1 files changed, 227 insertions, 0 deletions
diff --git a/netwerk/ipc/ChannelEventQueue.cpp b/netwerk/ipc/ChannelEventQueue.cpp
new file mode 100644
index 0000000000..911deaa7d9
--- /dev/null
+++ b/netwerk/ipc/ChannelEventQueue.cpp
@@ -0,0 +1,227 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set sw=2 ts=8 et tw=80 :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ChannelEventQueue.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Unused.h"
+#include "nsIChannel.h"
+#include "mozilla/dom/Document.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace net {
+
+ChannelEvent* ChannelEventQueue::TakeEvent() {
+  mMutex.AssertCurrentThreadOwns();
+  MOZ_ASSERT(mFlushing);
+
+  if (mSuspended || mEventQueue.IsEmpty()) {
+    return nullptr;
+  }
+
+  UniquePtr<ChannelEvent> event(std::move(mEventQueue[0]));
+  mEventQueue.RemoveElementAt(0);
+
+  return event.release();
+}
+
+void ChannelEventQueue::FlushQueue() {
+  // Events flushed could include destruction of channel (and our own
+  // destructor) unless we make sure its refcount doesn't drop to 0 while this
+  // method is running.
+  nsCOMPtr<nsISupports> kungFuDeathGrip;
+  {
+    MutexAutoLock lock(mMutex);
+    kungFuDeathGrip = mOwner;
+  }
+  mozilla::Unused << kungFuDeathGrip;  // Not used in this function
+
+#ifdef DEBUG
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mFlushing);
+  }
+#endif  // DEBUG
+
+  bool needResumeOnOtherThread = false;
+
+  while (true) {
+    UniquePtr<ChannelEvent> event;
+    {
+      MutexAutoLock lock(mMutex);
+      event.reset(TakeEvent());
+      if (!event) {
+        MOZ_ASSERT(mFlushing);
+        mFlushing = false;
+        MOZ_ASSERT(mEventQueue.IsEmpty() || (mSuspended || !!mForcedCount));
+        break;
+      }
+    }
+
+    nsCOMPtr<nsIEventTarget> target = event->GetEventTarget();
+    MOZ_ASSERT(target);
+
+    bool isCurrentThread = false;
+    nsresult rv = target->IsOnCurrentThread(&isCurrentThread);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      // Simply run this event on current thread if we are not sure about it
+      // in release channel, or assert in Aurora/Nightly channel.
+      MOZ_DIAGNOSTIC_ASSERT(false);
+      isCurrentThread = true;
+    }
+
+    if (!isCurrentThread) {
+      // Next event needs to run on another thread. Put it back to
+      // the front of the queue can try resume on that thread.
+      Suspend();
+      PrependEvent(std::move(event));
+
+      needResumeOnOtherThread = true;
+      {
+        MutexAutoLock lock(mMutex);
+        MOZ_ASSERT(mFlushing);
+        mFlushing = false;
+        MOZ_ASSERT(!mEventQueue.IsEmpty());
+      }
+      break;
+    }
+
+    event->Run();
+  }  // end of while(true)
+
+  // The flush procedure is aborted because next event cannot be run on current
+  // thread. We need to resume the event processing right after flush procedure
+  // is finished.
+  // Note: we cannot call Resume() while "mFlushing == true" because
+  // CompleteResume will not trigger FlushQueue while there is an ongoing flush.
+  if (needResumeOnOtherThread) {
+    Resume();
+  }
+}
+
+void ChannelEventQueue::Suspend() {
+  MutexAutoLock lock(mMutex);
+  SuspendInternal();
+}
+
+void ChannelEventQueue::SuspendInternal() {
+  mMutex.AssertCurrentThreadOwns();
+
+  mSuspended = true;
+  mSuspendCount++;
+}
+
+void ChannelEventQueue::Resume() {
+  MutexAutoLock lock(mMutex);
+  ResumeInternal();
+}
+
+void ChannelEventQueue::ResumeInternal() {
+  mMutex.AssertCurrentThreadOwns();
+
+  // Resuming w/o suspend: error in debug mode, ignore in build
+  MOZ_ASSERT(mSuspendCount > 0);
+  if (mSuspendCount <= 0) {
+    return;
+  }
+
+  if (!--mSuspendCount) {
+    if (mEventQueue.IsEmpty() || !!mForcedCount) {
+      // Nothing in queue to flush or waiting for AutoEventEnqueuer to
+      // finish the force enqueue period, simply clear the flag.
+      mSuspended = false;
+      return;
+    }
+
+    // Hold a strong reference of mOwner to avoid the channel release
+    // before CompleteResume was executed.
+    class CompleteResumeRunnable : public Runnable {
+     public:
+      explicit CompleteResumeRunnable(ChannelEventQueue* aQueue,
+                                      nsISupports* aOwner)
+          : Runnable("CompleteResumeRunnable"),
+            mQueue(aQueue),
+            mOwner(aOwner) {}
+
+      NS_IMETHOD Run() override {
+        mQueue->CompleteResume();
+        return NS_OK;
+      }
+
+     private:
+      virtual ~CompleteResumeRunnable() = default;
+
+      RefPtr<ChannelEventQueue> mQueue;
+      nsCOMPtr<nsISupports> mOwner;
+    };
+
+    if (!mOwner) {
+      return;
+    }
+
+    // Worker thread requires a CancelableRunnable.
+    RefPtr<Runnable> event = new CompleteResumeRunnable(this, mOwner);
+
+    nsCOMPtr<nsIEventTarget> target;
+    target = mEventQueue[0]->GetEventTarget();
+    MOZ_ASSERT(target);
+
+    Unused << NS_WARN_IF(
+        NS_FAILED(target->Dispatch(event.forget(), NS_DISPATCH_NORMAL)));
+  }
+}
+
+bool ChannelEventQueue::MaybeSuspendIfEventsAreSuppressed() {
+  // We only ever need to suppress events on the main thread, since this is
+  // where content scripts can run.
+  if (!NS_IsMainThread()) {
+    return false;
+  }
+
+  // Only suppress events for queues associated with XHRs, as these can cause
+  // content scripts to run.
+  if (mHasCheckedForXMLHttpRequest && !mForXMLHttpRequest) {
+    return false;
+  }
+
+  mMutex.AssertCurrentThreadOwns();
+  nsCOMPtr<nsIChannel> channel(do_QueryInterface(mOwner));
+  if (!channel) {
+    return false;
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+  // Figure out if this is for an XHR, if we haven't done so already.
+  if (!mHasCheckedForXMLHttpRequest) {
+    nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
+    mForXMLHttpRequest =
+        (contentType == nsIContentPolicy::TYPE_INTERNAL_XMLHTTPREQUEST);
+    mHasCheckedForXMLHttpRequest = true;
+
+    if (!mForXMLHttpRequest) {
+      return false;
+    }
+  }
+
+  // Suspend the queue if the associated document has suppressed event handling,
+  // *and* it is not in the middle of a synchronous operation that might require
+  // XHR events to be processed (such as a synchronous XHR).
+  RefPtr<dom::Document> document;
+  loadInfo->GetLoadingDocument(getter_AddRefs(document));
+  if (document && document->EventHandlingSuppressed() &&
+      !document->IsInSyncOperation()) {
+    document->AddSuspendedChannelEventQueue(this);
+    SuspendInternal();
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace net
+}  // namespace mozilla