dix: Add optional terminate delay

When the command line option "-terminate" is used, it could be
interesting to give it an optional grace period to let the Xserver
running for a little longer in case a new connection occurs.

This adds an optional parameter to the "-terminate" command line option
for this purpose.

v2: Use a delay in seconds instead of milliseconds
    (Martin Peres <martin.peres@mupuf.org>)
v3: Clarify man page entry, ensure terminateDelay is always >= 0,
    simplify TimerFree(). (Peter Hutterer <peter.hutterer@who-t.net>)

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>

dix/dispatch.c

@@ -165,6 +165,7 @@ static int nextFreeClientID;    /* always MIN free client ID */
 static int nClients;            /* number of authorized clients */
 
 CallbackListPtr ClientStateCallback;
+OsTimerPtr dispatchExceptionTimer;
 
 /* dispatchException & isItTimeToYield must be declared volatile since they
  * are modified by signal handlers - otherwise optimizer may assume it doesn't
@@ -400,6 +401,42 @@ SmartScheduleClient(void)
     return best;
 }
 
+static CARD32
+DispatchExceptionCallback(OsTimerPtr timer, CARD32 time, void *arg)
+{
+    dispatchException |= dispatchExceptionAtReset;
+
+    /* Don't re-arm the timer */
+    return 0;
+}
+
+static void
+CancelDispatchExceptionTimer(void)
+{
+    TimerFree(dispatchExceptionTimer);
+    dispatchExceptionTimer = NULL;
+}
+
+static void
+SetDispatchExceptionTimer(void)
+{
+    /* The timer delay is only for terminate, not reset */
+    if (!(dispatchExceptionAtReset & DE_TERMINATE)) {
+        dispatchException |= dispatchExceptionAtReset;
+        return;
+    }
+
+    CancelDispatchExceptionTimer();
+
+    if (terminateDelay == 0)
+        dispatchException |= dispatchExceptionAtReset;
+    else
+        dispatchExceptionTimer = TimerSet(dispatchExceptionTimer,
+                                          0, terminateDelay * 1000 /* msec */,
+                                          &DispatchExceptionCallback,
+                                          NULL);
+}
+
 static Bool
 ShouldDisconnectRemainingClients(void)
 {
@@ -3436,6 +3473,7 @@ ProcNoOperation(ClientPtr client)
  *********************/
 
 char dispatchExceptionAtReset = DE_RESET;
+int terminateDelay = 0;
 
 void
 CloseDownClient(ClientPtr client)
@@ -3492,7 +3530,7 @@ CloseDownClient(ClientPtr client)
 
     if (really_close_down) {
         if (client->clientState == ClientStateRunning && nClients == 0)
-            dispatchException |= dispatchExceptionAtReset;
+            SetDispatchExceptionTimer();
 
         client->clientState = ClientStateGone;
         if (ClientStateCallback) {
@@ -3523,7 +3561,7 @@ CloseDownClient(ClientPtr client)
     }
 
     if (ShouldDisconnectRemainingClients())
-        dispatchException |= dispatchExceptionAtReset;
+        SetDispatchExceptionTimer();
 }
 
 static void
@@ -3725,6 +3763,7 @@ SendConnSetup(ClientPtr client, const char *reason)
         clientinfo.setup = (xConnSetup *) lConnectionInfo;
         CallCallbacks((&ClientStateCallback), (void *) &clientinfo);
     }
+    CancelDispatchExceptionTimer();
     return Success;
 }
 

hw/xwayland/xwayland.pc.in

@@ -10,3 +10,4 @@ have_eglstream=@have_eglstream@
 have_initfd=true
 have_listenfd=true
 have_verbose=true
+have_terminate_delay=true

include/dix.h

@@ -130,6 +130,7 @@ extern _X_EXPORT ClientPtr clients[MAXCLIENTS];
 extern _X_EXPORT ClientPtr serverClient;
 extern _X_EXPORT int currentMaxClients;
 extern _X_EXPORT char dispatchExceptionAtReset;
+extern _X_EXPORT int terminateDelay;
 
 typedef int HWEventQueueType;
 typedef HWEventQueueType *HWEventQueuePtr;

man/Xserver.man

@@ -263,11 +263,14 @@ connected to the system.
 sets pointer acceleration threshold in pixels (i.e. after how many pixels
 pointer acceleration should take effect).
 .TP 8
-.B \-terminate
+.B \-terminate \fI[delay]\fP
 causes the server to terminate at server reset, instead of continuing to run.
 This overrides a previous
 .B \-noreset
 command line option.
+If a delay in seconds is specified, the server waits for at least
+the delay. At the end of this grace period if no client is
+connected, the server terminates immediately.
 .TP 8
 .B \-tst
 disables all testing extensions (e.g., XTEST, XTrap, XTestExtension1, RECORD).

os/utils.c

@@ -561,7 +561,7 @@ UseMsg(void)
     ErrorF("-s #                   screen-saver timeout (minutes)\n");
     ErrorF("-seat string           seat to run on\n");
     ErrorF("-t #                   default pointer threshold (pixels/t)\n");
-    ErrorF("-terminate             terminate at server reset\n");
+    ErrorF("-terminate [delay]     terminate at server reset (optional delay in sec)\n");
     ErrorF("-tst                   disable testing extensions\n");
     ErrorF("ttyxx                  server started from init on /dev/ttyxx\n");
     ErrorF("v                      video blanking for screen-saver\n");
@@ -917,6 +917,10 @@ ProcessCommandLine(int argc, char *argv[])
         }
         else if (strcmp(argv[i], "-terminate") == 0) {
             dispatchExceptionAtReset = DE_TERMINATE;
+            terminateDelay = -1;
+            if ((i + 1 < argc) && (isdigit(*argv[i + 1])))
+               terminateDelay = atoi(argv[++i]);
+            terminateDelay = max(0, terminateDelay);
         }
         else if (strcmp(argv[i], "-tst") == 0) {
             noTestExtensions = TRUE;