Bug 598076 - Create EventQueue class to allow multiple necko protocols to reuse IPDL queueing code. r=jduell a=blocking-fennec
authorJosh Matthews <josh@joshmatthews.net>
Mon, 20 Sep 2010 14:37:09 -0400
changeset 55159 f93c9ecd5f28887fc5ac20f9c74c16960e166521
parent 55158 6969aecdf5319beeee6b169e250d5d0da5bb2ece
child 55160 651854be26ecd5ddd3927f29d0716efeb7af95bc
push idunknown
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reviewersjduell, blocking-fennec
bugs598076
milestone2.0b8pre
Bug 598076 - Create EventQueue class to allow multiple necko protocols to reuse IPDL queueing code. r=jduell a=blocking-fennec
netwerk/ipc/ChannelEventQueue.h
netwerk/ipc/Makefile.in
new file mode 100644
--- /dev/null
+++ b/netwerk/ipc/ChannelEventQueue.h
@@ -0,0 +1,139 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at:
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Mozilla Code.
+ *
+ * The Initial Developer of the Original Code is
+ *   The Mozilla Foundation
+ * Portions created by the Initial Developer are Copyright (C) 2010
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Josh Matthews <josh@joshmatthews.net> (initial developer)
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef mozilla_net_ChannelEventQueue_h
+#define mozilla_net_ChannelEventQueue_h
+
+namespace mozilla {
+namespace net {
+
+class ChannelEvent
+{
+ public:
+  ChannelEvent() { MOZ_COUNT_CTOR(ChannelEvent); }
+  virtual ~ChannelEvent() { MOZ_COUNT_DTOR(ChannelEvent); }
+  virtual void Run() = 0;
+};
+
+// Workaround for Necko re-entrancy dangers. We buffer IPDL messages in a
+// queue if still dispatching previous one(s) to listeners/observers.
+// Otherwise synchronous XMLHttpRequests and/or other code that spins the
+// event loop (ex: IPDL rpc) could cause listener->OnDataAvailable (for
+// instance) to be called before mListener->OnStartRequest has completed.
+
+class ChannelEventQueue
+{
+ public:
+  ChannelEventQueue() : mQueuePhase(PHASE_UNQUEUED) {}
+  ~ChannelEventQueue() {}
+  
+ protected:
+  void BeginEventQueueing();
+  void EndEventQueueing();
+  void EnqueueEvent(ChannelEvent* callback);
+  bool ShouldEnqueue();
+
+  // Consumers must implement their own flushing routine, as there are too many
+  // implementation-specific details to generalize easily.
+  virtual void FlushEventQueue() = 0;
+
+  nsTArray<nsAutoPtr<ChannelEvent> > mEventQueue;
+  enum {
+    PHASE_UNQUEUED,
+    PHASE_QUEUEING,
+    PHASE_FINISHED_QUEUEING,
+    PHASE_FLUSHING
+  } mQueuePhase;
+
+  friend class AutoEventEnqueuer;
+};
+
+inline void
+ChannelEventQueue::BeginEventQueueing()
+{
+  if (mQueuePhase != PHASE_UNQUEUED)
+    return;
+  // Store incoming IPDL messages for later.
+  mQueuePhase = PHASE_QUEUEING;
+}
+
+inline void
+ChannelEventQueue::EndEventQueueing()
+{
+  if (mQueuePhase != PHASE_QUEUEING)
+    return;
+
+  mQueuePhase = PHASE_FINISHED_QUEUEING;
+}
+
+inline bool
+ChannelEventQueue::ShouldEnqueue()
+{
+  return mQueuePhase != PHASE_UNQUEUED;
+}
+
+inline void
+ChannelEventQueue::EnqueueEvent(ChannelEvent* callback)
+{
+  mEventQueue.AppendElement(callback);
+}
+
+// Ensures any incoming IPDL msgs are queued during its lifetime, and flushes
+// the queue when it goes out of scope.
+class AutoEventEnqueuer 
+{
+ public:
+  AutoEventEnqueuer(ChannelEventQueue* queue) : mEventQueue(queue) 
+  {
+    mEventQueue->BeginEventQueueing();
+  }
+  ~AutoEventEnqueuer() 
+  { 
+    mEventQueue->EndEventQueueing();
+    mEventQueue->FlushEventQueue(); 
+  }
+ private:
+  ChannelEventQueue *mEventQueue;
+};
+
+}
+}
+
+#endif
--- a/netwerk/ipc/Makefile.in
+++ b/netwerk/ipc/Makefile.in
@@ -50,16 +50,17 @@ EXPORT_LIBRARY = 1
 
 EXPORTS_NAMESPACES = mozilla/net
 
 EXPORTS_mozilla/net = \
   NeckoParent.h       \
   NeckoChild.h        \
   NeckoCommon.h       \
   NeckoMessageUtils.h \
+  ChannelEventQueue.h \
   $(NULL)
 
 CPPSRCS =               \
   NeckoChild.cpp        \
   NeckoParent.cpp       \
   $(NULL)
 
 LOCAL_INCLUDES +=                  \