From f57100bb36eae3b4d75f3c315973405f705b8de6 Mon Sep 17 00:00:00 2001
From: Jon TURNEY <jon.turney@dronecode.org.uk>
Date: Tue, 23 Feb 2010 13:38:48 +0000
Subject: [PATCH] hw/xwin: Process one Windows message per wakeup, rather than
 all of them.

De-queuing Windows messages and X events happens in the same thread of
execution.  Draining the windows message queue can lead to the X event queue
overflowing if lots of those windows messages cause X events (e.g. if a keyboard
macro program has just dumped thousands of keypresses into the Windows message
queue).  See the mailing list thread [1] for more details.

Processing one Windows message per wakeup, rather than all of them gives the X
server a chance to do stuff as well after each message.

[1] http://cygwin.com/ml/cygwin-xfree/2010-01/msg00056.html

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>
---
 hw/xwin/winblock.c  | 32 ++++++++++++++++----------------
 hw/xwin/winwakeup.c |  4 ++--
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/hw/xwin/winblock.c b/hw/xwin/winblock.c
index a4ae8669f..c3ef4becd 100644
--- a/hw/xwin/winblock.c
+++ b/hw/xwin/winblock.c
@@ -42,14 +42,26 @@ winBlockHandler(ScreenPtr pScreen,
 #if defined(XWIN_CLIPBOARD) || defined(XWIN_MULTIWINDOW)
     winScreenPriv(pScreen);
 #endif
-    MSG msg;
 
 #ifndef HAS_DEVWINDOWS
     struct timeval **tvp = pTimeout;
 
     if (*tvp != NULL) {
+      if (GetQueueStatus(QS_ALLINPUT | QS_ALLPOSTMESSAGE) != 0) {
+        /* If there are still messages to process on the Windows message
+           queue, make sure select() just polls rather than blocking.
+        */
+        (*tvp)->tv_sec = 0;
+        (*tvp)->tv_usec = 0;
+      }
+      else {
+        /* Otherwise, lacking /dev/windows, we must wake up again in
+           a reasonable time to check the Windows message queue. without
+           noticeable delay.
+         */
         (*tvp)->tv_sec = 0;
         (*tvp)->tv_usec = 100;
+      }
     }
 #endif
 
@@ -68,25 +80,13 @@ winBlockHandler(ScreenPtr pScreen,
         if (iReturn != 0) {
             ErrorF("winBlockHandler - pthread_mutex_unlock () failed: %d\n",
                    iReturn);
-            goto winBlockHandler_ProcessMessages;
         }
-
-        winDebug("winBlockHandler - pthread_mutex_unlock () returned\n");
+        else {
+            winDebug("winBlockHandler - pthread_mutex_unlock () returned\n");
+        }
     }
-
- winBlockHandler_ProcessMessages:
 #endif
 
-    /* Process all messages on our queue */
-    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
-        if ((g_hDlgDepthChange == 0
-             || !IsDialogMessage(g_hDlgDepthChange, &msg))
-            && (g_hDlgExit == 0 || !IsDialogMessage(g_hDlgExit, &msg))
-            && (g_hDlgAbout == 0 || !IsDialogMessage(g_hDlgAbout, &msg))) {
-            DispatchMessage(&msg);
-        }
-    }
-
   /*
     At least one X client has asked to suspend the screensaver, so
     reset Windows' display idle timer
diff --git a/hw/xwin/winwakeup.c b/hw/xwin/winwakeup.c
index 77c160533..795221a1a 100644
--- a/hw/xwin/winwakeup.c
+++ b/hw/xwin/winwakeup.c
@@ -43,8 +43,8 @@ winWakeupHandler(ScreenPtr pScreen,
 {
     MSG msg;
 
-    /* Process all messages on our queue */
-    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
+    /* Process one message from our queue */
+    if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
         if ((g_hDlgDepthChange == 0
              || !IsDialogMessage(g_hDlgDepthChange, &msg))
             && (g_hDlgExit == 0 || !IsDialogMessage(g_hDlgExit, &msg))