Fix flaky server shutdown mechanism

[truecarfield]

What?

• Define cancel_thread based on terminate_thread (win) and detach_thread (linux)
• Use cancel_thread for server shutdown
• Impl XcpReset to reset XCP status when server is shutdown

Why?

• Calling join_thread will shutdown server, but also crashes the program
• Calling join_thread/terminate_thread/detach_thread after XcpTlShutdown also crashes the program
• Using terminat_thread and detach_thread mechanism will shutdown the server only passively. But so long as the server receives a msg from a master, it can then shutdown normally
• If XCP session status is not reset after shutdown, then it will act flaky when reinitialized

[RainerZ]

Hello,

Thanks.

Do you have an idea, what the root cause for your crashes was ?

There seems to be another problem: XcpEthServerShutdown() calls XcpTlShutdown(), which should be XcpEthTlShutdown(). Right ?

I was unsure what the optimal solution - graceful or forceful thread shutdown - should be. Windows strongly recommends graceful thread termination, as better programming style ,to avoid resource leaks in general.

Seems the reinitialization use case has never been stressed. Of course this should work, but what exactly is your use case why you do reinitialization.

[RainerZ]

I did some more testing on the 2 solutions after fixing XcpEthTlShutdown():

'''

ifdef XCP_SERVER_FORCEFULL_TERMINATION

// Forcefull termination
if (gXcpServer.isInit) {
    DBG_PRINT3("Disconnect, cancel threads and shutdown XCP!\n");
    XcpDisconnect();
    cancel_thread(gXcpServer.ReceiveThreadHandle);
    cancel_thread(gXcpServer.TransmitThreadHandle);
    XcpEthTlShutdown();
    gXcpServer.isInit = FALSE;
    socketCleanup();
    XcpReset();
}

else

// Gracefull termination
if (gXcpServer.isInit) {
    XcpDisconnect();
    gXcpServer.ReceiveThreadRunning = FALSE;
    gXcpServer.TransmitThreadRunning = FALSE;
    XcpEthTlShutdown();
    join_thread(gXcpServer.ReceiveThreadHandle);
    join_thread(gXcpServer.TransmitThreadHandle);
    gXcpServer.isInit = FALSE;
    socketCleanup();
    XcpReset();
}

endif

'''

I am not lucky with the forcefull alternative, as it seems to start a race between cancel_thread and shutting down the socket, which leads to graceful termination via recvfrom. Did not check TCP yet.

[RainerZ]

Pushed changes to master v6.3 Added OPTION_SERVER_FORCEFULL_TERMINATION