Changeset 20267 in webkit

Timestamp:

Mar 17, 2007 5:54:44 PM (17 years ago)

Author:

hyatt

Message:

Tweaks to prevent timers from starving user input or painting.

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/win/SharedTimerWin.cpp (modified) (2 diffs)

trunk/WebCore/ChangeLog

@@ +1 @@
+2007-03-17  Dave Hyatt  <hyatt@apple.com>
+
+        Prevent starvation of user input and painting when processing timers.
+        If we are already in the processing of a custom timer message, don't allow that
+        processing to do another PostMessage.  Force SetTimer to be used instead.
+      
+        Reviewed by ggaren
+
+       * platform/win/SharedTimerWin.cpp:
+        (WebCore::TimerWindowWndProc):
+        (WebCore::setSharedTimerFireTime):
+
 2007-03-17  Geoffrey Garen  <ggaren@apple.com>
 

trunk/WebCore/platform/win/SharedTimerWin.cpp

@@ -41 +41 @@
 static UINT timerFiredMessage = 0;
 const LPCWSTR kTimerWindowClassName = L"TimerWindowClass";
+static bool processingCustomTimerMessage = false;
 
 LRESULT CALLBACK TimerWindowWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-    if (message == timerFiredMessage)
+    if (message == timerFiredMessage) {
+        processingCustomTimerMessage = true;
         sharedTimerFiredFunction();
-    else
+        processingCustomTimerMessage = false;
+    } else
         return DefWindowProc(hWnd, message, wParam, lParam);
     return 0;
@@ -95 +98 @@
     }
 
-    if (timerID)
+    if (timerID) {
         KillTimer(0, timerID);
+        timerID = 0;
+    }
 
-    if (intervalInMS == 0) {
-        timerID = 0;
+    // We don't allow nested PostMessages, since the custom messages will effectively starve
+    // painting and user input. (Win32 has a tri-level queue with application messages > 
+    // user input > WM_PAINT/WM_TIMER.)
+    if (intervalInMS < USER_TIMER_MINIMUM && !processingCustomTimerMessage) {
         // Windows SetTimer does not allow timeouts smaller than 10ms (USER_TIMER_MINIMUM)
         initializeOffScreenTimerWindow();
         PostMessage(timerWindowHandle, timerFiredMessage, 0, 0);
     } else
-        // FIXME: 1-9ms timeouts may fire too late.
         timerID = SetTimer(0, 0, intervalInMS, timerFired);
 }