Changeset 176133 in webkit

Timestamp:

Nov 14, 2014, 12:05:26 PM (10 years ago)

Author:

mitz@apple.com

Message:

Add some tracing to help investigating <rdar://problem/18905383> [iOS] Crash due to null m_webPageProxyForBackForwardListForCurrentSwipe in ViewGestureController::endSwipeGesture
​https://bugs.webkit.org/show_bug.cgi?id=138750

Reviewed by Tim Horton.

Emit trace messages at various points, and log them prior to crashing if the error condition
occurs. Otherwise, clear the trace messages.

• UIProcess/ios/ViewGestureControllerIOS.mm:

(WebKit::addLogEntry): Helper function that adds a message, including a time stamp and a
backtrace, to m_logEntries.
(WebKit::dumpLogEntries): Helper function that logs everything in m_logEntries.
(WebKit::ViewGestureController::beginSwipeGesture): Add a log entry.
(WebKit::ViewGestureController::endSwipeGesture): If
m_webPageProxyForBackForwardListForCurrentSwipe is null, dump the log entries just before
crashing. Otherwise, clear m_logEntries.
(WebKit::ViewGestureController::willCommitPostSwipeTransitionLayerTree): Add a log entry.
(WebKit::ViewGestureController::removeSwipeSnapshot): Add a log entry.

• UIProcess/mac/ViewGestureController.h: Defined ENABLE_VIEW_GESTURE_CONTROLLER_TRACING,

and added m_logEntries member variable.

Location:

trunk/Source/WebKit2

Files:

• ChangeLog (modified) (1 diff)
• UIProcess/ios/ViewGestureControllerIOS.mm (modified) (7 diffs)
• UIProcess/mac/ViewGestureController.h (modified) (2 diffs)

trunk/Source/WebKit2/ChangeLog

@@ +1 @@
+2014-11-14  Dan Bernstein  <mitz@apple.com>
+
+        Add some tracing to help investigating <rdar://problem/18905383> [iOS] Crash due to null m_webPageProxyForBackForwardListForCurrentSwipe in ViewGestureController::endSwipeGesture
+        https://bugs.webkit.org/show_bug.cgi?id=138750
+
+        Reviewed by Tim Horton.
+
+        Emit trace messages at various points, and log them prior to crashing if the error condition
+        occurs. Otherwise, clear the trace messages.
+
+        * UIProcess/ios/ViewGestureControllerIOS.mm:
+        (WebKit::addLogEntry): Helper function that adds a message, including a time stamp and a
+        backtrace, to m_logEntries.
+        (WebKit::dumpLogEntries): Helper function that logs everything in m_logEntries.
+        (WebKit::ViewGestureController::beginSwipeGesture): Add a log entry.
+        (WebKit::ViewGestureController::endSwipeGesture): If
+        m_webPageProxyForBackForwardListForCurrentSwipe is null, dump the log entries just before
+        crashing. Otherwise, clear m_logEntries.
+        (WebKit::ViewGestureController::willCommitPostSwipeTransitionLayerTree): Add a log entry.
+        (WebKit::ViewGestureController::removeSwipeSnapshot): Add a log entry.
+        * UIProcess/mac/ViewGestureController.h: Defined ENABLE_VIEW_GESTURE_CONTROLLER_TRACING,
+        and added m_logEntries member variable.
+
 2014-11-14  Beth Dakin  <bdakin@apple.com>
 

trunk/Source/WebKit2/UIProcess/ios/ViewGestureControllerIOS.mm

@@ -47 +47 @@
 #import <WebCore/IOSurface.h>
 #import <wtf/NeverDestroyed.h>
+#import <wtf/text/StringBuilder.h>
 
 using namespace WebCore;
@@ -171 +172 @@
 }
 
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+static void addLogEntry(Vector<String>& entries, const String& message)
+{
+    void* stack[32];
+    int size = WTF_ARRAY_LENGTH(stack);
+    WTFGetBacktrace(stack, &size);
+    StringBuilder stringBuilder;
+    stringBuilder.append(String::format("%f [ ]", CFAbsoluteTimeGetCurrent()));
+    for (int i = 2; i < size; ++i) {
+        if (i > 2)
+            stringBuilder.appendLiteral(", ");
+        stringBuilder.append(String::format("%p", stack[i]));
+    }
+    stringBuilder.appendLiteral(" ] ");
+    stringBuilder.append(message);
+    entries.append(stringBuilder.toString());
+}
+
+static void dumpLogEntries(const Vector<String>& entries, WebPageProxy* webPageProxy)
+{
+    for (const auto& entry: entries)
+        WTFLogAlways(entry.utf8().data());
+    WTFLogAlways("m_webPageProxy: %p", webPageProxy);
+}
+#endif
+
 void ViewGestureController::beginSwipeGesture(_UINavigationInteractiveTransitionBase *transition, SwipeDirection direction)
 {
@@ -179 +206 @@
 
     m_webPageProxyForBackForwardListForCurrentSwipe = m_alternateBackForwardListSourceView.get() ? m_alternateBackForwardListSourceView.get()->_page : &m_webPageProxy;
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+    addLogEntry(m_logEntries, String::format("m_webPageProxyForBackForwardListForCurrentSwipe: %p", m_webPageProxyForBackForwardListForCurrentSwipe.get()));
+#endif
     m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidBegin();
 
@@ -280 +310 @@
         RefPtr<WebPageProxy> webPageProxyForBackForwardListForCurrentSwipe = m_webPageProxyForBackForwardListForCurrentSwipe;
         removeSwipeSnapshot();
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+        if (!webPageProxyForBackForwardListForCurrentSwipe)
+            dumpLogEntries(m_logEntries, &m_webPageProxy);
+        m_logEntries.clear();
+#endif
+
         webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(false, *targetItem);
+
         return;
     }
@@ -287 +324 @@
     if (ViewSnapshot* snapshot = targetItem->snapshot())
         m_snapshotRemovalTargetRenderTreeSize = snapshot->renderTreeSize() * swipeSnapshotRemovalRenderTreeSizeTargetFraction;
+
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+    if (!m_webPageProxyForBackForwardListForCurrentSwipe)
+        dumpLogEntries(m_logEntries, &m_webPageProxy);
+    m_logEntries.clear();
+#endif
 
     m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(true, *targetItem);
@@ -308 +351 @@
 void ViewGestureController::willCommitPostSwipeTransitionLayerTree(bool successful)
 {
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+    addLogEntry(m_logEntries, String::format("successful: %d; m_activeGestureType: %d; m_webPageProxyForBackForwardListForCurrentSwipe: %p", successful, m_activeGestureType, m_webPageProxyForBackForwardListForCurrentSwipe.get()));
+#endif
     if (m_activeGestureType != ViewGestureType::Swipe)
         return;
@@ -342 +388 @@
     m_swipeWatchdogTimer.stop();
 
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+    addLogEntry(m_logEntries, String::format("m_activeGestureType: %d; m_webPageProxyForBackForwardListForCurrentSwipe: %p", m_activeGestureType, m_webPageProxyForBackForwardListForCurrentSwipe.get()));
+#endif
     if (m_activeGestureType != ViewGestureType::Swipe)
         return;

trunk/Source/WebKit2/UIProcess/mac/ViewGestureController.h

@@ -34 +34 @@
 #include <wtf/RunLoop.h>
 
+#define ENABLE_VIEW_GESTURE_CONTROLLER_TRACING 1
+
 OBJC_CLASS CALayer;
 
@@ -214 +216 @@
     WeakObjCPtr<WKWebView> m_alternateBackForwardListSourceView;
     RefPtr<WebPageProxy> m_webPageProxyForBackForwardListForCurrentSwipe;
+#if ENABLE(VIEW_GESTURE_CONTROLLER_TRACING)
+    Vector<String> m_logEntries;
+#endif
 #endif
 };