On Fri, Jan 17, 2014 at 1:37 PM, Ben Pfaff <b...@nicira.com> wrote:
> On Fri, Jan 17, 2014 at 01:30:27PM -0800, Gurucharan Shetty wrote:
>> On Fri, Jan 17, 2014 at 1:13 PM, Ben Pfaff <b...@nicira.com> wrote:
>> > On Fri, Jan 17, 2014 at 12:26:23PM -0800, Gurucharan Shetty wrote:
>> >> Start with ovs-vswitchd and ovsdb-server.
>> >>
>> >> Signed-off-by: Gurucharan Shetty <gshe...@nicira.com>
>> >
>> > Will poll_block() wake up if a service stop has been requested?
>> > Ideally, it would.
>> I did not think a lot about it. I suppose we have a time limit in ms
>> after which we wake up every time correct?
>
> No. In ovs-vswitchd, for example, if nothing is happening, and no
> bridges are configured, then poll_block() can block indefinitely.
Okay.
>
>> I haven't seen (during my tests) a negative consequence of a small
>> delay in stopping the service after a request. If that is indeed a
>> problem, I will investigate more.
>
> I assume a small delay is OK, too, but I don't think that the delay
> here is bounded.
>
I see that now. I think the following incremental that uses a
CreateEvent and SetEvent in daemon-windows.c (on top of patch3 of the
series) will fix the problem. The patch makes an assumption that
poll_block() will only be called at one place in the main thread's
loop. Otherwise, between two poll_block(), I will have to figure out a
way to call a poll_fd_wait() to re-register a event. Is my assumption
correct?
Incremental:
+/* Handle to an event object used to wakeup from poll_block(). */
+static HANDLE wevent;
+
/* Hold the arguments sent to the main function. */
static int sargc;
static char ***sargvp;
@@ -82,6 +86,14 @@
if (detached) {
init_service_status();
+ wevent = CreateEvent(NULL, TRUE, FALSE, NULL);
+ if (!wevent) {
+ ovs_lasterror_to_string((LPTSTR)&msg_buf);
+ VLOG_FATAL("Failed to create a event (%s).", msg_buf);
+ }
+
+ poll_fd_wait(0, wevent, POLLIN);
+
/* Register the control handler. This function is called by the service
* manager to stop the service. */
hstatus = RegisterServiceCtrlHandler(program_name,
@@ -162,6 +174,7 @@
case SERVICE_CONTROL_SHUTDOWN:
service_status.dwCurrentState = SERVICE_STOPPED;
service_status.dwWin32ExitCode = NO_ERROR;
+ SetEvent(wevent);
break;
default:
@@ -174,8 +187,12 @@
bool
should_service_stop(void)
{
- if (detached && service_status.dwCurrentState != SERVICE_RUNNING) {
- return true;
+ if (detached) {
+ if (service_status.dwCurrentState != SERVICE_RUNNING) {
+ return true;
+ } else {
+ poll_fd_wait(0, wevent, POLLIN);
+ }
}
return false;
}
@@ -186,6 +203,9 @@
void
service_stop()
{
+ ResetEvent(wevent);
+ CloseHandle(wevent);
+
service_status.dwCurrentState = SERVICE_STOPPED;
service_status.dwWin32ExitCode = NO_ERROR;
SetServiceStatus(hstatus, &service_status);
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