendList.begin(); itor != m_SendList.end();) {
delete (*itor);
itor = m_SendList.erase(itor);
}
}
{
for (SendListItor itor = m_TempSendList.begin(); itor != m_TempSendList.end();) {
delete (*itor);
itor = m_TempSendList.erase(itor);
}
}
UnlockSend();
LockACK();
{
for (ACKSendListItor itor = m_ACKSendList.begin(); itor != m_ACKSendList.end();) {
delete (*itor);
itor = m_ACKSendList.erase(itor);
}
}
{
for (ACKSendListItor itor = m_TempACKSendList.begin(); itor != m_TempACKSendList.end();) {
delete (*itor);
itor = m_TempACKSendList.erase(itor);
}
}
UnlockACK();
}
__except (this->CrashDump(GetExceptionInformation()))

Answer 1

Basically, SEH and C++ unwinding aren't exactly compatible; they require the compiler to modify the function on the machine code level, and MS apparently decided not to support the modifications for the two at the same time, so any function can only support either SEH unwind actions (__except or __finally) or C++ unwind actions (catch or objects with destructors).
I suspect the problem in your case are the iterators in your loops; they might have destructors. Although iterators are usually simple and don't need destructors, this is not the case for debug iterators, which often register their existence on construction and deregister it on destruction, in order to detect invalidated iterators and other invalid usage.
The usual workaround is to split the function. Make your run function contain just this:
void MSocketThread::Run()
{
__try {
RunNoSeh();
} __except (this->CrashDump(GetExceptionInformation())) {
}
}
void MSocketThread::RunNoSeh()
{
// Code that was inside the __try goes here.
}