From: Etienne Dechamps Date: Sat, 28 Jun 2014 14:19:11 +0000 (+0100) Subject: Use a Windows event to stop tinc when running as a service. X-Git-Tag: release-1.1pre11~94^2~1 X-Git-Url: https://git.tinc-vpn.org/git/browse?a=commitdiff_plain;h=ffbc99558cae4dff876645fe205349d8c4cd7acb;p=tinc Use a Windows event to stop tinc when running as a service. Currently, when the tinc service handler callback (which runs in a separate thread) receives a service shutdown request, it calls event_exit() to request the event loop to exit. This approach has a few issues: - The event loop will only notice the exit request when the next event fires. This slows down tinc service shutdown. In some extreme cases (DeviceStandby enabled, long PingTimeout and no connections), shutdown can take ages. - Strictly speaking, because of the absence of memory barriers, there is no guarantee that the event loop will even notice an exit request coming from another thread. I suppose marking the "running" variable as "volatile" is supposed to alleviate that, but it's unclear whether that provides any guarantees with modern systems and compilers. This commit fixes the issue by leveraging the new event loop Windows interface, using a custom Windows event that is manually set when shutdown is requested. --- diff --git a/src/event.c b/src/event.c index 5e6908f5..8f15ebea 100644 --- a/src/event.c +++ b/src/event.c @@ -35,7 +35,7 @@ static const long READ_EVENTS = FD_READ | FD_ACCEPT | FD_CLOSE; static const long WRITE_EVENTS = FD_WRITE | FD_CONNECT; static DWORD event_count = 0; #endif -static volatile bool running; +static bool running; static int io_compare(const io_t *a, const io_t *b) { #ifndef HAVE_MINGW diff --git a/src/process.c b/src/process.c index c1038bcd..98f4d33a 100644 --- a/src/process.c +++ b/src/process.c @@ -108,6 +108,8 @@ static bool install_service(void) { return true; } +static io_t stop_io; + DWORD WINAPI controlhandler(DWORD request, DWORD type, LPVOID boe, LPVOID bah) { switch(request) { case SERVICE_CONTROL_INTERROGATE: @@ -124,16 +126,25 @@ DWORD WINAPI controlhandler(DWORD request, DWORD type, LPVOID boe, LPVOID bah) { return ERROR_CALL_NOT_IMPLEMENTED; } - event_exit(); - status.dwWaitHint = 30000; + status.dwWaitHint = 1000; status.dwCurrentState = SERVICE_STOP_PENDING; SetServiceStatus(statushandle, &status); + if (WSASetEvent(stop_io.event) == FALSE) + abort(); return NO_ERROR; } +static void stop_handler(void *data, int flags) { + event_exit(); +} + VOID WINAPI run_service(DWORD argc, LPTSTR* argv) { extern int main2(int argc, char **argv); + io_add_event(&stop_io, stop_handler, NULL, WSACreateEvent()); + if (stop_io.event == FALSE) + abort(); + status.dwServiceType = SERVICE_WIN32; status.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN; status.dwWin32ExitCode = 0; @@ -160,6 +171,9 @@ VOID WINAPI run_service(DWORD argc, LPTSTR* argv) { SetServiceStatus(statushandle, &status); } + if (WSACloseEvent(stop_io.event) == FALSE) + abort(); + io_del(&stop_io); return; }