Commit 691628a3 authored by Bill McCloskey's avatar Bill McCloskey
Browse files

Bug 1364570 - Dispatch link prefetch events asynchronously to avoid DocGroup mismatches (r=bz) 

When we send out a prefetch request, we act as if the load came
from one of the possibly many documents containing <link> element
for the given URL. The docgroup assigned to this request is
derived from this document. Later, when the load finishes, the
OnStopRequest code runs in a runnable labeled with this
docgroup. OnStopRequest dispatches a load event to *all* the link
elements, including some that might be in different docgroups
from the OnStopRequest runnable. This generates an assertion.

To fix this, I decided to dispatch the load events
asynchronously. I'm hoping the extra round trip through the event
loop shouldn't hurt us too much since I doubt anyone actually
listens for these events.

MozReview-Commit-ID: FTkjuHO7RFp
parent ea01a3bc

dom/events/AsyncEventDispatcher.cpp

+18 −0
Original line number Diff line number Diff line
@@ -39,6 +39,13 @@ AsyncEventDispatcher::Run() 
  if (mCanceled) {

    return NS_OK;

  }

  if (mCheckStillInDoc) {

    nsCOMPtr<nsINode> node = do_QueryInterface(mTarget);

    MOZ_ASSERT(node);

    if (!node->IsInComposedDoc()) {

      return NS_OK;

    }

  }

  mTarget->AsyncEventRunning(this);

  RefPtr<Event> event = mEvent ? mEvent->InternalDOMEvent() : nullptr;

  if (!event) {
@@ -88,6 +95,17 @@ AsyncEventDispatcher::RunDOMEventWhenSafe() 
  nsContentUtils::AddScriptRunner(this);

}



void

AsyncEventDispatcher::RequireNodeInDocument()

{

#ifdef DEBUG

  nsCOMPtr<nsINode> node = do_QueryInterface(mTarget);

  MOZ_ASSERT(node);

#endif



  mCheckStillInDoc = true;

}



/******************************************************************************

 * mozilla::LoadBlockingAsyncEventDispatcher

 ******************************************************************************/

dom/events/AsyncEventDispatcher.h

+6 −0
Original line number Diff line number Diff line
@@ -64,12 +64,18 @@ public: 
  nsresult PostDOMEvent();

  void RunDOMEventWhenSafe();



  // Calling this causes the Run() method to check that

  // mTarget->IsInComposedDoc(). mTarget must be an nsINode or else we'll

  // assert.

  void RequireNodeInDocument();



  nsCOMPtr<dom::EventTarget> mTarget;

  nsCOMPtr<nsIDOMEvent> mEvent;

  nsString              mEventType;

  bool                  mBubbles = false;

  bool                  mOnlyChromeDispatch = false;

  bool                  mCanceled = false;

  bool                  mCheckStillInDoc = false;

};



class LoadBlockingAsyncEventDispatcher final : public AsyncEventDispatcher

uriloader/prefetch/nsPrefetchService.cpp

+18 −11
Original line number Diff line number Diff line
@@ -4,6 +4,13 @@ 
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */



#include "nsPrefetchService.h"



#include "mozilla/AsyncEventDispatcher.h"

#include "mozilla/Attributes.h"

#include "mozilla/CORSMode.h"

#include "mozilla/dom/HTMLLinkElement.h"

#include "mozilla/Preferences.h"



#include "nsICacheEntry.h"

#include "nsIServiceManager.h"

#include "nsICategoryManager.h"
@@ -25,10 +32,6 @@ 
#include "mozilla/Logging.h"

#include "plstr.h"

#include "nsIAsyncVerifyRedirectCallback.h"

#include "mozilla/Preferences.h"

#include "mozilla/Attributes.h"

#include "mozilla/CORSMode.h"

#include "mozilla/dom/HTMLLinkElement.h"

#include "nsIDOMNode.h"

#include "nsINode.h"

#include "nsIDocument.h"
@@ -494,13 +497,17 @@ nsPrefetchService::DispatchEvent(nsPrefetchNode *node, bool aSuccess) 
    for (uint32_t i = 0; i < node->mSources.Length(); i++) {

      nsCOMPtr<nsINode> domNode = do_QueryReferent(node->mSources.ElementAt(i));

      if (domNode && domNode->IsInComposedDoc()) {

        nsContentUtils::DispatchTrustedEvent(domNode->OwnerDoc(),

                                             domNode,

        // We don't dispatch synchronously since |node| might be in a DocGroup

        // that we're not allowed to touch. (Our network request happens in the

        // DocGroup of one of the mSources nodes--not necessarily this one).

        RefPtr<AsyncEventDispatcher> dispatcher =

          new AsyncEventDispatcher(domNode,

                                   aSuccess ?

                                    NS_LITERAL_STRING("load") :

                                    NS_LITERAL_STRING("error"),

                                             /* aCanBubble = */ false,

                                             /* aCancelable = */ false);

                                   /* aCanBubble = */ false);

        dispatcher->RequireNodeInDocument();

        dispatcher->PostDOMEvent();

      }

    }

}